IODP-ICDP Kolloquium 2008 in Hannover. Abstractband
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<strong>IODP</strong>-<strong>ICDP</strong><br />

<strong>Kolloquium</strong> <strong>2008</strong><br />

<strong>in</strong> <strong>Hannover</strong><br />

12. - 14. März <strong>2008</strong>

Umschlagphoto: Dünnschliff-Photographie e<strong>in</strong>es Troktoliths vom mittelatlantischen Rücken 1193,2 m<br />

unter dem Meeresboden, erbohrt durch <strong>IODP</strong> Expedition 305.<br />

(Fotos: <strong>IODP</strong> und <strong>ICDP</strong>)

Tagungsort: Leibniz – Universität <strong>Hannover</strong>, Welfengarten 1<br />

Mensa<br />

Tagungsort<br />

U-Bahn<br />

Toiletten (0. Stock)<br />

Institut für M<strong>in</strong>eralogie<br />

Imbiss (0. Stock)<br />

Bankomat<br />

Alex<br />

E 001 Audimax<br />

Lichthof: Poster + Kaffee C 109: Tagungsbüro

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Programm<br />

Mittwoch, 12. März <strong>2008</strong><br />

10:00 12:00 Registrierung<br />

12:00 13:00 Eröffnung<br />

Prof. Dr.-Ing. Erich Barke, Präsident der Leibniz Universität <strong>Hannover</strong><br />

Prof. Dr. Hans-Joachim Kümpel, Präsident der BGR<br />

Dr. Sören Dürr, DFG Programmdirektor<br />

Koord<strong>in</strong>atoren - Gastgeber<br />

Berichte / Entwicklungen<br />

13:00 13:10 A. Kopf, NanTroSEIZE Project Management Team, <strong>IODP</strong> Expedition 314 Scientific Party<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition 314 (NanTroSEIZE Logg<strong>in</strong>g-While-<br />

Drill<strong>in</strong>g Transect)<br />

13:10 13:20 J. Behrmann, B. Böckel, A. Kopf, F. Schmidt-Schierhorn, <strong>IODP</strong> Expedition 315 Science<br />

Party<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition 315 (NanTroSEIZE Megasplay Riser<br />

Pilot)<br />

13:20 13:30 M. Strasser, N. Ried<strong>in</strong>ger, Y. Kitamura & Expedition 316 Scientists<br />

<strong>IODP</strong> NanTroSEIZE Expedition 316 (Shallow Mega Splay and frontal thrust) – <strong>in</strong>itial<br />

results<br />

13:30 13:40 G. Wefer<br />

Bericht über SASEC-Sitzung 15.-16. Januar <strong>2008</strong><br />

13:40 13:50 S. W<strong>in</strong>kler-Nees<br />

ECORD und die Deep-Sea Frontier Initiative<br />

Seismogene Zone / Impaktstrukturen<br />

13:50 14:10 O. Ritter, M. Becken, U. Weckmann, P.A. Bedrosian, T. Ryberg, C. Haberland<br />

The electrical conductivity structure between the transitional (near SAFOD) and<br />

locked (SE of Cholame) segments of the San Andreas Fault, <strong>in</strong>clud<strong>in</strong>g the source<br />

region of the non-volcanic tremors<br />

14:10 14:30 A.M. Schleicher, L.N. Warr, B.A. van der Pluijm<br />

Mixed-layered clay m<strong>in</strong>erals and their geological significance <strong>in</strong> the San Andreas<br />

Fault Observatory at depth drillhole (SAFOD) <strong>in</strong> Parkfield, California<br />

14:30 14:50 T. Wiersberg & J. Erz<strong>in</strong>ger<br />

Characterization of gas from seismogenic depths of the San Andreas Fault at SAFOD<br />

14:50 17:15 Posterpräsentation der Themen: Berichte und Entwicklungen, Seismogene Zone,<br />

Impaktstrukturen, Gashydrate, Gase, Fluide,<br />

Kaffeepause<br />

Gashydrate / Gase / Fluide<br />

17:15 17:35 K. Bräuer, H. Kämpf, K. Hahne, G. Strauch<br />

The different degass<strong>in</strong>g behaviour of upper mantle-derived fluids <strong>in</strong> the western Eger<br />

rift area – a detailed characterization of a hidden presently active magmatic process<br />

17:35 17:55 M. Marquardt, T. Henke, R. Gehrmann, C. Hensen, C. Müller, K. Wallmann<br />

A simplified transfer function to estimate 2D mar<strong>in</strong>e gas hydrate <strong>in</strong>ventories<br />

ab 19:00 Icebreaker im ALEX <strong>Hannover</strong>, Am Klagesmarkt 38<br />

1

2<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Programm<br />

Donnerstag, 13. März <strong>2008</strong><br />

Tiefe Biosphäre<br />

09:00 09:20 A. Blazejak & A. Schippers<br />

Novel real-time PCR assays for the quantification of genes from Bacteria of the deep<br />

biosphere<br />

09:20 09:40 V. Heuer, J. Pohlman, M. Torres, M. Elvert, K.-U. H<strong>in</strong>richs<br />

Biogeochemistry of acetate <strong>in</strong> the deep mar<strong>in</strong>e biosphere – new <strong>in</strong>sights from stable<br />

carbon isotopic <strong>in</strong>vestigations<br />

Magmatische Petrologie / Metamorphismus<br />

09:40 10:00 J.C. Grimmer, X. Qi, Z. Xu<br />

Magnetofabrics of eclogites and ultramafic rocks from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental<br />

Scientific Drill<strong>in</strong>g (CCSD) project: evidence for ultrahigh-pressure (UHP) texture<br />

<strong>in</strong>heritance throughout retrogression<br />

10:00 11:00 Posterpräsentation der Themen: Tiefe Biosphäre, Magmatische Petrologie,<br />

Metamorphismus<br />

Kaffeepause<br />

11:00 11:20 B. Cordonnier, K.U. Hess, Y. Lavallée, D.B. D<strong>in</strong>gwell<br />

From a fluid like to a brittle behavior: Shear th<strong>in</strong>n<strong>in</strong>g effect of crystals on Mt Unzen<br />

rheology<br />

11:20 11:40 A. Kontny & B. Oliva Urcia<br />

Effects on magnetization <strong>in</strong> basalts from fluid-rock <strong>in</strong>teractions <strong>in</strong> volcanic<br />

geothermal systems<br />

11:40 12:00 S. Luetke, A. Deutsch, F. Langenhorst, R. Skala<br />

Formation and characteristics of impact glasses - the Lake Bosumtwi and Chesapeake<br />

cases<br />

12:00 12:20 A. Riemann & R. Oberhänsli<br />

Retrograde zircons <strong>in</strong> fluid zones<br />

12:20 14:00 Mittagspause<br />

Paläozeanographie / Paläoklima<br />

14:00 14:20 H. Strauss, M. Reuschel, V. Melezhik<br />

FAR-DEEP: Successful completion of the first phase<br />

14:20 14:40 S. Weyer, C. Montoya-P<strong>in</strong>o, J. Pross, W. Oschmann<br />

Mo- and U-isotope variations <strong>in</strong> black shales: Potential tracers for the quantification<br />

of oceanic anoxia<br />

14:40 15:00 C. März, S.W. Poulton, B. Beckmann, K. Küster, T. Wagner, S. Kasten<br />

Redox sensitivity of P and Fe cycl<strong>in</strong>g dur<strong>in</strong>g Late Cretaceous black shale formation<br />

15:00 17:00 Posterpräsentation der Themen: Paläozeanographie, Paläoklima<br />

Kaffeepause<br />

17:00 17:20 J. Etourneau, R. Schneider, P. Mart<strong>in</strong>ez, T. Blanz<br />

Nitrogen fixation dur<strong>in</strong>g Pliocene cool<strong>in</strong>g with<strong>in</strong> the Benguela Upwell<strong>in</strong>g System and<br />

the Eastern Equatorial Pacific, ODP Sites 1082 and 1239<br />

17:20 17:40 N. Khelifi, M. Sarnthe<strong>in</strong>, M. Frank, M. We<strong>in</strong>elt, N. Andersen, D. Garbe-Schönberg<br />

Pliocene Changes <strong>in</strong> the Composition of Mediterranean Outflow Water at DSDP Site<br />

548 and ODP Site 978<br />

17:40 18:00 M. Frank, B.A. Haley, R.F. Spielhagen, A. Eisenhauer, J. Backman, K. Moran<br />

Arctic Ocean circulation and weather<strong>in</strong>g <strong>in</strong>puts over the past 15 million years<br />

18:00 19:30 Pause mit belegten Brötchen<br />

19:30 21:00 Öffentlicher Abendvortrag:<br />

"Science meets Fiction"<br />

Frank Schätz<strong>in</strong>g & Prof. Dr. Gerhard Bohrmann<br />

Audimax der Leibniz Universität <strong>Hannover</strong>

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Programm<br />

Freitag, 14. März <strong>2008</strong><br />

Neue Projekte / Projektvorschläge<br />

08:30 08:50 T. Wilke, C. Albrecht, B. Wagner, S. Krastel, K. Reicherter, G. Daut, M. Wessels<br />

Molecular clock approaches: bridg<strong>in</strong>g the gap between cont<strong>in</strong>ental deep drill<strong>in</strong>g and<br />

evolutionary biology <strong>in</strong> ancient Lake Ohrid<br />

08:50 09:10 W. Bach, A. Schippers<br />

Microbiology of a Sediment Pond and the Underly<strong>in</strong>g Young, Cold, Hydrologically<br />

Active Ridge Flank (<strong>IODP</strong> Proposal 677)<br />

Paläozeanographie / Paläoklima<br />

09:10 09:30 M. Wille<br />

Aerial extent of palaeoenvironmental reconstructions <strong>in</strong> southern Patagonia<br />

09:30 09:50 B. Zolitschka, F.S. Anselmetti, D. Ariztegui, H. Corbella, T. Haberzettl, A. Lücke, C.<br />

Mayr, C. Ohlendorf, F. Schäbitz, M. Wille<br />

Climate and environmental variability dur<strong>in</strong>g the past 56 ka at Laguna Potrok Aike<br />

(southern Patagonia, Argent<strong>in</strong>a), the site of the <strong>ICDP</strong> lake drill<strong>in</strong>g project<br />

“PASADO”<br />

09:50 10:10 O. Juschus, M. Melles and Lake El´gygytgyn Scientific Party<br />

The warm stages with<strong>in</strong> the 340 ka sediment record of Lake El´gygytgyn/NE Siberia–<br />

a comparison<br />

10:10 11:30 Posterpräsentation der Themen: Neue Projekte, Projektvorschläge, Paläozeanographie,<br />

Paläoklima<br />

Kaffeepause<br />

11:30 11:50 T. Felis, R. Asami, E. Bard, S.Y. Cahyar<strong>in</strong>i, P. Deschamps, N. Durand, E. Hathorne, M.<br />

Köll<strong>in</strong>g, M. Pfeiffer<br />

Pronounced <strong>in</strong>terannual variability <strong>in</strong> South Pacific temperatures 15.0 kyr ago –<br />

Coral-based results from <strong>IODP</strong> Expedition 310<br />

11:50 12:10 Y. Fu, T. von Dobeneck, Ch. Franke, D. Heslop, S. Kasten<br />

Rock magnetic identification and geochemical process models of greigite formation <strong>in</strong><br />

Quaternary mar<strong>in</strong>e sediments from the Gulf of Mexico (<strong>IODP</strong> Hole U1319A)<br />

12:10 13:00 Posterprämierung und Schlussworte<br />

13:00 Tagungsende<br />

3

4<br />

Teilnehmerliste<br />

Name Vorname Institution und Ort<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Teilnehmer<br />

Abratis Michael Institut für Geowissenschaften, Universität Jena<br />

Almeev Renat Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Anders Erik Technische Universität Berl<strong>in</strong><br />

Bach Wolfgang Universität Bremen<br />

Bahr André IFM-GEOMAR, Kiel<br />

Beckmann Britta Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Beermann Oliver Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Behrens Harald Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Behrmann Jan IFM-GEOMAR, Kiel<br />

Berthold Susann DGFZ Dresdner Grundwasserforschungszentrum e.V.<br />

Betzler Christian Geologisch-Paläontologisches Institut, Hamburg<br />

Bickert Torsten MARUM, Bremen<br />

Blanchet Cecile Universität Bremen<br />

Blazejak Anna Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Bleil Ulrich Fachbereich Geowissenschaften, Universität Bremen<br />

Blum Norbert Forschungszentrum Jülich, Projektträger Jülich (PTJ-MGS), Rostock-Warnemünde<br />

Bock Barbara Universität Potsdam<br />

Boeckel Babette FB 5 Geowissenschaften, Universität Bremen<br />

Böhm Florian IFM-GEOMAR, Kiel<br />

Bönnemann Christian GGA-Institut, <strong>Hannover</strong><br />

Bohrmann Gerhard Universität Bremen<br />

Bornemann André Institut für Geophysik und Gelogie, Universität Leipzig<br />

Bosch Frank Applied Geophysics and Geothermal Energy, E.ON Energy Research Center, RWTH Aachen University<br />

Botcharnikov Roman Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Boucse<strong>in</strong> Bett<strong>in</strong>a Alfred-Wegener-Institut für Polar und Meeresforschung, Forschungsstelle Potsdam<br />

Bräuer Kar<strong>in</strong> Helmholtz-Zentrum für Umweltforschung - UFZ, Halle<br />

Breitzke Monika Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven<br />

Brey Gerhard JWG Universität, Geowissenschaften, Inst. für M<strong>in</strong>eralogie, Frankfurt<br />

Brückmann Warner Leibniz Institut für Meereswissenschaften, IFM-GEOMAR, Kiel<br />

Buske Stefan FU Berl<strong>in</strong><br />

Christl Marcus ETH-Zürich<br />

Cichy Sarah B. Institut fuer M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Conze Ronald GFZ Potsdam<br />

Cordonnier Benoît Earth and Environmental Sciences, LMU München<br />

Cypionka Heribert ICBM Oldenburg<br />

De Schepper Stijn Universität Bremen, Fachbereich Geowissenschaften<br />

Dehghani Ali Institut für Geophysik, Universität Hamburg<br />

Dersch-Hansmann Michaela Hessisches Landesamt für Umwelt und Geologie, Wiesbaden<br />

Desbois Guillaume Geologie - Endogene Dynamik, RWTH, Aachen University<br />

Diester-Haass Liselotte Universität des Saarlandes, Saarbrücken<br />

D<strong>in</strong>gwell Donald B. Earth and Environmental Sciences, LMU München<br />

Dobeneck, von Tilo Fachbereich Geowissenschaften, Universität Bremen<br />

Doose Heidi Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Drath Gabriela Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Duggen Svend IFM-GEOMAR, Leibniz-Institut für Meereswissenschaften, Kiel<br />

Dullo Wolf-Christian IFM-GEOMAR, Kiel<br />

Dultz Stefan Institut für Bodenkunde, Leibniz Universität <strong>Hannover</strong><br />

Dümmong Stefan Institute for Geophysics, University of Hamburg<br />

Dupont Lydie Marum, Universität Bremen<br />

Dürbaum H. Isernhagen<br />

Dürr Sören DFG, Bonn<br />

Dziony Wanja Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Eckhardt Jörg-Detlef Geologisches Institut, Universität Karlsruhe<br />

Eisenhauer Anton IFM-GEOMAR, Kiel<br />

Emeis Kay-Christian IfBM, Hamburg<br />

Engelen Bert ICBM Oldenburg<br />

Erbacher Jochen Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Etourneau Johan Christian-ALbrecht-Universität zu Kiel<br />

Fabian Marcus Universität Bremen<br />

Fehr Annick Applied Geophysics and Geothermal Energy, E.ON Energy Research Center, RWTH Aachen University<br />

Felis Thomas DFG-Forschungszentrum Ozeanränder, Universität Bremen<br />

Fenner Juliane M. Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Flechsig Christ<strong>in</strong>a Universität Leipzig, Institut für Geophysik und Geologie<br />

Forster Astrid L<strong>in</strong>gen (vormalig Royal Netherlands Institute for Sea Research, NIOZ, Niederlande)<br />

Frank Mart<strong>in</strong> IFM-GEOMAR, Kiel<br />

Fretzdorff Susanne Projektträger Jülich, FZ Jülich, Aussenstelle Warnemünde<br />

Friedrich Oliver National Oceanography Centre Southampton<br />

Gajewski Dirk Universität Hamburg, Institut für Geophysik<br />

Gebhardt Catal<strong>in</strong>a AWI Bremerhaven<br />

Gerdes Axel Institut für Geowissenschaften, FE M<strong>in</strong>eralogie, Frankfurt<br />

Geyh Mebus Universität Marburg<br />

Grimmer Jens C. Universität Karlsruhe (TH)<br />

Groeneveld Jeroen Research Center Ocean Marg<strong>in</strong>s, Universität Bremen<br />

Grützner Jens MARUM, Universität Bremen<br />

Gussone Nikolaus Institut für M<strong>in</strong>eralogie, Universität Münster<br />

Gutjahr St<strong>in</strong>e Freie Universität Berl<strong>in</strong><br />

Hanisch Sab<strong>in</strong>e Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven<br />

Harjes Hans-Peter Ruhr-Universität Bochum<br />

Harms Ulrich GFZ Potsdam<br />

Hathorne Ed DFG-Research Center Ocean Marg<strong>in</strong>s, Bremen<br />

Hecht Lutz Museum für Naturkunde, HU Berl<strong>in</strong><br />

Hefter Jens Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven<br />

Heid<strong>in</strong>ger Philipp Geophysikalisches Institut der Universität Karlsruhe

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Teilnehmer 5<br />

Henke Thomas Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Henrich Rüdiger Fachgebiet Sedimentologie/Paläozeanographie, Universität Bremen<br />

Hepp Daniel A. Universität Bremen<br />

Herfurth Robert Technische Universität Berl<strong>in</strong><br />

Hess Kaï-Uwe Earth and Environmental Sciences, LMU München<br />

Hesse Re<strong>in</strong>hard Ludwig Maximilians Universitaet München<br />

Heßler Ines Marum-Universität Bremen<br />

Heuer Verena RCOM & Fachbereich Geowisseschaften, Universität Bremen<br />

H<strong>in</strong>richs Kai-Uwe Universität Bremen, Fachbereich Geowissenschaften<br />

Hofmann Peter Universität zu Köln<br />

Holbourn Ann Institute of Geosciences, Christian-Albrechts-University, Kiel<br />

Holtz Francois Institut für M<strong>in</strong>eralogie, Universität <strong>Hannover</strong><br />

Huepers Andre DFG-Research Center Ocean Marg<strong>in</strong>s, University of Bremen<br />

Hunze Sab<strong>in</strong>e GGA-Institut <strong>Hannover</strong><br />

Jöns Niels Fachbereich Geowissenschaften, Universität Bremen<br />

Juschus Olaf Universität zu Köln, Institut für Geologie und M<strong>in</strong>eralogie<br />

Kämpf Horst GeoForschungsZentrum Potsdam<br />

Karas Cyrus IFM-GEOMAR, Kiel<br />

Kasten Sab<strong>in</strong>e Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven<br />

Kastner Stephanie AG Geopolar, Institut für Geographie, Universität Bremen<br />

Khelifi Nabil IfG - Kiel University<br />

Kitamura Yuj<strong>in</strong> IFM GEOMAR, Kiel<br />

Kle<strong>in</strong> Torsten Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig<br />

Kle<strong>in</strong> Björn Institut für Chemie und Biologie des Meeres (ICBM), Oldenburg<br />

Koepke Jürgen Universität <strong>Hannover</strong><br />

Kontny Agnes Geologisches Institut, Universität Karlsruhe<br />

Kopf Achim RCOM - Universität Bremen<br />

Köweker Gerrit Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Krastel Sebastian Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Kiel<br />

Krüger Mart<strong>in</strong> Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Kück Jochem GFZ Potsdam<br />

Kudraß Hermann-Rudolf Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Kuhnert Henn<strong>in</strong>g Universität Bremen<br />

Kuhnt Wolfgang Institute of Geosciences, Christian-Albrechts-University, Kiel<br />

Kümpel Hans-Joachim Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Kunze Sab<strong>in</strong>e Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Kuschel Lars Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

Lamy Frank AWI-Bremerhaven<br />

Landwehrkamp Lucas MPI Bremen<br />

Langenhorst Falko Bayerisches Geo<strong>in</strong>stitut, Bayreuth<br />

Lazarus David Museum für Naturkunde, Berl<strong>in</strong><br />

Leuschner Dirk C. Institut für Geophysik und Geologie, Leipzig<br />

Leythaeuser Detlev Institut für Geologie und M<strong>in</strong>eralogie,Universität Köln (i.R.)<br />

Lipp Julius Universität Bremen/RCOM MARUM<br />

Lippmann-Pipke Johanna Institut für Interdiszipl<strong>in</strong>äre Isotopenforschung (IIF) e.V. Leipzig<br />

Lippold Joerg Heidelberger Akademie der Wissenschaften<br />

Litt Thomas Universität Bonn, Paläontologie<br />

Lückge Andreas Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Lüniger Guido DFG, Bonn<br />

Luetke Sab<strong>in</strong>e Universität Münster<br />

Mangelsdorf Kai GeoForschungsZentrum (GFZ) Potsdam<br />

Markl Gregor Universität Tüb<strong>in</strong>gen<br />

Maronde Dietrich Bonn<br />

Marquardt Mathias IFM-GEOMAR, Kiel<br />

März Christian ICBM, Universität Oldenburg<br />

Matthiessen Jens Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, Bremerhaven<br />

Mayr Sibylle Technische Universität Berl<strong>in</strong>, Sekr. ACK2, Angew. Geophysik<br />

Meschede Mart<strong>in</strong> Institut für Geographie und Geologie Univ. Greifswald<br />

Möbius Jürgen Universität Hamburg, IfBM<br />

Mohr Barbara Museum für Naturkunde, Berl<strong>in</strong><br />

Montoya-P<strong>in</strong>o Stefan Universität Frankfurt, Institut für Geowissenschaften<br />

Müller Wolfgang F. Geomaterialwissenschaft, Fachbereich 11, TU Darmstadt<br />

Naafs David Alfred-Wegener-Institut for Polar and Mar<strong>in</strong>e Research, Bremerhaven<br />

Neben Sönke Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Niedermann Samuel GeoForschungsZentrum Potsdam<br />

Nowak Marcus Institut für Geowissenschaften - Universität Tüb<strong>in</strong>gen<br />

Numberger Lea Universität Tüb<strong>in</strong>gen, Mikropaläontologie<br />

Nürnberg Dirk IFM-GEOMAR, Kiel<br />

Oberhänsli Roland Institut für Geowissenschaften, Potsdam<br />

Ohlendorf Christian Geopolar, Universität Bremen<br />

Oliva Urcia Bélen Geologisches Institut, Universität Karlsruhe<br />

Pfeiffer Miriam Institut für Geologie und M<strong>in</strong>eralogie, Universität zu Köln<br />

Polster André Universität Bremen, FB 5, Meerestechnik/Sensorik<br />

Preiß-Daimler Inga Universität Bremen<br />

Prevedel Bernhard GFZ Potsdam<br />

Rausch Svenja Universität Bremen<br />

Reischmann Thomas Universität Ma<strong>in</strong>z<br />

Rettenmaier Detlev Universität Karlsruhe; Geologisches Institut; Abteilung Hydrogeologie<br />

Ried<strong>in</strong>ger Natascha MPI Bremen<br />

Riemann Astrid Universität Potsdam<br />

Ritter Oliver GeoForschungsZentrum, Potsdam<br />

Röhl Ursula MARUM - Zentrum für Mar<strong>in</strong>e Umweltwissenschaften, Bremen<br />

Rosner Mart<strong>in</strong> Bundesanstalt für Materialforschung und -prüfung Bioanalytik, Berl<strong>in</strong><br />

Roters Bastian Research Center Ocean Marg<strong>in</strong> - Universität Bremen<br />

Sanders Diethard Institute of Geology and Palaeontology, University of Innsbruck<br />

Sarnthe<strong>in</strong> Michael Institut für Geowissenschaften, Universität Kiel

6<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Teilnehmer<br />

Saukel Cornelia Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven<br />

Schippers Axel Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Schleicher Anja Universität Erlangen-Nürnberg<br />

Schm<strong>in</strong>cke Hans-Ulrich Leibniz-Institute of Mar<strong>in</strong>escience, IFM-GEOMAR, Kiel<br />

Schramm Andreas University of Aarhus, Dept. Biological Sciences, Microbiology<br />

Schreck Michael Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research (AWI), Bremerhaven<br />

Schulte Peter Institut für Geologie-M<strong>in</strong>eralogie, Universität Erlangen<br />

Schulz Hartmut Institut für Geowissenschaften, Tüb<strong>in</strong>gen<br />

Schulz Michael Universität Bremen, MARUM<br />

Schütze Claudia Universität Leipzig, Institut für Geophysik und Geologie<br />

Schwalb Antje Institut für Umweltgeologie, Braunschweig<br />

Schwamborn Georg Alfred-Wegener-Institut für Polar- und Meeresforschung, Potsdam<br />

Schwarz W<strong>in</strong>fried Universität Heidelberg - M<strong>in</strong>eralogisches Institut<br />

Schwarz-Schampera Ulrich Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Simonyan Anna Universität <strong>Hannover</strong>, Institut für Bodenkunde<br />

Smolka Peter P. Universität Münster<br />

Stegmann Sylvia RCOM / Universität Bremen<br />

Ste<strong>in</strong> Rüdiger Alfred-Wegener-Institut, Bremerhaven<br />

Ste<strong>in</strong>ke Stephan DFG-Forschungszentrum Ozeanränder der Universität Bremen<br />

Stell<strong>in</strong>g Jan Universität <strong>Hannover</strong>, Institut für M<strong>in</strong>eralogie<br />

Stipp Michael Leibniz-Institut für Meereswissenschaften IFM-GEOMAR, Kiel<br />

Stosch He<strong>in</strong>z-Günter Universität Karlsruhe<br />

Strack Dieter International Oil & Gas Consultant, Rat<strong>in</strong>gen<br />

Strasser Michael Universität Bremen MARUM<br />

Strauch Gerhard Helmholtzzentrum für Umweltforschung UFZ Leipzig-Halle<br />

Strauss Harald Geologisch-Paläontologisches Institut, WWU Münster<br />

Stroncik Nicole A. GeoForschungsZentrum Potsdam<br />

Sturm Arne AWI, Bremerhaven<br />

Sumita Mari Leibniz-Institute of Mar<strong>in</strong>escience, IFM-GEOMAR, Kiel<br />

Teichert Barbara Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), <strong>Hannover</strong><br />

Titschack Jürgen GeoZentrum Nordbayern, Erlangen<br />

Tougiannidis Nikolaos Institut für Geologie und M<strong>in</strong>eralogie der Universität zu Köln<br />

Trampe Anna F. Universität Bremen<br />

Uenzelmann-Neben Gabriele Alfred-Wegener-Institut, Bremerhaven<br />

Viereck-Götte Lothar Friedrich-Schiller-Universität Jena<br />

Vill<strong>in</strong>ger He<strong>in</strong>rich FB Geowissenschaften Universität Bremen<br />

Virgil Christopher Institut für Geophysik und Extraterrestrische Physik, TU-Braunschweig<br />

Vogt Christoph Kristallographie, Geowissenschaften, Universität Bremen<br />

Wagner Dirk Alfred-Wegener-Institut für Polar- und Meeresforschung, Potsdam<br />

Wagner Thomas Newcastle University<br />

Wallrabe-Adams Hans-Joachim Marum - Zentrum für Mar<strong>in</strong>e Umweltwissenschaften, Universität Bremen<br />

Weber Michael E. Institute of Geology and M<strong>in</strong>eralogy, Köln<br />

Wefer Gerold MARUM Zentrum für Mar<strong>in</strong>e Umweltwissenschaften, Bremen<br />

Weigelt Estella Alfred Wegener Institut, Bremerhaven<br />

Weller Petra Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, Bremerhaven<br />

Westerhold Thomas MARUM, Zentrum für Mar<strong>in</strong>e Umweltwissenschaften, Universität Bremen<br />

Weyer Stefan Universität Frankfurt, Institut für Geowissenschaften<br />

Wiersberg Thomas GeoForschungsZentrum Potsdam<br />

Wilhelm Helmut Geophysikalisches Institut der Universität Karlsruhe<br />

Wilke Thomas Justus-Liebig-Universität Giessen<br />

Wille Michael Universität zu Köln<br />

W<strong>in</strong>kler-Nees Stefan Deutsche Forschungsgeme<strong>in</strong>schaft, Bonn<br />

Wipf Mart<strong>in</strong> Geologisch und Paläontologisches Museum, Heidelberg<br />

Wohlgemuth Lothar GFZ Potsdam<br />

Wöhrl Thomas GFZ Potsdam<br />

Ziegelmüller Katja ICBM Oldenburg<br />

Zimmermann Katja DFG-Research Center Ocean Marg<strong>in</strong>s, Bremen<br />

Zolitschka Bernd GEOPOLAR, Institut für Geographie, Universität Bremen

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Abstractliste 7<br />

Autor Titel SPP Seite<br />

Almeev, R., Kuschel, L., Holtz, F.,<br />

Cathey, H., Nash, B., Koepke, J.,<br />

Shervais, J., Christiansen, E.<br />

Crystallization conditions of the basaltic and rhyolitic melts of the<br />

Snake River Pla<strong>in</strong> - Yellowstone hotspot track: First experimental<br />

results and implications (Project Ho 1337/17)<br />

Anders, E., Müller, W.H. Compact Multipurpose Sub-Sampl<strong>in</strong>g and Process<strong>in</strong>g of In-Situ<br />

Cores (COMPOSE)<br />

Bach, W., Kle<strong>in</strong>, F., Hentscher, M.,<br />

Jöns, N.<br />

Beckmann, B., Flögel, S., Hofmann,<br />

P., März, C., Wagner, T.<br />

Behrmann, J., Boeckel, B., Kopf, A.,<br />

Schmidt-Schierhorn, F., <strong>IODP</strong><br />

Expedition 315 scientific party<br />

Hydrogen generation <strong>in</strong> seawater-rock <strong>in</strong>teractions (ODP Leg 209):<br />

Insights from petrography and thermodynamic model<strong>in</strong>g<br />

Land-ocean <strong>in</strong>teraction and oceanic response <strong>in</strong> the Mid-<br />

Cretaceous western tropical Atlantic at ODP Site 1261<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition 315<br />

(NanTroSEIZE Megasplay Riser Pilot)<br />

<strong>ICDP</strong> 19<br />

<strong>IODP</strong> 20<br />

<strong>IODP</strong> 21<br />

<strong>IODP</strong> 22<br />

<strong>IODP</strong> 12<br />

Berthold, S., Börner, F. Identification and analysis of vertical convection <strong>in</strong> boreholes <strong>ICDP</strong> 23<br />

Betzler, C., Hübscher, C., Lüdmann, A new view of the Neogene to Quaternary evolution of the<br />

<strong>IODP</strong> 150<br />

T., Reijmer, J., Droxler, A., L<strong>in</strong>dhorst,<br />

S., Römer, M., M 74/4 Shipboard<br />

Scientific party<br />

Maldives carbonate platform (Indian Ocean)<br />

Bickert, T., Butz<strong>in</strong>, M., Lohmann, G. Indian and Southern Ocean dynamics dur<strong>in</strong>g the Miocene <strong>IODP</strong> 24<br />

Blanchet, C. L., Thouveny, N., Magnetic M<strong>in</strong>eral Inputs <strong>in</strong> Sediments Off Baja California. Inference <strong>IODP</strong> 24<br />

Vidal, L.<br />

on Climate Variability of the Last Glacial-Interglacial Cycle<br />

Blazejak, A., Schippers, A. Novel real-time PCR assays for the quantification of genes from<br />

Bacteria of the deep biosphere<br />

<strong>IODP</strong> 25<br />

Boeckel, B., Baumann, K.-H. Evolutionary trends of selected coccolithophore species <strong>in</strong> the<br />

North Atlantic dur<strong>in</strong>g the Pliocene to Pleistocene<br />

<strong>IODP</strong> 153<br />

Böhm, F., Rausch, S., Eisenhauer, Low Temperature Alteration Carbonates <strong>in</strong> the Ocean Crust and <strong>IODP</strong> 26<br />

A., Bach, W., Klügel, A.<br />

their Importance for CO2 Uptake and the Global Calcium Cycle<br />

Bornemann, A. A prelim<strong>in</strong>ary calcareous plankton biostratigraphy of the<br />

Paleocene-Eocene <strong>in</strong>terval at DSDP Site 401 (Bay of Biscay)<br />

<strong>IODP</strong> 26<br />

Botcharnikov, R.E., Koepke, J., The late-stage evolution of oceanic gabbros – Comb<strong>in</strong>ed<br />

<strong>IODP</strong> 27<br />

Horn, I., Stichnothe, J., Putlitz, B. experimental and <strong>in</strong>-situ isotope study on gabbros of the ODP Legs<br />

118/176 drilled at the Southwest Indian Ridge<br />

Boucse<strong>in</strong>, B., Knies, J., Ste<strong>in</strong>, R. How is black shale formation <strong>in</strong> the Early Eocene Arctic Ocean<br />

<strong>in</strong>fluenced by export of terrestrial organic matter? Details from an<br />

organic petrological approach on mar<strong>in</strong>e sediments from <strong>IODP</strong><br />

Hole 302 (Lomonosov Ridge)<br />

<strong>IODP</strong> 29<br />

Bräuer, K., Kämpf, H., Hahne, K., The different degass<strong>in</strong>g behaviour of upper mantle-derived fluids <strong>in</strong> <strong>ICDP</strong> 32<br />

Strauch, G.<br />

the western Eger rift area - A detailed characterisation of a hidden<br />

presently active magmatic process<br />

Buske, S., Gutjahr, S., Rentsch, S., Active and passive seismic images of the San-Andreas-Fault at <strong>ICDP</strong> 34<br />

Reshetnikov, A., Shapiro, S.<br />

SAFOD<br />

Cichy, S. B., Botcharnikov, R. E., Experimental Constra<strong>in</strong>ts on Magma Ascent at Unzen Volcano, <strong>ICDP</strong> 37<br />

Holtz, F., Behrens, H., Sato, H. Japan<br />

Cordonnier, B., Hess, K. U.,<br />

From a fluid like to a brittle behaviour: Shear th<strong>in</strong>n<strong>in</strong>g effect of <strong>ICDP</strong> 37<br />

Lavallée, Y., D<strong>in</strong>gwell, D. B.<br />

crystals on Mt Unzen rheology<br />

De Schepper, S., Head, M. J., Evidence for rapid on/off switch<strong>in</strong>g of the North Atlantic Current <strong>IODP</strong> 41<br />

Groeneveld, J.<br />

dur<strong>in</strong>g the warm Middle Pliocene<br />

Desbois, G., Urai, J. L. Application of the FIB-Cryo-SEM technology for quantitative study<br />

of fault gouge porosity <strong>in</strong> SAFOD drill core from the San Andreas<br />

Fault zone<br />

<strong>ICDP</strong> 40<br />

Diester-Haass, L., Billups, K.,<br />

Mid-Miocene Paleoproductivity and Implications for the Global <strong>IODP</strong> 41<br />

Groecke, D., Francois, L., Lefebre,<br />

V., Emeis, K.-C.<br />

Carbon Cycle<br />

Duggen, S., Hoernle, K., Hauff, F., Trace element and isotope geochemistry of ~15 Ma oceanic crust <strong>IODP</strong> 43<br />

Geldmacher, J.<br />

formed at a superfast spread<strong>in</strong>g ridge (Exp. 309/312, <strong>IODP</strong> Site<br />

1256D, Eastern Central Pacific): Constra<strong>in</strong>ts on sub-ridge<br />

processes at the East Pacific Rise, the style and tim<strong>in</strong>g of alteration<br />

and the orig<strong>in</strong> of ocean island basalts<br />

Dümmong, S., Meier, K., Beitz, M., Depth migration results from the Eastern Mediterranean /<br />

<strong>IODP</strong> 43<br />

Hübscher, C.<br />

Levant<strong>in</strong>e Bas<strong>in</strong><br />

Dupont, L. M. Holocene vegetation development <strong>in</strong> Angola -Palynology of ODP<br />

Site 1078<br />

<strong>IODP</strong> 45<br />

Dziony, W., Koepke, J., Holtz, F., The down-hole magmatic-metamorphic evolution <strong>in</strong> basalts and <strong>IODP</strong> 46<br />

Horn, I.<br />

gabbros monitored by Fe-Ti oxides: A complete section of<br />

Superfast Spread<strong>in</strong>g Crust at <strong>IODP</strong> Site 1256 (Project Ho 1337/14;<br />

SPP 527)

8<br />

Etourneau, J., Schneider, R.,<br />

Mart<strong>in</strong>ez, P., Blanz, T.<br />

Felis, T., Asami, R., Bard, E.,<br />

Cahyar<strong>in</strong>i, S. Y., Deschamps, P.,<br />

Durand, N., Hathorne, E., Köll<strong>in</strong>g, M.,<br />

Pfeiffer, M.<br />

Flechsig, C., Schütze, C.<br />

Forster, A., Schouten, S., Baas, M.,<br />

S<strong>in</strong>n<strong>in</strong>ghe Damsté, J. S.<br />

Forster, A., Kuypers, M. M. M,<br />

Turgeon, S. C., Brumsack, H.-J.,<br />

Petrizzo, M. R., S<strong>in</strong>n<strong>in</strong>ghe Damsté,<br />

J. S<br />

Frank, M., Haley, B. A., Spielhagen,<br />

R. F., Eisenhauer, A., Backman, J.,<br />

Moran, K.<br />

Friedrich, O., Norris, R. D., Erbacher,<br />

J.<br />

Fu, Y., von Dobeneck, T., Franke,<br />

C., Heslop, D., Kasten, S.<br />

Gajewski, D., Anikiev, D., Tessmer,<br />

E., Vanelle, C., Kashtan, B.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Abstractliste<br />

Nitrogen fixation dur<strong>in</strong>g Pliocene cool<strong>in</strong>g with<strong>in</strong> the Benguela<br />

Upwell<strong>in</strong>g System and the Eastern Equatorial Pacific, ODP Sites<br />

1082 and 1239<br />

Pronounced <strong>in</strong>terannual variability <strong>in</strong> South Pacific temperatures<br />

15.0 kyr ago - Coral-based results from <strong>IODP</strong> Expedition 310<br />

Research study for a geoelectrical pre-site survey of the drill<strong>in</strong>g<br />

location with<strong>in</strong> the Eger Rift - Investigation of the subsurface<br />

electrical conductivity distribution<br />

A paleo sea surface temperature record throughout the Cretaceous<br />

thermal maximum from an Albian-Santonian black shale sequence<br />

<strong>in</strong> the tropical Atlantic<br />

The Cenomanian/Turonian oceanic anoxic event <strong>in</strong> the South<br />

Atlantic: New <strong>in</strong>sights from a geochemical study of DSDP Site<br />

530A<br />

Arctic Ocean circulation and weather<strong>in</strong>g <strong>in</strong>puts over the past 15<br />

million years<br />

<strong>IODP</strong> 48<br />

<strong>IODP</strong> 48<br />

<strong>ICDP</strong> 50<br />

<strong>IODP</strong> 50<br />

<strong>IODP</strong> 51<br />

<strong>IODP</strong> 52<br />

A Cretaceous Benthic Foram<strong>in</strong>iferal Stable Isotope Compilation <strong>IODP</strong> 52<br />

Rock magnetic identification and geochemical process models of<br />

greigite formation <strong>in</strong> Quaternary mar<strong>in</strong>e sediments from the Gulf of<br />

Mexico (<strong>IODP</strong> Hole U1319A)<br />

Lokalisierung <strong>in</strong>duzierter Seismizität ohne Picken - E<strong>in</strong>e<br />

Stapelmethode<br />

<strong>IODP</strong> 147<br />

<strong>ICDP</strong> 53<br />

Gebhardt, A. C. Geometry of maar lake Laguna Potrok Aike, Patagonia <strong>ICDP</strong> 54<br />

Gerdes, A., Liu, F. L., Weyer, S., Chronological history of UHP rocks from the Dabie-Sulu terrane, <strong>ICDP</strong> 54<br />

Brey, G.<br />

Eastern Ch<strong>in</strong>a<br />

Grimmer, J. C., Qi, X., Xu, Z. Magnetofabrics of eclogites and ultramafic rocks from the Ch<strong>in</strong>ese<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g (CCSD) project: Evidence for<br />

ultrahigh-pressure (UHP) texture <strong>in</strong>heritance throughout<br />

retrogression<br />

<strong>ICDP</strong> 58<br />

Grützner, J., Higg<strong>in</strong>s, S. M., Ste<strong>in</strong>, Rapid changes <strong>in</strong> biogenic and siliciclastic sedimentation dur<strong>in</strong>g <strong>IODP</strong> 60<br />

R., Acton, G., Wefer, G.<br />

the last 1 Ma: Results from North Atlantic <strong>IODP</strong> Sites U1313 and<br />

U1314<br />

Hanisch, S., Gebhardt, C., Juschus, From land plants to anoxia - A pilot study of organic biomarkers <strong>ICDP</strong> 62<br />

O., Nowaczyk, N.<br />

gives <strong>in</strong>sight <strong>in</strong>to paleoclimate record of Lake El’gygytgyn<br />

Hathorne, E. C., Felis, T.<br />

Laser ablation ICP-MS as a tool for assess<strong>in</strong>g the preservation of<br />

fossil corals: Examples from deglacial Tahiti corals recovered by<br />

<strong>IODP</strong> Expedition 310<br />

<strong>IODP</strong> 62<br />

Hefter, J., Ste<strong>in</strong>, R., S<strong>in</strong>n<strong>in</strong>ghe The Biomarker Inventory, Trace, and Source of He<strong>in</strong>rich Events <strong>IODP</strong> 63<br />

Damsté, J. S.<br />

and He<strong>in</strong>rich-type Layers (MIS 8-16) <strong>in</strong> the North Atlantic<br />

Heid<strong>in</strong>ger, P., Wilhelm, H., Safanda, Geothermal <strong>in</strong>vestigations from well data of the Chesapeake <strong>ICDP</strong> 63<br />

J., Burkhardt, H., Mayr, S., Popov, Y. Pen<strong>in</strong>sula, USA<br />

Hepp, D. A., Mörz, T. A late Miocene-early Pliocene deepwater record of cyclic iron<br />

reduction events (Antarctic Pen<strong>in</strong>sula Pacific marg<strong>in</strong>, ODP Site<br />

1095)<br />

<strong>IODP</strong> 66<br />

Heuer, V., Pohlman, J., Torres, M., Biogeochemistry of acetate <strong>in</strong> the deep mar<strong>in</strong>e biosphere: New <strong>IODP</strong> 151<br />

Elvert, M., H<strong>in</strong>richs, K.-U.<br />

<strong>in</strong>sights from stable carbon isotopic <strong>in</strong>vestigations<br />

Hofmann, P., Wagner, T.<br />

Geochemical evolution of the Early Aptian Oceanic Anoxic Event<br />

1a <strong>in</strong> the tropical Atlantic, ODP Site 641C Galicia Marg<strong>in</strong>.<br />

<strong>IODP</strong> 66<br />

Holbourn, A., Kuhnt, W., Haley, B., Pacific circulation dur<strong>in</strong>g the middle Miocene climate transition: <strong>IODP</strong> 67<br />

Regenberg, M., Mix, A., Andersen, Monitor<strong>in</strong>g ocean overturn<strong>in</strong>g and the east-west hydrographic<br />

N.<br />

gradient<br />

Huepers, A., Kopf, A. On the role of temperature on the stress state of underthrust<br />

sediments at the Nankai marg<strong>in</strong><br />

<strong>IODP</strong> 70<br />

Jöns, N., Bach, W., Schroeder, T., Ve<strong>in</strong><strong>in</strong>g history of abyssal peridotites from a detachment fault <strong>IODP</strong> 71<br />

Rosner, M.<br />

sett<strong>in</strong>g (ODP Leg 209): From melt impregnations to lowtemperature<br />

alteration<br />

Juschus, O., Melles, M., and the The warm stages with<strong>in</strong> the 340 ka sediment record of Lake <strong>ICDP</strong> 72<br />

Lake El’gygytgyn Scientific Party El’gygytgyn/NE Siberia: A comparison<br />

Karas, C., Nürnberg, D., Gupta, A., The rapid constriction of the Indonesian Gateway across 3.4-3 Ma <strong>IODP</strong> 72<br />

Mohan, K., Tiedemann, R.<br />

as a ma<strong>in</strong> contribut<strong>in</strong>g factor for global climate change<br />

Kastner, S., Ohlendorf, C.,<br />

Lake <strong>in</strong>ternal depositional dynamics as revealed by the areal <strong>ICDP</strong> 73<br />

Haberzettl, T., Lücke, A., Maidana, distribution of surface sediments <strong>in</strong> Laguna Potrok Aike (Southern<br />

N. I., Mayr, C., Schäbitz, F.,<br />

Patagonia, Argent<strong>in</strong>a) - A prelim<strong>in</strong>ary study <strong>in</strong> the framework of the<br />

Zolitschka, B.<br />

<strong>ICDP</strong> project PASADO

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Abstractliste 9<br />

Khelifi, N., Sarnthe<strong>in</strong>, M., Frank, M.,<br />

We<strong>in</strong>elt, M., Andersen, N., Garbe-<br />

Schönberg, D.<br />

Kle<strong>in</strong>, B., Brassell, S. C., Rullkötter,<br />

J.<br />

Pliocene Changes <strong>in</strong> the Composition of Mediterranean Outflow<br />

Water at DSDP Site 548 and ODP Site 978<br />

Kerogen-bound organic matter <strong>in</strong> sediments represent<strong>in</strong>g the<br />

Oceanic Anoxic Event 1a<br />

Kontny, A., Oliva Urcia, B. Effects on magnetization <strong>in</strong> basalts from fluid-rock <strong>in</strong>teractions <strong>in</strong><br />

volcanic geothermal systems<br />

Kopf, A., NanTroSEIZE Project<br />

Management Team, <strong>IODP</strong><br />

Expedition 314 scientific party<br />

Köweker, G., Blazejak, A.,<br />

Schippers, A.<br />

Krastel, S., Wagner, B., Reicherter,<br />

K., Daut, G., Wessels, M., Wilke, T.<br />

Krüsmann, T., Niedermann, S.,<br />

Stroncik, N. A., Erz<strong>in</strong>ger, J.<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition 314<br />

(NanTroSEIZE Logg<strong>in</strong>g-While-Drill<strong>in</strong>g Transect)<br />

Deep Biosphere Quantification <strong>in</strong> Chesapeake Bay Impact<br />

Structure Sediments<br />

Evolutionary, Geological, and Environmental History of Lake Ohrid<br />

(EGEL): A new <strong>ICDP</strong> <strong>in</strong>itiative<br />

Helium, neon and argon isotope systematics of the Hawaiian<br />

hotspot<br />

Kuhnert, H., Bickert, T. Middle Miocene changes <strong>in</strong> the Southern Ocean deep-water<br />

carbonate chemistry<br />

Lazarus, D., Kotrc, B., Wulf, G.,<br />

Schmidt, D. N.<br />

Cenozoic trends <strong>in</strong> size and silica use <strong>in</strong> low and high latitude<br />

radiolarian faunas - evidence for co-evolution between diatoms and<br />

radiolarians, and <strong>in</strong>creas<strong>in</strong>g competition for dissolved biogenic<br />

silicia<br />

<strong>IODP</strong><br />

74<br />

<strong>IODP</strong> 74<br />

<strong>ICDP</strong> 76<br />

<strong>IODP</strong> 12<br />

<strong>ICDP</strong> 79<br />

<strong>ICDP</strong> 79<br />

<strong>ICDP</strong> 80<br />

<strong>IODP</strong> 80<br />

<strong>IODP</strong> 81<br />

Leuschner, D. C. Early Paleogene deep-water overturn<strong>in</strong>g <strong>in</strong> the South Atlantic<br />

(EPASA) – A progress report<br />

<strong>IODP</strong> 81<br />

Lipp, J. S., Morono, Y., Inagaki, F.,<br />

H<strong>in</strong>richs, K.-U.<br />

Distribution of Prokaryotic Biomass <strong>in</strong> the Deep Biosphere <strong>IODP</strong> 85<br />

Lippmann-Pipke, J., Erz<strong>in</strong>ger, J.,<br />

Zimmer, M., Kujawa, C., van<br />

Heerden, E., Bester, A., Moller, H.,<br />

Boettcher, M., Reches, Z.<br />

Lippold, J., Christl, M., Hofmann, A.,<br />

Bernsdorff, F., Lahaye, Y., Grützner,<br />

J., Mollenhauer, G., Mang<strong>in</strong>i, A.<br />

Litt, T., Heumann, G., Schm<strong>in</strong>cke,<br />

H.-U., Sumita, M.<br />

Luetke, S., Deutsch, A.,<br />

Langenhorst, F., Skala, R.<br />

Mangelsdorf, K., di Primio, R.,<br />

Cragg, B., Horsfield, B. and <strong>IODP</strong><br />

Expedition 307 Scientific Party<br />

Marquardt, M., Henke, T.,<br />

Gehrmann, R., Hensen, C., Müller,<br />

C., Wallmann, K.<br />

März, C., Poulton, S. W., Beckmann,<br />

B., Küster, K., Wagner, T., Kasten,<br />

S.<br />

Mayr, S. I., Popov, Y., Burkhardt, H.,<br />

Gorobtsov, D. N., Romushkevich, R.<br />

A., Wilhelm, H., Heid<strong>in</strong>ger, P.<br />

Direct observation of blast<strong>in</strong>g triggered geogas transport through<br />

an <strong>in</strong>active fault system at 3.6km depth, Tautona gold m<strong>in</strong>e, SA<br />

231 Pa/ 230 Th from Atlantic Ocean sediments - a proxy for deep water<br />

circulation over the past 30,000 years<br />

Environmental response to volcanic and climatic events <strong>in</strong> NE<br />

Anatolia dur<strong>in</strong>g the last 20,000 years based on annually lam<strong>in</strong>ated<br />

sediments from Lake Van<br />

Formation and characteristics of impact glasses - the Lake<br />

Bosumtwi and Chesapeake cases<br />

Investigation of microbial <strong>in</strong>dicators at the mound base of<br />

Challenger mound <strong>in</strong> the Belgica carbonate mound prov<strong>in</strong>ce<br />

(Porcup<strong>in</strong>e bas<strong>in</strong>, offshore Ireland)<br />

A simplified transfer function to estimate 2D mar<strong>in</strong>e gas hydrate<br />

<strong>in</strong>ventories<br />

Redox sensitivity of P and Fe cycl<strong>in</strong>g dur<strong>in</strong>g Late Cretaceous black<br />

shale formation<br />

<strong>ICDP</strong> 85<br />

<strong>IODP</strong> 87<br />

<strong>ICDP</strong> 88<br />

<strong>ICDP</strong> 88<br />

<strong>IODP</strong> 92<br />

<strong>IODP</strong> 93<br />

<strong>IODP</strong> 95<br />

Physical Rock Properties of the Chesapeake Bay Impact Structure <strong>ICDP</strong> 95<br />

Meissl, S., Behrmann, J. H. Geotechnical behaviour and magnetic fabrics of rapidly deposited<br />

Quaternary sediments, Ursa Bas<strong>in</strong>, Gulf of Mexico – First results<br />

Mohr, B. A. R. & ANDRILL<br />

Community<br />

Naafs, B. D. A., Hefter, J., Ste<strong>in</strong>, R.,<br />

Haug, G. H.<br />

Numberger, L., Hemleben, C.,<br />

Hoffmann, R., Mackensen, A.,<br />

Schulz, H., Kucera, M.<br />

Ohlendorf, C., Fey, M., Haberzettl,<br />

T., Janssen, S., Lücke, A., Mayr, C.,<br />

Oliva, G., Schäbitz, F., Wille, M.,<br />

Zolitschka, B.<br />

Perez, L., Scharf, B., von Geldern,<br />

R., Steeb, P., Samol, D., Lorenschat,<br />

J., Schwalb, A.<br />

Pfeiffer, M., Cahyar<strong>in</strong>i, S. Y., Dullo,<br />

W.-C., Weber, M., Felis, T., Ricken,<br />

W.<br />

Vegetation and climate development dur<strong>in</strong>g the Cenozoic <strong>in</strong><br />

Antarctica. Future drill<strong>in</strong>g of cont<strong>in</strong>ental marg<strong>in</strong> sections -<br />

ANDRILL, <strong>IODP</strong> and <strong>ICDP</strong>?<br />

Short-term variability of surface-water characteristics <strong>in</strong> the Late<br />

Neogene North Atlantic Ocean: Prelim<strong>in</strong>ary results of a biomarker<br />

record from <strong>IODP</strong> Site U1313<br />

Habitats of Globiger<strong>in</strong>oides ruber (d’Orbigny) <strong>in</strong> the eastern<br />

Mediterranean Sea s<strong>in</strong>ce the Mar<strong>in</strong>e Isotopic Stage 12<br />

Characterization of a pre-Holocene lake level high stand <strong>in</strong> Laguna<br />

Potrok Aike (Argent<strong>in</strong>a): Project POTROK<br />

Modern ostracodes from Lago Petén Itzá and lakes of the<br />

Península Yucatán as <strong>in</strong>dicators of environmental and climate<br />

change<br />

Assess<strong>in</strong>g the accuracy of SST and δ 18 Osw/sal<strong>in</strong>ity estimates from<br />

Tahiti corals us<strong>in</strong>g Monte Carlo simulations: Implications for the<br />

<strong>in</strong>terpretation of fossil corals<br />

<strong>IODP</strong> 148<br />

<strong>IODP</strong> 98<br />

<strong>IODP</strong> 99<br />

<strong>IODP</strong> 99<br />

<strong>ICDP</strong> 100<br />

<strong>ICDP</strong> 100<br />

<strong>ICDP</strong> 103

10<br />

Polster, A., Vill<strong>in</strong>ger, H., Fabian, M.,<br />

Gennerich, H.-H.<br />

Preiß-Daimler, I., Henrich, R.<br />

Rettenmaier, D., Förster, A., Hötzl,<br />

H.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Abstractliste<br />

Drift-Analysis of ocean bottom pressure measurements <strong>IODP</strong> 103<br />

Middle to late Miocene (12-9 MA) carbonate preservation and<br />

accumulation changes <strong>in</strong> the Atlantic (Céara Rise Sites) and<br />

Pacific (Site 1237)<br />

Thermo-hydraulic conditions <strong>in</strong> a seismically active zone<br />

(Gulf of Cor<strong>in</strong>th, Greece)<br />

<strong>IODP</strong> 103<br />

<strong>ICDP</strong> 104<br />

Riemann, A., Oberhänsli, R. Retrograde zircons <strong>in</strong> fluid zones <strong>ICDP</strong> 105<br />

R<strong>in</strong>con Mart<strong>in</strong>ez, D., Saukel, C., Pleistocene changes <strong>in</strong> terrigenous sediment <strong>in</strong>put to the eastern <strong>IODP</strong> 107<br />

Lamy, F., Steph, S., Sturm, A.,<br />

Tiedemann, R.<br />

tropical Pacific based on ODP Sites 1237 and 1239<br />

Ritter, O., Becken, M., Weckmann, The electrical conductivity structure between the transitional (near <strong>ICDP</strong> 108<br />

U., Bedrosian, P. A., Ryberg, T., SAFOD) and locked (SE of Cholame) segments of the San<br />

Haberland, C.<br />

Andreas Fault, <strong>in</strong>clud<strong>in</strong>g the source region of the non-volcanic<br />

tremors.<br />

Rosner, M., Peucker-Ehrenbr<strong>in</strong>k, B., The plat<strong>in</strong>um group element and osmium isotope <strong>in</strong>ventory of <strong>IODP</strong> 110<br />

Bach, W.<br />

Atlantis Massif<br />

Roters, B., Henrich, R. The Miocene climatic record of Southwest Africa: Results from a<br />

50-kyr resolution silt gra<strong>in</strong>-size record of DSDP Site 530A<br />

(Project: RCOM TP A5/A6)<br />

<strong>IODP</strong> 110<br />

Rüggeberg, A., Dullo, C. and <strong>IODP</strong> Cold-water coral mound <strong>in</strong>itiation and early development - Results <strong>IODP</strong> 111<br />

Exp. 307 Scientific Party<br />

of benthic foram<strong>in</strong>iferal assemblages and gra<strong>in</strong>-size analysis<br />

Sanders, D., Kra<strong>in</strong>er, K., Lucas, S. Different records of Late Palaeozoic sea-level driven cyclothems:<br />

One clue for better understand<strong>in</strong>g controls over cycle development<br />

<strong>ICDP</strong> 112<br />

Saukel, C., R<strong>in</strong>con Mart<strong>in</strong>ez, D., Pliocene changes <strong>in</strong> terrigenous sediment <strong>in</strong>put to the eastern <strong>IODP</strong> 112<br />

Lamy, F., Steph, S., Sturm, A., tropical and subtropical Pacific based on ODP sites 1237 and 1239<br />

Tiedemann, R.<br />

- First results from XRF core scann<strong>in</strong>g and gra<strong>in</strong> size analysis<br />

Schleicher, A. M., Warr, L. N., van Mixed-layered clay m<strong>in</strong>erals and their geological significance <strong>in</strong> the <strong>ICDP</strong> 113<br />

der Pluijm, B. A.<br />

San Andreas Fault Observatory at depth drillhole (SAFOD) <strong>in</strong><br />

Parkfield, California<br />

Schreck, M., Matthiessen, J. A Neogene Stratigraphic and Paleoenvironmental Transect across<br />

the Fram Strait (Arctic Ocean)<br />

<strong>IODP</strong> 88<br />

Schulte, P., Deutsch, A., Tobias, S., The Cretaceous-Paleogene (K-Pg) transition <strong>in</strong> ODP Leg 207, <strong>IODP</strong> 116<br />

Kontny, A., MacLeod, K. G., Krumm, Western Atlantic: From the Chicxulub impact to the first Paleocene<br />

S.<br />

hyperthermal events<br />

Schwamborn, G. Trac<strong>in</strong>g Siberian permafrost history <strong>ICDP</strong> 117<br />

Schwarz, W. H., Trieloff, M., Altherr, Noble gases and phengite 40Ar/39Ar ages <strong>in</strong> ultra-high-pressure <strong>ICDP</strong> 117<br />

R.<br />

eclogites of the CCSD core<br />

Schwarz-Schampera, U., Botz, R., Shallow submar<strong>in</strong>e hydrothermal systems along the Tonga-<br />

<strong>IODP</strong> 118<br />

Hann<strong>in</strong>gton, M. and Shipboard Kermadec island arc: First results from R/V SONNE Cruise<br />

Scientific Party<br />

SO192/2<br />

Simonyan, A. V., Dultz, S., Behrens, Porosity <strong>in</strong> different alteration types of the oceanic crust as a <strong>IODP</strong> 119<br />

H., Pastrana, J., Schwarz-<br />

control of element mobilization - Determ<strong>in</strong>ation of diffusion<br />

Schampera, U.<br />

transport by <strong>in</strong>-situ FTIR-spectroscopy<br />

Ste<strong>in</strong>ke, S., Groeneveld, J.,<br />

Late Miocene surface water history <strong>in</strong> the northern South Ch<strong>in</strong>a <strong>IODP</strong> 122<br />

Johnstone, H.<br />

Sea: Relationship to East Asian summer monsoon evolution and<br />

variability<br />

Strasser, M., Ried<strong>in</strong>ger, N.,<br />

<strong>IODP</strong> NantroSEIZE Expedition 316 (Shallow Mega Splay and <strong>IODP</strong> 15<br />

Kitamura, Y. & <strong>IODP</strong> Expedition 316<br />

scientists.<br />

Frontal Thrust) - Initial Results<br />

Strauss, H., Reuschel, M., Melezhik,<br />

V.<br />

FAR-DEEP: Successful completion of the first phase<br />

<strong>ICDP</strong> 150<br />

Sturm, A., Tiedemann, R., Steph, S. Atlantic-Pacific <strong>in</strong>termediate- and deep-water δ13C gradients<br />

dur<strong>in</strong>g the late Neogene (Leg 202)<br />

<strong>IODP</strong> 122<br />

Sumita, M., Schm<strong>in</strong>cke, H. U. Tephra <strong>in</strong>put <strong>in</strong>to Lake Van <strong>ICDP</strong> 123<br />

Titschak, J., Thierens, M., Dorschel, Cold-Water Coral Mound Growth: Implications from Challenger <strong>IODP</strong> 123<br />

B., Schulbert, C., Freiwald, A., Kano, Mound (<strong>IODP</strong> Exp. 307 - Modern carbonate mounds: Porcup<strong>in</strong>e<br />

A., Takashima, C., Kawagoe, N., Li,<br />

X. and the <strong>IODP</strong> expedition 307<br />

scientific party<br />

Drill<strong>in</strong>g)<br />

Tougiannidis, N., Seidler, T., Rolf, C., Cyclostratigraphy and Time Series Analysis From Borehole<br />

<strong>ICDP</strong> 127<br />

Weber, M., Antoniadis, P., Ricken,<br />

W.<br />

KAP/107 (Amynteon Bas<strong>in</strong>, northwestern Greece)<br />

Trampe, A. F., Krastel, S., Spiess, High resolution seismic <strong>in</strong>vestigations of Anholt Loch, Kattegat: <strong>IODP</strong> 127<br />

V., Andrèn, T., Harff, J.<br />

Reconstruction of the Quaternary depositional history<br />

Viereck-Goette, L., Niessen, F., ANDRILL: Drill<strong>in</strong>g for Geology <strong>in</strong> Antarctica: Aims, Concept, <strong>ICDP</strong> 131<br />

Kuhn, G. and the D-ANDRILL<br />

members<br />

Results and Future Perspectives of a Successful Program<br />

Vogt, C., Matthiessen, J., Brumsack, Climate Cycles and Events <strong>in</strong> the Plio-/Pleistocene of the Yermak <strong>IODP</strong> 131<br />

H.-J., Fischer, R. X.<br />

Plateau, Arctic Ocean: Causes and Consequences based on X-ray<br />

Fluorescence Scanner Data of ODP Sites 910 and 911

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong> - Abstractliste 11<br />

Wagner, D., Mangelsdorf, K.<br />

Wagner, T., Baumann, K.-H.,<br />

Holtvoeth, J., Meggers, H., Stuut, J.-<br />

B., Vogt, C., Egl<strong>in</strong>ton, T. I.<br />

Wallrabe-Adams, H.-J.,<br />

Diepenbroek, M., Huber, R.,<br />

Sch<strong>in</strong>dler, U., Grobe, H., Collier, J.<br />

Weber, M. E., Ricken, W., Kuhn, G.,<br />

Reichelt, L., Pfeiffer, M., Gersonde,<br />

R.<br />

Evolution of the Methane Cycle <strong>in</strong> the Siberian Arctic: Insights from<br />

Microbiological and Biogeochemical Studies<br />

Holocene millennial scale variability <strong>in</strong> surface and deepwater<br />

records <strong>in</strong> the North Atlantic (ODP Site 980, Feni Drift)<br />

New <strong>IODP</strong> data access: Scientific Earth Drill<strong>in</strong>g Information Service<br />

(SEDIS)<br />

New tools to determ<strong>in</strong>e paleoceanographic proxies at ultrahigh<br />

(sub-mm) resolution: Gray-scale generation and lam<strong>in</strong>ae count<strong>in</strong>g<br />

<strong>in</strong> sediments from the Antarctic Cont<strong>in</strong>ental Marg<strong>in</strong><br />

<strong>ICDP</strong> 132<br />

<strong>IODP</strong> 133<br />

<strong>IODP</strong> 135<br />

<strong>IODP</strong> 135<br />

Wefer, G. Bericht über SASEC-Sitzung 15./16.01.08 (Santa Cruz) <strong>IODP</strong> 17<br />

Weigelt, E., Uenzelmann-Neben, G. Late Miocene Mega Slump<strong>in</strong>g along the southwest African Coast <strong>IODP</strong> 135<br />

Weller, P., Ste<strong>in</strong>, R.<br />

Organic-carbon sources, anoxia, and sea-surface temperature <strong>in</strong><br />

the Paleocene central Arctic Ocean (<strong>IODP</strong> Expedition 302):<br />

Evidence from biomarkers<br />

<strong>IODP</strong> 136<br />

Westerhold, T., Röhl, U.<br />

A high-resolution chronostratigraphy from ODP Site 1258<br />

(Demerara Rise) - New <strong>in</strong>sights <strong>in</strong>to the early Eocene<br />

Geomagnetic Polarity Time Scale<br />

<strong>IODP</strong> 138<br />

Weyher, S., Montoya-P<strong>in</strong>o, C.,<br />

Pross, J., Oschmann, W.<br />

Mo- and U-isotope variations <strong>in</strong> black shales: Potential tracers for<br />

the quantification of oceanic anoxia<br />

Wiersberg, T., Erz<strong>in</strong>ger, J. Characterization of gas from seismogenic depths of the San<br />

Andreas Fault at SAFOD<br />

Wilke, T., Albrecht, C., Wagner, B.,<br />

Krastel, S., Reicherter, K., Daut, G.,<br />

Wessels, M.<br />

Molecular clock approaches: Bridg<strong>in</strong>g the gap between cont<strong>in</strong>ental<br />

deep drill<strong>in</strong>g and evolutionary biology <strong>in</strong> ancient Lake Ohrid<br />

<strong>IODP</strong> 139<br />

<strong>ICDP</strong> 139<br />

<strong>ICDP</strong> 140<br />

Wille, M. Aerial extent of paleoenvironmental reconstructions <strong>in</strong> southern<br />

Patagonia<br />

<strong>ICDP</strong> 141<br />

W<strong>in</strong>kler-Nees, S. ECORD und die Deep-Sea Frontier Initiative <strong>IODP</strong> 17<br />

Wittmann, A., Hecht, L., Reimold, W.<br />

U., Schmitt, R. T., Kenkmann, T.,<br />

Hansen, B., Fernandes, V. A.<br />

Xu, Z. Q., Müller, W. F., Brenker, F.<br />

E.<br />

Ziegelmüller, K., Könneke, M.,<br />

Cypionka, H., Engelen, B.<br />

Zimmermann, K., Hüpers, A., Kopf,<br />

A.<br />

Zolitschka, B., Anselmetti, F. S.,<br />

Ariztegui, D., Corbella, H.,<br />

Haberzettl, T., Lücke, A., Mayr, C.,<br />

Ohlendorf, C., Schäbitz, F., Wille, M.<br />

Petrology of melt bear<strong>in</strong>g lithologies <strong>in</strong> drill core Eyreville-B,<br />

Chesapeake Bay impact structure<br />

TEM of eclogite from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g<br />

project at Donghai<br />

Cultivation of Sulfate-Reduc<strong>in</strong>g Bacteria from Deep Sediment<br />

Layers that are Influenced by Crustal Fluids (<strong>IODP</strong> Leg 301)<br />

Physical Properties of Mar<strong>in</strong>e Sediments Undergo<strong>in</strong>g Subduction -<br />

Results from Heated Shear Experiments at the Nankai Covergent<br />

Marg<strong>in</strong><br />

Climate and environmental variability dur<strong>in</strong>g the past 56 ka at<br />

Laguna Potrok Aike (Southern Patagonia, Argent<strong>in</strong>a), the site of<br />

the <strong>ICDP</strong> lake drill<strong>in</strong>g project „PASADO“<br />

<strong>ICDP</strong> 141<br />

<strong>ICDP</strong> 142<br />

<strong>IODP</strong> 143<br />

<strong>IODP</strong> 146<br />

<strong>ICDP</strong> 146

12<br />

Fahrtberichte<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition<br />

314 (NanTroSEIZE Logg<strong>in</strong>g-While-Drill<strong>in</strong>g<br />

Transect)<br />

ACHIM KOPF (UNIV. BREMEN), NANTROSEIZE PROJECT<br />

MANAGEMENT TEAM, <strong>IODP</strong> EXPEDITION 314 SCIENTIFIC PARTY<br />

Subduction zones account for 90% of global seismic<br />

moment release, generat<strong>in</strong>g damag<strong>in</strong>g earthquakes and<br />

tsunamis, with potentially disastrous effects on heavily<br />

populated coastal areas. Understand<strong>in</strong>g the processes that<br />

govern the strength of earthquakes, and nature and<br />

distribution of slip along these plate boundary fault<br />

systems, are crucial steps toward evaluat<strong>in</strong>g and mitigat<strong>in</strong>g<br />

geohazards, <strong>in</strong>clud<strong>in</strong>g tsunamis. As a consequence, the<br />

foremost goal of the <strong>IODP</strong> project NanTroSEIZE is to<br />

understand the mechanics and dynamics of seismogenesis<br />

and rupture propagation along the active plate boundary<br />

faults of a subduction zone, <strong>in</strong> terms of direct <strong>in</strong> situ<br />

sampl<strong>in</strong>g and <strong>in</strong>strumentation at depth.<br />

NanTroSEIZE is a multi-expedition, multi-platform<br />

complex drill<strong>in</strong>g project which eventually will complete a<br />

transect of holes the deepest of which will penetrate the<br />

seismogenic zone off the Kii Pen<strong>in</strong>sula, Japan, <strong>in</strong> ca. 6 km<br />

depth. Stage 1 drill<strong>in</strong>g <strong>in</strong>cluded three coord<strong>in</strong>ated riserless<br />

expeditions with RV Chikyu to drill several sites across the<br />

cont<strong>in</strong>ental slope and rise <strong>in</strong> fall 2007 through early <strong>2008</strong>.<br />

The first of these was a logg<strong>in</strong>g while drill<strong>in</strong>g (LWD)<br />

expedition that is serv<strong>in</strong>g as a geophysical basel<strong>in</strong>e for all<br />

of the Stage 1A drill<strong>in</strong>g sites (Expedition 314: LWD<br />

Transect). This was followed by a cor<strong>in</strong>g expedition<br />

(Expedition 315: Megasplay Riser Pilot) aimed at sampl<strong>in</strong>g<br />

the materials and characteris<strong>in</strong>g <strong>in</strong> situ conditions with<strong>in</strong><br />

the accretionary wedge to 1 km below seafloor at Site<br />

C0001, the location of the 3.5 km-deep Stage 2 drill hole<br />

across the deep “mega-splay” out-of-sequence thrust.<br />

Expedition 316 (Shallow Megasplay and Frontal Thrusts)<br />

targeted another shallow fault zone of the “mega-splay”<br />

system <strong>in</strong> the older accretionary prism (Site C0004) as well<br />

as the frontal thrust at the toe of the young accretionary<br />

prism (Sites C0006 and C0007).<br />

Initial results from the first Stage 1A drill<strong>in</strong>g<br />

expedition reveal new <strong>in</strong>sights <strong>in</strong>to the stress history and<br />

temporal evolution of the Nankai forearc. A total of 5 drill<br />

sites were studied us<strong>in</strong>g state-of-the-art logg<strong>in</strong>g-whiledrill<strong>in</strong>g<br />

(LWD) techniques and drill<strong>in</strong>g to depths of 400 to<br />

1400 m. In the Kumano region, the Nankai Trough forearc<br />

can be divided <strong>in</strong>to (i) an <strong>in</strong>ner wedge, comprised of a<br />

relatively older accretionary complex and overly<strong>in</strong>g forearc<br />

bas<strong>in</strong> that are hypothesized to lie over the up-dip end of the<br />

locked seismogenic megathrust; and (ii) an “outer wedge”<br />

that may represent the active critical state accretionary<br />

wedge with essentially aseismic mechanics. Seismically<br />

imaged structural style and attributes vary markedly across<br />

this boundary. Resistivity image logs show borehole<br />

breakouts at all sites along the transect (i.e. C0001, -2, -3, -<br />

4 and –6), with variable development <strong>in</strong> different<br />

structural/lithologic doma<strong>in</strong>s. The orientation of the<br />

maximum horizontal stress axis (SHmax) from breakouts<br />

across the outer wedge is consistently perpendicular to the<br />

local strike of major structures and somewhat oblique to<br />

plate convergence direction. At the <strong>in</strong>ner wedge/forearc<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

bas<strong>in</strong> drill site (C0001), the SHmax orientation is subparallel<br />

to strike, even <strong>in</strong> the upper part of the accretionary<br />

wedge doma<strong>in</strong> beneath the bas<strong>in</strong>. These results are<br />

consistent with a compressional to transpressional stress<br />

state <strong>in</strong> the outer wedge, transition<strong>in</strong>g over a few<br />

kilometers maximum distance to an extensional stress state<br />

<strong>in</strong> the <strong>in</strong>ner wedge. As an <strong>in</strong>itial hypothesis, this stress<br />

transition is controlled by the position of the up-dip limit of<br />

the locked portion of the megathrust <strong>in</strong> the <strong>in</strong>terseismic<br />

period, and may be temporally variable.<br />

Prelim<strong>in</strong>ary results from <strong>IODP</strong> Expedition<br />

315 (NanTroSEIZE Megasplay Riser Pilot)<br />

JAN BEHRMANN (IFM-GEOMAR KIEL), BABETTE BÖCKEL,<br />

ACHIM KOPF, FRIEDERIKE SCHMIDT-SCHIERHORN (UNIVERSITY<br />

OF BREMEN), <strong>IODP</strong> EXPEDITION 315 SCIENCE PARTY<br />

Integrated Ocean Drill<strong>in</strong>g Program Expedition 315 is<br />

one of three Nankai Trough Seismogenic Zone Experiment<br />

(NanTroSEIZE) Stage 1 expeditions. The NanTroSEIZE<br />

project is a multistage, multiplatform drill<strong>in</strong>g project<br />

designed to <strong>in</strong>vestigate fault mechanics and seismogenesis<br />

along subduction, décollement, and megathrusts through<br />

direct sampl<strong>in</strong>g, <strong>in</strong> situ measurements, and long-term<br />

monitor<strong>in</strong>g <strong>in</strong> conjunction with allied seafloor laboratory<br />

and numerical model<strong>in</strong>g studies. Expedition 315 was<br />

assigned to the Chikyu operat<strong>in</strong>g under contract with the<br />

Center for Deep Earth Exploration (CDEX) from 16<br />

November to 19 December 2007. Four German scientists<br />

were able to participate <strong>in</strong> the expedition.<br />

The ma<strong>in</strong> aim of the expedition was to drill and core a<br />

>1000m long section through the active branch of an outof-sequence<br />

thrust, be<strong>in</strong>g part of the so called “megasplay”<br />

fault system <strong>in</strong>tersect<strong>in</strong>g the Nankai Trough accretionary<br />

complex. The hole was supposed to be cased thereafter to<br />

set the stage for a 3.5 km-deep Riser drillhole <strong>in</strong> the future.<br />

None of these goals were achieved ow<strong>in</strong>g to a comb<strong>in</strong>ation<br />

of strong Kuroshio Current, lack of experience by the<br />

drill<strong>in</strong>g eng<strong>in</strong>eers and extremely unstable hole conditions.<br />

As a result of the difficulties mentioned above, cor<strong>in</strong>g<br />

at two planned riser drill<strong>in</strong>g sites (C0001 and C0002), was<br />

conducted (Figs. 1-2). Geological and geothermal<br />

<strong>in</strong>formation <strong>in</strong> the shallow part of the accretionary prism<br />

and the overly<strong>in</strong>g slope/forearc bas<strong>in</strong> sequences was<br />

aquired. These sites will add significantly to our<br />

understand<strong>in</strong>g of the relationships between the growth of<br />

the accretionary prism and the evolution of the splay fault<br />

system.<br />

For NanTroSEIZE Project Stage 2, 3.5 km riser drill<strong>in</strong>g<br />

is planned at Site C0001. We cored at this site to 457 m<br />

logg<strong>in</strong>g-while-drill<strong>in</strong>g (LWD) depth below seafloor (LSF)<br />

and cut 59 cores (31 with the hydraulic piston cor<strong>in</strong>g<br />

system [HPCS], 2 with the extended shoe cor<strong>in</strong>g system<br />

[ESCS], and 26 with the rotary core barrel [RCB]) from<br />

five holes cover<strong>in</strong>g the slope apron (Unit I) and the top 250<br />

m of the underly<strong>in</strong>g accretionary prism (Unit II). The slope<br />

cover is composed ma<strong>in</strong>ly of Quaternary to late Pliocene<br />

silty clay and clayey silt with <strong>in</strong>tercalations of volcanic ash.<br />

The boundary between Units I and II, identified at 207.17<br />

m LSF, is an unconformity characterized by a thick sand<br />

layer.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Figure 1. Location of Sites C0001 and C0002<strong>in</strong> the Kumano Bas<strong>in</strong> off Japan. Other sites drilled dur<strong>in</strong>g Expedition 314 (Sites C0003,<br />

C0004, and C0006) are also shown.<br />

Fig. 2: Reflection seismic profiles show<strong>in</strong>g location of sites C0004 and C0008 (Fig. 2A), and C0006 and C0007 (Fig. 2B)<br />

13

14<br />

Unit II is composed of more consolidated mud-dom<strong>in</strong>ated<br />

sediments of late Pliocene to late Miocene age. Structural<br />

style and stress state vary widely across a highly deformed<br />

zone at 220 m LSF. A normal fault <strong>in</strong>dicat<strong>in</strong>g northeast–<br />

southeast extension is dom<strong>in</strong>ant above this zone; however,<br />

a few thrust faults dipp<strong>in</strong>g at 50° were encountered just<br />

above the deformed zone. These thrust faults are consistent<br />

with the northwest–southeast shorten<strong>in</strong>g subparallel to the<br />

direction of plate convergence. On the other hand, many<br />

thrust and strike-slip faults as well as a normal fault are<br />

found below the 220 m LSF deformed zone. The geometry<br />

and k<strong>in</strong>ematics of planar structures display great variation.<br />

Fault plane solutions computed from normal and thrust<br />

faults are consistent with northeast–southwest extension<br />

and southeast–northwest shorten<strong>in</strong>g, respectively.<br />

Figure 3. Stratigraphic summaries, Site C0001 (left hand side) and Site C0002 (right hand side).<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

A total of 48 whole-round samples were taken for<br />

<strong>in</strong>terstitial geochemistry. Obta<strong>in</strong>ed data show mean<strong>in</strong>gful<br />

trends for most elements, and potential contam<strong>in</strong>ation of<br />

drill<strong>in</strong>g fluid is taken <strong>in</strong>to consideration; however,<br />

chang<strong>in</strong>g trends do not necessarily correspond to unit<br />

boundaries. Methane and ethane concentrations and their<br />

ratio (C1/C2) decrease with depth to 100 m LSF and<br />

rema<strong>in</strong> constant to the base of Unit I. The <strong>in</strong>crease of<br />

methane concentrations and C1/C2 ratios <strong>in</strong> Unit II <strong>in</strong>dicate<br />

the contribution of biogenic methane. Total organic carbon<br />

and calcium carbonate decrease monotonously to the base<br />

of Unit I and rema<strong>in</strong> low throughout Unit II. Physical<br />

properties also show a clear break at the boundary between<br />

Units I and II. Porosity decreases downhole with<strong>in</strong> each<br />

unit; however, there is a gap across the unit boundary. Wet<br />

bulk density negatively correlates with porosity. Thermal<br />

conductivity is almost constant throughout Unit I and<br />

decreases with depth <strong>in</strong> Unit II. Downhole temperature was<br />

measured with the advanced piston corer temperature tool<br />

(APCT3) at seven depths to 170.98 m LSF and yielded a<br />

generally l<strong>in</strong>ear downhole temperature <strong>in</strong>crease, with a<br />

gradient of 0.042°C/m.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

For NanTroSEIZE Stage 3, 6 km riser drill<strong>in</strong>g is<br />

planned at Site C0002. This site is located at the southern<br />

marg<strong>in</strong> of Kumano bas<strong>in</strong>. We cored to 1057 m LSF and cut<br />

86 cores (18 with the HPCS, 2 with the ESCS, and 66 with<br />

the RCB) from three holes. We penetrated the basal<br />

unconformity of the Kumano forearc bas<strong>in</strong> at ~936 m LSF<br />

and cored another 120 m <strong>in</strong>to the accretionary prism. The<br />

forearc bas<strong>in</strong> sequence was divided <strong>in</strong>to two units based on<br />

lithofacies; these units corresponded to Units II and III<br />

def<strong>in</strong>ed by LWD, respectively. Both units are dom<strong>in</strong>ated<br />

by mud and mudstone; however, the Unit I conta<strong>in</strong>s more<br />

sand and silt <strong>in</strong>tercalation and has a much faster<br />

sedimentation rate.<br />

The age ranges from Quaternary to late Miocene.<br />

Depositional ages were considerably well determ<strong>in</strong>ed by<br />

micropaleontological and paleomagnetic <strong>in</strong>vestigations.<br />

Facies analysis revealed rapid sedimentation <strong>in</strong> the forearc<br />

bas<strong>in</strong> dur<strong>in</strong>g the Quaternary and sediment-starved<br />

conditions <strong>in</strong> the basal slope bas<strong>in</strong> dur<strong>in</strong>g the Pliocene.<br />

Further details of evolution of the forearc bas<strong>in</strong> and<br />

accretionary prism will be clarified by <strong>in</strong>tegration of<br />

shipboard and shore-based studies. Underly<strong>in</strong>g<br />

accretionary prism materials conta<strong>in</strong> <strong>in</strong>durated, deformed<br />

sediments. Only one nannofossil event, of late Miocene<br />

age, was determ<strong>in</strong>ed for Unit IV; hence, no gap was<br />

detected across the unconformity.<br />

Faults and shear zones are clustered at certa<strong>in</strong> depths<br />

around 700, 920–950, and 1000–1050 m LSF. Three<br />

deformation phases were recognized by fault analyses. The<br />

earliest phase is a thrust fault (and possibly a strike-slip<br />

fault) and exhibits northwest–southeast shorten<strong>in</strong>g. Two<br />

phases of normal fault<strong>in</strong>g occurred subsequent to thrust<strong>in</strong>g.<br />

The first is recorded <strong>in</strong> shear zones and <strong>in</strong>dicates northeast–<br />

southwest extension. The second is recorded <strong>in</strong> normal<br />

faults and <strong>in</strong>dicates north–south extension, consistent with<br />

the present stress direction acquired from LWD results. A<br />

total of 31 whole-round samples were taken for <strong>in</strong>terstitial<br />

water analyses. Changes <strong>in</strong> concentration for most<br />

elements seem to be controlled by unit boundaries. A<br />

downward <strong>in</strong>crease of ethane and concomitant decrease of<br />

C1/C2 ratios <strong>in</strong> Unit IV suggest some contribution of<br />

thermogenic hydrocarbons. Physical properties show<br />

complex trends with depth. Downhole temperature was<br />

measured at eight depths to 159.0 m LSF and showed an<br />

almost l<strong>in</strong>ear downhole <strong>in</strong>crease with a gradient of<br />

0.043°C/m, identical to that found at Site C0001.<br />

Reference<br />

Moore, G.F., Bangs, N.L., Taira, A., Kuramoto, S., Pangborn, E., and Tob<strong>in</strong>,<br />

H.J., 2007. Three-dimensional splay fault geometry and implications<br />

for tsunami generation. Science, 318(5853):1128–1131.<br />

doi:10.1126/science.1147195<br />

<strong>IODP</strong> NanTroSEIZE Expedition 316<br />

(Shallow Maga Splay and frontal thrust) –<br />

<strong>in</strong>itial results<br />

M. STRASSER 1 , N. RIEDINGER 2 , Y.KITAMURA 3 & EXPEDITION 316<br />

SCIENTISTS<br />

1<br />

Research Centre Ocean Marg<strong>in</strong>s, University of Bremen;<br />

mstrasser@uni-bremen.de<br />

2<br />

Max Planck Institute for Mar<strong>in</strong>e Micorbiology, Bremen;<br />

nried<strong>in</strong>g@mpi-bremen.de<br />

3<br />

Leibniz-Institut für Meereswissenschaften, Kiel; ykitamura@ifmgeomar.de<br />

Integrated Ocean Drill<strong>in</strong>g Program (<strong>IODP</strong>) Expedition<br />

316 is part of the Nankai Trough Seismogenic Zone<br />

Experiment (NanTroSEIZE) complex drill<strong>in</strong>g project. This<br />

coord<strong>in</strong>ated, multiplatform, and multi-expedition drill<strong>in</strong>g<br />

project is designed to <strong>in</strong>vestigate fault mechanics and<br />

seismogenesis along subduction megathrusts through direct<br />

sampl<strong>in</strong>g, <strong>in</strong> situ measurements, and long-term monitor<strong>in</strong>g<br />

<strong>in</strong> conjunction with allied laboratory and numerical<br />

model<strong>in</strong>g studies (Tob<strong>in</strong> & K<strong>in</strong>oshita, 2006).<br />

Expedition 316 was designed to evaluate the<br />

deformation, the <strong>in</strong>ferred depth of detachment, the<br />

structural partition<strong>in</strong>g, the fault zone physical<br />

characteristics and fluid flow at the frontal thrust and at the<br />

shallow portion of the megasplay system (proposed<br />

NanTroSEIZE Sites NT1-03 and NT2-01, respectively;<br />

Fig.1). To accomplish these objectives, drill<strong>in</strong>g was<br />

conducted from late December 2007 to early February<br />

<strong>2008</strong> at two sites <strong>in</strong> the megasplay region, one with<strong>in</strong> the<br />

fault zone and one <strong>in</strong> the slope bas<strong>in</strong> seaward of the<br />

megasplay (Sites C0004 and C0008; Fig. 2A). Two sites<br />

were also drilled with<strong>in</strong> the frontal thrust region (Sites<br />

C0006 and C0007; Fig. 2B).<br />

Fig. 1: 3D perspective of NanTroSEIZE study area show<strong>in</strong>g proposed<br />

drill sites. (Figure taken from G.Kimura)<br />

15

16<br />

Site C0004 is located along the slope of the<br />

accretionary prism landward of the <strong>in</strong>ferred <strong>in</strong>tersection of<br />

the megasplay fault zone with the seafloor (Fig. 2A).<br />

Drill<strong>in</strong>g at this site recovered young hemipelagic slope<br />

deposits that unconformaly overly Pliocene sedimentary<br />

breccias and hemipelagic sediments of the accretionary<br />

prism. At ~ 270 to 300 (mbsf), the megasplay fault zone<br />

was successfully drilled and sampled. The cores from the<br />

fault zone record a complex history of deformation based<br />

on structural observations and two age reversals suggested<br />

by nannofossil evidence. In the footwall of the megasplay<br />

fault zone, Pleistocene underthrust slope bas<strong>in</strong> sediments<br />

were recovered and sampled to understand their<br />

deformation, consolidation, and fluid flow history. Drill<strong>in</strong>g<br />

at Site C0008 targeted the slope bas<strong>in</strong> seaward of the<br />

megasplay fault and provides a reference for the<br />

underthrust sucession at Site C0004 (Fig. 2A). The<br />

recovered sedimentary sucession documents the Late<br />

Pliocene to Pleistocene hemipelagic sedimentation history<br />

<strong>in</strong> the slope bas<strong>in</strong>, that was puctuated by episodic sediment<br />

remobilization events as <strong>in</strong>dicated by the occurrence of<br />

discrete layers of remobilzed hemipelagic material. The<br />

drilled succession at site C0008 hence records the history<br />

of fault movement along the adjacent megasplay.<br />

Additionally, the sediments are characterized by frequent<br />

occurrence of ash layers and the presence of gas hydrates.<br />

Drill<strong>in</strong>g at Sites C0006 and C0007 exam<strong>in</strong>ed the<br />

frontal thrust region (Fig. 2B). Site C0006 captured several<br />

fault zones with<strong>in</strong> the accreted and uplifted Pliocene-to-<br />

Pleistocene bas<strong>in</strong>-to-trench sediment succession before<br />

be<strong>in</strong>g halted by drill<strong>in</strong>g conditions. Drill<strong>in</strong>g at Site C0007<br />

recovered the correlative accreted and uplifted trench<br />

wedge deposits <strong>in</strong> the hang<strong>in</strong>gwall and successfully drilled<br />

through the frontal thrust <strong>in</strong>to younger underthrust trench<br />

wedge deposits. Drill<strong>in</strong>g successfully recovered thrust fault<br />

material rang<strong>in</strong>g from breccia to fault gouge. The highly<br />

dynamic processes along the observed fault zones are also<br />

reflected <strong>in</strong> the geochmistry data.<br />

References:<br />

Tob<strong>in</strong>, Y., and M., K<strong>in</strong>oshita (2006), Investigations of seismogenesis at the<br />

Nankai Trough, Japan. <strong>IODP</strong> Scientific Prospectus, NanTroSEIZE<br />

Stage 1. doi:10.2204/iodp.sd.2.06.2006<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong>

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Berichte<br />

Bericht über SASEC-Sitzung 15.-16. Januar<br />

<strong>2008</strong><br />

G. WEFER<br />

MARUM<br />

Zentrum für Mar<strong>in</strong>e Umweltwissenschaften<br />

Universität Bremen<br />

Leobener Straße<br />

28359 Bremen<br />

gwefer@marum.de<br />

Das Science Advisory Structure Excecutive Committee<br />

(SASEC) ist das höchste Beratungs- und<br />

Entscheidungsgremium im <strong>IODP</strong>. Neben Mike Bickel aus<br />

Cambridge b<strong>in</strong> ich der zweite europäische Vertreter <strong>in</strong><br />

diesem Gremium. Japan und die USA s<strong>in</strong>d mit je vier<br />

Mitgliedern vertreten, Europa hat zwei Vertreter.<br />

Beratenden Status haben Südkorea und Australien. E<strong>in</strong><br />

weiteres Mitglied stellt das Science Plann<strong>in</strong>g Committee.<br />

Als Gäste anwesend s<strong>in</strong>d Vertreter der Lead Agencies und<br />

Fund<strong>in</strong>g Agencies. Die letzte Sitzung fand am 15. und 16.<br />

Januar <strong>2008</strong> <strong>in</strong> Santa Cruz, Kalifornien, statt. Wesentliche<br />

Themen waren:<br />

Mögliche Schwerpunktsetzungen der Bohrungen<br />

aufgrund der reduzierten Verfügbarkeit der Bohrschiffe<br />

(sowohl Nachfolge „JOIDES Resolution“ als auch<br />

„CHIKYU“ werden aus f<strong>in</strong>anziellen Gründen nur sieben<br />

Monate im Jahr e<strong>in</strong>zusetzen se<strong>in</strong>, und es kann nur alle zwei<br />

Jahre e<strong>in</strong>e „Mission specific platform operation“<br />

durchgeführt werden).<br />

Kosten für die Aufrechterhaltung und den Service des<br />

Programms.<br />

Planung der nächsten Phase von <strong>IODP</strong> nach 2013. Zur<br />

Def<strong>in</strong>ition der Zielsetzung ist e<strong>in</strong> Workshop <strong>in</strong> September<br />

2009 geplant. Mögliche Austragungsorte s<strong>in</strong>d Tokyo, La<br />

Jolla, Corvallis und Bremen.<br />

Die nächste SASEC-Sitzung f<strong>in</strong>det <strong>in</strong> der Woche vom<br />

21.-28. Juni <strong>in</strong> Pek<strong>in</strong>g statt, zusammen mit <strong>IODP</strong>-MI<br />

Sitzungen<br />

ECORD und die Deep-Sea Frontier Initiative<br />

S. WINKLER-NEES 1<br />

1 Deutsche Forschungsgeme<strong>in</strong>schaft (DFG)<br />

-Physik, Mathematik, Geowissenschaften-<br />

-ERA-Net ECORD-<br />

D-53170 Bonn<br />

Seit 2003 wird das unabhängig von der Europäischen<br />

Kommission agierende European Consortium for Ocean<br />

Research Drill<strong>in</strong>g (ECORD) durch das ERA-NET<br />

ECORDnet unterstützt. Das Instrument ERA-NET wurde<br />

seitens der EC e<strong>in</strong>gerichtet, um die Vernetzung der<br />

nationalen Förderorganisationen im H<strong>in</strong>blick auf die<br />

Bildung e<strong>in</strong>es Europäischen Forschungsraums zu<br />

unterstützen.<br />

E<strong>in</strong>e Teilaufgabe <strong>in</strong> ECORDnet ist es, die<br />

verschiedenen existierenden Tiefseeforschungsprogramme<br />

zusammen zu br<strong>in</strong>gen und Möglichkeiten zu erarbeiten,<br />

deren Aktivitäten zu koord<strong>in</strong>ieren. Im Rahmen der aus<br />

ECORDnet entstandenen Deep-Sea Frontier Initiative<br />

haben Vertreter der Programme ESOnet/EMSO<br />

(Tiefseeobservatorien), HERMES (Tiefseeökosysteme)<br />

und IMAGES (Past Global Changes) mit ECORD<br />

(Tiefseebohrungen) geme<strong>in</strong>sam e<strong>in</strong>en “Science Plan”<br />

veröffentlicht(1). Unter Berücksichtigung dieser<br />

wissenschaftlichen Fragestellungen, sowie neuer<br />

politischer Optionen seitens der EC soll nun unter dem<br />

Dach der Deep-Sea Frontier Initiative e<strong>in</strong> Netzwerk der<br />

europäischen Tiefseeforschungsprogramme entstehen. Ziel<br />

ist es neben e<strong>in</strong>er besseren wissenschaftlichen<br />

Koord<strong>in</strong>ierung, langfristig und nachhaltig diesen<br />

Teilbereich der Meeresforschung auf europäischer Ebene<br />

zu verankern und somit z.B. auch effizient kooperative<br />

Infrastrukturvorhaben zu adressieren.<br />

Die Deep-Sea Frontier Initiative ist hierbei als e<strong>in</strong><br />

Rahmen zu verstehen, der (1) strukturelle Bed<strong>in</strong>gungen<br />

bietet, mit europäischen Partnern geme<strong>in</strong>sam<br />

wissenschaftliche Kooperationen e<strong>in</strong>zugehen, und der,<br />

möglicherweise unterstützt durch e<strong>in</strong> weiteres ERA-NET,<br />

(2) im Rahmen von Ausschreibungen weitere<br />

Förderchancen eröffnet. Diese Chancen müssen jedoch<br />

seitens der “scientific community” ergriffen und mit<br />

Inhalten gefüllt werden. Zudem ermöglicht die Initiative<br />

die Sichtbarkeit und damit die gesellschaftliche Akzeptanz<br />

dieses zu wenig beachteten Teils der Meeresforschung zu<br />

erhöhen und auf politischer Ebene Unterstützung zu f<strong>in</strong>den.<br />

In Anbetracht der steigenden Kosten, <strong>in</strong>sbesondere der<br />

benötigten Forschungs<strong>in</strong>frastruktur, ersche<strong>in</strong>t es als<br />

unverzichtbar, dass vorallem diesem Aspekt im<br />

europäischen Kontext mehr Bedeutung als <strong>in</strong> der<br />

Vergangenheit beigemessen wird.<br />

E<strong>in</strong>e weitere Teilaufgabe <strong>in</strong> ECORDnet besteht somit<br />

dar<strong>in</strong>, ECORD politisch im europäischen Gesamtkontext<br />

zu verankern, um die Interessen der wissenschaftlichen<br />

“Community” nachhaltig zu sichern. Zum Beispiel hatte<br />

die Europäische Kommission 2006 im Rahmen e<strong>in</strong>es<br />

„Green-Book“ Prozesses die europäischen „Mar<strong>in</strong>e<br />

Stakeholder“ dazu aufgerufen, ihre Wünsche und<br />

Vorstellungen zu e<strong>in</strong>er zukünftigen europäischen<br />

Meerespolitik zu formulieren. Kurz vor Abschluss dieses<br />

Prozesses wurde mit Beteiligung von ECORD <strong>in</strong> Aberdeen<br />

am 22. Juni 2007 die gebündelte Antwort europäischer<br />

Meereswissenschaftler vorgestellt und <strong>in</strong> der sog.<br />

„Aberdeen Declaration“(2) zusammengefasst. Unter<br />

Berücksichtigung von <strong>in</strong>sgesamt knapp 500 E<strong>in</strong>gaben<br />

formulierte schließlich die EC das sog. „Blue Book: An<br />

<strong>in</strong>tegrated Maritime Policy for the Union”(3), das am 10.<br />

Oktober 2007 veröffentlich wurde. In diesem Dokument<br />

präsentiert die EC ihre Sicht im H<strong>in</strong>blick auf e<strong>in</strong>e<br />

<strong>in</strong>tegrierten Meerespolitik für die Europäische Union.<br />

Die hier angerissenen Aspekte zeigen, dass ECORD<br />

nicht nur wissenschaftlich Europa im weltweit<br />

renommiertesten geowissenschaftlichen Programm<br />

erfolgreich vertritt, sondern dass es gelungen ist sechzehn<br />

europäische Förderorganisationen (plus Kanada) zur<br />

Bündelung geme<strong>in</strong>samer Interessen zusammen zu br<strong>in</strong>gen.<br />

ECORD als EINE Stimme Europas <strong>in</strong> <strong>IODP</strong> ermöglicht e<strong>in</strong><br />

hohes Maß an Gestaltungsmöglichkeiten des globalen<br />

Programms, was sich u.a. am Anteil der erfolgreichen<br />

Bohrvorschläge zeigt. Zudem ist es gelungen, die Anzahl<br />

der für europäische Wissenschaftler verfügbaren<br />

Schiffsplätze überproportional zu erhöhen. Der nicht<br />

unerhebliche Mitgliedsbeitrag (<strong>in</strong> Zukunft 22 M US $ / a)<br />

an <strong>IODP</strong> wird durch ECORD “gepoolt” und durch die<br />

EMA (ECORD Management Agency) verwaltet. Der<br />

ECORD-<strong>in</strong>terne Auswahlprozess von Wissenschaftlern<br />

17

18<br />

sichert die hohe wissenschaftliche Qualität des Beitrags zu<br />

<strong>IODP</strong>. Dies <strong>in</strong>sbesondere ist 2006 <strong>in</strong> e<strong>in</strong>em unabhängigen<br />

Review bestätigt worden.<br />

Bis zur Gründung von ECORD beteiligte sich Europa<br />

(maßgeblich Deutschland, Frankreich und UK, sowie e<strong>in</strong><br />

Zusammenschluss verschiedener Länder mit ger<strong>in</strong>gerem<br />

Beitrag) auf nationaler Ebene an ODP, bzw. den<br />

Vorläuferprogrammen. Dies ermöglichte die Beteiligung<br />

von europäischen Wissenschaftlern an Bohrexpeditionen<br />

auf dem e<strong>in</strong>zigen, damals verfügbaren wissenschaftlichen<br />

US Bohrschiff Joides Resolution. E<strong>in</strong>e maßgebliche<br />

Gestaltung des Bohrprogramms war u.a. durch die<br />

Fragmentierung der "europäischen Beteiligung" nicht<br />

gegeben. Ende der 90er Jahre nun beschloss Japan das neue<br />

Bohrschiff Chikyu zu bauen, um <strong>in</strong>sbesondere die<br />

geodynamischen Besonderheiten rund um Japan erforschen<br />

zu können, was mit der bis dah<strong>in</strong> verfügbaren Technologie<br />

nicht möglich war. Dadurch erlangte Japan e<strong>in</strong>e tragende<br />

Rolle <strong>in</strong>nerhalb der <strong>IODP</strong> Struktur.<br />

Um sich am Gestaltungsprozess von <strong>IODP</strong> aktiv<br />

beteiligen zu können, sowie die europäische Rolle <strong>in</strong> der<br />

<strong>in</strong>ternationalen Tiefseeforschung zu stärken, haben sich<br />

2003 Förderorganisationen aus 16 europäischen Ländern<br />

plus Kanada zu ECORD zusammengeschlossen. Als<br />

Infrastrukturbeitrag entwickelte ECORD das Konzept der<br />

"mission-specific platforms" - Bohrschiffe bzw. -<br />

plattformen, die explizit für e<strong>in</strong>e Expedition mit<br />

technischen Sonderanforderungen ausgerüstet werden. So<br />

wurde z.B. für die ACEX Expedition e<strong>in</strong> Eisbrecher mit<br />

e<strong>in</strong>em Bohrturm ausgestattet und konnte nahe dem Nordpol<br />

Proben erbohren, die wissenschaftlich bisher e<strong>in</strong>malig s<strong>in</strong>d.<br />

E<strong>in</strong>e weitere Expedition erbohrte Kerne aus durch<br />

Meerespiegelanstieg versunkenen Korallenriffen bei Tahiti<br />

(Tahiti Sea Level). Im Jahr <strong>2008</strong> wird e<strong>in</strong>e ECORD<br />

Expedition geowissenschaftliche Fragestellungen <strong>in</strong> enger<br />

Zusammenarbeit mit dem kont<strong>in</strong>entalen Tiefbohrprogramm<br />

(<strong>ICDP</strong>) vor New Jersey bearbeiten (New Jersey Shallow<br />

Shelf; Verknüpfung von on und off shore<br />

Bohrkampagnen).<br />

References:<br />

(1) PDF Version “The deep-sea frontier - Science challenges for a<br />

susta<strong>in</strong>able future” erhältlich unter http://bookshop.europa.eu/<br />

(2) EUROCEAN 2007; The Aberdeen Declaration:<br />

http://ec.europa.eu/maritimeaffairs/eurocean2007.html<br />

(3) The EC Blue Book: „A Maritime Policy of the EU“:<br />

http://ec.europa.eu/maritimeaffairs/<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong>

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Crystallization conditions of the basaltic and<br />

rhyolitic melts of the Snake River Pla<strong>in</strong>-<br />

Yellowstone hotspot track: first experimental<br />

results and implications (Project Ho 1337/17)<br />

R. ALMEEV 1 , L. KUSCHEL 1 , F. HOLTZ 1 , H. CATHEY 2 , B. NASH 2 , J.<br />

KOEPKE 1 , J. SHERVAIS 3 , E. CHRISTIANSEN 4<br />

1 Institute of M<strong>in</strong>eralogy, Leibniz University of <strong>Hannover</strong><br />

2 Department of Geology and Geophysics, University of Utah<br />

3 Department of Geology, Utah State University<br />

4 Department of Geological Sciences, Brigham Young University<br />

The central scientific issue for the <strong>ICDP</strong> drill<strong>in</strong>g <strong>in</strong> the<br />

Snake River Pla<strong>in</strong> - Yellowstone (SRPY) volcanic prov<strong>in</strong>ce<br />

is to trace the mantle plume and its <strong>in</strong>teraction with the<br />

cont<strong>in</strong>ental lithosphere. This requires <strong>in</strong>formation on the<br />

orig<strong>in</strong> and peculiarity of the contrast<strong>in</strong>g magmatism, the<br />

evolution of chemistry, sources, differentiation and storage<br />

conditions of both the rhyolitic and basaltic magmas with<br />

time and space. The most important miss<strong>in</strong>g (or<br />

controversial) <strong>in</strong>formation is the range of <strong>in</strong>tensive<br />

parameters of crystallization prevail<strong>in</strong>g <strong>in</strong> the silicic and<br />

mafic magma chambers dur<strong>in</strong>g fractionation and prior to<br />

eruption (P-T-fO2-aH 2O of magmas). The ma<strong>in</strong> goal of our<br />

started project is to provide this <strong>in</strong>formation us<strong>in</strong>g<br />

experimental approach (rhyolites) and thermodynamic<br />

model<strong>in</strong>g (basalts). In this paper we present our first<br />

experimental results obta<strong>in</strong>ed for one typical rhyolite<br />

composition and prelim<strong>in</strong>ary results of the phase equilibria<br />

model<strong>in</strong>g conducted for the McK<strong>in</strong>ney basaltic suite.<br />

Rhyolites.<br />

Phase relations were determ<strong>in</strong>ed <strong>in</strong> the rhyolite BJR<br />

(Unit 9j) from the Cougar Po<strong>in</strong>t Tuff, Bruno-Jarbidge<br />

eruptive center (Cathey and Nash, 2004). The start<strong>in</strong>g glass<br />

was prepared from the powder of whole-rock rhyolitic<br />

ignimbrite by two-times fusion at 1600 °C and 1 atm <strong>in</strong> air.<br />

Crystallization experiments with BJR were performed at<br />

200 MPa <strong>in</strong> cold seal pressure vessel (CSPV) at<br />

temperatures 800 and 850°C, and <strong>in</strong> <strong>in</strong>ternally heated<br />

pressure vessel (IHPV) at temperatures 950 and 1000°C.<br />

The water activity aH2O of the experimental charges was<br />

varied by add<strong>in</strong>g a fluid composed of a mixture of H2O and<br />

CO 2. Experimental charges at dry conditions (XH 2O <strong>in</strong>itial =0)<br />

were prepared without add<strong>in</strong>g H2O and CO 2. In CSPV the<br />

oxygen fugacity was monitored by add<strong>in</strong>g a solid Ni-NiO<br />

buffer. In IHPV all experiments were conducted at <strong>in</strong>tr<strong>in</strong>sic<br />

oxygen conditions, correspond<strong>in</strong>g to the NNO+3 oxygen<br />

buffer under H2O-saturated conditions and ~NNO at<br />

(nom<strong>in</strong>ally) dry conditions (Botcharnikov et al., 2005). The<br />

run duration varied with temperature: 14 days for runs at<br />

800 and 850°C, and 7 days for runs at 950 and 1000°C.<br />

Results of these first crystallization experiments are<br />

summarized <strong>in</strong> the Fig. 1, where phase relations for<br />

composition BJR are shown as a function of temperature<br />

and XH2O <strong>in</strong>itial .<br />

At the <strong>in</strong>vestigated conditions we were not able to<br />

atta<strong>in</strong> the liquidus for the studied rhyolite. At 1000°C<br />

rhyolitic melt was coexist<strong>in</strong>g with magnetite <strong>in</strong> the range of<br />

all studied XH2O. With decreas<strong>in</strong>g temperature magnetite<br />

was followed by pigeonite and sanid<strong>in</strong>e up to XH2O=0.5 <strong>in</strong><br />

the system. At XH 2O>0.5 and T>800°C sanid<strong>in</strong>e was not<br />

stable, and pigeonite was followed by cl<strong>in</strong>opyroxene. In<br />

H2O-rich charge (XH 2O=0.9) only cl<strong>in</strong>opyroxene and<br />

magnetite were identified to be <strong>in</strong> equilibrium with melt.<br />

The stability curve of cl<strong>in</strong>opyroxene at low XH2O is not<br />

clear, it should probably crystallizes at T

20<br />

Fig. 1. Phase relations for composition BJR (Cougar Po<strong>in</strong>t Tuff,<br />

Unit 9j [Cathey and Nash, 2004]) as a function of temperature and<br />

XH2O <strong>in</strong>itial . Symbols represent experimental charges and stable<br />

m<strong>in</strong>eral phases at given run conditions. Stability curves are labeled<br />

with m<strong>in</strong>eral names; the fields of stability are always to the left of<br />

the curves. M<strong>in</strong>eral abbreviations: Gl – glass, Mt – magnetite, Pig<br />

– pigeonite, Cpx – cl<strong>in</strong>opyroxene, Fsp – sanid<strong>in</strong>e, Pl – plagioclase,<br />

Qtz – quartz, Fa – fayalite.<br />

18<br />

16<br />

14<br />

Al 2O3 McK<strong>in</strong>ney basalt<br />

10 kbar<br />

1 atm<br />

MgO<br />

MgO<br />

12<br />

2<br />

4 5 6 7 8 9 4 5 6 7 8 9<br />

18<br />

16<br />

14<br />

FeO<br />

12<br />

8<br />

10<br />

MgO<br />

7<br />

10 kbar<br />

MgO<br />

4 5 6 7 8 9 4 5 6 7 8 9<br />

Fig. 2. Compositions of the basaltic lavas of the McK<strong>in</strong>ney basalt<br />

suite and dry isobaric liquid l<strong>in</strong>es of descent calculated for the<br />

primitive sample s72-3B (Leeman and Vitaliano, 1976). The<br />

calculated fractionation trends are shown for six pressures (1 atm,<br />

2kbar to 10 kbar, with 2 kbar <strong>in</strong>crement).<br />

References:<br />

Almeev, R. R., Holtz, F., Koepke, J. & Parat, F. (2006). Effect of small<br />

amount of H2O on the liquidus of oliv<strong>in</strong>e, plagioclase and<br />

cl<strong>in</strong>opyroxene: an experimental study at 200 and 500 MPa. EMPG-XI.<br />

11th - 13th September, University of Bristol UK.<br />

Arisk<strong>in</strong>, A. A. & Barm<strong>in</strong>a, G. S. (2004). COMAGMAT: development of a<br />

magma crystallization model and its petrological applications.<br />

Geochemistry International 42, S1–S157.<br />

Botcharnikov, R. E., Koepke, J., Holtz, F., McCammon, C. & Wilke, M.<br />

(2005). The effect of water activity on the oxidation and structural state<br />

of Fe <strong>in</strong> a ferro-basaltic melt. Geochimica et Cosmochimica Acta 69,<br />

5071-5085.<br />

Cathey, H. E. & Nash, B. P. (2004). The Cougar Po<strong>in</strong>t Tuff: Implications for<br />

thermochemical zonation and longevity of high-temperature, largevolume<br />

silicic magmas of the Miocene Yellowstone Hotspot. Journal<br />

of Petrology 45, 27-58.<br />

Leeman, W. P. & Vitaliano, C. J. (1976). Petrology of Mck<strong>in</strong>ney-Basalt,<br />

Snake-River-Pla<strong>in</strong>, Idaho. Geological Society of America Bullet<strong>in</strong> 87,<br />

1777-1792.<br />

Whitaker, M. L., Nekvasil, H., L<strong>in</strong>dsley, D. H. & Difrancesco, N. J. (2007).<br />

The Role of Pressure <strong>in</strong> Produc<strong>in</strong>g Compositional Diversity <strong>in</strong><br />

Intraplate Basaltic Magmas. Journal of Petrology 48, 365-393.<br />

<strong>IODP</strong><br />

Compact Multipurpose Sub-Sampl<strong>in</strong>g and<br />

Process<strong>in</strong>g of In-Situ Cores (COMPOSE)<br />

E. ANDERS 1 , W. H. MÜLLER 1<br />

1 Technische U niversität Berl<strong>in</strong>, Institut für Mechanik, Lehrstuhl<br />

Kont<strong>in</strong>uumsmechanik und Materialtheorie, E<strong>in</strong>ste<strong>in</strong>ufer 5,<br />

10587 Berl<strong>in</strong><br />

5<br />

4<br />

3<br />

11<br />

10<br />

9<br />

TiO2<br />

CaO<br />

1 atm<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Precondition to understand the deep-biosphere and to<br />

achieve genu<strong>in</strong>e f<strong>in</strong>d<strong>in</strong>gs is research <strong>in</strong> prist<strong>in</strong>e habitat as<br />

close as possible to those <strong>in</strong>-situ, if environmentally<br />

relevant results are to be obta<strong>in</strong>ed. Thus, pressure cor<strong>in</strong>g<br />

became an <strong>in</strong>dispensable part of offshore gas hydrate<br />

expeditions dur<strong>in</strong>g the last few years, e.g. <strong>in</strong> the US,<br />

Canada, India, Ch<strong>in</strong>a and South Korea.<br />

A suite of research technologies to ma<strong>in</strong>ta<strong>in</strong> benthic<br />

conditions of sediment structure and gas hydrates,<br />

temperature, pressure and bio-geochemistry dur<strong>in</strong>g the<br />

sequences of sampl<strong>in</strong>g, retrieval, transfer, storage and<br />

downstream analysis have been developed by Technische<br />

Universität Berl<strong>in</strong> (TUB) and European partners <strong>in</strong> the EU<br />

Projects HYACE and HYACINTH; cont<strong>in</strong>uous<br />

improvements on the prototypes lead to great successes and<br />

made the tools more and more reliable.<br />

The <strong>in</strong>vestigation of the pressurized cores with various<br />

measurements like X-ray, gamma ray, and p-wave,<br />

revealed numerous details of gas hydrates which have been<br />

unknown before and can not be obta<strong>in</strong>ed with<br />

unpressurized cores. The PRESS (Pressurized Core Subsampl<strong>in</strong>g<br />

and Extrusion System) furthermore enables well<br />

def<strong>in</strong>ed section<strong>in</strong>g and transfer of drilled pressure-cores<br />

[obta<strong>in</strong>ed by HYACE Rotary Corer (HRC) and Fugro<br />

Percussion Corer (FPC)] <strong>in</strong>to transportation and<br />

<strong>in</strong>vestigation chambers. Coupled with DeepIsoBUG<br />

(University Cardiff, John Parkes) it allows sub-sampl<strong>in</strong>g<br />

and <strong>in</strong>cubation of coaxial core-sections to exam<strong>in</strong>e highpressure<br />

adapted bacteria or remote biogeochemical<br />

processes <strong>in</strong> def<strong>in</strong>ed research conditions of the laboratory;<br />

all sterile, anaerobic and without depressurisation. The<br />

PRESS Sub-sampl<strong>in</strong>g is conducted <strong>in</strong> temperature<br />

controlled conta<strong>in</strong>ers to ma<strong>in</strong>ta<strong>in</strong> temperatures close to<br />

those <strong>in</strong> situ. Liquid medium <strong>in</strong> the DeepIsoBUG pressure<br />

vessels enables samples to be slurred and then transferred<br />

via a transition adapter <strong>in</strong>to a number of high-pressure<br />

vessels (max 1000 bar). These can be <strong>in</strong>cubated under a<br />

range of conditions (different media, pressures,<br />

temperatures etc) to enrich for a range of different highpressure<br />

adapted bacteria (piezophiles) or study<br />

biogeochemical processes at high pressure, such as rates of<br />

activity us<strong>in</strong>g radiotracers. F<strong>in</strong>ally, pure cultures can be<br />

obta<strong>in</strong>ed from positive enrichments with<strong>in</strong> a high-pressure<br />

isolation chamber for further study and characterisation.<br />

Initial results are promis<strong>in</strong>g with consistently higher cell<br />

numbers obta<strong>in</strong>ed under elevated pressure (up to 780 bar)<br />

with a number of different enrichment media compared to<br />

1 bar <strong>in</strong>cubation.<br />

Numrous successful PRESS deployments substantiated<br />

the usability of the system and could successfully<br />

accommodate the demand for prist<strong>in</strong>e deep biosphere<br />

samples by us<strong>in</strong>g reliable <strong>in</strong>vestigation methods. Moreover<br />

it showed the desperate need for systems that are easy to<br />

handle, eco-nomically and broadly applicable and have the<br />

potential to become standard devices.<br />

Aided by Deutsche Forschungsgeme<strong>in</strong>schaft (DFG:<br />

Mu 1752/11-1; COMPOSE) TUB currently works on<br />

concepts to scale down the systems immense proportion<br />

(8m length, 1t weight) to reduce logistical and f<strong>in</strong>ancial<br />

expenses, to enhance the handl<strong>in</strong>g and likewise to enlarge<br />

its implementation. Redesign<strong>in</strong>g the cutt<strong>in</strong>g mechanism<br />

shall simultaneously adjust the system to harder cores (e.g.,<br />

<strong>ICDP</strong>). Novel transportation chambers for processed subsamples<br />

<strong>in</strong>tend to make the system more attractive for a

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

broad spectrum of users and reduce their <strong>in</strong>terdependence.<br />

Advanced design, improved function<strong>in</strong>g, high performance<br />

materials and safety eng<strong>in</strong>eer<strong>in</strong>g cont<strong>in</strong>ue to guide further<br />

technology developments.<br />

<strong>IODP</strong><br />

Hydrogen generation <strong>in</strong> seawater-rock<br />

<strong>in</strong>teractions (ODP Leg 209): <strong>in</strong>sights from<br />

petrography and thermodynamic model<strong>in</strong>g<br />

W. BACH 1 , F. KLEIN 1 , M. HENTSCHER 1 , N. JÖNS 1<br />

1 Geoscience Department, University of Bremen, Klagenfurter Str.<br />

2, 28359 Bremen, Germany, wbach@uni-bremen.de<br />

Dihydrogen dissolved <strong>in</strong> water (H 2,aq) is one of the<br />

pr<strong>in</strong>cipal electron donors <strong>in</strong> chemolithoautotrophy-based<br />

ecosystems associated with hydrothermal vents. Vent fluids<br />

from peridotite-hosted systems show particularly high<br />

hydrogen concentrations on the order of 10-20 mmol/kg<br />

(mM). The same fluids have much higher methane<br />

concentrations (2-3 mM) but lower H2S contents of 1-2<br />

mM, when compared to fluids from basalt-hosted systems.<br />

The reasons for those systematic differences are <strong>in</strong> the<br />

composition of the substrates (i.e, mafic versus ultramafic<br />

rock), but the specifics of fluid-<strong>in</strong>teractions responsible for<br />

the development of the differences rema<strong>in</strong> unclear.<br />

We have used a thermodynamic approach to exam<strong>in</strong>e<br />

the processes that set vent fluid chemistry of peridotitehosted<br />

hydrothermal systems and the impact hydrogen may<br />

have <strong>in</strong> terms of the bioenergetics of the associated<br />

ecosystems. (i) Drill core samples from ODP Leg 209 were<br />

<strong>in</strong>vestigated petrographically to determ<strong>in</strong>e m<strong>in</strong>eral<br />

assemblages develop<strong>in</strong>g <strong>in</strong> ma<strong>in</strong>-stage serpent<strong>in</strong>ization, at<br />

metasomatic fronts, and dur<strong>in</strong>g fluid migration <strong>in</strong><br />

detachment faults. (ii) Calculations of m<strong>in</strong>eral-fluid<br />

equilibria were conducted to assign activities of critical<br />

aqueous species (e.g., SiO2, Ca 2+ , H 2, and H 2S) to the stable<br />

and metastable assemblages identified. (iii) Geochemical<br />

reaction path models were used to exam<strong>in</strong>e how changes <strong>in</strong><br />

bulk rock composition, temperature and water/rock ratios<br />

will affect the composition of <strong>in</strong>teract<strong>in</strong>g fluids. (iv) The<br />

predicted hydrogen concentrations are then used to<br />

calculate both the thermodynamic driv<strong>in</strong>g force of abiotic<br />

organic synthesis reactions and the amount of H2metabolic<br />

energy released upon vent<strong>in</strong>g at the seafloor. A<br />

subset of our prelim<strong>in</strong>ary results and conclusions will be<br />

presented at the meet<strong>in</strong>g.<br />

(i) One of the first-order observations we were able to<br />

make perta<strong>in</strong>s to the critical role the activity of aqueous<br />

silica appears to play. Magnetite forms most readily when<br />

peridotite alters to low-aSiO2 serpent<strong>in</strong>e-brucite<br />

assemblages. Higher aSiO 2 chlorite-act<strong>in</strong>olite-oligoclase<br />

assemblages develop<strong>in</strong>g <strong>in</strong> basalt are associated with fluids<br />

that have much less dissolved dihydrogen, because Fe is<br />

predom<strong>in</strong>antly <strong>in</strong>corporated <strong>in</strong>to the secondary silicates and<br />

not <strong>in</strong>to magnetite. The petrographic relations provide<br />

additional <strong>in</strong>sights: magnetite does not appear to form<br />

directly dur<strong>in</strong>g oliv<strong>in</strong>e breakdown but from breakdown of<br />

ferroan brucite, which forms as an <strong>in</strong>termediate phase<br />

(Bach et al., 2006).<br />

(ii) Iron and nickel oxides and sulfides are sensitive<br />

<strong>in</strong>dicators of oxygen and sulfur fugacities dur<strong>in</strong>g waterperidotite<br />

<strong>in</strong>teractions (Frost 1985). Our observations<br />

suggest that early awaruite- or heazlewoodite-bear<strong>in</strong>g<br />

assemblages, both with pentlandite and magnetite, are<br />

subsequently replaced with millerite and pyrite, and,<br />

f<strong>in</strong>ally, polydymite and hematite. These changes reflect<br />

concomitant changes <strong>in</strong> oxygen and sulfur fugacities that<br />

can be related to concentrations of H2S on the order of 1<br />

mM. We hence propose that the H 2S concentrations <strong>in</strong><br />

peridotite-hosted systems are buffered by reactions<br />

between the fluid and Fe-Ni-O-S phases (Kle<strong>in</strong> et al.,<br />

2007).<br />

(iii) Reaction path models <strong>in</strong>dicate that magnetite and<br />

hydrogen formation peak at temperatures around 300°C<br />

where roughly 300 mmoles of H2 may form <strong>in</strong> a system<br />

<strong>in</strong>tially composed of 1 kg of fluid and 1 kg of rock<br />

(McCollom and Bach, <strong>2008</strong>). These hydrogen yields are<br />

similar to the amounts of hydrogen estimated from<br />

petrographic observations and mass balance calculations<br />

(250 mmoles per kg oliv<strong>in</strong>e; Bach et al., 2006). Reaction<br />

path models can also help elucidate the development of<br />

metasomatic rocks, such as soapstone, chlorite fels, and<br />

rod<strong>in</strong>gite. The latter form from diffusive mass transfers<br />

driven by large gradients <strong>in</strong> the chemical potential of silica<br />

(Bach and Kle<strong>in</strong>, submitted).<br />

(iv) Hydrogen concentrations <strong>in</strong> excess of roughly 5-10<br />

mM are high enough to generate aff<strong>in</strong>ity for the<br />

methanogenesis reaction at 350-400°C. At lower<br />

temperatures, even less hydrogen is needed so that the<br />

driv<strong>in</strong>g force for methanogenesis is extremely high <strong>in</strong> the<br />

Lost City fluids (100°C, 15 mM H2; Kelley et al., 2005).<br />

Because there is no methanogenesis equilibrium <strong>in</strong> any of<br />

the serpent<strong>in</strong>ite-hosted systems, there is potential for the<br />

metastable formation of organics. Thermodynamic<br />

predictions of the levels of metastable formate at Lost City<br />

are basically identical to the concentrations measured <strong>in</strong> the<br />

fluids (Lang et al., 2007). The predicted and observed<br />

levels of abiotic formate are three times higher than the<br />

total dissolved organic contents of deep-sea waters,<br />

<strong>in</strong>dicat<strong>in</strong>g that abiotic carbon compounds may be important<br />

carbon and energy sources <strong>in</strong> serpent<strong>in</strong>ite-hosted<br />

hydrothermal systems.<br />

References:<br />

Bach W. and Kle<strong>in</strong> F. (<strong>2008</strong>) The petrology of seafloor rod<strong>in</strong>gites: <strong>in</strong>sights<br />

from geochemical reaction path model<strong>in</strong>g. Lithos, submitted.<br />

Bach W., Paulick H., Garrido C. J., Ildefonse B., Meurer W. P., and<br />

Humphris S. E. (2006) Unravel<strong>in</strong>g the sequence of serpent<strong>in</strong>itzation<br />

reactions: petrography, m<strong>in</strong>eral chemistry, and petrophyscis of<br />

serpent<strong>in</strong>ites from MAR 15ºN (ODP Leg 209, Site 1274). Geophys.<br />

Res. Lett. 33, L13306, doi:10.1029/2006GL025681.<br />

Frost B. R. (1985) On the stability of sulfides, oxides and native metals <strong>in</strong><br />

serpent<strong>in</strong>ite. J. Petrol. 26, 31-63.<br />

Kelley D. S., et al. (2005) A serpent<strong>in</strong>ite-hosted ecosystem: The Lost City<br />

Hydrothermal Field. Science 307, 1428-1434.<br />

Kle<strong>in</strong> F., Bach W., and Garrido C. J. (2007) Fe-Ni-O-S phase relations<br />

dur<strong>in</strong>g serpent<strong>in</strong>ization (MAR 15°N). Goldschmidt conference.<br />

Lang S., Lilley M. D., and Butterfield D. A. (2007) Organic geochemistry of<br />

the Lost City hydrothermal system. Abstract, InterRidge Workshop,<br />

Woods Hole.<br />

McCollom T. M. and Bach W. (<strong>2008</strong>) Thermodynamic and K<strong>in</strong>etic<br />

Constra<strong>in</strong>ts on Hydrogen Generation Dur<strong>in</strong>g Serpent<strong>in</strong>ization of<br />

Ultramafic Rocks: Implications for Fluid Chemistry, Magnetization of<br />

the Ocean Crust, Abiotic Synthesis of Hydrocarbons, and Microbial<br />

Processes. Geochim Cosmochim Acta, submitted.<br />

21

22<br />

<strong>IODP</strong><br />

Land-ocean <strong>in</strong>teraction and oceanic response<br />

<strong>in</strong> the Mid-Cretaceous western tropical<br />

Atlantic at ODP Site 1261<br />

B. BECKMANN 1, 2 , S. FLÖGEL 3 , P. HOFMANN 1 , C. MÄRZ 4 , T.<br />

WAGNER 5<br />

1 University of Cologne, Institute for Geology and M<strong>in</strong>eralogy,<br />

Zülpicher Str. 49a, 50674 Köln, Germany<br />

2 Federal Institute for Geosciences and Natural Resources,<br />

Stilleweg 2, 30655 <strong>Hannover</strong>, Germany<br />

(Britta.Beckmann@bgr.de)<br />

3 IFM-GEOMAR Leibniz-Institute of Mar<strong>in</strong>e Sciences,<br />

Wischhofstr. 1-3, 24148 Kiel, Germany<br />

4 University of Oldenburg, ICBM, Carl-von-Ossietzky-Strasse 9-<br />

11, 26129 Oldenburg, Germany<br />

5 School of Civil Eng<strong>in</strong>eer<strong>in</strong>g and Geosciences, University of<br />

Newcastle, Newcastle upon Tyne, NE1 7RU, United K<strong>in</strong>gdom<br />

Upper Cretaceous oceanic anoxic events (OAEs)<br />

represent significant and rapid perturbations of the global<br />

carbon cycle (e.g. Jenkyns, 2003) and provide natural<br />

examples of the processes lead<strong>in</strong>g to large variations <strong>in</strong> sea<br />

surface temperatures, ocean chemistry, and ecosystem<br />

response. To obta<strong>in</strong> detailed <strong>in</strong>formation on<br />

biogeochemical cycles and their feedbacks, organic carbon<br />

(OC)-rich black shale deposited dur<strong>in</strong>g the OAEs <strong>in</strong> the<br />

western tropical Atlantic at Demerara Rise has become one<br />

focal po<strong>in</strong>t of recent research. This project anticipates<br />

develop<strong>in</strong>g <strong>in</strong>tegrated, orbital-scale climate records of the<br />

last Cretaceous, the Coniacian-Santonian OAE 3 by<br />

<strong>in</strong>vestigation of sediments from ODP Site 1261 deposited<br />

<strong>in</strong> the transition from the Turonian OAE 2 to the early<br />

Santonian (biozones CC13 – CC15). In a f<strong>in</strong>al step, we<br />

anticipate to compare results from the western tropical<br />

Atlantic with f<strong>in</strong>d<strong>in</strong>gs from the time-equivalent eastern<br />

tropical Atlantic off Ivory Coast and Ghana at ODP Site<br />

959 with regard to a l<strong>in</strong>k between climate variability and<br />

oceanic response across the Equatorial Atlantic Gateway.<br />

An approximately 28 m long section (592 – 564 mcd)<br />

of ODP Holes 1261 A and B consist<strong>in</strong>g of cyclic<br />

alternat<strong>in</strong>g lam<strong>in</strong>ated marlstone with organic matter and<br />

limestone beds was sampled at 5 cm resolution. Based on<br />

the revised biostratigraphy, this depth record is equivalent<br />

to 8 – 10 kyr time resolution for the respective biozones.<br />

We exam<strong>in</strong>ed terrigenous matter supply, organic matter<br />

production and burial, sea-surface temperature (SST) and<br />

the development of photic zone and bottom water anoxia,<br />

therefore apply<strong>in</strong>g a comb<strong>in</strong>ation of elemental (LECO,<br />

XRF), pyrolytic (Rock Eval pyrolysis), and biomarker<br />

analyses (photic zone eux<strong>in</strong>ia markers, TEX86-derived<br />

SSTs).<br />

A prom<strong>in</strong>ent cycle pattern which is best documented <strong>in</strong><br />

the carbonate record is locally disrupted by <strong>in</strong>tervals<br />

display<strong>in</strong>g unusually high carbonate contents (> 90%<br />

CaCO3), low OC values (< 2% OC), and a high density.<br />

Most of these limestone beds vary significantly from the<br />

surround<strong>in</strong>g sediment by display<strong>in</strong>g <strong>in</strong>ternal structures such<br />

as variable lam<strong>in</strong>ation, graded, and rarely convolute<br />

bedd<strong>in</strong>g. The upper boundaries of the limestone beds are<br />

often gradual, some lower boundaries display a sharp basal<br />

contact. Thus the limestone beds are tentatively considered<br />

to represent <strong>in</strong>terruptions of the normal mar<strong>in</strong>e<br />

sedimentation cover<strong>in</strong>g hardly any geological time.<br />

Frequency analyses and wavelet power spectra of the<br />

limestone-free record reveal strong spectral peaks at<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Milankovitch related frequencies when the ma<strong>in</strong> periods<br />

are calculated accord<strong>in</strong>g to the respective sedimentation<br />

rates. Apart from a dom<strong>in</strong>ance of long and short<br />

eccentricity cycles, some contributions of obliquity bands<br />

are present. As our average sample spac<strong>in</strong>g is not ideal to<br />

detect precessional cycles, we resampled a 120 cm long<br />

<strong>in</strong>terval between 571.4 to 570.2 mcd <strong>in</strong> 1 cm <strong>in</strong>crements<br />

(equivalent to approx. 2 kyr per sample). Spectral analysis<br />

of this section did provide some additional <strong>in</strong>dication for<br />

precessional forc<strong>in</strong>g for the OC and carbonate records.<br />

The widespread occurrence of lam<strong>in</strong>ated sediments on<br />

both sides of the open<strong>in</strong>g Equatorial Atlantic (e.g. Wagner<br />

& Pletsch, 1999; Erbacher et al., 2004) testifies to the<br />

importance of low bottom water oxygenation for enhanced<br />

OC burial <strong>in</strong> that area. A comb<strong>in</strong>ation of bulk organic,<br />

molecular and <strong>in</strong>organic geochemical techniques was used<br />

to reconstruct the development of sea floor anoxia/eux<strong>in</strong>ia.<br />

Our bulk organic geochemical analyses focus ma<strong>in</strong>ly on<br />

biozones CC14 and CC15, display<strong>in</strong>g the best-developed<br />

cycle pattern. Results from Rock Eval pyrolysis suggest the<br />

dom<strong>in</strong>ance of lipid-rich, thermally immature mar<strong>in</strong>e<br />

organic matter dur<strong>in</strong>g the upper Cretaceous. Long-term<br />

trends <strong>in</strong> molecular and trace metal markers provide<br />

evidence for persistent, but nevertheless variable deep<br />

ocean anoxia throughout the Coniacian-early Santonian<br />

<strong>in</strong>terval. Bottom water redox conditions were repeatedly<br />

<strong>in</strong>terrupted by fluctuations of the oxygen m<strong>in</strong>imum zone,<br />

which at times may have expanded down to the sea floor at<br />

Site 1261 support<strong>in</strong>g sulfidic conditions.The observed<br />

changes <strong>in</strong> deep water redox conditions seem to have<br />

occurred on the order of few kyrs as can be deduced from<br />

millennial-scale biomarker and trace metal analysis from<br />

the resampled 120 cm <strong>in</strong>terval (see also contribution by<br />

März et al.). Sulfidic conditions <strong>in</strong> the photic zone, as<br />

<strong>in</strong>dicated by the preservation of traces of isorenieratane<br />

derivates, was restricted to the early Coniacian <strong>in</strong>terval.<br />

The conf<strong>in</strong>ement of photic zone eux<strong>in</strong>ia markers to this<br />

<strong>in</strong>terval probably reflects a more vigorous exchange of<br />

more oxygenated shallow waters across the open<strong>in</strong>g<br />

Equatorial Atlantic compared to deep waters from the mid-<br />

Coniacian onwards.<br />

F<strong>in</strong>ally, we compare our conclusions from Site 1261<br />

with data from the conjugate equatorial Atlantic marg<strong>in</strong> at<br />

ODP Site 959 and relate them to results from global<br />

climate model<strong>in</strong>g, thus putt<strong>in</strong>g our f<strong>in</strong>d<strong>in</strong>gs <strong>in</strong>to greater<br />

perspective. A comb<strong>in</strong>ation of geochemical data from<br />

mar<strong>in</strong>e sections and results from numeric climate<br />

simulations respond<strong>in</strong>g to variations <strong>in</strong> the orbital<br />

precession from the Late Cretaceous provides new views<br />

<strong>in</strong>to the regional dynamics of the tropical climate system,<br />

both <strong>in</strong> atmosphere and the ocean along the Equatorial<br />

Atlantic Gateway. The simulated numeric runoff volumes<br />

from tropical South American and African tropical<br />

catchment areas reveal that both sides of the equatorial<br />

Atlantic experienced pronounced Late Cretaceous<br />

precessional-driven fluctuations <strong>in</strong> river discharge. Both<br />

catchments reveal a strong seasonal pattern with highest<br />

runoff dur<strong>in</strong>g the wet season <strong>in</strong> northern hemisphere<br />

spr<strong>in</strong>g. Runoff from tropical Africa reveals exceptionally<br />

high values dur<strong>in</strong>g maximum seasonality exceed<strong>in</strong>g a<br />

proposed local threshold on the order of 2.5 mm/day that<br />

forced the Deep Ivory Bas<strong>in</strong> <strong>in</strong>to anoxic conditions<br />

(Beckmann et al., 2005). Simulated peak runoff was allover<br />

higher from S-America compared to tropical Africa, as wet

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

season runoff from South America exceeds the proposed<br />

threshold for Africa <strong>in</strong> 3 out of 4 orbital configurations.<br />

Maximum discharge off South America not only shifted<br />

between months of the wet season but also developed a<br />

bimodal peak with two similar runoff maxima dur<strong>in</strong>g one<br />

orbital configuration.<br />

To expla<strong>in</strong> the miss<strong>in</strong>g strong precessional footpr<strong>in</strong>t <strong>in</strong><br />

the South American geochemical records, as evident from<br />

frequency analysis, we argue that the oceanographic<br />

conditions and depositional sett<strong>in</strong>g differed markedly from<br />

those off tropical Africa at Site 959. The oceanographic<br />

sett<strong>in</strong>g at Site 959 was a semi-enclosed bas<strong>in</strong> l<strong>in</strong>ked to the<br />

cont<strong>in</strong>ental marg<strong>in</strong> with rather limited circulation and<br />

exchange to the central part of the open<strong>in</strong>g of the South<br />

Atlantic (Wagner & Pletsch, 1999). Different from that,<br />

Site 1261 was probably under much more open<br />

oceanographic <strong>in</strong>fluence and directly exposed to the<br />

circum-equatorial circulation of the Late Cretaceous (Otto-<br />

Bliesner et al., 2002). Be<strong>in</strong>g directly l<strong>in</strong>ked to the Tethys-<br />

North Atlantic gyre circulation which was driven by a<br />

Trade-W<strong>in</strong>d system similar to that of today (Bush, 1997),<br />

Site 1261 certa<strong>in</strong>ly experienced different atmospheric and<br />

oceanic forc<strong>in</strong>gs than Site 959. Due to the miss<strong>in</strong>g<br />

connection to any ‘large-scale’ ocean circulation, Site 959<br />

was much stronger <strong>in</strong>fluenced by the regional climate<br />

conditions <strong>in</strong> tropical Africa. As a result, a more direct<br />

impact of changes <strong>in</strong> river discharge on mar<strong>in</strong>e<br />

sedimentation was possible off Africa whereas the<br />

Demerara site 1261 was ma<strong>in</strong>ly <strong>in</strong>fluenced by open-ocean<br />

circulation and longer response times to orbital forc<strong>in</strong>g.<br />

References:<br />

Beckmann, B., Flögel, S., Hofmann, P., Schulz, M., Wagner, T., 2005.<br />

Orbital forc<strong>in</strong>g of Cretaceous river discharge <strong>in</strong> tropical Africa and<br />

ocean response. Nature 437, 241-244.<br />

Bush, A. B. G., 1997. Numerical Simulation of the Cretaceous Tethys<br />

Circumglobal Current. Science, 275, 807-810.<br />

Erbacher, J., Mosher, D.C., Malone, M.J., et al., 2004. Proceed<strong>in</strong>gs of the<br />

Ocean Drill<strong>in</strong>g Program, Initial Reports 207, Ocean Drill<strong>in</strong>g Program,<br />

College Station, doi:10.2973/odp.proc.ir.207.2004.<br />

Jenkyns, H.C., 2003. Evidence for rapid climate change <strong>in</strong> the Mesozoic-<br />

Paleogene greenhouse world. Philosophical Transactions of the Royal<br />

Society, Series A, 361, 1885-1916.<br />

Otto-Bliesner, B., Brady, E. C., Shields, C., 2002. Late Cretaceous ocean:<br />

Coupled simulations with the National Center for Atmospheric<br />

Research Climate System Model. Journal of Geophysical Research,<br />

107, D2, ACL 11 1-14.<br />

Wagner, T., Pletsch, T., 1999. Tectono-sedimentary controls on Cretaceous<br />

black shale depostion along the open<strong>in</strong>g Equatorial Atlantic Gateway<br />

(ODP Leg 159). In: Cameron, N.R., Bate, R.H., Clure, V.S. (Eds.), The<br />

Oil and Gas Habitats of the South Atlantic. Geological Society Special<br />

Publication 153, London, 241-265.<br />

<strong>ICDP</strong><br />

Identification and analysis of vertical<br />

convection <strong>in</strong> boreholes<br />

S. BERTHOLD, F. BÖRNER<br />

DGFZ Dresdner Grundwasserforschungszentrum e.V., Meraner<br />

Str. 10, 01217 Dresden, Germany<br />

It is known, that <strong>in</strong> water and mud filled boreholes<br />

vertical convections can occur which lead to transport of<br />

mass and heat. As temperatures <strong>in</strong> thermally unstable water<br />

columns may depart significantly from the ones <strong>in</strong><br />

surround<strong>in</strong>g rock, understand<strong>in</strong>g convective flow with<strong>in</strong><br />

the borehole is crucial for geothermics and subsurface<br />

water movement (e.g. determ<strong>in</strong><strong>in</strong>g reliable heat-flow<br />

density and rock thermal properties us<strong>in</strong>g temperature<br />

profiles). Know<strong>in</strong>g about the presence of vertical flows <strong>in</strong><br />

water columns is also important for hydrological<br />

<strong>in</strong>vestigations (e.g. determ<strong>in</strong><strong>in</strong>g po<strong>in</strong>ts of <strong>in</strong>- and outflow),<br />

and for borehole geophysics (e.g. f<strong>in</strong>d<strong>in</strong>g leakages <strong>in</strong><br />

cas<strong>in</strong>gs).<br />

Strong convective flow with<strong>in</strong> the water column may<br />

further on affect water samples. Gases, as well as other<br />

substances are possibly transported <strong>in</strong>to new depths, where<br />

vary<strong>in</strong>g chemical processes may arise.<br />

The general objective of this research project is the<br />

adaptation and further development of an <strong>in</strong>terpretation<br />

method for temperature and mudresistivity logs for the<br />

detection, differentiation and quantification of vertical<br />

flows <strong>in</strong> deep boreholes. Besides the well-known forced<br />

convection, especially the detection of free convection with<br />

its various density-driven transport processes and their<br />

differentiation will be the focal po<strong>in</strong>t of the project.<br />

The foundations were laid <strong>in</strong> a project which dealt with<br />

the <strong>in</strong>vestigation of free vertical convections <strong>in</strong><br />

groundwater monitor<strong>in</strong>g wells and its quantification<br />

accord<strong>in</strong>g to its data adulterat<strong>in</strong>g effect (Berthold and<br />

Börner 2007). These <strong>in</strong>vestigations of convective processes<br />

<strong>in</strong>cluded numerical simulations, medium scale<br />

experiments, and field tests (borehole measurements).<br />

Fundamental elements of two computational algorithms for<br />

detect<strong>in</strong>g and quantify<strong>in</strong>g vertical flows <strong>in</strong> the water<br />

column have been already tested <strong>in</strong> numerous shallow<br />

boreholes (< 400 m) under the prevail<strong>in</strong>g measur<strong>in</strong>g<br />

conditions. With one algorithm the causes (driv<strong>in</strong>g forces)<br />

and with the other one the effects (forced, free convection<br />

or double diffusion) of vertical transport processes can be<br />

detected based on geophysical borehole measurements<br />

(temperature and fluid conductivity) <strong>in</strong> the water column.<br />

The comb<strong>in</strong>ation of both algorithms improves the<br />

reliability of the <strong>in</strong>terpretation.<br />

Us<strong>in</strong>g these algorithms, the occurrence of densitydriven<br />

convective transport processes could be proven <strong>in</strong><br />

many groundwater monitor<strong>in</strong>g wells and shallow boreholes<br />

under normal conditions, as the critical threshold for the<br />

onset of a density-driven flow is considerably low<br />

(depend<strong>in</strong>g on the borehole radius down to some<br />

hundredths of Kelv<strong>in</strong>). It was found that several sections<br />

with different types of density-driven vertical flows may<br />

exist <strong>in</strong> the water column at the same time. Results from<br />

medium-scale experimental <strong>in</strong>vestigations and from<br />

numerical model<strong>in</strong>g agreed well with parameters of <strong>in</strong>-situ<br />

detected convection cells.<br />

As the effects of vertical free convective and doublediffusive<br />

transport play an important role when <strong>in</strong>terpret<strong>in</strong>g<br />

borehole logs or other measurements, the water column<br />

should be exam<strong>in</strong>ed accord<strong>in</strong>g the occurrence of vertical<br />

transport processes <strong>in</strong> case of geothermal <strong>in</strong>vestigations,<br />

hydrological <strong>in</strong>vestigations, water sampl<strong>in</strong>g, and technical<br />

borehole control.<br />

With<strong>in</strong> the scope of this project, the borehole log<br />

<strong>in</strong>terpretation method shall be adapted to deep boreholes.<br />

The difficulty is now to obta<strong>in</strong> a similar good result of<br />

<strong>in</strong>terpretation us<strong>in</strong>g available data from deep boreholes.<br />

The characteristic properties of the borehole logs expected<br />

from deep boreholes <strong>in</strong>clude e.g. higher speed while<br />

lower<strong>in</strong>g the probe, larger sampl<strong>in</strong>g <strong>in</strong>terval, and higher<br />

viscosity of the fluid (mud). Additionally to the differences<br />

related to the measurement technique, deep boreholes can<br />

be characterized by very dist<strong>in</strong>ct temperature gradients and<br />

temporal water <strong>in</strong>- and outflows.<br />

23

24<br />

References:<br />

Berthold S., Börner F. (2007): Detection of free vertical convection and<br />

double-diffusion <strong>in</strong> groundwater monitor<strong>in</strong>g wells with geophysical<br />

borehole measurements, Environmental Geology (Onl<strong>in</strong>e First), DOI:<br />

10.1007/s00254-007-0936-y.<br />

<strong>IODP</strong><br />

Indian and Southern Ocean dynamics dur<strong>in</strong>g<br />

the Miocene<br />

T. BICKERT 1 , M. BUTZIN 2 , G. LOHMANN 3<br />

1 MARUM, Universitaet Bremen, 28334 Bremen, Germany<br />

2 Alfred-Wegener-Institut, 27580 Bremerhaven, Germany<br />

The middle to late Miocene glaciation of Antarctica is<br />

characterized by several cool<strong>in</strong>g steps, which might be<br />

attributed to changes <strong>in</strong> ocean circulation. Here, we report<br />

results of a model<strong>in</strong>g study <strong>in</strong> which we aimed to identify<br />

the driv<strong>in</strong>g mechanisms for the development and the<br />

dynamics of the Southern Ocean frontal system dur<strong>in</strong>g this<br />

cool<strong>in</strong>g phase. Special emphasis is put on the potential<br />

climatic effects of ocean gateway changes, such as the<br />

constriction of the eastern Tethys. We employ a global<br />

ocean circulation and carbon cycle model (MPI-OM) with<br />

a curvil<strong>in</strong>ear grid focuss<strong>in</strong>g on the Southern hemisphere,<br />

which means that the Southern Ocean is <strong>in</strong>vestigated at<br />

higher resolution than the rest of the world. This model<strong>in</strong>g<br />

approach circumvents some typical problems of common<br />

models <strong>in</strong> regional model<strong>in</strong>g studies, such as the<br />

specification of proper boundary conditions if us<strong>in</strong>g standalone<br />

regional models, or the rather coarse resolution of<br />

global circulation models.<br />

Us<strong>in</strong>g a new and more realistic forc<strong>in</strong>g for the middle<br />

Miocene ocean conditions, we arrive at significant<br />

hydrographic changes compared to present day. In the<br />

Southern Ocean, circumpolar SST decrease by about 3°C,<br />

whereas subantarctic SST <strong>in</strong>crease. Subtropical SST are<br />

also elevated <strong>in</strong> the Southern Indian Ocean while <strong>in</strong> the<br />

South Atlantic the sea surface temeprature cools by about<br />

2°C. At the thermocl<strong>in</strong>e level, most parts <strong>in</strong> the<br />

subantarctic and circumpolar realm are about 3°C colder<br />

than at present day while <strong>in</strong> the subtropics, water<br />

temperatures <strong>in</strong>crease by about 3°-5°C with the Indian<br />

Ocean be<strong>in</strong>g warmer than the South Atlantic. In the<br />

<strong>in</strong>termediate water layer, the simulation for the middle<br />

Miocene yields cool<strong>in</strong>g almost everywhere <strong>in</strong> the Southern<br />

Ocean, but significant warm<strong>in</strong>g of more than 5°C <strong>in</strong> the<br />

Indian Ocean. Mid-Miocene sal<strong>in</strong>ities are generally<br />

elevated above modern values <strong>in</strong> all subsurface water<br />

layers. Similar to temperature, the sal<strong>in</strong>ity anomalies are<br />

most pronounced (more than 2 psu) <strong>in</strong> the <strong>in</strong>termediate<br />

water layer of the Indian Ocean. The Miocene ocean<br />

circulation is characterized by absence of deep water <strong>in</strong> the<br />

North Atlantic. Moreover, at all levels <strong>in</strong> the Southern<br />

Ocean we f<strong>in</strong>d a strengthen<strong>in</strong>g of the South Atlantic<br />

Current while the leakage of the Agulhas Current <strong>in</strong>to the<br />

South Atlantic and the subantarctic circumpolar flow are<br />

reduced. Regard<strong>in</strong>g the role of the Tethys, we f<strong>in</strong>d that<br />

surface and subsurface water flows from the Indian Ocean<br />

<strong>in</strong>to the eastern Tethys. Below 400 m, this flow reverses,<br />

and warm and sal<strong>in</strong>e water is exported from the Tethys to<br />

the Indian. These results are confirmed by observations of<br />

former studies (e.g., Woodruff and Sav<strong>in</strong>, 1989; Wright et<br />

al., 1992; Flower and Kenneth, 1994) and own results.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Magnetic M<strong>in</strong>eral Inputs <strong>in</strong> Sediments Off<br />

Baja California. Inference on Climate<br />

Variability of the Last Glacial-Interglacial<br />

Cycle<br />

C.L. BLANCHET 1 , N. THOUVENY 2 , L. VIDAL 2<br />

1 Mar<strong>in</strong>e Geophysics, Fachbereich Geowissenschaften, Postfach<br />

330440, 28334 Bremen, Deutschland<br />

2 CEREGE-CNRS, University Paul Cezanne, Europole de l’Arbois,<br />

13545 Aix en Provence, Frankreich<br />

The sediments of the western marg<strong>in</strong> of the Baja<br />

California pen<strong>in</strong>sula have demonstrated their ability to<br />

record climate changes at millennial time scale. Both the<br />

sedimentary dynamics (van Geen et al., 2003) and the<br />

export of biogenic compounds (Ortiz et al., 2004) respond<br />

to a northern latitude climatic forc<strong>in</strong>g dur<strong>in</strong>g the last 52 ka<br />

BP. The core MD02-2508 has been collected dur<strong>in</strong>g the<br />

scientific cruise IMAGESVIII-MONA at the latitude of<br />

Tropic of Cancer (23°N). The present sedimentation is<br />

characterized by high terrigenous <strong>in</strong>puts, deposited under<br />

the <strong>in</strong>fluence of a strong seasonal and spatial climatic<br />

variability and with high accumulation rates (35 cm/ka),<br />

allow<strong>in</strong>g to monitor the rhythms of the terrigenous <strong>in</strong>put at<br />

a centennial resolution.<br />

The magnetic parameters (magnetic susceptibility,<br />

anhysteretic and isothermal remanent magnetizations and<br />

hysteresis properties) here trace variations <strong>in</strong> concentration<br />

and nature of magnetic m<strong>in</strong>erals orig<strong>in</strong>at<strong>in</strong>g from the<br />

cont<strong>in</strong>ent and carried follow<strong>in</strong>g different ways (aeolian or<br />

fluvial), provid<strong>in</strong>g reliable <strong>in</strong>sights on climate variability<br />

on-land. The relative contents of major and trace elements<br />

(measured by X-ray fluorescence scanner) and<br />

concentrations of carbonates and organic carbon on key<br />

<strong>in</strong>terval of the cores, helped to improve the <strong>in</strong>terpretations.<br />

The sedimentary sequence was dated us<strong>in</strong>g 12<br />

calibrated 14 C ages and identification of paleomagnetic<br />

excursions and covers the last glacial-<strong>in</strong>terglacial cycle (0-<br />

120 ka).<br />

The magnetic m<strong>in</strong>erals are more concentrated dur<strong>in</strong>g<br />

the bioturbated <strong>in</strong>tervals, correspond<strong>in</strong>g to glacial and<br />

stadial periods of North Atlantic whilst low concentrations<br />

are recorded <strong>in</strong> <strong>in</strong>tervals present<strong>in</strong>g millimetric to<br />

centimetric lam<strong>in</strong>ations, correspond<strong>in</strong>g to <strong>in</strong>terglacial and<br />

<strong>in</strong>terstadial periods. High (low) magnetic m<strong>in</strong>eral<br />

concentrations are also associated to high (low) total<br />

reflectance, high (low) carbonate contents and low (high)<br />

organic carbon contents. The relative concentrations of<br />

titanium and iron, vary<strong>in</strong>g similarly to the magnetic<br />

parameters <strong>in</strong>dicate that the concentration of magnetic<br />

m<strong>in</strong>erals is ma<strong>in</strong>ly modulated by variations of the<br />

terrigenous <strong>in</strong>put, rather than dissolution of the iron oxides.<br />

The magnetic susceptibility signal trac<strong>in</strong>g variations of<br />

coarse magnetite concentration is supposed to be l<strong>in</strong>ked<br />

with fluvial transport; it closely matches the Greenland<br />

oxygen isotope record. The Hard IRM (HIRM) signal,<br />

carried by high coercivity m<strong>in</strong>eral (hematite and/or<br />

goethite) classically <strong>in</strong>terpreted as tracers of aeolian<br />

transport, conta<strong>in</strong>s its major power <strong>in</strong> the precessional<br />

frequency band. Strong (resp. weak) hematite or goethite<br />

concentrations matches low (resp. high) <strong>in</strong>solation. The<br />

residual magnetic terrigenous <strong>in</strong>put off Baja California<br />

recorded two types of climatic variability dur<strong>in</strong>g the last<br />

Glacial/Interglacial cycle: fluvial (Ti)magnetite <strong>in</strong>put was

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

governed by the Northern hemisphere variability and<br />

aeolian hematite/goethite <strong>in</strong>put was governed by the low<br />

latitudes variability.<br />

<strong>IODP</strong><br />

Novel real-time PCR assays for the<br />

quantification of genes from Bacteria of the<br />

deep biosphere<br />

ANNA BLAZEJAK AND AXEL SCHIPPERS<br />

Bundesanstalt für Geowissenschaften und Rohstoffe<br />

(BGR),Referat Geomikrobiologie, Stilleweg 2, 30655<br />

<strong>Hannover</strong><br />

The deep biosphere of mar<strong>in</strong>e sediments shall harbour<br />

over half of all prokaryotic cells on earth. Despite this huge<br />

numbers of subsurface microorganisms and their likely<br />

significant <strong>in</strong>fluence on the global biogeochemical cycles,<br />

only little is known about the microbial diversity and<br />

abundance. To <strong>in</strong>vestigate these two aspects we applied<br />

molecular techniques such as quantitative, real-time<br />

polymerase cha<strong>in</strong> reaction (PCR) for quantification of<br />

microbial genes and denatur<strong>in</strong>g gradient gel electrophoresis<br />

(DGGE) to analyse their diversity. In particular two<br />

different groups of microorganisms relevant to the deep<br />

biosphere attend our focus: Bacteria belong<strong>in</strong>g to the “JS1<br />

candidate group” and the Chloroflexi subphylum I which<br />

appear to be abundant <strong>in</strong> the subsurface sediments, and<br />

bacteria <strong>in</strong>volved <strong>in</strong> the sulfur cycle. We have developed<br />

novel real-time PCR assays for the quantification of genes<br />

of these bacteria and applied them to mar<strong>in</strong>e sediments.<br />

Bacteria belong<strong>in</strong>g to the “JS1 candidate group” and the<br />

Chloroflexi subphylum I have shown to be a mayor part of<br />

the bacterial community <strong>in</strong> different mar<strong>in</strong>e sediments.<br />

Results for bacteria <strong>in</strong>volved <strong>in</strong> the sulfur cycle are present<br />

<strong>in</strong> more detail below.<br />

Sulfur-oxidiz<strong>in</strong>g and sulfate-reduc<strong>in</strong>g bacteria are<br />

ma<strong>in</strong>ly responsible for biogeochemical sulfur-cycl<strong>in</strong>g <strong>in</strong><br />

mar<strong>in</strong>e sediments. To specifically quantify these organisms<br />

we developed a new real-time PCR assay target<strong>in</strong>g the<br />

adenos<strong>in</strong>e 5´-phosphosulfate reductase (aprA) gene cod<strong>in</strong>g<br />

for the α-subunit of the enzyme APS reductase. In sulfatereducers,<br />

APS reductase catalyzes the two-electron<br />

reduction of APS to sulfite and AMP, and <strong>in</strong> sulfuroxidizers<br />

the reverse reaction. The aprA gene was<br />

amplified with the specific primers APS1F and APS4R and<br />

has a length of ca 350 bp (Blazejak et al. 2006). The new<br />

real-time PCR assay could be successfully applied to<br />

mar<strong>in</strong>e sediment samples taken off the cost of Peru (SO147<br />

Station 2MC) and from the Black Sea (M72/5 Station 20).<br />

Results are shown <strong>in</strong> Figure 1.<br />

Figure 1. DNA copy numbers of the 16S rRNA gene of Bacteria<br />

and the functional genes, dsrA and aprA, <strong>in</strong> near-surface sediment<br />

(0-0.34 mbsf) from the Peru marg<strong>in</strong> (Station 2MC; SO147) and<br />

deeper sediment (0-6 mbsf) from the Black Sea (Station 20; M72-<br />

5).<br />

25

26<br />

The graphs show depth profiles of DNA copy numbers<br />

of the aprA gene, the 16S rRNA gene orig<strong>in</strong>at<strong>in</strong>g from<br />

Bacteria <strong>in</strong> total, and the dsrA gene occurr<strong>in</strong>g only <strong>in</strong><br />

sulfate-reducers. The dsrA and the 16S rRNA gene copy<br />

numbers <strong>in</strong> the Peru marg<strong>in</strong> sediments were almost<br />

identical to the values produced three years before<br />

(Schippers et al. 2005, Schippers and Neret<strong>in</strong> 2006),<br />

show<strong>in</strong>g the reproducibility of the real-time PCR analysis.<br />

The depth profiles of the aprA and dsrA gene copy<br />

numbers <strong>in</strong> Figure 1 are almost identical for both sediment<br />

sites. This result shows that ma<strong>in</strong>ly sulfate-reducers but not<br />

sulfur-oxidizers were detected s<strong>in</strong>ce aprA occurs <strong>in</strong> sulfuroxidizers<br />

and sulfate-reducers, and dsrA only <strong>in</strong> sulfatereducers.<br />

The number of both functional genes decrease<br />

with sediment depth together with the bacterial 16S rRNA<br />

gene copy numbers, however s<strong>in</strong>ce both functional genes<br />

occur <strong>in</strong> much smaller numbers than the bacterial 16S<br />

rRNA gene, sulfate-reducers are obviously only a m<strong>in</strong>or<br />

part of the bacterial community <strong>in</strong> agreement with previous<br />

dsrA data for the Peru marg<strong>in</strong> sediments (Schippers and<br />

Neret<strong>in</strong> 2006), Black Sea sediments and water column<br />

(Leloup et al. 2007, Neret<strong>in</strong> et al. 2007).<br />

In addition to the aprA gene quantification also its<br />

diversity was <strong>in</strong>vestigated us<strong>in</strong>g DGGE under the same<br />

PCR conditions as performed for the real-time PCR assay<br />

to the sediments samples from the Black Sea. The DGGE<br />

band patterns show a clear difference between surface and<br />

deeper sediment layers. The phylogenetic characterization<br />

of the dom<strong>in</strong>ant DNA bands from particular depths is<br />

currently conducted for the analysis.<br />

The novel aprA real-time PCR assay has also been<br />

applied to sediments (12 m depth) off the coast of Sumatra<br />

(FS Sonne SO189-2) and deep sediments (120 m depth)<br />

from the Peru marg<strong>in</strong> (ODP Leg 201 Station 1227). First<br />

data confirmed the above described results.<br />

References:<br />

A. Schippers, L. N. Neret<strong>in</strong>, J. Kallmeyer, T. G. Ferdelman, B. A. Cragg, R.<br />

J. Parkes and B. B. Jørgensen. 2005. Prokaryotic cells of the deep subseafloor<br />

biosphere identified as liv<strong>in</strong>g bacteria. Nature 433: 861-864.<br />

A. Blazejak, J. Kuever, C. Erséus, R. Amann, and N. Dubilier. 2006.<br />

Phylogeny of 16S rRNA, RubisCO, and APS reductase genes from<br />

gamma- and alphaproteobacterial symbionts <strong>in</strong> gutless mar<strong>in</strong>e worms<br />

(Oligochaeta) from Bermuda and Bahamas. Applied and<br />

Environmental Microbiology 72: 5527-5536.<br />

A. Schippers and L. N. Neret<strong>in</strong>. 2006. Quantification of microbial<br />

communities <strong>in</strong> near-surface and deeply buried mar<strong>in</strong>e sediments on<br />

the Peru cont<strong>in</strong>ental marg<strong>in</strong> us<strong>in</strong>g real-time PCR. Environmental<br />

Microbiology 8: 1251-1260.<br />

J. Leloup, A. Loy, N. J. Knab, C. Borowski, M. Wagner, and B. B.<br />

Jørgensen. 2007. Diversity and abundance of sulfate-reduc<strong>in</strong>g<br />

microorganisms <strong>in</strong> the sulfate and methane zones of a mar<strong>in</strong>e sediment,<br />

Black Sea. Environmental Microbiology 9: 131-142.<br />

L. N. Neret<strong>in</strong>, R. M. M. Abed, A. Schippers, C. J. Schubert, K. Kohl, and<br />

M. M. M. Kuypers. 2007. Inorganic carbon fixation by sulfate-reduc<strong>in</strong>g<br />

bacteria <strong>in</strong> the Black Sea water column. Environmental Microbiology<br />

9: 3019–3024.<br />

<strong>IODP</strong><br />

Low Temperature Alteration Carbonates <strong>in</strong><br />

the Ocean Crust and their Importance for<br />

CO2 Uptake and the Global Calcium Cycle<br />

FLORIAN BÖHM 1 , SVENJA RAUSCH 2 , ANTON EISENHAUER 1 ,<br />

WOLFGANG BACH 2 , ANDREAS KLÜGEL 2<br />

1<br />

IFM-GEOMAR, Kiel<br />

2<br />

Universität Bremen, Fachbereich Geowissenschaften<br />

Calcium carbonate precipitated <strong>in</strong> vugs, ve<strong>in</strong>s and<br />

vesicles of basaltic rocks of the ocean crust are an<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

important s<strong>in</strong>k for carbonate and calcium ions dissolved <strong>in</strong><br />

seawater and hydrothermal fluids. Nevertheless only rough<br />

estimates exist of the rates of uptake, which are based on a<br />

limited set of data derived from only a few ocean drill sites.<br />

DSDP, ODP and <strong>IODP</strong> sites have penetrated ocean crust<br />

sections of a wide range of ages and of crust formed at<br />

slow and fast spread<strong>in</strong>g ridges. A systematic evaluation of<br />

the available cores should help to better constra<strong>in</strong> CaCO3<br />

uptake rates and their temporal evolution. We have<br />

therefore recently started to log and sample CaCO3 filled<br />

vugs, ve<strong>in</strong>s and vesicles <strong>in</strong> cores from a range of ocean<br />

crust drill sites. First results po<strong>in</strong>t to variations of the<br />

carbonate ve<strong>in</strong> abundances related to sett<strong>in</strong>g and crustal<br />

age.<br />

The total calcium flux <strong>in</strong>to ocean crust basalt has been<br />

estimated previously as represent<strong>in</strong>g about 10 % of the<br />

total calcium output flux from the oceans (Alt & Teagle<br />

1999). First results from a study of the calcium isotopic<br />

composition of carbonate precipitates <strong>in</strong> the ocean crust<br />

(Am<strong>in</strong>i 2007) po<strong>in</strong>t to a significant fractionation dur<strong>in</strong>g<br />

precipitation. Therefore, these low temperature alteration<br />

(LTA) carbonates probably represent a significant factor <strong>in</strong><br />

the global ocean calcium isotope budget. They may help to<br />

expla<strong>in</strong> discrepancies <strong>in</strong> the Neogene calcium isotope<br />

budget that have recently been po<strong>in</strong>ted out by Fantle &<br />

DePaolo (2005). LTA carbonates may further be used as<br />

recorders of the ocean water calcium isotope composition<br />

and its variations dur<strong>in</strong>g the last 100 to 150 million years,<br />

complement<strong>in</strong>g and test<strong>in</strong>g exisit<strong>in</strong>g records based on<br />

biogenic carbonates and phosphates (e.g. Farkas et al.<br />

2007; Soudry et al. 2006).<br />

References:<br />

Alt, J.C., Teagle, D.A.H. (1999) The uptake of carbon dur<strong>in</strong>g alteration of<br />

ocean crust. Geochim. Cosmochim. Acta., 63, 1527-1535.<br />

Am<strong>in</strong>i, M. (2007) The Role of High- and Low-Temperature Ocean Crust<br />

Alteration for the Mar<strong>in</strong>e Calcium Budget. Ph.D. thesis, University of<br />

Kiel, 93pp.<br />

Fantle, M.S., DePaolo, D.J. (2005): Variations <strong>in</strong> the mar<strong>in</strong>e Ca cycle over<br />

the past 20 million years. Earth Planet. Sci. Lett., 237, 102-117.<br />

Farkaš J., Böhm F., Wallmann K., Blenk<strong>in</strong>sop J., Eisenhauer A., van<br />

Geldern R., Munnecke A., Voigt S., Veizer J. (2007): Calcium isotope<br />

record of Phanerozoic oceans: Implications for chemical evolution of<br />

seawater and its causative mechanisms. Geochim. Cosmochim. Acta,<br />

71, 5117-5134.<br />

Soudry, D., Glenn C.R., Nathan Y., Segal I., Vonderhaar D. (2006):<br />

Evolution of Tethyan phosphogenesis along the northern edges of the<br />

Arabian-African shield dur<strong>in</strong>g the Cretaceous-Eocene as deduced from<br />

temporal variations of Ca and Nd isotopes and rates of P accumulation.<br />

Earth Sci. Rev., 78, 27-57.<br />

<strong>IODP</strong><br />

A prelim<strong>in</strong>ary calcareous plankton<br />

biostratigraphy of the Paleocene-Eocene<br />

<strong>in</strong>terval at DSDP Site 401 (Bay of Biscay)<br />

A. BORNEMANN 1<br />

1 Institut für Geophysik und Geologie, Universität Leipzig,<br />

Talstrasse 35, D-04103 Leipzig<br />

The Paleogene period represents one of the most<br />

prom<strong>in</strong>ent long-term climate transitions <strong>in</strong> Earth history.<br />

The view of a Paleocene/early Eocene “greenhouse” is<br />

supported by numerous paleontological, isotopical and<br />

sedimentological f<strong>in</strong>d<strong>in</strong>gs suggest<strong>in</strong>g warm temperatures<br />

also <strong>in</strong> subpolar regions. Polar ice-sheets were either small<br />

or did not exist. Bottom water temperatures <strong>in</strong>ferred from<br />

benthic foram<strong>in</strong>iferal δ 18 O were substantially higher than <strong>in</strong><br />

modern oceans. The Paleocene/Eocene warmth culm<strong>in</strong>ated

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>in</strong> the Early Eocene Climatic Optimum (EECO; 55-51 Ma),<br />

and is subsequently followed by a long-term cool<strong>in</strong>g,<br />

which f<strong>in</strong>ally led to the Oligocene “icehouse”.<br />

As a first step towards a paleoceanographic study of<br />

this long-term climate change by employ<strong>in</strong>g calcareous<br />

nannofossils and planktic foram<strong>in</strong>ifera I present a<br />

calcareous plankton biostratigraphy for the late Paleocene<br />

to the Middle Eocene at DSDP Site 401. This site is<br />

situated <strong>in</strong> the Bay of Biscay and represents one of the<br />

most northern sites which provide Paleogene carbonates.<br />

Other DSDP/ODP sites which have previously been<br />

studied for this <strong>in</strong>terval are either from the equatorial<br />

oceans (Shatsky Rise, Allison Guyot, Demerara Rise) or<br />

the southern hemisphere (Maud Rise, Walvis Ridge).<br />

Therefore DSDP Site 401, which consists of a nearly<br />

cont<strong>in</strong>uous sedimentary record through the study <strong>in</strong>terval<br />

and provides well preserved calcareous nannofossils and<br />

planktic foram<strong>in</strong>ifera, will give us a more complete picture<br />

by consider<strong>in</strong>g also the northern hemisphere.<br />

<strong>IODP</strong><br />

The late-stage evolution of oceanic gabbros -<br />

Comb<strong>in</strong>ed experimental and <strong>in</strong>-situ isotope<br />

study on gabbros of the ODP Legs 118/176<br />

drilled at the Southwest Indian Ridge<br />

R.E. BOTCHARNIKOV 1 , J. KOEPKE 1 , I. HORN 1 , J. STICHNOTHE 1 , B.<br />

PUTLITZ 2<br />

1 Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong>, Call<strong>in</strong>str.<br />

3, 30167 <strong>Hannover</strong><br />

2 Institute of M<strong>in</strong>eralogy and Geochemistry, University of<br />

Lausanne, Anthropole, CH-1015 Lausanne,Switzerland<br />

R.Botcharnikov@m<strong>in</strong>eralogie.uni-hannover.de<br />

Gabbroic rocks from Hole 735B at the Southwest<br />

Indian Ridge (SWIR; Legs 118 and 176) represent the<br />

longest cont<strong>in</strong>uous section of oceanic lower crust ever<br />

drilled by ODP (Ocean Drill<strong>in</strong>g Program).<br />

The drill<strong>in</strong>g provides an <strong>in</strong>sight <strong>in</strong>to <strong>in</strong>teractive<br />

processes of crustal accretion, igneous differentiation,<br />

high-temperature crystal-plastic deformation, and cooler<br />

static hydrothermal alteration of the lower ocean crust at a<br />

very slowly spread<strong>in</strong>g ridge (Natland et al., 2002). About<br />

25% of the core is strongly <strong>in</strong>fluenced by late-stage<br />

magmatic processes lead<strong>in</strong>g to Fe-rich (ferrogabbros) and<br />

Si-rich (plagiogranites) compositions as end-members.<br />

Presumably two different major processes <strong>in</strong> the little<strong>in</strong>vestigated<br />

<strong>in</strong>terface between igneous and hydrothermal<br />

conditions were active dur<strong>in</strong>g the late-stage evolution of<br />

the deep SWIR crust: crystallization from a percolat<strong>in</strong>g Fe-<br />

Ti-rich late-stage melts and hydrous partial melt<strong>in</strong>g of<br />

solidified gabbro. For a comprehensive understand<strong>in</strong>g of<br />

the late magmatic processes, occurr<strong>in</strong>g <strong>in</strong> the deep oceanic<br />

crust, we present here an approach comb<strong>in</strong><strong>in</strong>g three<br />

experimental subprojects and one subproject focus<strong>in</strong>g on<br />

natural gabbros from the ~ 1500 m long section drilled at<br />

SWIR.<br />

For evaluat<strong>in</strong>g a typical late-stage composition as start<strong>in</strong>g<br />

material for our experiments, we follow an approach by<br />

consider<strong>in</strong>g fresh Fe-Ti-rich glasses from mid-ocean ridges<br />

(MOR) which can be regarded as frozen liquids generated<br />

by late-stage MORB differentiation occurr<strong>in</strong>g <strong>in</strong> the<br />

eruptive sequence of the oceanic crust. For this purpose we<br />

used analyses of MORB-type, fresh glasses from the<br />

"PETDB" database (Lehnert et al., 2000) from oceanic<br />

ridges all over the world, <strong>in</strong>clud<strong>in</strong>g all glasses from<br />

"normal" spread<strong>in</strong>g centers but exclud<strong>in</strong>g all data from<br />

back-arc spread<strong>in</strong>g centers which resulted <strong>in</strong> more than 14<br />

000 datasets. The late-stage composition (LS) of <strong>in</strong>terest<br />

which can be regarded as representative for a MORB latestage<br />

system for our experimental study, lies "at the end" of<br />

the ferrobasaltic trends, show<strong>in</strong>g high amounts of FeO,<br />

TiO2, and P 2O 5 (Table 1). In additon, the Si-rich<br />

composition (plagiogranite) for immiscibility experiments<br />

was evaluated as an average of 25 compositions analyzed<br />

<strong>in</strong> felsic ve<strong>in</strong>s from SWIR gabbro (Table 1).<br />

1) Phase relations and phase compositions <strong>in</strong> a typical<br />

late-stage system<br />

The understand<strong>in</strong>g of the late-stage processes with<strong>in</strong><br />

the deep oceanic crust requires the experimental data on the<br />

phase relations <strong>in</strong> a late-stage silicate system under<br />

conditions prevail<strong>in</strong>g at depth. Therefore, we have<br />

performed a phase-equilibria study <strong>in</strong> a typical late-stage<br />

system at 200 MPa with a special focus on the role of<br />

water, oxygen fugacity, and sulphur. The crystallization<br />

experiments were done <strong>in</strong> a range of temperatures from 850<br />

to 1050°C and water activities (aH2O) from 0.1 to 1 at two<br />

different fixed fH2 (correspond<strong>in</strong>g to the nom<strong>in</strong>al oxygen<br />

buffers QFM+4 and QFM+1, at aH2O=1). The ma<strong>in</strong><br />

phases are magnetite (MT), ilmenite (ILM), cl<strong>in</strong>opyroxene<br />

(CPX), plagioclase (PL), apatite (AP) and amphibole<br />

(AMPH) as illustrated <strong>in</strong> Fig.1.<br />

The results show that <strong>in</strong> this Fe- and Ti-rich late-stage<br />

system, Fe-Ti-oxides are the liquidus phases at both<br />

<strong>in</strong>vestigated redox conditions. However, due to<br />

experimental difficulties with Fe-rich system (Fe loss to the<br />

capsule material), the crystallization liquidus temperatures<br />

for oxide phases have not been exactly determ<strong>in</strong>ed. The<br />

oxides are followed by CPX, AP and PL, which is more<br />

stable at low water activity <strong>in</strong> the system. The AP<br />

crystallizes at temperature 2 wt.%<br />

P2O5, AP is stable also at 1050°C; see subproject 2). At<br />

reduced conditions, ILM appears at lower temperatures<br />

than CPX, whereas MT rema<strong>in</strong>s the liquidus phase (Fig. 1).<br />

Amphibole is stable at high aH2O and at temperatures<br />

lower than 900°C, which is surpris<strong>in</strong>gly low compared with<br />

the temperatures of AMPH crystallization <strong>in</strong> Fe-rich<br />

basaltic systems (i.e.,

28<br />

compositions (Toplis&Carroll, 1995; Thy et al., 2006;<br />

Botcharnikov et al, <strong>in</strong> revision). It must be noted that<br />

orthopyroxene is not stable <strong>in</strong> all <strong>in</strong>vestigated Fe-rich<br />

systems at studied experimental conditions. Experiments <strong>in</strong><br />

S-bear<strong>in</strong>g system (1 wt.% bulk S) show formation of<br />

additional S-bear<strong>in</strong>g phase: anhydrite (ANH) at oxidiz<strong>in</strong>g<br />

conditions and pyrhotite (PYR) at reduced conditions.<br />

Remarkable is that the phase stability and composition of<br />

the ma<strong>in</strong> m<strong>in</strong>eral assemblage (MT, ILM, CPX, AP,<br />

AMPH) is not significantly affected by added S.<br />

Temperature, °C<br />

Temperature, °C<br />

1200<br />

1150<br />

1100<br />

1050<br />

1000<br />

950<br />

900<br />

850<br />

800<br />

1200<br />

1150<br />

1100<br />

1050<br />

1000<br />

950<br />

900<br />

850<br />

800<br />

CPX<br />

Ap<br />

MT+IL<br />

QFM+4 Amph<br />

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0<br />

ILM <strong>in</strong><br />

QFM+1<br />

Ap <strong>in</strong><br />

a H2O<br />

MT+CPX <strong>in</strong><br />

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0<br />

a H2O<br />

Fig.1. Phase relations <strong>in</strong> the late stage magmas as a<br />

function of temperature and water activity at QFM+4 (a)<br />

and QFM+1 (b).<br />

(2) Experimental liquid immiscibility<br />

In the experiemntal approach aimed to understand<br />

whether liquid immiscibility does occur <strong>in</strong> natural hydrous<br />

tholeiitic systems under crustal pressure or not we used<br />

synthetic start<strong>in</strong>g materials with compositions similar to<br />

natural compositions from SWIR gabbros, where<br />

ferrogabbroic and felsic sections are associated. Two series<br />

of experiments have been conducted at 1050°C, 200 MPa<br />

and QFM+4 to <strong>in</strong>vestigate the mix<strong>in</strong>g ability of<br />

ferrobasaltic and plagiogranitic liquids. Three mixures of<br />

LS and felsic compositions were prepared <strong>in</strong> mass<br />

proportion of 80/20, 60/40 and 40/60, respectively, and<br />

were placed <strong>in</strong> Au capsules. Water was added <strong>in</strong> the<br />

amounts to simulate H2O-saturated and undersaturated<br />

conditions <strong>in</strong> melt mixtures. Another experimental<br />

approach was focused on the possible role of phosphorous<br />

PL<br />

PL <strong>in</strong><br />

Amph <strong>in</strong><br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>in</strong> the processes of immiscibility <strong>in</strong> LS system: a series of<br />

experiments with up to 10 wt.% bulk P2O5 added to the LS<br />

composition was run at the same T, P, fO2 conditions. The<br />

electron microprobe analyses of the experimental products<br />

from all runs do not reveal any traces of immiscible liquids,<br />

at least at the detection limit of electron microprobe. It<br />

must be noted, however, that recent experimental work of<br />

Veksler et al. (2007) showed that the separation of Fe-rich<br />

and Si-rich liquids might be controlled by k<strong>in</strong>etic<br />

nucleation barriers at the time-scale of laboratory<br />

experiments and coexistence of two liquids can be visible<br />

<strong>in</strong> some cases as f<strong>in</strong>e emulsions at nanoscale only. We plan<br />

one additional experimental series with Fe-enriched<br />

compositions, however, it will probably also result <strong>in</strong><br />

k<strong>in</strong>etic hamper<strong>in</strong>g of liquid unmix<strong>in</strong>g. Thus, although our<br />

experiments are probably unable to reproduce unmix<strong>in</strong>g <strong>in</strong><br />

natural systems, we can not exclude liquid separation<br />

occur<strong>in</strong>g at the time-scale on natural geological processes<br />

<strong>in</strong> deep oceanic crust.<br />

(3) Experimental percolation of late-stage melts<br />

through normal gabbro<br />

It is believed that a considerable part of the deep<br />

oceanic crust at SWIR was modified by a permeable flow<br />

of late Fe-rich melts through the just solidified gabbro pile,<br />

caus<strong>in</strong>g both dissolution-precipitation reactions and<br />

diffusion-controlled processes <strong>in</strong> the primary m<strong>in</strong>eral<br />

assemblages. We started an experimental simulation of<br />

these processes, by perform<strong>in</strong>g percolation experiments<br />

us<strong>in</strong>g a synthetic late-stage melt and a natural "pure"<br />

cumulate gabbro from Hole 735B.<br />

In the first run, the LS melt was pre-saturated with H2O<br />

at 1200°C and 200 MPa <strong>in</strong> Au 80Pd 20 capsule. The capsule<br />

was cut <strong>in</strong> several pieces (cyl<strong>in</strong>ders). The H2O-saturated<br />

cyl<strong>in</strong>der of LS composition was placed under the drilled<br />

cyl<strong>in</strong>der of natural gabbro and the result<strong>in</strong>g pair was closed<br />

shut <strong>in</strong> Au capsule, simulat<strong>in</strong>g scenario where hot gabbro<br />

<strong>in</strong>teracts with H2O-rich late-stage melt. In the second<br />

approach, the dry powder of LS was placed <strong>in</strong> the capsule,<br />

followed by ~5 wt.% bulk H2O and f<strong>in</strong>ally the cyl<strong>in</strong>der of<br />

natural gabbro. Such an assembladge simulated an<br />

<strong>in</strong>eraction between partly crystallized LS magma, gabbro<br />

and free fluid phase present at the <strong>in</strong>terface between LS<br />

melt and gabbro. Both capsules were run at 200 MPa,<br />

1050°C and fO2~QFM+1 for 48 hours.<br />

Fig 2. CT image of a product from percolation experiments.<br />

Shown are one length section (a) and two cross sections at<br />

different heights (b, c). Three different zones are visible: (1) an<br />

<strong>in</strong>ner core of unreacted gabbro; (2) a diffuse reaction zone<br />

surround<strong>in</strong>g the gabbroic core; (3) the frozen late-stage melt, now<br />

glass. Different phases can be recognized by their different gray<br />

levels. See text for details.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

In the first run, the LS melt was pre-saturated with H 2O<br />

at 1200°C and 200 MPa <strong>in</strong> Au80Pd 20 capsule. The capsule<br />

was cut <strong>in</strong> several pieces (cyl<strong>in</strong>ders). The H 2O-saturated<br />

cyl<strong>in</strong>der of LS composition was placed under the drilled<br />

cyl<strong>in</strong>der of natural gabbro and the result<strong>in</strong>g pair was closed<br />

shut <strong>in</strong> Au capsule, simulat<strong>in</strong>g scenario where hot gabbro<br />

<strong>in</strong>teracts with H2O-rich late-stage melt. In the second<br />

approach, the dry powder of LS was placed <strong>in</strong> the capsule,<br />

followed by ~5 wt.% bulk H 2O and f<strong>in</strong>ally the cyl<strong>in</strong>der of<br />

natural gabbro. Such an assembladge simulated an<br />

<strong>in</strong>eraction between partly crystallized LS magma, gabbro<br />

and free fluid phase present at the <strong>in</strong>terface between LS<br />

melt and gabbro. Both capsules were run at 200 MPa,<br />

1050°C and fO2~QFM+1 for 48 hours.<br />

For study<strong>in</strong>g the three-dimensional distribution of the<br />

percolat<strong>in</strong>g melt with<strong>in</strong> <strong>in</strong> the host gabbro, we applied an<br />

<strong>in</strong>novative new tool: High-resolution X-ray computed<br />

tomography (CT; collaboration with L. Baumgartner <strong>in</strong><br />

Lausanne, Switzerland). First rough CT analyses are shown<br />

<strong>in</strong> Fig. 2, further analysis with higher resolution is <strong>in</strong><br />

progress. S<strong>in</strong>ce this method must be used before destroy<strong>in</strong>g<br />

the experimental product for microprobe preparation, and<br />

s<strong>in</strong>ce the long-last<strong>in</strong>g measurements are still <strong>in</strong> progress,<br />

we do not have microanalytical results of the <strong>in</strong>volved<br />

phases, yet. The CT images show one length section and<br />

two cross sections <strong>in</strong> different heights of the cyl<strong>in</strong>der; the<br />

process<strong>in</strong>g of the composite 3-D computer model of the<br />

whole cyl<strong>in</strong>der is <strong>in</strong> progress. Our results show three<br />

different zones: (1) an <strong>in</strong>ner core of unreacted gabbro; (2) a<br />

diffuse, some hundred microns broad reaction zone<br />

surround<strong>in</strong>g the gabbroic core; (3) the frozen late-stage<br />

melt which was <strong>in</strong>itially placed only at one side of the<br />

capsule and which is now surround<strong>in</strong>g the whole <strong>in</strong>ner,<br />

gabbroic part of the cyl<strong>in</strong>der. In the reaction zone at least<br />

four different phases can be recognized by their different<br />

gray levels. We assume that <strong>in</strong> addition to the three phases<br />

of the primary gabbro (plagioclase, cl<strong>in</strong>opyroxene, oliv<strong>in</strong>e)<br />

one or more new phases, produced by melt reaction were<br />

generated. Detailed microprobe work which will be carried<br />

out after f<strong>in</strong>ish<strong>in</strong>g the CT <strong>in</strong>vestigations will shed light on<br />

the mechanism of the reaction, e.g., the quantitative<br />

treatment of precipitated (<strong>in</strong>terstitial) m<strong>in</strong>erals, or the<br />

record of diffusional processes. The comb<strong>in</strong>ed techniques<br />

of CT and microanalytical analyses will lead to the<br />

determ<strong>in</strong>ation of realistic rates of reaction and/or diffusion,<br />

enabl<strong>in</strong>g, for the first time, the quantification of the time<br />

scales on late-stage melt percolation ongo<strong>in</strong>g <strong>in</strong> the deep<br />

oceanic crust.<br />

(4) In-situ isotope analyses on late-stage parageneses <strong>in</strong><br />

natural rocks.<br />

S<strong>in</strong>ce it has been recently discussed whether late-stage<br />

magmatic processes can also be the result of hydrothermal<br />

circulation <strong>in</strong> the deep oceanic crust at very high<br />

(magmatic) temperatures, we applied <strong>in</strong>-situ isotope<br />

analyses on late-stage parageneses <strong>in</strong> natural rocks <strong>in</strong> order<br />

to discrim<strong>in</strong>ate between hydrous primary magmatic, and<br />

seawater-<strong>in</strong>duced late-stage processes. We used the LA-<br />

MC-ICPMS system, recently developed <strong>in</strong> <strong>Hannover</strong>,<br />

consist<strong>in</strong>g of a femtosecond laser and a multiple collector<br />

<strong>in</strong>ductively coupled plasma mass spectrometer on selected<br />

late-stage phases <strong>in</strong> the 735B gabbros <strong>in</strong> order to clarify the<br />

nature of these fluids, i.e., whether they are pure magmatic<br />

or seawater-<strong>in</strong>fluenced. Provided that the fluids show a<br />

general impr<strong>in</strong>t of seawater, these results may help to<br />

establish new cool<strong>in</strong>g models of the deep oceanic crust<br />

consider<strong>in</strong>g the additional cool<strong>in</strong>g effect of hydrothermal<br />

circulation at very high temperatures.<br />

First <strong>in</strong>-situ Sr isotope analyses are done. In spite of<br />

severe analytical difficulties (e.g. extreme low Sr<br />

concentration <strong>in</strong> the correspond<strong>in</strong>g An-enriched<br />

plagioclases, irregularities due to variable concentrations<br />

of N2 <strong>in</strong> the Ar used so far based on a bottle supply), first<br />

reliable <strong>in</strong>-situ Sr measurements on An-enriched<br />

plagioclases from a 735B gabbro from SWIR reveal<br />

enriched<br />

29<br />

87 Sr/ 86 Sr-ratios, imply<strong>in</strong>g an <strong>in</strong>fluence of<br />

seawater-derived fluids dur<strong>in</strong>g formation.<br />

The <strong>in</strong>-situ iron isotope measurements on a late-stage<br />

oxide paragenesis <strong>in</strong> a 735B gabbro from SWIR, consist<strong>in</strong>g<br />

of ilmenite-magnetite-pyrrhotite, reveal that the pyrrhotite<br />

cannot be <strong>in</strong> isotopic equilibrium with magnetite and<br />

ilmenite which is suggested by the texture. Most probably,<br />

the pyrrhotite was formed by sulfidic precursor material<br />

which was previously altered by seawater, or the pyrrhotite<br />

was re-equilibrated <strong>in</strong> the presence of seawater at high<br />

temperature after the formation of this paragenesis.<br />

References:<br />

Botcharnikov R.E. et al. (<strong>in</strong> revision) Experimental phase relations, m<strong>in</strong>eralmelt<br />

equilibria and liquid l<strong>in</strong>es of descent <strong>in</strong> a hydrous ferrobasalt -<br />

Implications for the Skaergaard <strong>in</strong>trusion and Columbia River flood<br />

basalts. J.Petrol.<br />

Natland J.H., Dick H..J.B., Miller D.J., Von Herzen R.P., (Eds.), 2002. Proc.<br />

ODP, Sci. Results, 176 [CD-ROM]. Available: Ocean Drill<strong>in</strong>g<br />

Program, Texas A&M University, College Station TX 77845-9547,<br />

USA.<br />

Lehnert K., Su Y., Langmuir C.H., Sarbas B., Nohl U. (2000) A global<br />

geochemical database structure for rocks. Geochem Geophys Geosyst<br />

1: 1999GC000026.<br />

Thy P. et al. (2006) Experimental constra<strong>in</strong>ts on the Skaergaard liquid l<strong>in</strong>e<br />

of descent. Lithos 92(1-2), 154-180.<br />

Toplis M. J. & Carroll M. R. (1995) An experimental study of the <strong>in</strong>fluence<br />

of oxygen fugacity on Fe-Ti oxide stability, phase relations, and<br />

m<strong>in</strong>eral-melt equilibra <strong>in</strong> ferro-basaltic systems. J. Petrol. 36(5), 1137-<br />

1170.<br />

Veksler IV, Dorfman AM, Borisov AA, et al. (2007) Liquid immiscibility<br />

and the evolution of basaltic magma. J. Petrol. 48, 2187-2210.<br />

<strong>IODP</strong><br />

How is black shale formation <strong>in</strong> the Early<br />

Eocene Arctic Ocean <strong>in</strong>fluenced by export of<br />

terrestrial organic matter? Details from an<br />

organic petrological approach on mar<strong>in</strong>e<br />

sediments from <strong>IODP</strong> Hole 302 (Lomonosov<br />

Ridge)<br />

B.BOUCSEIN 1 , J.KNIES 2 , R.STEIN 3<br />

1 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research,<br />

Research Unit Potsdam, D-14473 Potsdam, Germany<br />

2 Geological Survey of Norway, NO-7491 Trondheim, Norway<br />

3 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, D-27568<br />

Bremerhaven, Germany<br />

In 2004 the <strong>IODP</strong> Expedition 302 (ACEX) recovered a<br />

430m thick sequence of upper Cretaceous to Quaternary<br />

sediments on the Lomonosov Ridge <strong>in</strong> the central Arctic<br />

Ocean (Backman et al. 2006). For the first time <strong>in</strong>sights <strong>in</strong><br />

the environmental Pre-Pleistocene history of the Arctic<br />

Ocean are possible (see e.g. Br<strong>in</strong>khuis et al. 2006, Moran et<br />

al. 2006). Our results of the organic geochemical basis<br />

parameters (total organic carbon (TOC), stable carbon<br />

isotopes (δ13C), total organic carbon/total nitrogen (C/N)<br />

ratios, total organic carbon/total sulphur (C/S) ratios,<br />

Hydrogen <strong>in</strong>dices) and first maceral data on the entire ca.

30<br />

200m thick Paleogene organic carbon (OC) rich section<br />

have been published recently (Ste<strong>in</strong> et al. 2006).<br />

Here, we will focus on the black shales formed dur<strong>in</strong>g<br />

the global δ 13 C-events Paleocene/Eocene Thermal<br />

Maximum (PETM) and Elmo. New detailed organic<br />

petrographical data (maceral analysis) are compared with<br />

the results of organic geochemistry (basis parameter,<br />

organic and <strong>in</strong>organic nitrogen fraction). Such comb<strong>in</strong>ed<br />

petrographical and organic geochemical approaches were<br />

established dur<strong>in</strong>g the last decades, especially to solve<br />

questions concern<strong>in</strong>g the paleoenvironmental conditions of<br />

recent and ancient mar<strong>in</strong>e deposits.<br />

Dur<strong>in</strong>g the Paleocene/Eocene the Early Arctic Ocean<br />

was an enclosed bas<strong>in</strong> <strong>in</strong>fluenced by warm surface-water<br />

temperatures as <strong>in</strong>dicated by TEX86’ data (Sluijs et al.<br />

2006). Data on e.g. radiolarians, terrestrial palynomorphs<br />

(Backman et al. 2006) and maceral data (Boucse<strong>in</strong> and<br />

Ste<strong>in</strong>, subm.) give evidence for river run-off caus<strong>in</strong>g lowsurface<br />

sal<strong>in</strong>ity. Therefore, fluvial nutrient supply may<br />

have <strong>in</strong>duced primary productivity as it is also suggested<br />

from the abundances of mar<strong>in</strong>e diatoms and diatom rest<strong>in</strong>g<br />

spores (Backman et al. 2006). The isolated position of the<br />

Arctic Ocean dur<strong>in</strong>g that time comb<strong>in</strong>ed with freshwater<br />

discharge support the idea of OC accumulation <strong>in</strong> an<br />

anoxic bas<strong>in</strong> with a stratified water column. We found<br />

abundances of f<strong>in</strong>ely dispersed and small sized pyrite<br />

framboids (20%) are found and correlate with <strong>in</strong>creased OI values<br />

(200-400mg CO2/gC). Moreover, we found pyrofus<strong>in</strong>ite <strong>in</strong><br />

the <strong>in</strong>ert<strong>in</strong>ite fraction which is <strong>in</strong>terpreted as an <strong>in</strong>dicator<br />

for vegetation fires <strong>in</strong> the h<strong>in</strong>terland.<br />

Drastic environmental changes are supposed for the<br />

depostion of the ACEX black-shales dur<strong>in</strong>g the Early<br />

Eocene. Especially dur<strong>in</strong>g the PETM and Elmo event a<br />

significant <strong>in</strong>crease <strong>in</strong> the 'aquatic/mar<strong>in</strong>e group' is found.<br />

High amounts of alg<strong>in</strong>itic material (40-45%) and bitum<strong>in</strong>ite<br />

(up to 50%) together with <strong>in</strong>creased HI values (250-300<br />

mgHC/gC) are found. Characteristically are the f<strong>in</strong>ely<br />

lam<strong>in</strong>ated sediments of bitum<strong>in</strong>itic layers, <strong>in</strong>clud<strong>in</strong>g well<br />

preserved alg<strong>in</strong>ite bodies of freshwater and mar<strong>in</strong>e orig<strong>in</strong>.<br />

Here, the major aquatic macerals are lamalg<strong>in</strong>ite and<br />

liptodetr<strong>in</strong>ite (fragmented lipt<strong>in</strong>itic particles

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Littke, R. (1993): Deposition, diagenesis, and weather<strong>in</strong>g of organic matterrich<br />

sediments: Lect. Earth Sci. 47, Berl<strong>in</strong>, Spr<strong>in</strong>ger Verlag, 217 p.<br />

Moran, K., Backman, J., Br<strong>in</strong>khuis, H., Clemens, S.C., Cron<strong>in</strong>, T., Dickens,<br />

G.R., Eynaud, F., Gattacceca, J., Jakobsson, M., Jordan, R.W.,<br />

Kam<strong>in</strong>ski, M., K<strong>in</strong>g, J., Koc, N., Krylov, A., Mart<strong>in</strong>ez, N.,<br />

Matthiessen, J., McInroy, D., Moore, T.C., Onodera, J., O’Regan,<br />

A.M., Pälike, H., Rea, B. Rio, D., Sakamoto, T. Smith, D.C., Ste<strong>in</strong>, R.,<br />

John, K., Suto, I., Suzuki, N., Takahashi, K., Watanabe, M.,<br />

Yamamoto, M., Frank, M., Jokat, W., Kristoffersen, Y. (2006): The<br />

Cenozoic paleoenvironment of the Arctic Ocean. Nature 441, 601-605.<br />

Sluijs, A., Schouten, S., Pagani, M., Wolter<strong>in</strong>g, M., Br<strong>in</strong>khuis, H.,<br />

S<strong>in</strong>n<strong>in</strong>ghe Damsté, J.S., Dickens, G.R., Huber, M., Reichart, G.J, Ste<strong>in</strong>,<br />

R., Matthiessen, J., Lourens, L.J., Pedentchouk, N., Backman, J.,<br />

Moran, K. , the Expedition 302 Scientists, 2006. Subtropical Arctic<br />

Ocean temperatures dur<strong>in</strong>g the Paleocene Eocene thermal maximum,<br />

Nature, 441, 610-613.<br />

Ste<strong>in</strong>, R., Boucse<strong>in</strong>, B. and Meyer, H. (2006): Anoxia and high primary<br />

production <strong>in</strong> the Paleogene central Arctic Ocean: First detailed records<br />

from Lomonosov Ridge, Geophys. Res. Lett., 33, L18606. doi:<br />

10.1029/2006GL026776<br />

31

32<br />

<strong>ICDP</strong><br />

The different degass<strong>in</strong>g behaviour of upper<br />

mantle-derived fluids <strong>in</strong> the western Eger rift<br />

area – a detailed characterization of a hidden<br />

presently active magmatic process<br />

K. BRÄUER 1 , H. KÄMPF 2 , K. HAHNE 3 , G. STRAUCH 1<br />

1 Helmholtz Centre for Environmental Research -UFZ<br />

2 GeoForschungsZentrum Potsdam a Helmholtz Centre<br />

3 Bundesanstalt für Geowissenschaften und Rohstoffe, <strong>Hannover</strong><br />

The figure 1 rem<strong>in</strong>ds at the situation with<strong>in</strong> the shallow<br />

Neogene Cheb bas<strong>in</strong>. The position of our monitor<strong>in</strong>g<br />

locations is shown <strong>in</strong> relation to the major fault zones as<br />

well as to the epicentral areas of two micro-swarms which<br />

have taken place dur<strong>in</strong>g our <strong>in</strong>vestigation period. As a<br />

result of the detailed fluid monitor<strong>in</strong>g studies before,<br />

dur<strong>in</strong>g and after the seismically active period 2000 could<br />

be shown that the sensitivity of the locations due to<br />

seismically <strong>in</strong>duced changes of the fluid characteristics<br />

depends on the distance to the hypocenter and to active<br />

fault (Bräuer et al. submitted).<br />

The cont<strong>in</strong>ued monthly monitor<strong>in</strong>g of the gas and<br />

isotope composition have been focused to locations closed<br />

to the faults. Two micro-swarms have been established <strong>in</strong><br />

June 2005 and February 2007 and seismically <strong>in</strong>duced<br />

release of crustal-derived helium has been observed aga<strong>in</strong>.<br />

The spr<strong>in</strong>gs Kopan<strong>in</strong>a and U Mostku are characterized by<br />

greater variations of the gas and isotope composition than<br />

the Bublák mofette. At both locations the gas flux is clearly<br />

lower than at the Bublák mofette although at all three<br />

locations the gas percolates only through low m<strong>in</strong>eralised<br />

water and with low pH values. The production of HCO3 -<br />

may be negligibly and therefore not responsibly for the<br />

observed variations of the δ 13 C values<br />

But more <strong>in</strong>terest<strong>in</strong>gly there is a clear contemporaneous<br />

<strong>in</strong>crease of the 3 He/ 4 He ratios at locations U Mostku and<br />

Bublák along the Počatky Plesná fault zone (Fig. 2) for<br />

about three months. This <strong>in</strong>crease of mantle-derived helium<br />

from March to May 2006 may be an <strong>in</strong>dication of a small<br />

magmatic (dyke) <strong>in</strong>trusion at the PPZ from uppermost<br />

mantle <strong>in</strong>to the lower crust. An <strong>in</strong>crease of upper mantlederived<br />

helium is <strong>in</strong>dicated at Kopan<strong>in</strong>a, too. The reason<br />

for the smaller <strong>in</strong>crease of mantle helium may be that the<br />

helium content of the Kopan<strong>in</strong>a gas is considerably higher<br />

than at the other locations and so a small addition of mantle<br />

helium can not be observed so clearly. On the other hand,<br />

the supply with mantle-helium could take place<br />

preferentially along the PPZ. However the helium transport<br />

can not be separated from the CO2 the major component of<br />

the magmatic fluids which act as carrier for the helium.<br />

Several clear δ 13 C shifts were found before and dur<strong>in</strong>g the<br />

period of <strong>in</strong>creased 3He/4He ratios at all monitor<strong>in</strong>g<br />

<strong>ICDP</strong><br />

The different degass<strong>in</strong>g behaviour of upper<br />

mantle-derived fluids <strong>in</strong> the western Eger rift<br />

area – a detailed characterization of a hidden<br />

presently active magmatic process<br />

K. BRÄUER 1 , H. KÄMPF 2 , K. HAHNE 3 , G. STRAUCH 1<br />

1 Helmholtz Centre for Environmental Research -UFZ<br />

2 GeoForschungsZentrum Potsdam a Helmholtz Centre<br />

3 Bundesanstalt für Geowissenschaften und Rohstoffe, <strong>Hannover</strong><br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

The figure 1 rem<strong>in</strong>ds at the situation with<strong>in</strong> the shallow<br />

Neogene Cheb bas<strong>in</strong>. The position of our monitor<strong>in</strong>g<br />

locations is shown <strong>in</strong> relation to the major fault zones as<br />

well as to the epicentral areas of two micro-swarms which<br />

have taken place dur<strong>in</strong>g our <strong>in</strong>vestigation period. As a<br />

result of the detailed fluid monitor<strong>in</strong>g studies before,<br />

dur<strong>in</strong>g and after the seismically active period 2000 could<br />

be shown that the sensitivity of the locations due to<br />

seismically <strong>in</strong>duced changes of the fluid characteristics<br />

depends on the distance to the hypocenter and to active<br />

fault (Bräuer et al. submitted).<br />

The cont<strong>in</strong>ued monthly monitor<strong>in</strong>g of the gas and<br />

isotope composition have been focused to locations closed<br />

to the faults. Two micro-swarms have been established <strong>in</strong><br />

June 2005 and February 2007 and seismically <strong>in</strong>duced<br />

release of crustal-derived helium has been observed aga<strong>in</strong>.<br />

The spr<strong>in</strong>gs Kopan<strong>in</strong>a and U Mostku are characterized by<br />

greater variations of the gas and isotope composition than<br />

the Bublák mofette. At both locations the gas flux is clearly<br />

lower than at the Bublák mofette although at all three<br />

locations the gas percolates only through low m<strong>in</strong>eralised<br />

water and with low pH values. The production of HCO3 -<br />

may be negligibly and therefore not responsibly for the<br />

observed variations of the δ 13 C values<br />

But more <strong>in</strong>terest<strong>in</strong>gly there is a clear contemporaneous<br />

<strong>in</strong>crease of the 3 He/ 4 He ratios at locations U Mostku and<br />

Bublák along the Počatky Plesná fault zone (Fig. 2) for<br />

about three months. This <strong>in</strong>crease of mantle-derived helium<br />

from March to May 2006 may be an <strong>in</strong>dication of a small<br />

magmatic (dyke) <strong>in</strong>trusion at the PPZ from uppermost<br />

mantle <strong>in</strong>to the lower crust. An <strong>in</strong>crease of upper mantlederived<br />

helium is <strong>in</strong>dicated at Kopan<strong>in</strong>a, too. The reason<br />

for the smaller <strong>in</strong>crease of mantle helium may be that the<br />

helium content of the Kopan<strong>in</strong>a gas is considerably higher<br />

than at the other locations and so a small addition of mantle<br />

helium can not be observed so clearly. On the other hand,<br />

the supply with mantle-helium could take place<br />

preferentially along the PPZ. However the helium transport<br />

can not be separated from the CO2 the major component of<br />

the magmatic fluids which act as carrier for the helium.<br />

Several clear δ 13 C shifts were found before and dur<strong>in</strong>g the<br />

period of <strong>in</strong>creased 3 He/ 4 He ratios at all monitor<strong>in</strong>g<br />

locations.Dur<strong>in</strong>g the period of exam<strong>in</strong>ation<br />

superimposition of both effects - seismically <strong>in</strong>duced<br />

release of crustal components and the <strong>in</strong>crease of mantlederived<br />

components - have to be taken <strong>in</strong>to account. This<br />

fact makes the <strong>in</strong>terpretation of the distribution pattern<br />

more difficult. Up to now no isotope data are available<br />

accompany<strong>in</strong>g such hidden actual non-volcanic magmatic<br />

process at depth range of uppermost mantle/lower crust.<br />

Based on the isotope signature (He, CO2) it is assumed<br />

that the Mt. Etna volcano is supplied by upper mantlederived<br />

fluids. The δ 13 C values of this prist<strong>in</strong>e magmatic<br />

gas range between -2 and -1‰. Here, the monthly sampl<strong>in</strong>g<br />

at CO2 rich natural gas emissions resulted <strong>in</strong> the<br />

observation of variations of the gas composition, δ 13 C<br />

variations as well as of the 3 He/ 4 He ratios <strong>in</strong> terms of<br />

progressive gas release from separate batches of magma<br />

ascend<strong>in</strong>g <strong>in</strong> a step-wise manner. The observed anomalies<br />

have been <strong>in</strong>terpreted as <strong>in</strong>dications of <strong>in</strong>creased magmatic<br />

degass<strong>in</strong>g from an up-ris<strong>in</strong>g body of fresh magma<br />

(Pecora<strong>in</strong>o and Giammanco, 2005).<br />

In spr<strong>in</strong>g 2007 we repeated the annual sampl<strong>in</strong>g at<br />

several locations of the Cheb bas<strong>in</strong> and of the Mariánské

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig.1 Sampl<strong>in</strong>g locations <strong>in</strong> relation to major faults (MLF =<br />

Mariánské Lázně fault zone; PPZ = Počatky-Plesná fault zone) and<br />

to the Nový Kostel focal zone. The stars mark the June 2005 and<br />

February 2007 micro-swarms. Dashed are the CO2-mapped areas.<br />

The po<strong>in</strong>ted area marks a mofette field that has been characterised<br />

by measurements of CO2-soil gas, gas flux, 13C and 3 He/ 4 He<br />

ratios.<br />

Lázně degass<strong>in</strong>g centre, too. The level of upper mantlederived<br />

helium <strong>in</strong> the eastern part of the Cheb bas<strong>in</strong> is on<br />

the same level as 2005 and consequently still clearly higher<br />

than 1994 whereas the 3 He/ 4 He ratios at the degass<strong>in</strong>g<br />

locations of Mariánské Lázně are nearly the same like 1994<br />

and show only small variations. Further could be confirmed<br />

that the highest values were found at the mofettes along the<br />

PPZ between Hartoušov and Milhostov. At the previous<br />

sampl<strong>in</strong>g 2006 we had found still higher 3 He/ 4 He ratios at<br />

the mofettes Dolni Častkov and Hartoušov. The regional<br />

sampl<strong>in</strong>g has been taken place <strong>in</strong> April 2006 and these high<br />

values are <strong>in</strong> consistence with period of <strong>in</strong>creased 3 He/ 4 He<br />

ratios at the monitor<strong>in</strong>g locations (Fig. 2) and support these<br />

f<strong>in</strong>d<strong>in</strong>gs. That means <strong>in</strong>dications for magma ascent <strong>in</strong> 2006<br />

have been found at all degass<strong>in</strong>g locations along the PPZ as<br />

well as at the Mariánské Lázně fault zone (MLF) (Fig. 1),<br />

however the highest values are measured along the PPZ.<br />

The situation seems to be different <strong>in</strong> the western part of<br />

the Cheb bas<strong>in</strong>. The long-time trend at the Kaiserquelle<br />

(Soos) - unfortunately the sole location, where we have<br />

taken samples several times - shows no <strong>in</strong>crease of mantle<br />

helium. There are high CO2 fluxes with clear upper mantlederived<br />

helium <strong>in</strong> the nature reserve Soos and Františkový<br />

Lázně but apparently no <strong>in</strong>crease of the mantle helium<br />

level.<br />

In 2006 a detailed mapp<strong>in</strong>g of <strong>in</strong>dications for CO2<br />

degass<strong>in</strong>g have been carried out between Hartoušov and<br />

Oldřišska. Based on this mapp<strong>in</strong>g soil CO2 measurements<br />

have been <strong>in</strong>volved consequently <strong>in</strong> the <strong>in</strong>vestigation<br />

program. In the spr<strong>in</strong>gtime 2007 we have started a soil gas<br />

mapp<strong>in</strong>g <strong>in</strong> the ma<strong>in</strong> degass<strong>in</strong>g area of the PPZ between<br />

Milhostov and Hartoušov south (Fig. 1). More than 400<br />

soil gas measurements were carried out from mid of April<br />

to end of May, 2007. The soil gas measurements have been<br />

carried out at soil depths between 0.6 and 0.8 m us<strong>in</strong>g with<br />

a mobile NDIR-Photometer system. The distance between<br />

measur<strong>in</strong>g po<strong>in</strong>ts varied from 5 to 10 m. Twelve sub-areas<br />

have been selected based on the mapp<strong>in</strong>g results of 2006<br />

and <strong>in</strong>vestigated from north to south between Milhostov<br />

and Hartoušov south. As a result l<strong>in</strong>ear strik<strong>in</strong>g Diffuse<br />

Degass<strong>in</strong>g Structure (DDS) have been found <strong>in</strong> the subfield<br />

Hartoušov whereas the data of sub-field Bublák north<br />

tend to oval-shaped DDS. The term Diffuse Degass<strong>in</strong>g<br />

Structures (DDS) was <strong>in</strong>troduced by Chiod<strong>in</strong>i et al. (2001).<br />

The soil gas measurements <strong>in</strong> the surround<strong>in</strong>g of Bublák let<br />

us assume a large highly permeable degass<strong>in</strong>g zone<br />

(dimension: ca. 1 km <strong>in</strong> length and 0.5 km <strong>in</strong> width, signed<br />

as grey area <strong>in</strong> Fig. 3). The strike direction of the Bublák<br />

degass<strong>in</strong>g zone is 340°, which corresponds to the ma<strong>in</strong><br />

strike direction of the PPZ. The distribution pattern of<br />

Hartoušov and surround<strong>in</strong>g, po<strong>in</strong>t to more isolated<br />

structures. The soil gas measurements aimed to trace the<br />

PPZ <strong>in</strong> more detail to get <strong>in</strong>dications for CO2 migration<br />

paths and the <strong>in</strong>ternal structures of the fault zone. Us<strong>in</strong>g<br />

results of Bankwitz et al. (2003) and Schunk et al. (2005)<br />

the PPZ is to specify as active bl<strong>in</strong>d fault zone. We have<br />

used the carbon dioxide concentration <strong>in</strong> soil gas for<br />

trac<strong>in</strong>g bl<strong>in</strong>d fault segments <strong>in</strong> accord<strong>in</strong>g to Ch<strong>in</strong>g-Chou Fu<br />

et al. (2005).<br />

33

34<br />

The understand<strong>in</strong>g of fault zone weaken<strong>in</strong>g connected<br />

with fluid- and seismically active processes along the<br />

<strong>in</strong>tersection of the PPZ zone and the MLF zone has to be<br />

supported by quantify<strong>in</strong>g the gas flux. Therefore beneath<br />

the soil gas mapp<strong>in</strong>g gas flow measurement at water-filled<br />

mofettes have been started. Funnels with diameters up to<br />

0.70 m we used to cover the mofettes. The gas flow was<br />

measured us<strong>in</strong>g gas flow meters (Ritter/TG05/5, TG5/5,<br />

TG25-5) with different sensibility due to different strong<br />

gas flow. The summarized gas flow rate of 15 measur<strong>in</strong>g<br />

po<strong>in</strong>ts of the mofette field Bublák was about 28,000 L/h<br />

measured 1995/96 (We<strong>in</strong>lich et al. (1998). In 2007 we have<br />

measured about 34,000 L/h for the same area. This f<strong>in</strong>d<strong>in</strong>g<br />

corresponds to an <strong>in</strong>creased gas flow rate of approximately<br />

20% s<strong>in</strong>ce 1996.<br />

Figure 3 shows the position of gas rich vents <strong>in</strong>clud<strong>in</strong>g<br />

their isotope signatures and po<strong>in</strong>ts to the great<br />

importance of Bublák mofette field (grey marked).<br />

Our latest results suppose that the detected degass<strong>in</strong>g<br />

area <strong>in</strong> the surround<strong>in</strong>g of Bublák which is characterized by<br />

a extreme high level of gas flow comb<strong>in</strong>ed with a subcont<strong>in</strong>ental<br />

isotopic signature of the free gas phase is the<br />

structure segment <strong>in</strong>side of the Počatky-Plesná fault act<strong>in</strong>g<br />

as deep-reach<strong>in</strong>g mantle-fluid <strong>in</strong>jection zone.<br />

The ris<strong>in</strong>g upper mantle-derived helium portions<br />

between 1993 and 2007, the <strong>in</strong>crease of the gas flux rate of<br />

the Bublák mofette field between 1995 and 2007, and the<br />

three months last<strong>in</strong>g contemporaneous <strong>in</strong>crease of the<br />

3 He/ 4 He ratios at U Mostku and Bublák <strong>in</strong> 2006 po<strong>in</strong>t to a<br />

long last<strong>in</strong>g active magmatic processes beneath the area<br />

comparable to the magmatic unrest beneath Mammoth<br />

Mounta<strong>in</strong>, California (Hill and Prejean, 2005).<br />

In Europe, it is the first time that such hidden, presently<br />

active magmatic process has been discovered and<br />

successfully acompanied by detailed isotope-geochemical<br />

monitor<strong>in</strong>g studies.<br />

Fig. 2 Time-series of the 3 He/ 4 He ratios of the monitor<strong>in</strong>g locations<br />

with<strong>in</strong> the Cheb bas<strong>in</strong> between April 2005 and August 2007.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 3 The po<strong>in</strong>ted area marks the characterised mofette field. The<br />

dimension of the stars correspond to the gas flux, the numbers<br />

present the 13C values (above) and the 3 He/ 4 He ratios as R/Ra<br />

values (below) of s<strong>in</strong>gle vents, respectively.<br />

References:<br />

Bräuer K., H. Kämpf, S. Niedermann, G. Strauch and J. Tesař, The natural<br />

laboratory NW Bohemia – Comprehensive fluid studies between 1992<br />

and 2005 to trace geodynamic processes. Submitted to Geochemistry,<br />

Geophysics, Geosystems<br />

Chiod<strong>in</strong>i G., F. Frond<strong>in</strong>i, C. Cardell<strong>in</strong>i, D. Granieri, L. Mar<strong>in</strong>i and G.<br />

Ventura, CO2 degass<strong>in</strong>g and energy release at Solfatara volcano,<br />

Campi Flegrei, Italy, J. Geophys. Res. 106, B8, 16,213-16,221, 2001.<br />

Fu C.-C, T. F. Yang, V. Walita and C.-H. Chen, Reconnaissance of soil gas<br />

composition over the buried fault and fracture zone <strong>in</strong> southern Taiwan,<br />

Geochem. J. 39, 427-439, 2005.<br />

Hill D.P. and S. Prejean.: Magmatic unrest beneath Mammoth Mounta<strong>in</strong>,<br />

California, J. Volcanol. Geotherm. Res. 146, 257-283, 2005.<br />

Pecora<strong>in</strong>o G,, Giammanco S., Geochemical characterization and temporal<br />

changes <strong>in</strong> parietal gas emissions at Mt. Etna (Italy) dur<strong>in</strong>g the period<br />

July 2000 – July 2003, TAO 16, 805-841, 2005.<br />

Schunk R., A. Peterek and C.-D. Reuther, Stop 6a-c.- In: Kämpf H., A.<br />

Peterek, J. Rohrmüller, H.-J. Kümpel and W.H. Geissler (Eds.), The<br />

KTB Deep Crustal Laboratory and the western Eger Graben,<br />

Schriftenreihe der Deutschen Gesellschft für Geowissenschaften, H.<br />

40, 65-71, 2005.<br />

We<strong>in</strong>lich, F.H., J. Tesar, S.M. Weise, K. Bräuer and H. Kämpf, Gas flux<br />

distribution <strong>in</strong> m<strong>in</strong>eral spr<strong>in</strong>gs and tectonic structure <strong>in</strong> the western<br />

Eger Rift, J. Czech Geol. Soc. 43/1-2, 91-110, 1998.<br />

<strong>ICDP</strong><br />

Active and passive seismic images of the San-<br />

Andreas-Fault at SAFOD<br />

S. BUSKE 1 , S. GUTJAHR 1 , S. RENTSCH 1 , A., RESHETNIKOV 1 , S.<br />

SHAPIRO 1<br />

1 Freie Universität Berl<strong>in</strong>, Institute for Geological Sciences,<br />

Malteserstrasse 74-100, 12249 Berl<strong>in</strong>, Germany,<br />

buske@geophysik.fu-berl<strong>in</strong>.de<br />

High-quality active and passive seismic data have been<br />

acquired <strong>in</strong> the vic<strong>in</strong>ity of the San-Andreas-Fault (SAF)<br />

system with<strong>in</strong> EarthScope project SAFOD (San-Andreas-<br />

Fault Observatory at Depth). We have processed parts of<br />

the available data sets us<strong>in</strong>g newly developed techniques <strong>in</strong><br />

order to derive a high-resolution image of the subsurface <strong>in</strong><br />

the vic<strong>in</strong>ity of the fault system.<br />

On one hand we applied Fresnel-Volume-Migration to<br />

the SAFOD2003 reflection seismic data set. This imag<strong>in</strong>g<br />

approach delivers high-quality images with many steeply<br />

dipp<strong>in</strong>g structures related to the SAF system. On the other<br />

hand we applied a novel migration-type location algorithm<br />

to passive seismic data recorded <strong>in</strong> the SAFOD ma<strong>in</strong> hole.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

We have located a number of local events <strong>in</strong> the vic<strong>in</strong>ity of<br />

the fault system. Most of the located events show a clear<br />

correlation to the obta<strong>in</strong>ed structural fault image. A<br />

modification of the location algorithm also allowed the<br />

precise location of a so called ‘target event’, which was the<br />

subject of the planned drill<strong>in</strong>g activities <strong>in</strong> SAFOD Phase<br />

3.<br />

We have comb<strong>in</strong>ed our results (target events, structural<br />

image) with additional available <strong>in</strong>formation (seismicity,<br />

borehole logs, shallow seismic images, etc.). Altogether<br />

this comb<strong>in</strong>ed image provides a basis for a comb<strong>in</strong>ed<br />

<strong>in</strong>terpretation of the structure and the earthquake dynamics<br />

of this mega-shear zone on different scales and <strong>in</strong> particular<br />

<strong>in</strong> the vic<strong>in</strong>ity of the SAFOD borehole.<br />

Active seismic imag<strong>in</strong>g<br />

In the year 2003 an approximately 50 km long<br />

comb<strong>in</strong>ed reflection/refraction profile has been acquired<br />

perpendicular to the strike of the San-Andreas-Fault-<br />

System at Parkfield (California, USA) (Hole et al. 2006,<br />

Bleib<strong>in</strong>haus et al. 2006). The survey layout consisted of<br />

912 three-component receivers for each shot along the<br />

whole profile. We used the vertical component of 42 shot<br />

gathers of this data set. The preprocess<strong>in</strong>g consisted of<br />

bandpass filter<strong>in</strong>g, AGC and trace normalization. In<br />

particular we avoided any k<strong>in</strong>d of wavenumber filter<strong>in</strong>g <strong>in</strong><br />

order not to suppress deeply stipp<strong>in</strong>g reflections. We<br />

applied Fresnel-Volume-Migration (FVM) (Lüth et al.,<br />

2005, Buske et al., 2006) to each shot gather separately and<br />

stacked the absolute values of these s<strong>in</strong>gle migrated shot<br />

gathers. The velocity model used for the computation of<br />

the Green’s functions was derived from first-arrival<br />

tomography (Bleib<strong>in</strong>haus et al. 2006). Fig 1a shows the<br />

FVM result. The green, red and blue ticks along the upper<br />

boundary of the image mark the surface trace position of<br />

the Buzzard-Canyon-Fault (BCF), the San-Andreas-Fault<br />

(SAF) and the Waltham-Canyon-Fault (WCF),<br />

respectively. In order to verify the result<strong>in</strong>g structural<br />

features we also constructed ‘one-sided’ images by<br />

stack<strong>in</strong>g only those migrated shot gathers for which the<br />

shot location was ‘left’ or ‘right’ of the SAF. These ‘leftlateral’<br />

(LL) and ‘right-lateral’ (RL) images illum<strong>in</strong>ate the<br />

SAF system from only one side and allow for a verification<br />

of the dip and lateral position of the observed reflector<br />

elements. The LL-image (Fig. 1b) conta<strong>in</strong>s 23 migrated<br />

shot gathers and the RL-image (Fig. 1c) 19 migrated shot<br />

gathers, respectively. The SAF appears <strong>in</strong> Fig. 1a as well as<br />

<strong>in</strong> the LL-image (Fig. 1b) as a strong subvertical reflector<br />

which can be followed from its surface trace down to about<br />

4 km depth. At that depth it converges to a second even<br />

stronger subvertical reflector (Fig. 1a and RL-image <strong>in</strong> Fig.<br />

1c) which correlates with the BCF approximately 2 km left<br />

of the SAF. Also the WCF about 9 km right of the SAF<br />

shows up down to a depth of 5 km (especially <strong>in</strong> the RLimage<br />

<strong>in</strong> Fig. 1c). Furthermore a bunch of subvertical<br />

reflectors appears at shallow depths over a distance of 10<br />

km left of the SAF. Another slightly diffuse reflector is<br />

visible <strong>in</strong> the RL-image approximately 15 km left of the<br />

SAF down to a depth of 10 km (Fig. 1c). Both latter<br />

features have no yet known surface expression and do not<br />

show any k<strong>in</strong>d of tectonic activity (seismicity), however a<br />

comparison with geodynamic model<strong>in</strong>g results shows that<br />

the existence of such faults is realistic.<br />

Passive seismic imag<strong>in</strong>g<br />

We have applied a novel migration-type location<br />

algorithm (Rentsch et al., 2007a, b) to passive seismic data<br />

recorded with an 80-level-3C-receiver array <strong>in</strong> the SAFOD<br />

ma<strong>in</strong> hole. A modification of the location algorithm<br />

allowed the precise location of the ‘target event’ of May 5,<br />

2005. Fig. 2 shows vertical and horizontal depth slices<br />

through the image volume. The high amplitudes of stacked<br />

energy mark the hypocenter of the event. It is located<br />

approximately 150 m above the borehole trajectory which<br />

has meanwhile passed this area. Estimated (maximum)<br />

errors of our location are on the order of 50-75 meters.<br />

This target event of May 5, 2005 belongs to the San-<br />

Francisco target event cluster, which was the orig<strong>in</strong>ally<br />

planned subject of the drill<strong>in</strong>g activities <strong>in</strong> SAFOD Phase<br />

3. Unfortunately the orig<strong>in</strong>al plans have been changed and<br />

the currently ongo<strong>in</strong>g SAFOD drill<strong>in</strong>g phase 3 is<br />

concentrated on the Hawaii cluster target events below the<br />

orig<strong>in</strong>al borehole trajectory.<br />

Beside the mentioned target event we have located a<br />

number of local events <strong>in</strong> the vic<strong>in</strong>ity of the fault system.<br />

Most of these local events show a clear correlation to<br />

certa<strong>in</strong> reflect<strong>in</strong>g elements of the SAF system (Fig. 3).<br />

Outlook<br />

Our current work is concentrated towards the usage of<br />

reflections from nearby branches of the SAF system<br />

conta<strong>in</strong>ed with<strong>in</strong> the passive seismic borehole data. We<br />

therefore process the recorded earthquakes as ‘pseudoactive’<br />

shots with known (located) source coord<strong>in</strong>ates.<br />

Then we try to image these reflections <strong>in</strong> order to obta<strong>in</strong> a<br />

high-resolution image of the fault structure <strong>in</strong> the direct<br />

vic<strong>in</strong>ity of the SAFOD borehole. This will allow a<br />

calibration of the active surface image (Fig. 1) as well as<br />

direct comparison with other imag<strong>in</strong>g approaches, e.g.<br />

<strong>in</strong>terferometric techniques, which are currently undertaken<br />

by various work<strong>in</strong>g groups.<br />

References<br />

Bleib<strong>in</strong>haus, F., Hole, J.A., Ryberg, T. and Fuis, G.S., Structure of the<br />

California coast ranges and San Andreas Fault at SAFOD from seismic<br />

wavef<strong>in</strong>version and reflection imag<strong>in</strong>g. Journal of Geophysical<br />

Research, 2007.<br />

Buske, S., Heigel, M. and Lüth, S., Fresnel-Volume-Migration of s<strong>in</strong>glecomponent<br />

seismic data. EAGE 68th annual meet<strong>in</strong>g and technical<br />

exhibition, Vienna, Expanded Abstracts, G044, 2006.<br />

Hole, J.A., Ryberg, T., Fuis, G.S., Bleib<strong>in</strong>haus, F. and Sharma, A.K.,<br />

Structure of the San Andreas fault zone at SAFOD from a seismic<br />

refraction survey. Geophysical Research Letters 33(7), 1-4, 2006.<br />

Lüth, S., Buske, S., Görtz, A. and Giese, R., Fresnel-Volume-Migration of<br />

multicomponent data. Geophysics 70(6), S121-S129, 2005.<br />

Rentsch, S., Buske, S.., Lüth, S. and Shapiro, S., Fast location of seismicity:<br />

a migration-type approach with application to hydraulic fractur<strong>in</strong>g data.<br />

Geophysics, vol. 72, No. 1, S33-S40, 2007a.<br />

Rentsch, S., Buske, S., Gutjahr, S., Kummerow, J. and Shapiro, S.A.,<br />

Migration-based location of SAFOD target earthquakes. EAGE 69th<br />

annual meet<strong>in</strong>g and technical exhibition, London, Expanded Abstracts,<br />

H003, 2007b.<br />

35

36<br />

Fig. 1 SAFOD2003 - FVM results. (a) Stack of 42 migrated shot<br />

gathers along the whole profile. (b) ‘left-lateral’ (LL) image<br />

obta<strong>in</strong>ed by stack<strong>in</strong>g 23 migrated shot gathers left of the SAF. (c)<br />

‘right-lateral’ (RL) image obta<strong>in</strong>ed by stack<strong>in</strong>g 19 migrated shot<br />

gathers right of the SAF. All images are two times vertically<br />

exaggerated.<br />

Fig. 2 Vertical and horizontal slices through the location<br />

image volume. The target event location is marked by the high<br />

amplitude values.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 3 Zoomed and mirrored part of the reflection image <strong>in</strong> the<br />

vic<strong>in</strong>ity of the SAFOD borehole. Most of the located events (black<br />

dots) are related to certa<strong>in</strong> branches of the SAF system.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Experimental Constra<strong>in</strong>ts on Magma Ascent<br />

at Unzen Volcano, Japan<br />

CICHY, S.B. 1 , BOTCHARNIKOV, R.E. 1 , HOLTZ, F. 1 , BEHRENS, H. 1 ,<br />

SATO, H. 2<br />

1 Institut fuer M<strong>in</strong>eralogie, Leibniz Universitaet <strong>Hannover</strong>,<br />

Call<strong>in</strong>str.3, 30167 <strong>Hannover</strong>, Germany<br />

(s.cichy@m<strong>in</strong>eralogie.uni-hannover.de)<br />

2 Dept. of Earth and Planetary Science, Kobe University, Japan<br />

The project is aimed to model physical and chemical<br />

processes occurr<strong>in</strong>g <strong>in</strong> the conduit of Unzen volcano on<br />

magma ascent dur<strong>in</strong>g recent (1991-1995) eruption. The<br />

ma<strong>in</strong> objective of this experimental approach is to<br />

reproduce experimentally the vesicularity, texture, m<strong>in</strong>eral<br />

assemblage and m<strong>in</strong>eral composition analyzed <strong>in</strong><br />

groundmass of Unzen volcanic rocks sampled at the<br />

surface and at depth (core samples from <strong>ICDP</strong>-drill<strong>in</strong>g).<br />

Isothermal decompression experiments, performed at<br />

different decompression rates (us<strong>in</strong>g rhyodacite or Unzen<br />

groundmass composition as start<strong>in</strong>g material), will simulate<br />

magma ascent from ca. 10 to 1.5 km depth (below the<br />

<strong>ICDP</strong> target) and from ~1.5 km to shallow depths (above<br />

the <strong>ICDP</strong> target) parts of the Unzen magmatic conduit.<br />

Here we report first results on magma ascent <strong>in</strong> the deeper<br />

conduit obta<strong>in</strong>ed from experiments on decompression from<br />

300 to 50 MPa at 850°C. The multi-step decompression<br />

experiments have been conducted with decompression<br />

rates vary<strong>in</strong>g from 0.0005 to 20 MPa/s. Two experimental<br />

series were carried out <strong>in</strong> parallel: one us<strong>in</strong>g only water as<br />

a fluid component (H2O-saturated) and the other us<strong>in</strong>g<br />

water and carbon dioxide fluid (H 2O+CO 2-bear<strong>in</strong>g; with<br />

mole fraction of H2O <strong>in</strong> the fluid ~0.6).<br />

The experimental products consist of pyroxenes,<br />

amphiboles (Amph), plagioclases (Pl), oxides and glass. At<br />

isobaric conditions at 300 MPa Pl microlites are not<br />

observed <strong>in</strong> the water-saturated system and crystallize as a<br />

result of decompression only at the very slow<br />

decompression rate of 0.0005 MPa/s. Chemical analysis of<br />

the experimental products showed that the width of Amph<br />

reaction rims <strong>in</strong> water-saturated samples <strong>in</strong>creases with<br />

decreas<strong>in</strong>g decompression rate and reach up to 4 µm at<br />

decompression of 0.0005 MPa/s. On the other hand, the<br />

Mg numbers of Amph cores (Mg#=0.64-0.69) and reaction<br />

rims (Mg#=0.60-0.66) do not show systematic dependence<br />

on decompression rate and are slightly lower than the<br />

values of 0.65-0.75 <strong>in</strong> natural Amph <strong>in</strong> the Unzen<br />

groundmass. The anorthite (An) contents of the<br />

experimentally grown Pl microlites (An ~45-65 mol%) are<br />

consistent with An values of natural Pl microlites. The<br />

SiO2-content of the residual melt <strong>in</strong>creases with decreas<strong>in</strong>g<br />

decompression rate po<strong>in</strong>t<strong>in</strong>g out that melts produced at<br />

slow decompression rate (H2O+CO2-bear<strong>in</strong>g sample ~79<br />

wt%; H2O-saturated sample ~74.5 wt%) are close to the<br />

natural matrix glasses with SiO2-content of 78-80 wt%.<br />

Our determ<strong>in</strong>ed bubble number density (BND) values<br />

range from 1014 m-3 to 1016 m-3 at slow and fast<br />

decompression, respectively, except at 0.0005 MPa/s where<br />

the BND value of the water-saturated system <strong>in</strong>creases 1-2<br />

orders of magnitude with the crystallization of Pl. Those Pl<br />

microlites <strong>in</strong> the H2O-saturated sample might provide<br />

additional nucleation sites for bubbles and therefore have<br />

an <strong>in</strong>fluence on the BND. The length of those<br />

experimentally grown Pl reaches up to 200-250 μm which<br />

is consistent with Pl sizes <strong>in</strong> natural samples (Noguchi et<br />

al., <strong>in</strong> press). Our microlite number density (MND) values<br />

range from 1016 m-3 to 1018 m-3 at slow and fast<br />

decompression, respectively. The experimental BND<br />

values obta<strong>in</strong>ed at slow decompression are close to the<br />

values of natural samples (BND=1010-1015 m-3) while the<br />

experimental MNDs are at least one order of magnitude<br />

higher than that from natural samples (MND=1014-1015<br />

m-3).<br />

The water exsolution rates, calculated from MND<br />

values us<strong>in</strong>g the model of Toramaru et al. (<strong>in</strong> press),<br />

decrease with decreas<strong>in</strong>g decompression rate vary<strong>in</strong>g from<br />

1.9x10-4 wt%/s at slow to 1.3x10-3 wt%/s at fast<br />

decompression whereas the water exsolution rates<br />

calculated for natural samples are lower, rang<strong>in</strong>g from<br />

3.7x10-6 to 1.7x10-5 wt%/s. Thus, the experimental results<br />

<strong>in</strong>dicate that the ascent rates of Unzen magmas were close<br />

to or lower than ~ 6 m/hour. These values are <strong>in</strong> the same<br />

order of magnitude as the estimated rate of 12-30 m/hour<br />

(Nakada and Motomura, 1999). However, it has to be noted<br />

that ascent rates are probably not constant over the whole<br />

conduit and that the experimental dataset needs to be<br />

completed to better bracket the possible range of natural<br />

conditions.<br />

Further decompression experiments for lower pressures<br />

(from <strong>in</strong>itial 50 MPa to f<strong>in</strong>al 10 and to 5 Mpa) are planed to<br />

reproduce the conditions at shallower depths. In addition,<br />

we will perform similar decompression experiments at a<br />

temperature higher than 850°C (e.g. 930°C which is close<br />

to the pre-eruptive temperature). Those experiments shall<br />

be conducted <strong>in</strong> <strong>in</strong>ternal heated pressure vessels (IHPV),<br />

which is requir<strong>in</strong>g the <strong>in</strong>stallation of specific<br />

decompression-compatible devices. We have also started<br />

an experimental series to study the phase stabilities of the<br />

1991-1995 Unzen groundmass, ma<strong>in</strong>ly Amph and Pl. We<br />

will conduct isobaric experiments at 300, 200, 100 and 50<br />

MPa, and at different temperatures (800-950°C) and mole<br />

fraction of H2O <strong>in</strong> the fluid. This will provide better<br />

understand<strong>in</strong>g and background <strong>in</strong>formation necessary to<br />

<strong>in</strong>terpret our decompression experiments.<br />

References: Nakada, S. & Motomura,Y.: JVGR 89 (1999) 173-196;<br />

Noguchi, S. et al. (<strong>2008</strong>) JVGR, <strong>in</strong> press; Toramaru, A. et al. (<strong>2008</strong>)<br />

JVGR, <strong>in</strong> press<br />

<strong>ICDP</strong><br />

From a fluid like to a brittle behavior: Shear<br />

th<strong>in</strong>n<strong>in</strong>g effect of crystals on Mt Unzen<br />

rheology.<br />

B. CORDONNIER 1 , K.U. HESS 1 , Y. LAVALLÉE 1 , D.B. DINGWELL 1<br />

1 Department of Earth and Environmental Sciences, LMU Munich<br />

Mt Unzen is a back arc volcano located <strong>in</strong> Kyushu<br />

Island (Japan). Its last eruption between 1990 and 1995 can<br />

be described by two major eruptive phases, approximately<br />

20 months <strong>in</strong> duration, and marked by the growth and<br />

destruction of 13 domes. Such behavior generates debris<br />

and pyroclastic flows and is a source of hazard for the<br />

population surround<strong>in</strong>g this volcanic system.<br />

Two common goals of scientific drill<strong>in</strong>g - 1)<br />

understand<strong>in</strong>g the geological structure of the area drilled<br />

and 2) reach<strong>in</strong>g a given target and characteriz<strong>in</strong>g it - have<br />

been achieved by the Unzen Scientific Drill<strong>in</strong>g Program at<br />

Unzen volcano. The project has been divided <strong>in</strong> four<br />

37

38<br />

drill<strong>in</strong>g sites. The first two characterize the global geology<br />

of Beppu-Shimabara graben, the last two have achieved the<br />

first penetration of a recently active volcanic conduit.<br />

Those last two drillholes have facilitated a significant<br />

improvement <strong>in</strong> our understand<strong>in</strong>g of magma evolution<br />

dur<strong>in</strong>g ascent. They do so by provid<strong>in</strong>g a w<strong>in</strong>dow on the<br />

state of the magma at a given depth and permit, by<br />

comparison with erupted lavas, a better understand<strong>in</strong>g of<br />

magma evolution dur<strong>in</strong>g its critical and complex f<strong>in</strong>al<br />

ascent towards the surface.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Here, we review the rheological analysis of Unzen<br />

rocks through experimentation us<strong>in</strong>g a high-load and hightemperature<br />

uniaxial press (Hess, Cordonnier et al. 2007).<br />

Initially, we constra<strong>in</strong>ed the rheology of rocks from Mt<br />

Unzen dome and compared them to the observations made<br />

<strong>in</strong> the conduit. The apparent viscosity of Unzen dome rocks<br />

has been analyzed for stresses rang<strong>in</strong>g from 1 to 70MPa<br />

and temperatures from 940 to 1010 °C. Our results to date<br />

suggest that crystal-bear<strong>in</strong>g magmas are affected by two<br />

types of shear-th<strong>in</strong>n<strong>in</strong>g, render<strong>in</strong>g the assumption of<br />

Newtonian fluids for such degassed, crystallized volcanic<br />

systems <strong>in</strong>valid.<br />

A petrophysacally based model for the Unzen eruption of 1990-1995. Also represented, the USDP4 which penetrate the magmatic<br />

conduit.<br />

On the left hand side: The large volume uniaxial press us<strong>in</strong>g <strong>in</strong> Non-Newtonian rheological <strong>in</strong>vestigations of lavas of Unzen. On the<br />

right hand side, the onset of viscous heat<strong>in</strong>g dur<strong>in</strong>g the deformation of natural lavas.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Before constra<strong>in</strong><strong>in</strong>g the effect of crystal on melts, we<br />

needed to approach the non-Newtonian behavior of pure<br />

glass. Therefore a study on viscous heat<strong>in</strong>g has been<br />

performed. Dur<strong>in</strong>g magmatic flow, viscous heat<strong>in</strong>g effect<br />

may play a major role <strong>in</strong> eruption dynamics. In order to<br />

systematically document viscous heat<strong>in</strong>g dur<strong>in</strong>g<br />

deformation of magma, we have conducted a series of<br />

deformation experiments where viscous dissipation is<br />

directly monitored via thermocouples <strong>in</strong> high-viscosity<br />

silicate melts (without crystal and bubbles). We thus<br />

experimentally measure the stra<strong>in</strong>-rate dependence of<br />

viscous heat<strong>in</strong>g. Viscous heat<strong>in</strong>g becomes rheologically<br />

significant <strong>in</strong> the highly viscous silicate melts <strong>in</strong>vestigated<br />

at stra<strong>in</strong> rates above ca. 10-3 s-1. A simple analysis shows<br />

that the temperature <strong>in</strong>crease generated through viscous<br />

dissipation dur<strong>in</strong>g deformation of melts with viscosities<br />

rang<strong>in</strong>g from 108 and 1012 Pa*s can account for their<br />

apparent non-Newtonian rheology <strong>in</strong> these experiments.<br />

This thermal correction transforms apparent non-<br />

Newtonian, stra<strong>in</strong>-rate dependent rheology of magma to a<br />

Newtonian behavior over the range of conditions accessed<br />

<strong>in</strong> this work. (Hess, Cordonnier et al. <strong>2008</strong>)<br />

IAVD: General relations of this non-Newtonian rheology of domes lavas <strong>in</strong>clud<strong>in</strong>g Unzen.<br />

Concern<strong>in</strong>g crystal bear<strong>in</strong>g lavas from Mt Unzen, the<br />

apparent viscosity measured <strong>in</strong> our experiments is<br />

composed of an elastic, viscous and brittle mixture. Act<strong>in</strong>g<br />

together the apparent viscosity decreases <strong>in</strong> two ways: an<br />

<strong>in</strong>stantaneous decrease (IAVD) and a time dependent<br />

decrease (DAVD). The IAVD is a characteristic of crystalbear<strong>in</strong>g<br />

melts (be<strong>in</strong>g negligible for pure glass systems).<br />

The DAVD sees the viscosity decrease with time as a<br />

function of the applied stresses. Above a critical stress<br />

complete failure of the sample is observed.<br />

The IAVD conta<strong>in</strong>s a brittle and/or an elastic<br />

contribution. The brittle one is l<strong>in</strong>ked with a stress <strong>in</strong>crease,<br />

possibly activat<strong>in</strong>g cracks <strong>in</strong>side the samples. The high<br />

crystal fraction of the system may act as an elastic body<br />

that <strong>in</strong>troduces at least one more relaxation time to the<br />

system. There is a clear need to differentiate brittle and<br />

elastic part <strong>in</strong> the IAVD. We <strong>in</strong>tend to obta<strong>in</strong> this <strong>in</strong>sight<br />

through neutron tomographic analysis of stra<strong>in</strong> <strong>in</strong> our<br />

deformed samples. The IAVD is l<strong>in</strong>ear and can be easily<br />

modeled (Lavallee, Hess et al. 2007).<br />

On the left hand side: L<strong>in</strong>k between the non-Newtonian rheology of Unzen dome lava (here DAVD); and the acoustic emmission data<br />

obta<strong>in</strong>ed <strong>in</strong> situ. On the right hand side: neutron tomographic analysis of Mt Unzen. This method will be performed systematically <strong>in</strong><br />

future <strong>in</strong>vestigations. It will allow to carachetisize phenocrystal crack<strong>in</strong>g.<br />

39

40<br />

The DAVD relates to a decrease of the viscosity and<br />

becomes <strong>in</strong>creas<strong>in</strong>gly important with applied stress. For<br />

stresses below 3 MPa, we observed that the melt behaves<br />

as a Newtonian fluid over a timescale of several days.<br />

Between 3 and 10 MPa, the DAVD rate is small and<br />

believed to be the result of crystals rotation and<br />

alignement. At higher stresses, the viscosity decrease<br />

accentuates, show<strong>in</strong>g a non-Newtonian behavior until<br />

deformation crosses the ductile-brittle transition<br />

(Cordonnier, Hess & al submitted) .<br />

We recently added acoustic systems to our device to<br />

<strong>in</strong>vestigate the evolution of the DAVD and the process of<br />

complete lava failure (Lavallée, Meredith et al. submitted).<br />

Cracks can be identified through the acoustic wave that<br />

they produced and which travel through the pistons to the<br />

acoustic sensors. Prelim<strong>in</strong>ary tests made with this new<br />

configuration confirm the important localization of<br />

crack<strong>in</strong>g <strong>in</strong> the DAVD and therefore give a new<br />

opportunity to understand the ductile-brittle transition.<br />

Mt Unzen dome evolution occurred heavily brittlely<br />

due to the high crystal content of the lava. Yet, sampl<strong>in</strong>g of<br />

the conduit at a depth of 1 km below the dome (from<br />

USDP4 drill<strong>in</strong>g site), revealed a less crystallized lava.<br />

Here, the lava conta<strong>in</strong>s less microlites than the dome:<br />

moreover the crystals are less cracked. Accord<strong>in</strong>g to<br />

E<strong>in</strong>ste<strong>in</strong>-Roscoe rheological law, this difference would lead<br />

to a highly reduced viscosity <strong>in</strong> the conduit. Unfortunately<br />

the samples recovered from USDP4 are hydrothermally<br />

altered, mak<strong>in</strong>g them <strong>in</strong>adequate for subsequent<br />

experimental test<strong>in</strong>g with the press. Now, this material is<br />

guid<strong>in</strong>g us to reproduce analogous synthetic samples to<br />

study how magma with such crystal content would flow.<br />

This comb<strong>in</strong>ed effort will lead to the development of a<br />

visco-elastic model where viscous and elastic moduli are<br />

dependant of the crystal content.<br />

To conclude, the crystall<strong>in</strong>e phase is believed to<br />

<strong>in</strong>crease the viscosity accord<strong>in</strong>g to the E<strong>in</strong>ste<strong>in</strong>-Roscoe<br />

equations. Indeed, those equations are viable for low<br />

stresses and stra<strong>in</strong> rates. However, more importantly, these<br />

crystal-bear<strong>in</strong>g lavas have apparent viscosities that become<br />

strongly stress and stra<strong>in</strong>-rate dependent above the onset of<br />

the non-Newtonian doma<strong>in</strong>. E<strong>in</strong>ste<strong>in</strong>-Roscoe overestimates<br />

this apparent viscosity by several orders of magnitude. This<br />

study demonstrates the dom<strong>in</strong>ance of non-Newtonian<br />

rheology <strong>in</strong> understand<strong>in</strong>g the extrusion of dome lavas at<br />

Mt Unzen. Dur<strong>in</strong>g the eruption, the ascent dynamics <strong>in</strong> the<br />

conduit may have been <strong>in</strong>itially affected by viscous<br />

heat<strong>in</strong>g, and as cool<strong>in</strong>g and crystallization occurred near<br />

the surface, it formed a brittle lava dome, which<br />

occasionally fractured and generated large explosions.<br />

Next, we wish to experimentally characterize the<br />

different ratios between the elastic/brittle behavior for the<br />

IAVD and viscous/brittle for the DAVD. Also we plan<br />

further acoustic emission measurements and plan to test the<br />

importance of fractur<strong>in</strong>g with <strong>in</strong>creas<strong>in</strong>g conf<strong>in</strong><strong>in</strong>g<br />

pressure. Lastly, numerical simulations of visco- elastic<br />

fluids are on go<strong>in</strong>g and aim to generate a viable physical<br />

model, expla<strong>in</strong><strong>in</strong>g the experiments and thus, valid to ref<strong>in</strong>e<br />

current eruption forecast models.<br />

References:<br />

Cordonnier, B., K. U. Hess, Y. Lavallee and D. B. D<strong>in</strong>gwell (Submitted).<br />

"Rheology of Unzen dome lava." Earth and Planetary Science Letters.<br />

Hess, K. U., B. Cordonnier, Y. Lavallee and D. B. D<strong>in</strong>gwell (2007). "Highload,<br />

high-temperature deformation apparatus for synthetic and natural<br />

silicate melts." Review of Scientific Instruments 78(7)<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Hess, K. U., B. Cordonnier, Y. Lavallée and D. B. D<strong>in</strong>gwell (submitted).<br />

"Viscous heat<strong>in</strong>g <strong>in</strong> rhyolite: an <strong>in</strong> situ determ<strong>in</strong>ation." Earth and<br />

Planetary Science Letters.<br />

Lavallee, Y., K. U. Hess, B. Cordonnier and D. B. D<strong>in</strong>gwell (2007). "Non-<br />

Newtonian rheological law for highly crystall<strong>in</strong>e dome lavas." Geology<br />

35(9): 843-846.<br />

Lavallée, Y., P. Meredith, D. B. D<strong>in</strong>gwell, K. U. Hess, J. Wasserman, B.<br />

Cordonnier, J. Kruhl and A. Gerik (submitted). "Seismogenic lavas:<br />

acoustic emission and volcanic eruption forecasts." Nature.<br />

<strong>ICDP</strong><br />

Application of the FIB-Cryo-SEM technology<br />

for quantitative study of fault gouge porosity<br />

<strong>in</strong> SAFOD drill core from the San Andreas<br />

Fault zone<br />

G. DESBOIS & J.L. URAI<br />

Geologie - Endogene Dynamik, RWTH, Aachen University,<br />

Lochnerstr. 4-20, 52056 Aachen, Germany<br />

Porosity, pore fluids and pore pressure play an<br />

important role <strong>in</strong> the evolution of the active fault zones but<br />

they are difficult to study doe to the f<strong>in</strong>e pore size and<br />

difficult sample preparation.<br />

Classical studies of porosity <strong>in</strong>clude metal <strong>in</strong>jection<br />

methods (Hildenbrandt, 2003; Esteban et al., 2006),<br />

magnetic susceptibility measurement (Esteban et al., 2007)<br />

and SEM observations on dry samples (Hildenbrandt,<br />

2005). However, observations and <strong>in</strong>terpretations rema<strong>in</strong><br />

difficult because none of these approaches is able to<br />

directly describe the <strong>in</strong>-situ porosity at the pore scale.<br />

Recently, we have developed the FIB-cryo-SEM<br />

technique (Desbois et al., <strong>in</strong> press) for the <strong>in</strong>-situ<br />

<strong>in</strong>vestigation of the pore space microstructures <strong>in</strong> clay<br />

materials. This approach comb<strong>in</strong>es the vitrification of the<br />

pore fluids by very rapid cool<strong>in</strong>g and the excavation of the<br />

sample by FIB (Focussed Ion Beam) to prepare smooth<br />

surfaces for high resolution imag<strong>in</strong>g of the pore<br />

microstructures and the <strong>in</strong>-situ fluids. Our first results show<br />

that we are able to <strong>in</strong>vestigate pores down to the resolution<br />

of 10 nm and reconstruct the pore network <strong>in</strong> 3D without<br />

any artifacts and modification of the <strong>in</strong>-situ pore<br />

morphology.<br />

We would like to apply the FIB-cryo-SEM approach to<br />

study the evolution of the distribution and the<br />

microstructures of the porosity along the San Andreas Fault<br />

gauge (SAFOD drill<strong>in</strong>g project) with the aim to make the<br />

role of the porosity <strong>in</strong> the mechanical behavior of this<br />

active fault zone clearer.<br />

We are <strong>in</strong>terested <strong>in</strong> two k<strong>in</strong>ds of samples: (1) sampls<br />

conta<strong>in</strong><strong>in</strong>g strong transitions like boundaries of shear zones<br />

and cataclasites where we can see the evolution of the<br />

porosity, and (2) samples collected from the ma<strong>in</strong> fault<br />

gouges with slickensides to characterize porosity <strong>in</strong> several<br />

places <strong>in</strong> one sample.<br />

Our FIB-cryo-SEM approach would be very suitable<br />

for analyz<strong>in</strong>g the fault gouge, especially if we can <strong>in</strong>tegrate<br />

the results with other microstructural studies.<br />

Key words: clay material, <strong>in</strong>-situ porosity, cryo-SEM,<br />

FIB, SAFOD, Sam Andreas Fault zone<br />

References:<br />

Desbois G., Urai J.L., Burkhardt C., Drury M., Hayles M. and Humbel B.<br />

(In press). Cryogenic vitrification and 3D serial section<strong>in</strong>g us<strong>in</strong>g high<br />

resolution cryo-FIB-SEM technology for br<strong>in</strong>e-filled gra<strong>in</strong> boundaries<br />

<strong>in</strong> halite: first results. Geofluids.<br />

Esteban L., Géraud Y. And Bouchez J.L. (2006). Pore network geometry <strong>in</strong><br />

low permeability argillites from magnetic fabric data and oriented

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

mercury <strong>in</strong>jections. Geophysical Research Letters, vol. 33, L18311,<br />

doi : 10.1029/2006GL026908.<br />

Esteban L., Géraud Y. And Bouchez J.L. (2007). Pore network connectivity<br />

anisotropy <strong>in</strong> Jurassic argillite specimens from eastern Paris Bas<strong>in</strong><br />

(France). Physics and Chemistry of the Earth, 32(1) :161-169.<br />

Hildenbrand A., Krooss B. M. and Urai J. L. (2005). Relationship between<br />

pore structure and fluid transport <strong>in</strong> argillaceous rocks. Solid<br />

Mechanics and Its Applications, IUTAM Symposium on<br />

Physicochemical and Electromechanical Interactions <strong>in</strong> Porous Media,<br />

125 : 231-237, doi : 10.1007/1-4020-3865-8_26.<br />

Hildenbrand A. (2003a). Fluid transport processes <strong>in</strong> mudstones. PhD thesis<br />

at RWTH Aachen, 137pp.<br />

Key words: clay material, <strong>in</strong>-situ porosity, cryo-SEM, FIB, SAFOD, Sam<br />

Andreas Fault zone<br />

Fig. 1: FIB polished cross-section perpendiculat to the bedd<strong>in</strong>g of<br />

Boom-clay material (Belgium). Fluids fill<strong>in</strong>g pores are vitrified<br />

and stabilized <strong>in</strong> <strong>in</strong>-situ conditions.<br />

<strong>IODP</strong><br />

Evidence for rapid on/off switch<strong>in</strong>g of the<br />

North Atlantic Current dur<strong>in</strong>g the warm<br />

Middle Pliocene<br />

S. DE SCHEPPER 1 , M. J. HEAD 2 , J. GROENEVELD 3<br />

1 Fachbereich-5, Geowissenschaften, Universität Bremen, Postfach<br />

330 440, D-28334, Germany <br />

2 Department of Earth Sciences, Brock University, 500 Glenridge<br />

Avenue, St. Cathar<strong>in</strong>es, Ontario L2S 3A1, Canada<br />

<br />

3 Research Centre Ocean Marg<strong>in</strong>s, Universität Bremen, Leobener<br />

Strasse, D-28359 Bremen, Germany <br />

D<strong>in</strong>oflagellate cyst assemblages have been compared to<br />

<strong>in</strong>dependent proxies for sea surface temperature (SST) and<br />

sea surface sal<strong>in</strong>ity (SSS) based on 18O and Mg/Ca ratios<br />

of the planktonic foram<strong>in</strong>ifer Globiger<strong>in</strong>a bulloides for the<br />

Pliocene glacial–<strong>in</strong>terglacial cycle spann<strong>in</strong>g Mar<strong>in</strong>e Isotope<br />

Stage (MIS) M2 (c. 3.30 Ma), which represents the first<br />

episode of <strong>in</strong>tense cool<strong>in</strong>g <strong>in</strong> the Pliocene. A same-sample<br />

d<strong>in</strong>oflagellate cyst and geochemical study has documented<br />

changes <strong>in</strong> surface water masses across this <strong>in</strong>terval from<br />

DSDP Hole 610A (53˚13.297’N, 18˚53.213’W), at the SW<br />

edge of the Rockall Trough <strong>in</strong> the subpolar environment of<br />

the eastern North Atlantic. Its location is ideal to monitor<br />

changes <strong>in</strong> the pathway and/or <strong>in</strong>tensity of the North<br />

Atlantic Current.<br />

Measurements of 18O and Mg/Ca on the planktonic<br />

foram<strong>in</strong>ifera Globiger<strong>in</strong>a bulloides suggest a temperature<br />

variation of c. 4˚C between MIS M2 and its bound<strong>in</strong>g<br />

<strong>in</strong>terglacials, with MIS M2 similar <strong>in</strong> temperature to today.<br />

The d<strong>in</strong>oflagellate cyst assemblages are dom<strong>in</strong>ated by<br />

Bitectatod<strong>in</strong>ium tepikiense and other cool-water species<br />

dur<strong>in</strong>g MIS M2, and by Operculod<strong>in</strong>ium centrocarpum<br />

sensu Wall and Dale dur<strong>in</strong>g the <strong>in</strong>terglacials. This overturn<br />

is relatively rapid (less than 4–6 kyrs), signall<strong>in</strong>g an abrupt<br />

disturbance of the North Atlantic Current, which is<br />

corroborated by a lowered sal<strong>in</strong>ity ( 18Oseawater)<br />

dur<strong>in</strong>g MIS M2. Mg/Ca analyses, <strong>in</strong> contrast, reveal more<br />

gradual temperature changes, suggest<strong>in</strong>g an on/off control<br />

of the NAC <strong>in</strong> the Pliocene by threshold/feedback<br />

mechanisms perhaps similar to those <strong>in</strong> Quaternary. These<br />

results <strong>in</strong>dicate that Operculod<strong>in</strong>ium centrocarpum,<br />

accompanied with 18O and Mg/Ca measurements, are<br />

precise <strong>in</strong>dicators for on and off switches of the North<br />

Atlantic Current, even dur<strong>in</strong>g the warm, relatively stable<br />

climates of the Middle Pliocene.<br />

<strong>IODP</strong><br />

Mid-Miocene Paleoproductivity and<br />

Implications for the Global Carbon Cycle<br />

L DIESTER-HAASS, K.BILLUPS, D.GROECKE, L.FRANCOIS,<br />

V.LEFEBRE, K.-C. EMEIS<br />

l.haass@mx.uni-saarland.de1 kbillups@udel.edu;<br />

d.r.grocke@durham.ac.uk; francois@astro.ulg.ac.be;<br />

v<strong>in</strong>cent.lefebvre@ed.univ-lille1.fr; emeis@geowiss.unihamburg.de<br />

The mid-Miocene time <strong>in</strong>terval from 17-14 Ma is<br />

characterized by a period of relative warmth and the<br />

highest benthic and planktic foram<strong>in</strong>iferal δ 13 C values<br />

s<strong>in</strong>ce the Paleocene. The mid-Miocene period of relative<br />

warmth is followed by a major step <strong>in</strong> Antarctic ice sheet<br />

expansion at 14 Ma and a shift towards lower foram<strong>in</strong>iferal<br />

δ 13 C values.<br />

We aim at f<strong>in</strong>d<strong>in</strong>g an answer to the question whether<br />

the climatic evolution is related to organic carbon<br />

sequestration <strong>in</strong> mar<strong>in</strong>e sediments of the circum-Pacific<br />

marg<strong>in</strong>s that reduced the 12 C content <strong>in</strong> the global carbon<br />

pool and that caused cool<strong>in</strong>g and related Antarctic ice sheet<br />

expansion (the “Monterey Hypothesis” of V<strong>in</strong>cent and<br />

Berger, 1985), or whether productivity changes <strong>in</strong> openocean<br />

areas are <strong>in</strong>volved <strong>in</strong> this major climatic change.<br />

Recent calculations show that the amount of organic<br />

carbon buried <strong>in</strong> the Monterey Formation may not be<br />

sufficient to expla<strong>in</strong> the carbon isotope shift and climate<br />

change (Isaacs et al., 2001; Föllmi et al., 2005). We also<br />

want to see whether the mid-Miocene atmospheric CO2<br />

concentration as reconstructed by Pagani et al. (1999) is<br />

related to variations <strong>in</strong> mar<strong>in</strong>e biological productivity.<br />

Our study is based on six DSDP/ODP/<strong>IODP</strong> Sites from<br />

the Atlantic (608, 925 and 1265) and Indo-Pacific Oceans<br />

(Site 747, 1171, 588). Paleoproductivity as established by<br />

means of benthic foram<strong>in</strong>iferal accumulation rates (BFAR)<br />

does not show a change that would parallel the overall,<br />

long-term maximum <strong>in</strong> the mid-Miocene benthic<br />

foram<strong>in</strong>iferal δ 13 C records (Fig.1). An <strong>in</strong>trigu<strong>in</strong>g f<strong>in</strong>d<strong>in</strong>g is<br />

that productivity <strong>in</strong>creases at all sites at the onset of the<br />

negative shift at about 13.5 Ma, the time of the return to<br />

nearly pre-Monterey δ 13 C values, dur<strong>in</strong>g the period of<br />

cool<strong>in</strong>g and Antarctic ice extension (Fig.1). This f<strong>in</strong>d<strong>in</strong>g<br />

can be attributed to the expansion of grass land and C4<br />

plants that have enriched δ 13 C values (Sage, 2004;<br />

Retallak, 2001) and to the destruction of terrestrial<br />

vegetation and erosion of cont<strong>in</strong>ental soil material, thus a<br />

redistribution of terrestrial light carbon <strong>in</strong>to the global<br />

carbon reservoir. Enhanced erosion and related nutrient<br />

transfer – similar to processes dur<strong>in</strong>g the late Miocene<br />

“Biogenic Bloom” period ( Diester-Haass et al., 2005;<br />

2006) – fostered mar<strong>in</strong>e biological productivity, as seen <strong>in</strong><br />

41

42<br />

our export productivity values that are 2-3 times higher<br />

than modern ones.<br />

Because the data from mar<strong>in</strong>e open ocean sediments do<br />

not <strong>in</strong>dicate enhanced oceanic carbon sequestration <strong>in</strong> the<br />

Mid-Miocene δ 13 C maximum, we exam<strong>in</strong>e the amount of<br />

extra carbon stored and explore possible reasons for the<br />

shift with a numerical model (Francois and Lefebre).<br />

Sequestration of 1.5x10 18 mol C over the period of 3 Myr<br />

leads to a 0.9‰ δ 13 C positive excursion <strong>in</strong> the deep ocean,<br />

which is the observed magnitude <strong>in</strong> our records. An<br />

<strong>in</strong>crease <strong>in</strong> cont<strong>in</strong>ental organic carbon sequestration is the<br />

easiest way to enrich the ocean’s carbon pool with 13 C, and<br />

is consistent with coeval lignite deposits world wide<br />

(Utescher,2000).<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

The δ 13 C records (foram<strong>in</strong>iferal and bulk sedimentary<br />

organic matter) (D.Groecke) over the mid-Miocene show<br />

broadly similar changes, thus imply<strong>in</strong>g that the positive<br />

δ 13 C excursions dur<strong>in</strong>g the mid-Miocene affected the total<br />

oceanic carbon reservoir. This is particularly evident <strong>in</strong> the<br />

delta-delta (Δ 13 C = δ 13 C carb – δ 13 C org) curves which<br />

show no major shift <strong>in</strong> the isotopic fractionation between<br />

the carbonate and organic reservoirs. Therefore, this would<br />

suggest that there is no evidence for chang<strong>in</strong>g atmospheric<br />

CO2 levels over the <strong>in</strong>vestigated <strong>in</strong>terval of time: which<br />

concur with other <strong>in</strong>dependent proxies [Pagani et al., 1999,<br />

2005] which po<strong>in</strong>t to very low pCO2 of

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Depth migration results from the Eastern<br />

Mediterranean / Levant<strong>in</strong>e Bas<strong>in</strong><br />

S. DÜMMONG 1 , K.MEIER 1 , M.BEITZ 1 AND C. HÜBSCHER 1<br />

1 Institue for Geophysics, University of Hamburg, Bundestr. 55<br />

20146 Hamburg, Germany<br />

In this paper depth migration results from the Eastern<br />

Mediterranean / Levant<strong>in</strong>e Bas<strong>in</strong> are presented. The<br />

seismic sections will serve as pre-site survey data for a<br />

future <strong>IODP</strong>-proposal. High-resolution <strong>in</strong>dustry data sets<br />

were used to obta<strong>in</strong> depth migration results which reveal <strong>in</strong><br />

detail the <strong>in</strong>ternal structure of the Mobile Unit of the<br />

Mess<strong>in</strong>ian Evaporites. The data sets covers the bas<strong>in</strong>al<br />

succession or mobile (MU) of the Mess<strong>in</strong>ian Evaporites,<br />

the Pliocene-Quaternary overburden, and the upper pre-<br />

Mess<strong>in</strong>ian succession. 2D-l<strong>in</strong>es were acquired with 25m<br />

shot, 12.5 receiver spac<strong>in</strong>g, and with maximum offsets of<br />

7325m. The depth-migrated sections allow the<br />

quantification of layer thicknesses and deformation due to<br />

salt tectonics <strong>in</strong> the Levant<strong>in</strong>e Bas<strong>in</strong> for the first time.<br />

Accord<strong>in</strong>g to the chronostratigraphic scheme of<br />

Clauzon et al. (1996) or Krijgsman et al. (1999) the<br />

precipitation of the MU started around 5.6Ma dur<strong>in</strong>g the<br />

Mess<strong>in</strong>ian Sal<strong>in</strong>ity Crisis (MSC). The duration of the MU<br />

formation and the rapidity with which the Mediterranean<br />

bas<strong>in</strong> was refilled at the end of the MSC are still a matter of<br />

debate.<br />

Recent publications showed a complex seismic<br />

stratigraphy of the MU <strong>in</strong> the Levant<strong>in</strong>e Bas<strong>in</strong> (Gradmann<br />

et al., 2005; Netzeband et al., 2006a; Bertoni and<br />

Cartwright, 2006), which can be divided <strong>in</strong>to six sequences<br />

(Hübscher et al., 2007; Hübscher and Netzeband, 2007).<br />

Sequences ME-I, II, IV are seismically transparent and<br />

sequences ME-III and ME-V reveal several <strong>in</strong>ternal and<br />

subparallel reflections (Hübscher and Netzeband, 2007).<br />

The <strong>in</strong>ternal reflections have been <strong>in</strong>terpreted as<br />

<strong>in</strong>tercalated (and presumably overpressurized) clastics by<br />

Garfunkel et al. (1979) and Gradmann et al. (2005).<br />

However, 3D-seismic data analysis proved a high lateral<br />

cont<strong>in</strong>uity of seismic reflection characters and identified<br />

polarity changes which are more <strong>in</strong>dicative of chemical<br />

sedimentation processes (Bertoni and Cartwright, 2007).<br />

The deformation pattern of the <strong>in</strong>tra-evaporitic<br />

sequences <strong>in</strong>clude folds and thrust fault<strong>in</strong>g, which gives<br />

evidence for extensive salt tectonics and shorten<strong>in</strong>g,<br />

respectively, dur<strong>in</strong>g the depositional phase. Both, the<br />

identified evaporitic facies of the <strong>in</strong>dividual <strong>in</strong>tra-evaporitic<br />

sequences and the driv<strong>in</strong>g forces for the syn-depositional<br />

shorten<strong>in</strong>g rema<strong>in</strong> unclear.<br />

Velocity model build<strong>in</strong>g and depth-migration <strong>in</strong> salt<br />

bear<strong>in</strong>g bas<strong>in</strong>s is a challeng<strong>in</strong>g task for several reasons.<br />

High lateral and vertical velocity constrats occur and the<br />

data process<strong>in</strong>g is quite challeng<strong>in</strong>g. For the generation of<br />

the migration results, presented here, different approaches<br />

of tomographic methods were applied and exam<strong>in</strong>ed <strong>in</strong><br />

detail on two characteristic parts of the profiles. Two of<br />

these tomographic methods also use seismic attribute<br />

<strong>in</strong>formation additional to traveltime, so the results can be<br />

considered as better constra<strong>in</strong>ed. Common Image Gathers<br />

were evaluated to verify the velocity distributions. The<br />

depth migrations were performed with special emphasize<br />

on detailed imag<strong>in</strong>g of the <strong>in</strong>ternal structures of the MU of<br />

the Mess<strong>in</strong>ian Evaporites. Therefore up to six fazies were<br />

traced over the whole profiles <strong>in</strong> the depth doma<strong>in</strong>.<br />

Secondary the description of the <strong>in</strong>ternal structure of the<br />

MU by seismic velocities was possible for the first time.<br />

The derived velocity distribution of the distal part of the<br />

evaporites supports the previously published <strong>in</strong>terpretation<br />

of a vertical succession of alternat<strong>in</strong>g evaporitic facies<br />

with <strong>in</strong>tercalated clastics. Additionally velocities of<br />

refracted waves were processed. The velocities show that<br />

the term<strong>in</strong>ation of s<strong>in</strong>gle fazies of the evaporites<br />

corresponds with leaps <strong>in</strong> the refracted waves velocity<br />

distribution, which also gives a further h<strong>in</strong>t that the <strong>in</strong>ternal<br />

structure of the MU consists of layers of different<br />

composition.<br />

Hence form the evaluation of the depth migrated<br />

images, the velocity models, and the velocity distribution<br />

of the refracted waves new implication for the tectonic and<br />

structural <strong>in</strong>terpretation of the Mess<strong>in</strong>ian Evaporites <strong>in</strong> the<br />

Eastern Mediterranean / Levant<strong>in</strong>e Bas<strong>in</strong> are possible. The<br />

depth migrated images allow for the first time the<br />

quantification of fault displacement and, consequently, the<br />

dist<strong>in</strong>ction between plate- or salt tectonic events.<br />

References:<br />

Bertoni, C. and J. Cartwright, 2006, Controls on the bas<strong>in</strong>wide architecture<br />

of late Miocene (Mess<strong>in</strong>ian) Evaporites on the Levant marg<strong>in</strong> (Eastern<br />

Mediterranean): Sedimentary Geology, 188-189, 93–114.<br />

Bertoni, C. and J. Cartwright, 2007, Ma jor erosion a the end of the<br />

Mess<strong>in</strong>ian Sal<strong>in</strong>ity crisis: evidence from the Levant Bas<strong>in</strong>/ Eastern<br />

Mediterrranean: Bas<strong>in</strong> Research, 19, 1–18.<br />

Clauzon, G., J. Suc, F. Gautier, A. Berger, and M. Loutre, 1996, Alternate<br />

<strong>in</strong>terpretation of the mess<strong>in</strong>ian sal<strong>in</strong>ity crisis: controversy resolved?:<br />

Geology, 24, 363–366.<br />

Garfunkel, Z., A. Arad, and A. Almagor, 1979, The Palmahim Disturbance<br />

and its regional sett<strong>in</strong>g: Geological Survey of Israel Bullet<strong>in</strong>, 72, 56.<br />

Gradmann, S., C. Hübscher, Z. Ben-Avraham, D. Ga jewski, and G.<br />

Netzeband, 2005, Salt tectonics off northern israel: Mar<strong>in</strong>e and<br />

Petroleum Geology, 22, 597–611.<br />

Hübscher, C., J. Cartwright, H. Cypionka, G. De Lange, A. Robertson, J.<br />

Suc, and J. Urai, 2007, Global look at dalt giants: EOS, 88, 177–179.<br />

Hübscher, C. and G. Netzeband, 2007, Evolution of a young salt giant: The<br />

example of the Mess<strong>in</strong>ian evaporites <strong>in</strong> the Levante bas<strong>in</strong>: In: Wallner,<br />

M.; Lux, K.-H.; M<strong>in</strong>kley, W.; Hardy, Jr., H.R. (Eds.) The Mechanical<br />

behavior of Salt - Understand<strong>in</strong>g of THMC Processes of Salt, Taylor<br />

and Francis Group, London, 175–184.<br />

Krijgsman, W., F. Hilgen, I. Raffi, F. Sierro, and D. Wilson, 1999,<br />

Chronology, causes and progression of the mess<strong>in</strong>ian sal<strong>in</strong>ity crisis:<br />

Nature, 400, 652–655.<br />

Netzeband, G., K. Gohl, H. C., Z. Ben-Avraham, A. Dehghani, D. Ga<br />

jewski, and P. Liersch, 2006a, The Levant<strong>in</strong>e Bas<strong>in</strong> - crustal structure<br />

and orig<strong>in</strong>: Tectonophysics, 418, 178–188.<br />

<strong>IODP</strong><br />

Trace element and isotope geochemistry of<br />

~15 Ma oceanic crust formed at a superfast<br />

spread<strong>in</strong>g ridge (Exp. 309/312, <strong>IODP</strong> Site<br />

1256D, Eastern Central Pacific): Constra<strong>in</strong>ts<br />

on sub-ridge processes at the East Pacific<br />

Rise, the style and tim<strong>in</strong>g of alteration and<br />

the orig<strong>in</strong> of ocean island basalts<br />

S. DUGGEN 1 , K. HOERNLE 1 , F. HAUFF 1 AND J. GELDMACHER 2<br />

1 IFM-GEOMAR, Leibniz-Institute of Mar<strong>in</strong>e Sciences, Research<br />

Division 4: Dynamics of the Ocean Floor, Wischhofstrasse 1-<br />

3, 24148 Kiel<br />

2 Integrated Ocean Drill<strong>in</strong>g Program, Texas A&M University, 1000<br />

Discovery Drive, College Station, TX 77845-9547<br />

The geochemical composition of drilled oceanic crust<br />

can provide important <strong>in</strong>sights <strong>in</strong>to processes occurr<strong>in</strong>g at<br />

mid-ocean ridges, the subsequent alteration of oceanic<br />

crust and the chemical evolution of seawater. Moreover, as<br />

oceanic crust is recycled <strong>in</strong>to the Earth´s mantle at<br />

43

44<br />

subduction zones, a better knowledge of small-scale<br />

compositional variations <strong>in</strong> the oceanic crust will also<br />

improve our understand<strong>in</strong>g of the chemical evolution of the<br />

Earth´s mantle, <strong>in</strong>clud<strong>in</strong>g subduction zone processes<br />

caus<strong>in</strong>g arc volcanism and the orig<strong>in</strong> of ocean island<br />

basalts.<br />

The ongo<strong>in</strong>g project was designed to characterise the<br />

downhole trace element and radiogenic isotopic variation<br />

of the lower section of oceanic crust drilled at Site 1256<br />

(Exp. 309/312) <strong>in</strong> the Guatemala Bas<strong>in</strong> on the Cocos Plate<br />

<strong>in</strong> the Eastern Central Pacific. The oceanic crust of Site<br />

1256 was formed ~15 Ma ago dur<strong>in</strong>g a phase (~11-20 Ma)<br />

of superfast spread<strong>in</strong>g at a full rate of ~200-220 mm/y.<br />

The drill hole, reach<strong>in</strong>g the <strong>in</strong> situ lower gabbroic crust for<br />

the first time, is considered to be one of the most important<br />

drill holes <strong>in</strong>to igneous oceanic crust <strong>in</strong> the history of<br />

scientific ocean drill<strong>in</strong>g (Wilson, et al. 2006). In the course<br />

of three expeditions, drill<strong>in</strong>g penetrated mar<strong>in</strong>e sediments<br />

to ~250 meters below sea floor (mbsf), followed by a<br />

volcanic zone with sheet and massive flows to ~1004 mbsf,<br />

a lava-sheeted dike transition zone as previously found at<br />

the nearby Hole 504 (Eastern Central Pacific), a sheeted<br />

dike complex to ~1407 mbsf and for the first time the<br />

sheeted dike-gabbro transition zone at 1400 mbsf (Teagle,<br />

et al. 2006). This project, funded by the German Science<br />

Foundation with<strong>in</strong> the priority program “Integrated Ocean<br />

Drill<strong>in</strong>g Program/Ocean Drill<strong>in</strong>g Program (<strong>IODP</strong>/ODP)<br />

(SPP 527), focuses on material drilled at Expeditions 309<br />

and 312 from 750-1500 mbsf.<br />

Below we briefly summarise the results currently<br />

available from the ongo<strong>in</strong>g project. An <strong>in</strong>troduction to the<br />

project was presented at the <strong>IODP</strong> <strong>Kolloquium</strong> <strong>in</strong> Potsdam<br />

2007 and results were presented at the Exp. 309/312 Post-<br />

Cruise Meet<strong>in</strong>g <strong>in</strong> Japan 2007 and the AGU Fall Meet<strong>in</strong>g<br />

<strong>in</strong> San Francisco 2007 or are scheduled for presentation <strong>in</strong><br />

a Site 1256 Special Session at the EGU meet<strong>in</strong>g <strong>in</strong> Vienna<br />

spr<strong>in</strong>g <strong>2008</strong>. The first new geochemical data from the<br />

project are reported <strong>in</strong> a manuscript that has been written<br />

up and is currently subject to <strong>in</strong>ternal revision (Duggen, et<br />

al. <strong>in</strong> prep.). Our new data for Exp. 309/312 material are<br />

<strong>in</strong>tegrated with some data available for Leg 206 at Site<br />

1256 (the upper part of the volcanic zone, ~250-750 mbsf)<br />

that are reported by our work<strong>in</strong>g group <strong>in</strong> a paper <strong>in</strong> press<br />

(Sadofsky, et al. <strong>2008</strong>, <strong>in</strong> press) and with published<br />

geochemical data for ~6.6 Ma old oceanic crust from Hole<br />

504 formed at the Galápagos Spread<strong>in</strong>g Centre (Bach, et al.<br />

2003; Pedersen and Furnes 2001).<br />

Analytical requirements –high-precision Pb isotope<br />

analysis<br />

In order to be able to detect even very small down-hole<br />

Pb-isotopic variations, an important part of the project was<br />

to establish the high-precision Pb-isotope technique by<br />

means of a double spike and to apply it to Site 1256<br />

samples. The technique comprises a major advancement <strong>in</strong><br />

terms of precision and accuracy compared to conventional<br />

Pb-isotope analysis and was established for Thermal<br />

Ionisation Mass Spectrometry (TIMS) at IFM-GEOMAR.<br />

R<strong>in</strong>s<strong>in</strong>g experiments performed dur<strong>in</strong>g this study reveals<br />

that proper treatment of the altered oceanic crust material<br />

(the use of matrix chips that are briefly surface r<strong>in</strong>sed with<br />

dilute acid and ultrapure water prior to digestion) is crucial<br />

for achiev<strong>in</strong>g high-quality Pb-isotope data of altered<br />

oceanic crust. For Pb double spik<strong>in</strong>g we used an isotopic<br />

tracer artificially enriched <strong>in</strong> 207Pb and 204Pb. Prior to<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

use, the spike had to be calibrated which <strong>in</strong>volved analysis<br />

of the pure SBL74 spike composition (n = 37<br />

measurements), 2) the composition of Pb-standard<br />

SRM982 (n = 28) and 3) adequate mixtures of SBL74 and<br />

SRM982 (n = 30) followed by a complex data reduction.<br />

The calibrated SBL74 spike was then tested based on<br />

unspiked (n = 16) and spiked (n = 16) determ<strong>in</strong>ations of<br />

another Pb-standard (SRM981). The technique now<br />

established for the ongo<strong>in</strong>g <strong>IODP</strong> project yield values for<br />

SRM 981 that are identical with<strong>in</strong> error to those provided<br />

by other laboratories us<strong>in</strong>g different double and triple<br />

spikes and both TIMS and Multi-Collector-Inductively<br />

Coupled Plasma-Mass Spectrometry (MC-ICP-MS).<br />

Magma formation - processes at the East Pacific Rise<br />

Immobile trace elements and radiogenic isotope ratios<br />

po<strong>in</strong>t to a temporal change <strong>in</strong> the composition of the<br />

equatorial EPR magma source between 15 Ma and Present.<br />

This is found by compar<strong>in</strong>g Nd-Pb- and partly Sr-isotope<br />

ratios of ~15 Ma old Site 1256 basalts with data of Recent<br />

equatorial EPR lavas, suggest<strong>in</strong>g that the Site 1256 EPR<br />

magma source was more heterogenous ~15 Ma ago.<br />

Geochemical similarities of Site 1256 basalts with ocean<br />

island basalts from the Galápagos hotspot <strong>in</strong>dicate that an<br />

enriched component <strong>in</strong> the EPR 15 Ma ago may stem from<br />

the Galápagos mantle plume or an enriched component<br />

with<strong>in</strong> the ambient upper mantle. A period of <strong>in</strong>creased<br />

ridge suction dur<strong>in</strong>g a phase of superfast spread<strong>in</strong>g rates at<br />

the EPR at ~11-20 Ma ago may have <strong>in</strong>troduced enriched<br />

material <strong>in</strong>to the EPR sub-ridge mantle.<br />

Alteration processes <strong>in</strong> the lava-sheeted dike transition<br />

zone<br />

The lava-sheeted dike transition zone was so far only<br />

drilled twice <strong>in</strong> the history of the scientific ocean drill<strong>in</strong>g:<br />

The first time at Hole 504 and more recently at Site 1256<br />

(Leg 309). The transition zones were penetrated at different<br />

depths (~581-790 m and ~754-810 m below the top of the<br />

basaltic crust basement, respectively) and have different<br />

thicknesses (~209 m at Hole 504 versus ~57 m at Site<br />

1256) (Alt, et al. 1986; Teagle, et al. 2006). Trace element<br />

and Sr-Nd-Pb-isotope data across the lava-dike transition<br />

zone of ~15 Ma old oceanic crust at Site 1256 show some<br />

similarities and differences to the geochemical variations of<br />

the transition zone <strong>in</strong> ~6.6 Ma old oceanic crust at Hole<br />

504. Similar to Hole 504, the formation of the Site 1256<br />

transition zone obviously arises from mix<strong>in</strong>g of upwell<strong>in</strong>g<br />

hydrothermal fluids from deeper levels <strong>in</strong> the oceanic crust<br />

(at (sub-)greenschist facies conditions) with cooler<br />

seawater from above. The key difference between the Site<br />

1256 and Hole 504 transition zones appears to be the<br />

<strong>in</strong>tensity of alteration, probably as a function of the<br />

duration of fluid movement and/or the amount of fluids<br />

penetrat<strong>in</strong>g the transition zone. Alteration is less <strong>in</strong>tense at<br />

Site 1256, which may ultimately be l<strong>in</strong>ked to the higher<br />

spread<strong>in</strong>g rates at the East Pacific Rise ~11-20 Ma ago<br />

(superfast) compared to the Galápagos Spread<strong>in</strong>g Centre<br />

(<strong>in</strong>termediate) as these may govern the duration of<br />

exposure of oceanic crust to vigorous near-axis upwell<strong>in</strong>g<br />

of hydrothermal fluids and seawater circulation. We<br />

<strong>in</strong>terpret the pyrite-rich brecciated 2.8 m layer <strong>in</strong> the Site<br />

1256 lava-sheeted dike transition zone to represent a<br />

juvenile stage of the metal sulphide-rich stockwork zone of<br />

the Hole 504 transition zone.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Tim<strong>in</strong>g of alteration of Site 1256 oceanic crust<br />

Two different backward modell<strong>in</strong>g approaches were<br />

advanced to provide constra<strong>in</strong>ts on the tim<strong>in</strong>g of alteration<br />

of Site 1256 oceanic crust. It can be <strong>in</strong>ferred from<br />

radiogenic isotope and relevant trace element ratios that<br />

alteration at Site 1256 term<strong>in</strong>ated ~6-9 Ma after the<br />

formation at the East Pacific Rise. Silica-rich layers (chert<br />

bed and diatom mat) that formed ~2.8 Ma and ~4.2 Ma<br />

after the igneous basement and eventually act<strong>in</strong>g as lowdiffusivity<br />

barriers (Teagle, et al. 2006) may have played a<br />

vital role <strong>in</strong> significantly decreas<strong>in</strong>g the seawater flux <strong>in</strong>to<br />

the upper oceanic crust. However, igneous activity at<br />

seamounts occurr<strong>in</strong>g 15-20 km northeast of Site 1256 may<br />

locally have ma<strong>in</strong>ta<strong>in</strong>ed seawater-rich fluid communication<br />

between the ocean and the upper oceanic crust for millions<br />

of years after formation of the low-diffusivity sedimentary<br />

barriers (Fisher, et al. 2003).<br />

Recycl<strong>in</strong>g <strong>in</strong> the Earth´s mantle<br />

Altered oceanic crust is recycled <strong>in</strong>to the Earth´s<br />

mantle through subduction and is thought to be <strong>in</strong>volved <strong>in</strong><br />

mantle plumes and <strong>in</strong> the magma source of ocean island<br />

basalts. Based on our new geochemical data of Site 1256<br />

oceanic crust and backward and forward geochemical<br />

modell<strong>in</strong>g <strong>in</strong>volv<strong>in</strong>g radiogenic <strong>in</strong>growth and subduction<br />

zone modification, we exam<strong>in</strong>e the significance of altered<br />

oceanic crust for the orig<strong>in</strong> of ocean island basalts. Our<br />

study shows that low- to high-temperature alteration<br />

processes <strong>in</strong> oceanic crust may produce Rb/Sr, Sm/Nd and<br />

(U, Th)/Pb more variable than <strong>in</strong> the precursor basaltic<br />

material. Secondary m<strong>in</strong>erals (e.g. sulphides) precipitated<br />

from fluids percolat<strong>in</strong>g <strong>in</strong> oceanic crust appear to play a<br />

major role <strong>in</strong> the distribution of some trace elements (e.g.<br />

Pb), <strong>in</strong> controll<strong>in</strong>g ratios conta<strong>in</strong><strong>in</strong>g these elements (e.g.<br />

(U, Th)/Pb) and <strong>in</strong> the evolution of isotope ratios over<br />

geological time-scales. Modell<strong>in</strong>g <strong>in</strong> the Sr-Nd-Pb-isotope<br />

space and comparison with present day radiogenic isotope<br />

ratios of ocean island basalts suggests that only altered<br />

oceanic crust is required to expla<strong>in</strong> the radiogenic isotope<br />

composition of ocean island basalts with Pb-isotopic ratios<br />

along or below the Northern Hemisphere Reference L<strong>in</strong>e<br />

and relatively high Nd-isotope ratios (e.g. Canaries,<br />

Galápagos, Iceland, Madeira). The results further <strong>in</strong>dicate<br />

that additional enriched mantle (EM) components, most<br />

likely associated with subducted sediments or cont<strong>in</strong>ental<br />

lithospheric material, are only <strong>in</strong>volved <strong>in</strong> the source of<br />

ocean island basalts with relatively low Nd-isotopic<br />

composition (e.g. Pitcairn, Tristan, Samoa).<br />

References:<br />

Alt JC, Honnorez J, Laverne C, Emmermann R (1986) Hydrothermal<br />

alteration of a 1 km section through the upper oceanic crust. DSDP<br />

Hole 504B: M<strong>in</strong>eralogy, chemistry and evolution of seawater-basalt<br />

<strong>in</strong>teractions. Journal of Geophysical Research 91:309–335<br />

Bach W, Peucker-Ehrenbr<strong>in</strong>k B, Hart SR, Blusztaijn JS (2003)<br />

Geochemistry of hydrothermally altered oceanic crust: DSDP/ODP<br />

Hole 504B – Implications for seawater-crust exchange budgets and Sr-<br />

and Pb-isotopic evolution of the mantle. Geochemistry Geophysics<br />

Geosystems 4(3)<br />

Duggen S, Hoernle K, Hauff F, Geldmacher J (<strong>in</strong> prep.) Geochemistry of the<br />

lava-dike transition zone <strong>in</strong> young oceanic crust formed at a superfast<br />

spread<strong>in</strong>g ridge (Site 1256, Cocos Plate, Eastern Pacific): Constra<strong>in</strong>ts<br />

on alteration processes and temporal changes of mantle heterogeneity<br />

at the East Pacific Rise. Geochemistry Geophysics Geosystems<br />

Fisher AT, Davis EE, Hutnak M, Spiess V, Zühlsdorff L, Charkaoul A,<br />

Christiansen L, Edwards K, Macdonald R, Vill<strong>in</strong>ger H, Mottl MJ,<br />

Wheat CG, Becker K (2003) Hydrothermal recharge and discharge<br />

across 50 km guided by seamounts on a young ridge flank. Nature<br />

421:618-621<br />

Pedersen RB, Furnes H (2001) Nd- and Pb-isotopic variations through the<br />

upper oceanic crust <strong>in</strong> DSDP/ODP Hole 504B, Costa Rica Rift. Earth<br />

and Planetary Science Letters 189:221-235<br />

Sadofsky S, Hoernle K, Duggen S, Hauff F, Werner R, Garbe-Schönberg D<br />

(<strong>2008</strong>, <strong>in</strong> press) Trace element and Sr-Nd-Pb isotope geochemistry of<br />

the sedimentary and upper igneous section of the subduct<strong>in</strong>g Cocos<br />

Plate offshore of Central America International Journal of Earth<br />

Sciences<br />

Teagle DAH, Alt JC, Um<strong>in</strong>o S, Miyashita S, Banerjee NR, Wilson DS,<br />

Scientists atE (2006) Proceed<strong>in</strong>gs of the Integrated Ocean Drill<strong>in</strong>g<br />

Program, 309/312, vol. Integrated Ocean Drill<strong>in</strong>g Program,<br />

Wash<strong>in</strong>gton D.C.<br />

Wilson DS, Teagle DAH, Alt JC, Banerjee NR, Um<strong>in</strong>o S, Miyashita S,<br />

Acton GD, Anma R, Barr SR, Belghoul A, Carlut J, Christie DM,<br />

Coggon RM, Cooper KM, Cordier C, Crisp<strong>in</strong>i L, Rodriguez Durand S,<br />

E<strong>in</strong>audi F, Galli L, Gao Y, Geldmacher J, Gilbert LA, Hayman NW,<br />

Herrero-Bervera E, Hirano N, Holter S, Ingle S, Jiang S, Kalberkamp<br />

U, Kerneklian M, Koepke J, Laverne C, Lledo Vasquez HL,<br />

Maclennan J, Morgan S, Neo N, Nichols HJ, Park S-H, Reichow MK,<br />

Sakuyama T, Sano T, Sandwell R, Scheibner B, Smith-Duque CE,<br />

Swift SA, Tartarotti P, Tikku AA, Tom<strong>in</strong>aga M, Veloso EA, Yamasaki<br />

T, Yamazaki S, Ziegler C (2006) Drill<strong>in</strong>g to Gabbro <strong>in</strong> Intact Ocean<br />

Crust. Science 312(5776):1016-1020<br />

<strong>IODP</strong><br />

Holocene vegetation development <strong>in</strong> Angola –<br />

Palynology of ODP Site 1078<br />

L.M. DUPONT 1<br />

1 Marum / Uni-Bremen, Leobener Str., 28359 Bremen.<br />

dupont@uni-bremen.de<br />

Record<strong>in</strong>g and understand<strong>in</strong>g vegetation change <strong>in</strong><br />

southern Africa is important because it opens a w<strong>in</strong>dow to<br />

study the variability of both tropical and subtropical<br />

systems <strong>in</strong> the Southern Hemisphere. ODP Site 1078<br />

situated under the coast of Angola provides a unique record<br />

of vegetation history of tropical SW Africa. The upper 16<br />

meters of the core covers the past 50 thousand years.<br />

Previously we reported on glacial and deglacial parts of the<br />

record. Here, we focus on the vegetation changes of the<br />

Holocene. Our results <strong>in</strong>dicate that the rich forests cover<strong>in</strong>g<br />

Angola dur<strong>in</strong>g deglaciation changed <strong>in</strong> composition at the<br />

beg<strong>in</strong>n<strong>in</strong>g of the Holocene; dry forest and Miombo<br />

woodlands became <strong>in</strong>creas<strong>in</strong>gly important, while ra<strong>in</strong><br />

forest elements retreated. After a disturbance around 8 ka,<br />

Podocarpus dom<strong>in</strong>ated between 7.8 and 3.7 ka. Dur<strong>in</strong>g this<br />

period, either Miombo woodland or wetter types of ra<strong>in</strong><br />

forest expanded and replaced open savannah vegetation.<br />

After 3.7 ka savannahs spreaded aga<strong>in</strong> and even more so<br />

after 2 ka. Forests might have become patchy grow<strong>in</strong>g<br />

light-lov<strong>in</strong>g and fire hardy trees. The thus reconstructed<br />

vegetation changes are compared to other African<br />

environmental records.<br />

45

46<br />

Pollen (%)<br />

Grass<br />

Dry forest<br />

Savannah<br />

Miombo<br />

Ra<strong>in</strong> forest<br />

Podocarpus<br />

40<br />

20<br />

0<br />

16<br />

8<br />

0<br />

8<br />

0<br />

8<br />

4<br />

0<br />

40<br />

20<br />

0<br />

0 4 8<br />

Age (ka)<br />

12<br />

Flux<br />

2<br />

(N/cm /ka)<br />

100<br />

10<br />

1<br />

100<br />

1000<br />

FIig.1: Selection of pollen curves of ODP Site 1078. Percentages<br />

of total pollen and spores (l<strong>in</strong>es, left Y-axes). Pollen flux values <strong>in</strong><br />

numbers/cm2/ka (shaded, right Y-axes).<br />

<strong>IODP</strong><br />

The down-hole magmatic-metamorphic<br />

evolution <strong>in</strong> basalts and gabbros monitored<br />

by Fe-Ti oxides: A complete section of<br />

Superfast Spread<strong>in</strong>g Crust at <strong>IODP</strong> Site<br />

1256(Project HO 1337/14; SPP 527)<br />

W. DZIONY 1 , J. KOEPKE 1 , F. HOLTZ 1 , I. HORN 1<br />

1 Institut für M<strong>in</strong>eralogie, Leibniz Universität <strong>Hannover</strong><br />

General research Objectives. The <strong>IODP</strong> multi-cruise<br />

mission "Superfast Spread<strong>in</strong>g Crust" drilled successfully a<br />

complete section of the upper oceanic crust <strong>in</strong>to the<br />

underly<strong>in</strong>g gabbros (Site 1256; eastern equatorial Pacific;<br />

15 Ma crust formed at the East Pacific Rise). The<br />

recovered rocks, now represent<strong>in</strong>g the first reference<br />

profile through fast-spread<strong>in</strong>g upper oceanic crust, reveal a<br />

complex <strong>in</strong>teraction between magmatic and metamorphic<br />

processes:<br />

Primary crystallization; low- and high-temperature<br />

alteration; contact-metamorphism; partial<br />

melt<strong>in</strong>g/assimilation; magma mix<strong>in</strong>g. The petrographic<br />

record of the whole section reveals that all processes<br />

<strong>in</strong>volve the formation of, or the reaction with, Fe-Ti oxides,<br />

which can consequently be used as suitable proxies for<br />

monitor<strong>in</strong>g the different stages <strong>in</strong> the magmaticmetamorphic<br />

evolution of fast-spread<strong>in</strong>g oceanic crust. In<br />

100<br />

10<br />

1<br />

100<br />

10<br />

10<br />

1<br />

100<br />

10<br />

1<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

this project, it is to (1) evaluate the temperature-oxygen<br />

fugacity evolution of gabbros/basalts dur<strong>in</strong>g late and post<br />

magmatic processes, (2) to improve our understand<strong>in</strong>g of<br />

the <strong>in</strong>terplay between hydrothermal circulation and primary<br />

magmatic processes us<strong>in</strong>g <strong>in</strong>-situ analysis of iron isotopes,<br />

(3) to constra<strong>in</strong> the conditions prevail<strong>in</strong>g <strong>in</strong> the axial<br />

magma chamber us<strong>in</strong>g an experimental approach. This<br />

report will focus on the presentation of first results<br />

obta<strong>in</strong>ed <strong>in</strong> tasks (1) and (2).<br />

First results<br />

(1) Temperatures and redox conditions for dist<strong>in</strong>ct<br />

stages of the metamorphic-magmatic evolution, with<br />

particular attention to the granoblastic dikes and gabbros.<br />

The downhole evolution of the primary magmatic<br />

phases <strong>in</strong> the lavas and dikes were evaluated by<br />

petrographic <strong>in</strong>vestigation of ~ 100 th<strong>in</strong> sections and based<br />

on several thousands of microprobe analyses (Dziony et al.,<br />

<strong>2008</strong>). In addition to direct implications for the research<br />

project, the systematic petrographic descriptions and the<br />

analytical data can be used as a comprehensive data basis<br />

for the magmatic/metamorphic evolution <strong>in</strong> the volcanic<br />

part of the Hole 1256D drill<strong>in</strong>g section which is of<br />

importance for other <strong>IODP</strong> 1256D work<strong>in</strong>g groups.<br />

One key observation was the detection and analysis of<br />

low-Ca pyroxene as relics <strong>in</strong> the cl<strong>in</strong>opyroxenes, which<br />

shed light on the “orthopyroxene paradoxon” mean<strong>in</strong>g that<br />

orthopyroxene is present <strong>in</strong> many oceanic gabbros, but<br />

practically absent as phenocrysts <strong>in</strong> the correspond<strong>in</strong>g<br />

extrusives (Dziony et al., 2007a, b).<br />

The results of this work is the basis for the a further<br />

study (Koepke et al., 2007a) focuss<strong>in</strong>g on the metamorphic<br />

evolution of the lowermost dikes, the “granoblastic dikes”<br />

(Fig. 1; dotted area with<strong>in</strong> the sheeted dike complex),<br />

which have been collected <strong>in</strong> the vic<strong>in</strong>ity of gabbroic<br />

samples. The “granoblastic dikes” were identified to be the<br />

conduct<strong>in</strong>g boundary layer (CBL, Coogan et al., 2003)<br />

between the magmatic system of the melt lens and the<br />

hydrothermal system convect<strong>in</strong>g at much lower<br />

temperatures <strong>in</strong> the sheeted dikes. The downhole evolution<br />

of the granoblastic overpr<strong>in</strong>t is expressed by systematical<br />

changes of textures, phase compositions and calculated<br />

equilibrium temperatures, which are <strong>in</strong> agreement with a<br />

model of contact metamorphism caused by a heat source<br />

below the sheeted dikes. Us<strong>in</strong>g the analysis of diffusion<br />

profiles <strong>in</strong> former phenocrysts which survived the<br />

granoblastic metamorphic overpr<strong>in</strong>t and thermal model<strong>in</strong>g,<br />

we calculated that a heat source must have been active over<br />

several thousands of years. This long last<strong>in</strong>g heat source is<br />

most probably related to a steady-state high-level axial<br />

magma chamber (AMC) located at the base of the sheeted<br />

dikes. These are the first quantitative results based on<br />

direct observation of such a horizon.<br />

The analytical data were also applied to reconstruct the<br />

redox condition dur<strong>in</strong>g the primary magmatic stage and the<br />

granoblastic overpr<strong>in</strong>t. We applied successfully the<br />

improved two-oxide geo-oxybarometer (Sauerzapf et al.,<br />

2007 submitted) to the granoblastic dikes, which <strong>in</strong>dicates<br />

that magmatic processes occur at reduc<strong>in</strong>g conditions (as<br />

expected for MOR basalts) and that the granoblastic<br />

overpr<strong>in</strong>t is accompanied by a dramatic shift of the f(O2)<br />

(nearly 4 orders of magnitude) towards more oxidiz<strong>in</strong>g<br />

conditions (Koepke et al., 2007a submitted). This opens<br />

<strong>in</strong>terest<strong>in</strong>g perspectives to monitor the<br />

magmatic/metamorphic evolution of the whole profile from

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

the lava flows to the gabbros with the help of the oxide<br />

m<strong>in</strong>erals.<br />

Us<strong>in</strong>g a femtoLA-MC-ICPMS system recently<br />

developed at <strong>Hannover</strong>, we analyzed iron isotopes <strong>in</strong><br />

different Fe-bear<strong>in</strong>g phases (magnetite, ilmenite,<br />

sulphides), <strong>in</strong> the Fe-Ti phases and sulphides of<br />

gabbros/basalts <strong>in</strong> order to unravel the complex <strong>in</strong>terplay<br />

between alteration/metamorphism and magmatic cycle at<br />

fast-spread<strong>in</strong>g mid-ocean ridges. Fe isotopes were<br />

measured <strong>in</strong> oxides and sulfides of a ferrogabbro from the<br />

Southwest Indian Ridge (dill hole 735B) and a fresh basalt<br />

from our 1256D superfast EPR crust. The analytical and<br />

methodical techniques are given by Horn et al. (2006) and<br />

prelim<strong>in</strong>ary results were reported by (Koepke et al., 2007b)<br />

Δ 5 6/5 4 Fe magnetite - X<br />

1.2<br />

0.8<br />

0.4<br />

0.0<br />

-0.4<br />

Fe O -FeS<br />

3 4<br />

Fe O -Fe O<br />

3 4 2 3<br />

gabbro assembl. 1<br />

gabbro assembl. 2<br />

fresh basalt<br />

Fe O -FeS<br />

3 4 2<br />

Gabbro<br />

MT-PYR<br />

Gabbro<br />

MT-ILM<br />

300 400 500 600 700 800 900 1000 1100<br />

temperature (°C)<br />

Δ 56 Fe (Ti-)m agn etite-ilm enite<br />

Consider<strong>in</strong>g that the primary goal of this study is to use<br />

the Fe isotopes as a monitor for seawater overpr<strong>in</strong>t (drastic<br />

fractionation effects are expected), the knowledge of the<br />

equilibrium fractionation between the <strong>in</strong>volved phases is<br />

essential, and a part of our efforts are focused on<br />

establish<strong>in</strong>g the rationale beh<strong>in</strong>d this topic. Therefore we<br />

compared the fractionation coefficients of δ 56 Fe obta<strong>in</strong>ed<br />

from the analyses of different natural Fe-bear<strong>in</strong>g phases<br />

(magnetite, ilmenite, sulphides) <strong>in</strong> gabbros and basalt with<br />

the fractionation coefficients derived from Mössbauer data<br />

( Polyakov et al., 2007). First results are presented <strong>in</strong> Fig.<br />

2. In order to quantify the fractionation behaviour under<br />

equilibrium conditions, we measured also δ56Fe values <strong>in</strong><br />

magnetite and ilmenite from experimental samples<br />

provided by D. Lattard (Heidelberg) synthesized at<br />

different temperature/redox conditions (Fig. 2). Most<br />

measured values are <strong>in</strong> the range predicted from the<br />

literature ( Polyakov et al., 2007), imply<strong>in</strong>g that there is a<br />

high probability that those fractionation values derived<br />

from natural samples, which are outside of the predicted<br />

range can be used for trac<strong>in</strong>g the <strong>in</strong>fluence of hydrothermal<br />

fluids. This result opens very <strong>in</strong>terest<strong>in</strong>g perspectives for<br />

our future survey on the 1256D rocks.<br />

0,6<br />

0,5<br />

0,4<br />

0,3<br />

0,2<br />

0,1<br />

0,0<br />

-0,1<br />

-0,2<br />

-0,3<br />

-0,4<br />

magnetite-ilmenite equlibrium fractionation predicted by<br />

Polyakov and M<strong>in</strong>eev, 2000; Polyakov et al. 2007<br />

1F92Qc (ox)<br />

1P63IW (red)<br />

6F92x0 (ox)<br />

6F57x34 (red)<br />

maximum/m<strong>in</strong>imum values<br />

connected by vertical l<strong>in</strong>es<br />

600 700 800 900 1000 1100 1200 1300 1400<br />

Fig. 2: Results of LA-ICP-MS measurements of δ56Fe. Left: Results from natural rocks and predicted ranges after Polyakov and M<strong>in</strong>eev, 2000;<br />

Polyakov et al., 2007. Right: Results from experimental magnetite / ilmenite pairs.<br />

T (°C)<br />

47

48<br />

Dziony, W., Koepke, J., Holtz.F., 2007 submitted. Data report: Petrography<br />

and phase analyses <strong>in</strong> lavas and dikes from the hole 1256D (ODP Leg<br />

206 and <strong>IODP</strong> Expedition 309, East Pacific Rise). In: Teagle, D.A.H.<br />

et al. (Eds.), Proc. <strong>IODP</strong>, Sci. Results, 309/312. College Station, TX,<br />

Ocean Drill<strong>in</strong>g Program.<br />

Dziony, W., Koepke, J., Holtz, F., 2007. Low-Ca pyroxene relics <strong>in</strong> drilled<br />

basalts from EPR crust (<strong>IODP</strong> Site 1256D). Geochim. Cosmochim.<br />

Acta Suppl. 71, A248-A248.<br />

Dziony, W., Koepke, J., Holtz, F., <strong>2008</strong> <strong>in</strong> press. Downhole evolution of<br />

m<strong>in</strong>eral phases <strong>in</strong> drilled lavas and dikes from EPR crust (<strong>IODP</strong> Site<br />

1256, Equatorial Pacific). Geophys. Res. Abstr.<br />

Koepke, J., Christie, D.M., Dziony, W., Holtz, F., Lattard, D., Maclennan,<br />

J., Park, S., Scheibner, B., Yamasaki, T., Yamasaki, S., 2007<br />

submitted. Petrography of the Dike/Gabbro Transition at <strong>IODP</strong> Site<br />

1256D (Equatorial Pacific): The evolution of the Granoblastic Dikes.<br />

Geochem. Geophys. Geosyst.<br />

Koepke, J., Ste<strong>in</strong>höfel, G., Schuessler, J.A., Horn, I., Dziony, W.,<br />

Botcharnikov, R., 2007. In-situ Fe isotope measurements <strong>in</strong> gabbros<br />

and basalts from the ocean crust. Geochim. Cosmochim. Acta Suppl.<br />

71, A502-A502.<br />

Coogan, L.A., Mitchell, N.C., O'Hara, M.J., 2003. Roof assimilation at fast<br />

spread<strong>in</strong>g ridges: An <strong>in</strong>vestigation comb<strong>in</strong><strong>in</strong>g geophysical,<br />

geochemical, and field evidence. J. Geophys. Res. 108,<br />

doi:10.1029/2001JB001171.<br />

Horn, I., von Blanckenburg, F., Schoenberg, R., Ste<strong>in</strong>hoefel, G., Markl, G.,<br />

2006. In situ iron isotope ratio determ<strong>in</strong>ation us<strong>in</strong>g UV-femtosecond<br />

laser ablation with application to hydrothermal ore formation<br />

processes. Geochim. Cosmochim. Acta 70, 3677–3688.<br />

Polyakov, V.B., M<strong>in</strong>eev, S.D., 2000. The use of Mossbauer spectroscopy <strong>in</strong><br />

stable isotope geochemistry. Geochim.Cosmochim. Acta 64, 849-865.<br />

Polyakov, V.B.,Clayton, R.N., Horita, J., and M<strong>in</strong>eev, S.D.,2007.<br />

Equilibrium iron isotope fractionation factors of m<strong>in</strong>erals: Reevaluation<br />

from the data of nuclear <strong>in</strong>elastic resonant X-ray scatter<strong>in</strong>g and<br />

Mossbauer spectroscopy. Geochimica et Cosmochimica Acta, 71(15),<br />

3833-3846.<br />

Sauerzapf, U., Lattard, D., Burchard, M., Engelmann, R., 2007 submitted.<br />

New experimental data and a simple version of the titanomagnetiteilmenite<br />

thermo-oxybarometer for high temperature and reduced to<br />

moderatly oxidised conditions. J. Petrol.<br />

<strong>IODP</strong><br />

Nitrogen fixation dur<strong>in</strong>g Pliocene cool<strong>in</strong>g<br />

with<strong>in</strong> the Benguela Upwell<strong>in</strong>g System and<br />

the Eastern Equatorial Pacific, ODP Sites<br />

1082 and 1239<br />

J. ETOURNEAU 1 , R. SCHNEIDER 1 , P. MARTINEZ 2 , T. BLANZ 1<br />

1 Institut für Geowissenschaften, Christian Albrecht Universität,<br />

24118 Kiel, Germany.<br />

2 Département de Géologie et Océanographie, UMR CNRS 5805<br />

EPOC, Université de Bordeaux I, 33405 Talence, France.<br />

The Pliocene cool<strong>in</strong>g (2.7-2.1 Ma) is ma<strong>in</strong>ly attributed<br />

to the f<strong>in</strong>ale closure of the Panama Gateway after 2.73 Ma,<br />

a major tectonic event which led to a profound<br />

reorganization of the global thermohal<strong>in</strong>e circulation, an<br />

extension of the cont<strong>in</strong>ental ice sheet especially <strong>in</strong> the<br />

Northern Hemisphere as well as a more vigorous<br />

atmospheric circulation. Pronounced stratification of the<br />

Southern and the Northern Pacific Oceans and <strong>in</strong>itiation of<br />

the modern Gulf Stream <strong>in</strong> the Caribbean Sea are<br />

considered as supplementary causes of this climatic<br />

change. With<strong>in</strong> low-latitudes highly productive coastal<br />

upwell<strong>in</strong>g regions, however a change <strong>in</strong> redistribution of<br />

nutrient supply probably modified the nature of the<br />

productivity and therefore may have been <strong>in</strong>fluential on the<br />

atmospheric CO2 level dur<strong>in</strong>g the Pliocene.<br />

In this study, we provide a comparison over the past<br />

3.5 Ma between the ODP Sites 1082 and 1239 located<br />

with<strong>in</strong> the Benguela Upwell<strong>in</strong>g system and <strong>in</strong> the Eastern<br />

Equatorial Pacific, respectively. We used alkenonesderived<br />

sea surface temperature (SST) and sedimentary<br />

nitrogen isotopes ratios (δ 15 N) <strong>in</strong> order to determ<strong>in</strong>e the<br />

impacts of the Pliocene cool<strong>in</strong>g on the changes of the<br />

oceanic conditions and of the phytoplanktonic productivity<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

with<strong>in</strong> both bas<strong>in</strong>s. At these two sites, the two proxy<br />

records revealed similar trends with a two-step SSTs<br />

decrease correspond<strong>in</strong>g to a two-step bulk-sediment δ 15 N<br />

<strong>in</strong>crease, progressively show<strong>in</strong>g values closer to the<br />

modern conditions and those from the Pleistocene (~ 1.5<br />

Ma). The Eastern Equatorial Pacific site exhibited warmer<br />

SST (> 22°C) than the Benguela upwell<strong>in</strong>g (>14°C). This<br />

is consistent with the fact that the site 1082 is located<br />

nearer to an active upwell<strong>in</strong>g cell while the site 1239 is<br />

only <strong>in</strong>fluenced by the rim of the Peruvian upwell<strong>in</strong>g. The<br />

most <strong>in</strong>terest<strong>in</strong>g feature observed at these sites corresponds<br />

to the negative shift of the bulk-sediment δ 15 N just after 2.7<br />

Ma. At this period very low δ 15 N values (

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Gu<strong>in</strong>ea). These coral records suggest that glacial ENSO<br />

variability was weaker than today’s (Tudhope et al., 2001).<br />

This f<strong>in</strong>d<strong>in</strong>g is not necessarily <strong>in</strong>consistent with climate<br />

model simulations that <strong>in</strong>dicate an amplification of ENSO<br />

variance dur<strong>in</strong>g the LGM, but weakened ENSO<br />

teleconnections (An et al., 2004; Otto-Bliesner et al., 2003;<br />

Peltier and Solheim, 2004). Other proxy-based<br />

reconstructions of <strong>in</strong>terannual climate variability dur<strong>in</strong>g<br />

glacial boundary conditions do not exist <strong>in</strong> the Pacific<br />

Ocean, and reefs of this age are usually difficult to access.<br />

With respect to mar<strong>in</strong>e sediment records Trenberth and<br />

Otto-Bliesner (2003) have emphasized that conclusions<br />

about changes <strong>in</strong> ENSO from proxy records that do not<br />

resolve <strong>in</strong>terannual variability are especially fraught with<br />

difficulty.<br />

<strong>IODP</strong> Expedition 310 “Tahiti Sea Level” aimed to<br />

recover the coral reef record of the last deglacial sea-level<br />

rise <strong>in</strong> the South Pacific Ocean (Camo<strong>in</strong> et al., 2005).<br />

Dur<strong>in</strong>g this Mission-Specific Platform (MSP) Expedition<br />

conducted by the European Consortium for Ocean<br />

Research Drill<strong>in</strong>g (ECORD), more than 600 m of cores<br />

with an exceptional recovery were retrieved from 37 holes<br />

drilled <strong>in</strong>to the drowned reefs around the island of Tahiti<br />

(French Polynesia), <strong>in</strong> water depths between 41 and 117 m<br />

(Expedition 310 Scientists, 2006). A total of 30 m of the<br />

reef cores consist of massive coral colonies, mostly of the<br />

genus Porites. The aragonitic skeletons of such annuallybanded<br />

corals provide an opportunity to study changes <strong>in</strong><br />

seasonality and <strong>in</strong>terannual climate variability dur<strong>in</strong>g the<br />

last deglaciation <strong>in</strong> the South Pacific Ocean. Subseasonally<br />

resolved records of Sr/Ca and oxygen isotopes<br />

derived from well-preserved and well-dated (U-series<br />

dat<strong>in</strong>g) coral skeletons can provide reconstructions of<br />

variations <strong>in</strong> temperature and hydrologic balance at the sea<br />

surface.<br />

Here we present results of sub-seasonally resolved coral<br />

records from Tahiti for time w<strong>in</strong>dows around 14 to 15 kyr<br />

BP, a time <strong>in</strong>terval that is characterized by abrupt climatic<br />

changes <strong>in</strong> the North Atlantic region, such as He<strong>in</strong>rich<br />

event 1, the Bøll<strong>in</strong>g warm<strong>in</strong>g and the Older Dryas cool<strong>in</strong>g.<br />

In particular, we have generated a 22-year record of<br />

monthly resolved Sr/Ca and oxygen isotope variations from<br />

an <strong>in</strong>dividual 60-cm-high Porites colony that was drilled <strong>in</strong><br />

growth position. The coral was recovered at a depth of<br />

about 111 m below present sea level, 21 m below sea floor.<br />

X-ray powder diffraction analyses, th<strong>in</strong> sections and<br />

scann<strong>in</strong>g electron microscope imag<strong>in</strong>g along the<br />

microsampl<strong>in</strong>g transect <strong>in</strong>dicate that the coral’s aragonitic<br />

skeleton is well-preserved. U-series dat<strong>in</strong>g <strong>in</strong>dicates that<br />

this coral grew 15.0 kyr BP, prior to the Bøll<strong>in</strong>g warm<strong>in</strong>g<br />

at the time of He<strong>in</strong>rich event 1. This period was<br />

characterized by a near or complete shut-down of the<br />

Atlantic Meriodional Overturn<strong>in</strong>g Circulation (AMOC)<br />

(McManus et al., 2004).<br />

Our new coral record from Tahiti shows clear annual<br />

cycles and <strong>in</strong>dicates a pronounced <strong>in</strong>terannual variability.<br />

Spectral analysis of the coral Sr/Ca paleothermometer<br />

record identifies significant peaks at periods of 5 and 2<br />

years, suggest<strong>in</strong>g a pronounced <strong>in</strong>terannual variability <strong>in</strong><br />

the ENSO frequency band <strong>in</strong> South Pacific sea surface<br />

temperatures at 15.0 kyr BP. This f<strong>in</strong>d<strong>in</strong>g is somewhat<br />

surpris<strong>in</strong>g, because today the ENSO <strong>in</strong>fluence on sea<br />

surface temperatures and coral Sr/Ca at Tahiti is weak and<br />

non-stationary (Cahyar<strong>in</strong>i, 2006). Our fossil coral drilled<br />

on <strong>IODP</strong> Expedition 310 provides the first record of<br />

<strong>in</strong>terannual variability <strong>in</strong> Pacific sea surface temperatures<br />

dur<strong>in</strong>g He<strong>in</strong>rich event 1. Our result of pronounced<br />

<strong>in</strong>terannual variability <strong>in</strong> South Pacific temperatures<br />

around 15.0 kyr ago is consistent with recent climate model<br />

simulations that suggest that a weaken<strong>in</strong>g of the AMOC<br />

can lead, via atmospheric teleconnections, to an<br />

<strong>in</strong>tensification of ENSO variability (Timmermann et al.,<br />

2007).<br />

Figure 1. Top: X-radiograph positive pr<strong>in</strong>t of a fossil Porites sp. coral from Tahiti drilled dur<strong>in</strong>g <strong>IODP</strong> Expedition 310 at a depth of about<br />

111 m below present sea level, 21 m below sea floor. The coral grew cont<strong>in</strong>uously for a time <strong>in</strong>terval of more than 22 years around 15.0<br />

kyr BP, a period that corresponds to He<strong>in</strong>rich event 1 <strong>in</strong> the North Atlantic. Bottom: Monthly-resolved coral δ 18 O (red) and Sr/Ca (blue)<br />

records. The records show clear annual cycles and a pronounced <strong>in</strong>terannual variability.<br />

49

50<br />

References:<br />

An, S.-I. et al., 2004. Model<strong>in</strong>g evidence for enhanced El Niño-Southern<br />

Oscillation amplitude dur<strong>in</strong>g the Last Glacial Maximum.<br />

Paleoceanography, 19: PA4009, doi:10.1029/2004PA001020.<br />

Cahyar<strong>in</strong>i, S.Y., 2006. Paired δ 18 O and Sr/Ca records of Porites corals from<br />

Tahiti (French Polynesia) and Timor (Indonesia), University of Kiel,<br />

Kiel, Germany, PhD Thesis, 180 pp.<br />

Camo<strong>in</strong>, G.F., Iryu, Y., McInroy, D. and Expedition 310 Project Team,<br />

2005. The last deglacial sea level rise <strong>in</strong> the South Pacific: offshore<br />

drill<strong>in</strong>g <strong>in</strong> Tahiti (French Polynesia). <strong>IODP</strong> Sci. Prosp., 310,<br />

doi:10.2204/iodp.sp.310.2005.<br />

Expedition 310 Scientists, 2006. Tahiti Sea Level: the last deglacial sea<br />

level rise <strong>in</strong> the South Pacific: offshore drill<strong>in</strong>g <strong>in</strong> Tahiti (French<br />

Polynesia). <strong>IODP</strong> Prel. Rept., 310, doi:10.2204/iodp.pr.310.2006.<br />

McManus, J.F., Francois, R., Gherardi, J.M., Keigw<strong>in</strong>, L.D. and Brown-<br />

Leger, S., 2004. Collapse and rapid resumption of Atlantic meridional<br />

circulation l<strong>in</strong>ked to deglacial climate changes. Nature, 428: 834-837.<br />

Otto-Bliesner, B.L., Brady, E.C., Sh<strong>in</strong>, S.-I., Liu, Z. and Shields, C., 2003.<br />

Model<strong>in</strong>g El Niño and its tropical teleconnections dur<strong>in</strong>g the last<br />

glacial-<strong>in</strong>terglacial cycle. Geophysical Research Letters, 30: 2198,<br />

doi:10.1029/2003GL018553.<br />

Peltier, W.R. and Solheim, L.P., 2004. The climate of the Earth at Last<br />

Glacial Maximum: statistical equilibrium state and a mode of <strong>in</strong>ternal<br />

variability. Quaternary Science Reviews, 23: 335-357.<br />

Timmermann, A. et al., 2007. The <strong>in</strong>fluence of a weaken<strong>in</strong>g of the Atlantic<br />

Meridional Overturn<strong>in</strong>g Circulation on ENSO. Journal of Climate, 20:<br />

4899-4919.<br />

Trenberth, K.E. and Otto-Bliesner, B.L., 2003. Toward <strong>in</strong>tegrated<br />

reconstruction of past climates. Science, 300: 589-591.<br />

Tudhope, A.W. et al., 2001. Variability <strong>in</strong> the El Niño-Southern Oscillation<br />

through a glacial-<strong>in</strong>terglacial cycle. Science, 291: 1511-1517.<br />

Acknowledgements:<br />

We acknowledge the support of the Deutsche<br />

Forschungsgeme<strong>in</strong>schaft (DFG) through a grant to G.<br />

Wefer (We 992/51-1), University of Bremen.<br />

<strong>ICDP</strong><br />

Research study for a geoelectrical pre-site<br />

survey of the drill<strong>in</strong>g location with<strong>in</strong> the<br />

Eger Rift - Investigation of the subsurface<br />

electrical conductivity distribution<br />

CH. FLECHSIG 1 , C. SCHÜTZE 1<br />

1<br />

Universität Leipzig, Institut für Geophysik und Geologie,<br />

Talstrasse 35, 04103 Leipzig<br />

The epicentral area around Nový Kostel/NW-Bohemia<br />

is favourised as location for a deep borehole. The target<br />

area of the proposed drill<strong>in</strong>g project is situated <strong>in</strong> the Eger<br />

Rift, a geodynamically active part of the Variscan orogenic<br />

belt <strong>in</strong> Europe. Western part of the Eger Rift is<br />

characterised by repeated occurrence of <strong>in</strong>traplate<br />

earthquake swarms, by numerous m<strong>in</strong>eral spr<strong>in</strong>gs, and CO2<br />

emissions. Such phenomena are usually related to volcanic<br />

activity.<br />

The comprehensive geoelectrical study <strong>in</strong> the context<br />

of a pre-site survey could greatly benefit the<br />

establishment/characterization of an <strong>ICDP</strong> drill<strong>in</strong>g site<br />

location <strong>in</strong> the western part of the Eger Rift and recent<br />

research projects (for <strong>in</strong>stance project <strong>ICDP</strong> Eger Rift<br />

Fluids, GFZ Potsdam).<br />

Related questions are:<br />

Is there any evidence <strong>in</strong> the upper crust for the different<br />

degass<strong>in</strong>g behaviour with<strong>in</strong> the area near Novy Kostel (low<br />

degass<strong>in</strong>g rates) and the south of Novy Kostel situated<br />

mofettes area Bublak with permanent high degass<strong>in</strong>g rates?<br />

Do the gas ascent paths and the descent paths for<br />

meteoric water respectively are detectable with the<br />

geoelectrical methods?<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

What k<strong>in</strong>d of tectonical <strong>in</strong>formation are deducible from<br />

the electrical conductivity distribution <strong>in</strong> the subsurface of<br />

the western Eger Rift?<br />

We propose to carry out an electrical pre-site survey for<br />

the submitted <strong>ICDP</strong> drill<strong>in</strong>g project <strong>in</strong> the western part of<br />

the Eger Rift. In the context of ongo<strong>in</strong>g research to f<strong>in</strong>d an<br />

optimal location the <strong>in</strong>tent of this study is to exam<strong>in</strong>e the<br />

structure of the Earth’s crust up to a depth of 4 to 5 km.<br />

The distribution of the electrical conductivity reproduces a<br />

model of geological structural units with its different<br />

electrical characterisation <strong>in</strong>clud<strong>in</strong>g the fault zones with<br />

fluid pathways <strong>in</strong> the subsurface. The survey area is the<br />

potential drill<strong>in</strong>g location <strong>in</strong> the vic<strong>in</strong>ity of the most active<br />

swarm earthquake zone Novy Kostel.<br />

Prior to the field measurements our proposal conta<strong>in</strong>s a<br />

one year preparatory study, which on the one hand aims the<br />

theoretical model<strong>in</strong>g of expected electrical measur<strong>in</strong>g<br />

effects of a deep geoelectrical exploration (necessary array<br />

size up to 25 km). A priori <strong>in</strong>formation of previous and<br />

recent research activities (results from seismology,<br />

seismics, magnetotellurics, gas-geochemistry) <strong>in</strong> the target<br />

area should be <strong>in</strong>cluded. On the other hand, test<strong>in</strong>g<br />

measurements to check e.g. the signal quality and the<br />

logistic efforts are planned with<strong>in</strong> the preparatory study to<br />

optimize the further field work.<br />

<strong>IODP</strong><br />

A paleo sea surface temperature record<br />

throughout the Cretaceous thermal<br />

maximum from an Albian-Santonian black<br />

shale sequence <strong>in</strong> the tropical Atlantic<br />

A. FORSTER 1,2 , S. SCHOUTEN 1 , M. BAAS 1 , J.S. SINNINGHE DAMSTÉ 1<br />

1 Royal Netherlands Institute for Sea Research, Department of<br />

Mar<strong>in</strong>e Biogeochemistry and Toxicology, P.O. Box 59, 1790<br />

AB Den Burg, Texel, The Netherlands<br />

2 Present address: Rommelstr. 34, 49809 L<strong>in</strong>gen (Ems), Germany<br />

(astrid.forster@gmx.net)<br />

Paleoclimate records of geologic time periods<br />

characterized by extreme global warmth like the mid-<br />

Cretaceous are important for a better understand<strong>in</strong>g of the<br />

Earth’s climate system operat<strong>in</strong>g <strong>in</strong> an exceptionally warm<br />

mode. Here we applied an organic geochemical proxy, the<br />

TetraEther <strong>in</strong>deX of 86 carbon atoms (TEX86), on organic<br />

matter-rich Albian to Santonian sediments to reconstruct<br />

sea surface temperatures (SSTs) <strong>in</strong> the western equatorial<br />

Atlantic (Fig. 1). This sequence of Cretaceous mar<strong>in</strong>e black<br />

shales was recovered by Ocean Drill<strong>in</strong>g Program Leg 207<br />

sites 1258 and 1259 on Demerara Rise that is located<br />

offshore Sur<strong>in</strong>ame/French Guiana. Preceded by a stepwise<br />

Cenomanian warm<strong>in</strong>g trend (~31–35°C), the onset of the<br />

Cretaceous thermal maximum co<strong>in</strong>cided here with the<br />

Cenomanian/Turonian boundary event. Once established,<br />

this extreme warm climate regime, characterized by<br />

averaged tropical SSTs close to 35°C, lasted up to the<br />

Turonian/Coniacian transition. Two pronounced cooler<br />

<strong>in</strong>tervals (~2–3°C) <strong>in</strong>terrupt this otherwise remarkably<br />

stable record, provid<strong>in</strong>g the first δ18O <strong>in</strong>dependent<br />

evidence for middle Turonian cool<strong>in</strong>g that previously has<br />

been attributed to glacioeustatic sea level lower<strong>in</strong>g.<br />

Coniacian SSTs decl<strong>in</strong>e stepwise, reach<strong>in</strong>g a m<strong>in</strong>imum <strong>in</strong><br />

the Santonian (~32–33°C), where cool<strong>in</strong>g is most<br />

pronounced, presumably concomitant with the first,

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

progressive open<strong>in</strong>g of a deep water passage through the<br />

Equatorial Atlantic Gateway. These observations from<br />

Demerara Rise show that rapid tropical SST-changes<br />

occurred also dur<strong>in</strong>g the Cretaceous thermal maximum,<br />

and imply that even the mid-Cretaceous ''supergreenhouse''<br />

climate may have been less stable than<br />

previously thought.<br />

References:<br />

Forster, A., Schouten, S., Baas, M., and S<strong>in</strong>n<strong>in</strong>ghe Damsté, J.S. (2007):<br />

Mid-Cretaceous (Albian-Santonian) sea surface temperature record of<br />

the tropical Atlantic Ocean. Geology, 35, 919-922,<br />

doi:910.1130/G23874A.<br />

Albian Cenomanian<br />

Time<br />

<strong>in</strong>tervals<br />

12<br />

11<br />

δ<br />

-30 -25 -20<br />

13 Corg (‰)<br />

490<br />

Ca.<br />

San.<br />

500<br />

δ<br />

-30 -25 -20<br />

31 32 33 34 35 36<br />

Paleo-SST (°C)<br />

13 Site 1258 Corg (‰)<br />

8<br />

7<br />

530<br />

Ca.<br />

415<br />

Tur.<br />

420<br />

Unit III<br />

6<br />

6<br />

CTBE<br />

540<br />

Ce.<br />

425<br />

430<br />

CTBE<br />

5<br />

Unit V<br />

550 ?<br />

Depth Age<br />

435<br />

440<br />

4<br />

31 32 33 34 35 36 (mcd)<br />

Paleo-SST (°C)<br />

Site 1259<br />

445<br />

450<br />

455<br />

460<br />

MCE<br />

3<br />

465<br />

470<br />

475<br />

2<br />

Unit IV<br />

480<br />

485<br />

490<br />

Unit V<br />

495<br />

500<br />

505<br />

510<br />

515<br />

520<br />

1<br />

Age Depth<br />

(mcd)<br />

10<br />

9<br />

Unit III<br />

Unit IV<br />

Fig. 1. ODP Leg 207 sites 1258 and 1259 (Demerara Rise):<br />

Stratigraphy, stable carbon isotopic composition of organic matter<br />

(δ13Corg, black dots), and paleo-sea surface temperatures (SSTs,<br />

solid crosses) reconstructed by TEX86 (time-<strong>in</strong>tervals T1-T12<br />

differentiated accord<strong>in</strong>g to the paleo-SST record; mcd: meters<br />

composite depth; CTBE: Cenomanian-Turonian boundary event;<br />

MCE: mid-Cenomanian event).<br />

<strong>IODP</strong><br />

The Cenomanian/Turonian oceanic anoxic<br />

event <strong>in</strong> the South Atlantic:new <strong>in</strong>sights from<br />

a geochemical study of DSDP Site 530A<br />

A. FORSTER 1,2 , M.M.M. KUYPERS 1,3 , S.C. TURGEON 4,5 ,H.-J.<br />

BRUMSACK 4 , M.R. PETRIZZO 6 , J.S. SINNINGHE DAMSTÉ 1<br />

1 Royal Netherlands Institute for Sea Research, Department of<br />

Mar<strong>in</strong>e Biogeochemistry and Toxicology, P.O. Box 59, 1790<br />

AB Den Burg, Texel, The Netherlands<br />

2 Present address: Rommelstr. 34, 49809 L<strong>in</strong>gen (Ems), Germany<br />

(astrid.forster@gmx.net)<br />

3 Present address: Max Planck Institute (MPI) for Mar<strong>in</strong>e<br />

Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany<br />

4 Institut für Chemie und Biologie des Meeres (ICBM), Carl von<br />

Ossietzky Univers. Oldenburg, P.O. Box 2503, 26111<br />

Oldenburg, Germany<br />

5 Present address: Department of Earth & Atmospheric Sciences,<br />

University of Alberta, Edmonton AB T6G 2E3, Canada<br />

6 Ardito Desio Department of Earth Sciences, University of Milan,<br />

Via Mangiagalli 34, 20133 Milano, Italy<br />

510<br />

520<br />

Turonian Coniac.<br />

One of the key objectives of Deep Sea Drill<strong>in</strong>g Project<br />

(DSDP) Leg 75 was to shed light on the underly<strong>in</strong>g causes<br />

of Cretaceous oceanic anoxia <strong>in</strong> the South Atlantic by<br />

address<strong>in</strong>g two major hypotheses: productivity driven<br />

anoxia vs. enhanced ocean stratification lead<strong>in</strong>g to<br />

preservation of organic matter and black shale deposition.<br />

Here we present a detailed geochemical dataset from<br />

sediments deposited dur<strong>in</strong>g the Cenomanian/Turonian<br />

(C/T) transition and the global oceanic anoxic event 2<br />

(OAE 2) at DSDP Site 530A, located offshore Namibia<br />

(southeast Angola Bas<strong>in</strong>, north of Walvis Ridge). To<br />

characterize the succession of alternat<strong>in</strong>g black and green<br />

shales at this site and to reconstruct the evolution of their<br />

paleoenvironmental sett<strong>in</strong>g, we have comb<strong>in</strong>ed data<br />

derived from <strong>in</strong>vestigations on bulk organic matter,<br />

biomarkers and the <strong>in</strong>organic fraction. The location of the<br />

C/T boundary itself is biostratigraphically not well<br />

constra<strong>in</strong>ed due to the carbonate-poor (but organic matterrich)<br />

facies of these sediments. The bulk δ 13 C org record and<br />

compound-specific δ 13 C data, <strong>in</strong> comb<strong>in</strong>ation with<br />

published as well as new biostratigraphic data, enabled to<br />

more precisely locate the C/T boundary at DSDP Site<br />

530A. The compound specific δ 13 C record is the first of<br />

this k<strong>in</strong>d reported from C/T black shales <strong>in</strong> the South<br />

Atlantic. It is employed for paleoenvironmental<br />

reconstructions and chemostratigraphic correlation to other<br />

C/T sections <strong>in</strong> order to discuss the paleoceanographic<br />

aspects and implications of the observations at DSDP Site<br />

530A <strong>in</strong> a broader context, e.g., with regard to the potential<br />

trigger mechanisms of OAE 2, global changes <strong>in</strong> black<br />

shale deposition and climate. On a stratigraphic level, an<br />

approximation and monitor<strong>in</strong>g of the syndepositional<br />

degree of oxygen depletion with<strong>in</strong> the sediments/bottom<br />

waters <strong>in</strong> comparison to the upper water column is<br />

achieved by compar<strong>in</strong>g normalized concentrations of<br />

redox-sensitive trace elements with the abundance of<br />

highly source specific molecular compounds. These<br />

biomarkers are derived from photoautotrophic and<br />

simultaneously anoxygenic green sulphur bacteria<br />

(Chlorobiacea) and are <strong>in</strong>terpreted as paleo<strong>in</strong>dicators for<br />

events of photic zone eux<strong>in</strong>ia. In contrast to a number of<br />

other OAE 2 sections that are characterized by cont<strong>in</strong>uous<br />

black shale sequences, DSDP Site 530 represents a highly<br />

dynamic sett<strong>in</strong>g where newly deposited black shales were<br />

repeatedly exposed to conditions of subtle bottom water reoxidation,<br />

presumably lead<strong>in</strong>g to their progressive<br />

alteration <strong>in</strong>to green shales. The frequent alternation<br />

between both facies and the related anoxic to slight<br />

oxygenated conditions can be best expla<strong>in</strong>ed by variations<br />

<strong>in</strong> vertical extent of an oxygen m<strong>in</strong>imum zone <strong>in</strong> response<br />

to changes <strong>in</strong> a highly productive western cont<strong>in</strong>ental<br />

marg<strong>in</strong> sett<strong>in</strong>g driven by upwell<strong>in</strong>g.<br />

51

52<br />

<strong>IODP</strong><br />

Arctic Ocean circulation and weather<strong>in</strong>g<br />

<strong>in</strong>puts over the past 15 million years<br />

M. FRANK 1 , B.A. HALEY 1 , ROBERT F. SPIELHAGEN 1,2 , A.<br />

EISENHAUER 1 , J. BACKMAN 3 , K. MORAN 4<br />

1<br />

Leibniz Institute of Mar<strong>in</strong>e Sciences, IFM-GEOMAR,<br />

Wischhofstrasse 1-3, 24148 Kiel, Germany<br />

2<br />

Academy of Sciences, Humanities and Literature, 55131 Ma<strong>in</strong>z,<br />

Germany<br />

3<br />

Dept. of Geology and Geochemistry, Stockholm University,<br />

Stockholm, SE-106 91, Sweden<br />

4<br />

Graduate School of Oceanography and Department of Ocean<br />

Eng<strong>in</strong>eer<strong>in</strong>g, University of Rhode Island, Narragansett, RI<br />

02882, U.S.A.<br />

We present cosmogenic (10Be) and radiogenic (Nd,<br />

Pb) isotope records from the central Arctic Ocean for the<br />

late Cenozoic (past 15 Ma) obta<strong>in</strong>ed from the ACEX cores<br />

drilled at 1250 m water depth dur<strong>in</strong>g <strong>IODP</strong> Leg 302 on the<br />

Lomonosov Ridge. These cores for the first time enable<br />

paleoceanographic and paleoclimatic research <strong>in</strong> the Arctic<br />

Ocean which had previously been unaccesssible by long<br />

sediment cores.<br />

A profile of cosmogenic 10Be contributed to the<br />

establishment of an age model for the upper 150 m of the<br />

ACEX sediments result<strong>in</strong>g <strong>in</strong> a total age of 12.3 million<br />

years at this depth (Frank et al., <strong>2008</strong>). These sediments are<br />

almost completely barren of biogenic material and<br />

therefore difficult to date by common paleoceanographic<br />

techniques. The 10Be-based results showed that the<br />

average sedimentation rate <strong>in</strong> this section is 14.5 m/Ma,<br />

which is <strong>in</strong> very good agreement with the few other<br />

available biostratigraphic results <strong>in</strong> the upper 190 m of the<br />

ACEX drill cores (Backman et al., <strong>2008</strong>). In addition, the<br />

data po<strong>in</strong>t to the existence of an almost cont<strong>in</strong>uous Arctic<br />

sea ice cover over the past 12 million years.<br />

The radiogenic isotope records of authigenic metal<br />

oxide phases <strong>in</strong> the sediments reflect the bottom water<br />

isotope composition at the time of deposition of the<br />

sediments, whereas bulk sediment analyses provide<br />

<strong>in</strong>formation about the sources of the sediments. In<br />

comb<strong>in</strong>ation with late Quaternary radiogenic isotope<br />

signatures obta<strong>in</strong>ed from sediment leaches of a wellcharacterized<br />

piston core from a position near the ACEX<br />

sites (PS2185), the obta<strong>in</strong>ed seawater Nd isotope data<br />

document that <strong>in</strong>termediate water circulation has changed<br />

dramatically as a consequence of tectonic and climatic<br />

forc<strong>in</strong>g on million year, as well as millennial time scales.<br />

Significantly more mantle-like Nd isotope compositions of<br />

past <strong>in</strong>termediate waters were found dur<strong>in</strong>g most of the<br />

past 15 million years with the exception of the <strong>in</strong>terglacial<br />

periods of the Late Quaternary. These systematic mantlelike<br />

signatures can only orig<strong>in</strong>ate from the Putorana Flood<br />

Basalts and their weather<strong>in</strong>g products on the Kara Sea<br />

shelves. The transfer to <strong>in</strong>termediate depths is ascribed to a<br />

strong <strong>in</strong>fluence of salty br<strong>in</strong>es that were produced and<br />

sank dur<strong>in</strong>g periods of pronounced sea ice formation north<br />

of the Kara Sea shelves, which were largely covered by ice<br />

sheets dur<strong>in</strong>g these periods of time (Haley et al., <strong>2008</strong>a).<br />

Compared with the present day situation, a strongly<br />

dim<strong>in</strong>ished exchange with the Atlantic Ocean through the<br />

newly opened Fram Strait must have co<strong>in</strong>cided with the<br />

periods of enhanced br<strong>in</strong>e <strong>in</strong>fluence.<br />

The isotope composition of Pb <strong>in</strong> past Arctic<br />

<strong>in</strong>termediate water only shows small variations (Haley et<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

al., <strong>2008</strong>b). In view of the short oceanic residence time of<br />

Pb this <strong>in</strong>dicates relatively constant weather<strong>in</strong>g <strong>in</strong>puts over<br />

the past 15 Million years, which is <strong>in</strong> agreement with the<br />

relatively constant radiogenic isotope composition of the<br />

bulk sediments over this period of time. The bulk sediment<br />

isotope composition also <strong>in</strong>dicates that the supply areas for<br />

sediments at the core site on the Lomonosov Ridge have<br />

been ma<strong>in</strong>ly located on the Eurasian marg<strong>in</strong> of the Arctic<br />

Ocean rather than on cont<strong>in</strong>ental North America and<br />

Greenland. The constancy of the detrital <strong>in</strong>put signatures<br />

supports the early existence of an Arctic sea ice cover,<br />

whereas the major <strong>in</strong>itiation of Northern Hemisphere<br />

glaciation at 2.7 Ma appears to have had little impact on<br />

the weather<strong>in</strong>g regime of the Eurasian cont<strong>in</strong>ental marg<strong>in</strong>.<br />

References:<br />

Backman, J., Jakobsson, M., Frank, M., Sangiorgi, F., Br<strong>in</strong>khuis, H.,<br />

Stickley, C., O’Regan, M., Løvlie, R., Pälicke, H. Spofforth, D.,<br />

Gattacecca, J., Moran, K., K<strong>in</strong>g, J. and Heil, C. (<strong>2008</strong>): Age model and<br />

core-seismic <strong>in</strong>tegration for the Cenozoic ACEX sediments from the<br />

Lomonosov Ridge.- Paleoceanography, doi:10.1029/2007PA001476, <strong>in</strong><br />

press.<br />

Frank, M., Backman, J., Jakobsson, M., Moran, K., O’Regan, M., K<strong>in</strong>g, J.,<br />

Haley, B.A., Kubik, P.W. and Garbe-Schönberg, D. (<strong>2008</strong>): Beryllium<br />

isotopes <strong>in</strong> central Arctic Ocean sediments over the past 12.3 million<br />

years: Stratigraphic and paleoclimatic implications.- Paleoceanography,<br />

<strong>in</strong> press, doi:10.1029/2007PA001478.<br />

Haley, B.A., Frank, M., Spielhagen, R.F. and Eisenhauer, A. (<strong>2008</strong>a):<br />

Influence of br<strong>in</strong>e formation on Arctic Ocean circulation over the past<br />

15 million years.- Nature Geoscience 1, 68-72.<br />

Haley, B.A., Frank, M., Spielhagen, R.F., and Fietzke, J. (<strong>2008</strong>b): The<br />

radiogenic isotope record of Arctic Ocean circulation and weather<strong>in</strong>g<br />

<strong>in</strong>puts of the past 15 million years.- Paleoceanography,<br />

doi:10.1029/2007PA001486, <strong>in</strong> press.<br />

<strong>IODP</strong><br />

A Cretaceous benthic foram<strong>in</strong>iferal stable<br />

isotope compilation<br />

O. FRIEDRICH 1,2 , R.D. NORRIS 2 , J. ERBACHER 3<br />

1 National Oceanography Centre, School of Ocean and Earth<br />

Sciences, European Way, Southampton, SO14 3ZH, UK<br />

2 Scripps Institution of Oceanography, 9500 Gilman Drive, La<br />

Jolla, CA 92093, USA<br />

3 Bundesanstalt fuer Geowissenschaften und Rohstoffe, Stilleweg<br />

2, 30655 <strong>Hannover</strong>, Germany<br />

We produced new stable isotope data sets of<br />

Cenomanian to Santonian benthic foram<strong>in</strong>ifera from the<br />

western equatorial Atlantic (ODP Leg 207) and from the<br />

tropical Pacific Ocean (DSDP Sites 305 and 463). Together<br />

with literature data our results are compiled <strong>in</strong>to a global<br />

isotope compilation, result<strong>in</strong>g <strong>in</strong> a cont<strong>in</strong>uous benthic δ 18 O<br />

record from 115-65 Ma. This compilation shows four ma<strong>in</strong><br />

<strong>in</strong>tervals: (1) <strong>in</strong>creas<strong>in</strong>g temperatures before 97 Ma and (2)<br />

a subsequent super-greenhouse which are both paralleled<br />

by <strong>in</strong>creas<strong>in</strong>g δ 13 C values, (3) a long-last<strong>in</strong>g cool<strong>in</strong>g and<br />

decrease <strong>in</strong> carbon isotopes (90-78 Ma), and (4) globally<br />

similar δ 13 C and δ 18 O values after 78 Ma. Increas<strong>in</strong>g seasurface<br />

temperatures sometimes exceed<strong>in</strong>g 35°C are wellknown<br />

for Intervals 1 and 2. But our compilation shows,<br />

that deep-ocean temperatures were significantly warmer<br />

than today, especially <strong>in</strong> the proto- North Atlantic (20-<br />

28°C). These high temperatures are expla<strong>in</strong>ed by a lack of<br />

cold bottom-water formation, the restricted nature of the<br />

North Atlantic, and the formation of warm sal<strong>in</strong>e bottom<br />

waters that sporadically were formed with<strong>in</strong> epicont<strong>in</strong>ental<br />

seas. The parallel positive trend <strong>in</strong> δ 13 C is believed to<br />

reflect massive storage of Corg dur<strong>in</strong>g Cretaceous black<br />

shale formation. Interest<strong>in</strong>gly, however, δ 13 C values of the

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

tropical Atlantic show a similar trend but more negative<br />

values. We propose that this reflects a comb<strong>in</strong>ation of<br />

extensive rem<strong>in</strong>eralization of 12C and a long residence<br />

time due to the sporadic formation of warm and sal<strong>in</strong>e<br />

waters. Dur<strong>in</strong>g the follow<strong>in</strong>g <strong>in</strong>terval 3, benthic δ 18 O<br />

values of all ocean bas<strong>in</strong>s show similar values. This trend is<br />

<strong>in</strong>terpreted to be the result of the beg<strong>in</strong>n<strong>in</strong>g open<strong>in</strong>g of the<br />

Equatorial Atlantic Gateway. This deepen<strong>in</strong>g and a parallel<br />

reorganization of the oceanic circulation with longitud<strong>in</strong>al<br />

water-mass and heat exchange may have favoured the<br />

observed cool<strong>in</strong>g trend of <strong>in</strong>terval 3. This explanation is<br />

supported by the global decrease <strong>in</strong> δ 13 C, proposed to<br />

reflect a better connection of the former restricted North<br />

Atlantic that allows the oxidization of the organic-rich<br />

sediments formed <strong>in</strong> this bas<strong>in</strong>. In contrast to the former<br />

<strong>in</strong>tervals, the last 13 Ma of the Cretaceous are, on a global<br />

scale, characterized by similar values for both, oxygen and<br />

carbon isotopes. This is proposed to <strong>in</strong>dicate a full<br />

connection between all ocean bas<strong>in</strong>s.<br />

<strong>ICDP</strong><br />

Lokalisierung <strong>in</strong>duzierter Seismizität ohne<br />

Picken – E<strong>in</strong>e Stapelmethode<br />

D. GAJEWSKI 1 , D. ANIKIEV 2 , E. TESSMER 1 , C. VANELLE 1 , B.<br />

KASHTAN 2<br />

1 Universität Hamburg, Institut für Geophysik, Bundesstr. 55,<br />

20146 Hamburg<br />

2 St. Petersburg State University<br />

Für die Interpretation von <strong>in</strong>duzierter Seismizität, z.B.<br />

bei Injektionsexperimenten, ist die Lokalisierung der<br />

erzeugten akustischen Ereignisse und ihre raum-zeitliche<br />

Variation e<strong>in</strong>e notwendige E<strong>in</strong>gangsgröße. Hierzu müssen<br />

teilweise mehrere tausend Events ausgewertet werden, was<br />

e<strong>in</strong>en großen Aufwand an Datenbearbeitung erfordert, da<br />

diese Events <strong>in</strong> jeder seismischen Spur des Monitor<strong>in</strong>g-<br />

Netzwerkes identifiziert werden müssen. Dies wird<br />

üblicherweise mit automatischen Pick<strong>in</strong>g-Verfahren<br />

realisiert, die im Anschluss e<strong>in</strong>er manuellen<br />

Qualitätskontrolle unterzogen werden. Für die Detektion<br />

der Ereignisse werden also E<strong>in</strong>spurverfahren benutzt, da<br />

jeweils nur e<strong>in</strong> e<strong>in</strong>zelnes Seismogramm betrachtet wird. Ist<br />

die Energie des Ereignisses zu kle<strong>in</strong> und das Signal-Stör-<br />

Verhältnis deswegen nicht h<strong>in</strong>reichend, versagen die<br />

Verfahren.<br />

In der letzten Zeit wurden neue Methoden entwickelt,<br />

die ke<strong>in</strong> Picken von Events mehr erfordern und bei der<br />

Lokalisierung simultan alle Spuren des beobachtenden<br />

Netzwerks benutzen <strong>in</strong>dem e<strong>in</strong>e Feldfortsetzung <strong>in</strong> die<br />

Tiefe vorgenommen wird. Die Feldfortsetzung kann über<br />

reverse modell<strong>in</strong>g (Gajewski und Tessmer, 2005) oder über<br />

e<strong>in</strong>e Diffraktionsstapelung realisiert werden (Gajewski et<br />

al., 2007). Diese Methoden bieten nicht nur den Vorteil,<br />

dass ke<strong>in</strong> picken der Events mehr erforderlich ist, sondern<br />

sie erhöhen auch den Detektionslevel des beobachtenden<br />

Netwerkes um den Faktor N, wobei N die Anzahl der<br />

Empfänger im Netzwerk ist. Dadurch können<br />

kostengünstige Oberflächennetzwerke e<strong>in</strong>gesetzt werden,<br />

die durch Beobachtungen aus Bohrlöchern ergänzt werden<br />

können. In diesem Beitrag wird die Lokalisierung mittels<br />

Feldfortsetzung durch e<strong>in</strong>e Diffraktionsstapelung<br />

präsenteirt. Das Ergebnis dieses Prozesses ist e<strong>in</strong>e<br />

sogenannte Image Function, deren Maximum den Ort der<br />

Quelle repräsentiert. E<strong>in</strong>e Anwendung auf verrauschte<br />

Oberflächendaten ist <strong>in</strong> Abb. 1 dargestellt. Die räumliche<br />

Ausdehnung des Maximums ist dabei e<strong>in</strong> Maß für die<br />

Lokalisierungsunschärfe und hängt von der Genauigkeit<br />

des Geschw<strong>in</strong>digkeitsmodells, der Apertur des Netzwerks<br />

und der Bandbreite des Signals ab. Numerische Studien<br />

zeigen, dass durch die Diffraktionsstapelung auch dann<br />

noch Events lokalisiert werden können, wenn diese im<br />

e<strong>in</strong>zelnen Seismogramm des Netzwerks nicht erkannt<br />

werden können (Abb. 1). Studien zum E<strong>in</strong>fluss von<br />

Heterogenitäten an der Oberfläche (z.B.<br />

Verwitterungsschicht) zeigen, dass dieser E<strong>in</strong>fluss<br />

vernachlässigt werden kann, wenn die räumliche<br />

Ausdehnung deutlich unterhalb der vorherrschenden<br />

Wellenlänge liegt. Größere Anomalien lassen sich im<br />

Geschw<strong>in</strong>digkeitmodell erfassen, da sie determ<strong>in</strong>istischen<br />

Charakter haben. Weitere numerische Studien zeigen, dass<br />

e<strong>in</strong>e Lokalisierung auch mit ungenauen Geschw<strong>in</strong>digkeiten<br />

möglich ist. Der Ort des Maximums der Image Function<br />

fällt dabei mit dem Ort der Quelle zusammen, allerd<strong>in</strong>gs ist<br />

die räumliche Ausdehnung des Maximums nun größer und<br />

damit auch die Lokalisierungsunschärfe.<br />

References:<br />

Gajewski, D., Tessmer, E., 2005, Reverse modell<strong>in</strong>g for seismic event<br />

characterization, Geophys. J. Int., 164, 276-284.<br />

Gajewski, D., Anikiev, D., Kashtan, B., Tessmer, E., Vanelle, C., 2007,<br />

Source Location by Diffraction Stack<strong>in</strong>g,69th EAGE Conference &<br />

Exhibition, London.<br />

Abbildung 1: Verrauschte Daten (l<strong>in</strong>ks, S/N=0.5) registriert an der<br />

Oberfläche e<strong>in</strong>es homogenen Modells <strong>in</strong> denen e<strong>in</strong> seismisches<br />

Ereignis <strong>in</strong> 2 km Tiefe bei x=1.2 km enthalten ist sowie<br />

zugehörige Image Function (rechts) nach der<br />

Diffraktionsstapelung. Das Maximum der Image Function liegt <strong>in</strong><br />

der Nähe der tatsächlichen Quelle, die durch e<strong>in</strong>en weißen Punkt<br />

gekennzeichnet ist. Die Breite des Maximums ist e<strong>in</strong> Maß für die<br />

Lokalisierungsunschärfe, die wegen der Asymmetrie der Aperture<br />

<strong>in</strong> Bezug auf die Quellposition leicht geneigt ist. Lateral ist die<br />

Unschärfe wesentlich kle<strong>in</strong>er als vertikal. Zusätzliche<br />

Beobachtungen des Events im Bohrloch verkle<strong>in</strong>ern die vertikale<br />

Lokalisierungsunschärfe.<br />

53

54<br />

<strong>ICDP</strong><br />

Geometry of maar lake Laguna Potrok Aike,<br />

Patagonia<br />

A. C. GEBHARDT<br />

AWI Bremerhaven, Am Alten Hafen 26, 27568 Bremerhaven<br />

Laguna Potrok Aike is a maar lake located <strong>in</strong> Southern<br />

Patagonia, Argent<strong>in</strong>a, at 52°S and 70°W. The lake with a<br />

diameter of 3.5 km is almost circular and bowl-shaped.<br />

Steep flanks separate the lake shoulders at 15 to 35 m water<br />

depth from the central pla<strong>in</strong> at approximately 100 m water<br />

depth. The lake is situated <strong>in</strong> the Pali Aike Volcanic Field<br />

at the present boundary between the Southern Hemispheric<br />

Westerlies and the Antarctic Polar Front. Its lake level is<br />

highly susceptible to changes <strong>in</strong> the Antarctic Circumpolar<br />

Current that controls the regional precipitation patterns.<br />

Changes <strong>in</strong> precipitation lead to lake level fluctuations of<br />

up to several tens of meters. The lake’s sedimentary <strong>in</strong>fill<br />

possibly conta<strong>in</strong>s a long and cont<strong>in</strong>uous record of several<br />

glacial and <strong>in</strong>terglacial cycles, which is unique <strong>in</strong> the<br />

southern South American realm. Laguna Potrok Aike has<br />

thus become one of the major present goals of <strong>ICDP</strong>. Three<br />

drill sites have been identified and will be drilled <strong>in</strong> the<br />

near future<br />

Four seismic surveys were carried out as an <strong>ICDP</strong> presite<br />

survey. S<strong>in</strong>gle- and multi-channel seismic reflection<br />

data as well as refraction data (sonobuoys and land station)<br />

were used to <strong>in</strong>vestigate the maar geometry and the <strong>in</strong>ternal<br />

structures of its lacustr<strong>in</strong>e sedimentary <strong>in</strong>fill.<br />

Maar craters are generally caused by the contact of<br />

ris<strong>in</strong>g magma with groundwater result<strong>in</strong>g <strong>in</strong> explosive,<br />

phreatomagmatic eruptions. The <strong>in</strong>itial diatreme is formed<br />

by viscous lava that gets stuck <strong>in</strong> the vent. Collapse of the<br />

surround<strong>in</strong>g, destructed rock fills the root zone with<br />

breccias. The collapse structure propagates to the surface<br />

and results <strong>in</strong> the <strong>in</strong>itial maar crater that will conta<strong>in</strong> a lake<br />

as long as groundwater or meteoritic water is available.<br />

Steep diatreme flanks are clearly visible <strong>in</strong> the seismic data<br />

(seismic refraction data, sparker and multi-channel<br />

reflection data) and are also pronounced <strong>in</strong> the bathymetry.<br />

Seismic sections from Laguna Potrok Aike are well<br />

comparable to other maar profiles (e.g. the Maar Pit near<br />

Darmstadt, Germany) and thus confirm its<br />

phreatomagmatic orig<strong>in</strong>.<br />

Two major stratigraphic units (I and II) were<br />

dist<strong>in</strong>guished <strong>in</strong> the seismic sections. Unit I consists of the<br />

lacustr<strong>in</strong>e <strong>in</strong>fill and was further subdivided <strong>in</strong>to Sub-units<br />

I-a and I-b on the lake shoulders and I-ab, I-c, I-d and I-e <strong>in</strong><br />

the central bas<strong>in</strong>. Sub-units I-a and I-b on the lake<br />

shoulders are separated by a major unconformity and<br />

conta<strong>in</strong> several paleoshorel<strong>in</strong>e structures formed dur<strong>in</strong>g a<br />

step-wise transgression after a lake level lowstand of<br />

approx. 35 m below the present lake level. In the central<br />

bas<strong>in</strong>, Sub-units I-a and I-b are merged <strong>in</strong>to Sub-unit I-ab,<br />

not be<strong>in</strong>g separated by any unconformity. Mass movement<br />

deposits were found <strong>in</strong> the southern, western and eastern<br />

parts close to the steep diatreme flanks, and pelagic<br />

sedimentation dom<strong>in</strong>ates <strong>in</strong> the northern and central parts.<br />

The boundary between I-ab and I-c is non-erosive with I-ab<br />

form<strong>in</strong>g downlaps onto I-c from the eastern and western<br />

parts of the lake, po<strong>in</strong>t<strong>in</strong>g at a significantly lower lake level<br />

dur<strong>in</strong>g its accumulation. Sub-unit I-d shows similar<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

characteristics as I-ab and forms downlaps onto Sub-unit Ie.<br />

The bedrock (Unit II) that forms the steep diatreme<br />

flanks consists of the well-layered sandstones of the Santa<br />

Cruz formation found <strong>in</strong> outcrops <strong>in</strong> the lake surround<strong>in</strong>gs.<br />

<strong>ICDP</strong><br />

Chronological history of UHP rocks from the<br />

Dabie-Sulu terrane, Eastern Ch<strong>in</strong>a<br />

A. GERDES 1 , F.L. LIU 2 , S. WEYER 1 , G. BREY 1<br />

1<br />

Institut für Geowissenschaften, Altenhöferallee 1, 60438<br />

Frankfurt/Ma<strong>in</strong><br />

2<br />

Institute of Geology, Ch<strong>in</strong>ese Academy of Geological Science,<br />

Beij<strong>in</strong>g 100037<br />

Ultrahigh pressure (UHP) rocks from the Ch<strong>in</strong>ese<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g (CCSD) program were<br />

chosen for detailed studies to ga<strong>in</strong> a better understand<strong>in</strong>g of<br />

(1) the complex metamorphic evolution of the Sulu-Dabie<br />

terrane, and (2) the limitations and robustness of the<br />

different chronological method for dat<strong>in</strong>g high-grade<br />

metamorphism<br />

Multistage zircon growth can be observed <strong>in</strong> most<br />

Sulu-Dabie UHP rocks. Inherited and metamorphic zircons<br />

were dist<strong>in</strong>guished on the basis of transmitted light<br />

microscopy, cathodolum<strong>in</strong>escence (CL) imag<strong>in</strong>g, trace<br />

element contents, Hf isotope composition, U-Pb ages and<br />

their m<strong>in</strong>eral <strong>in</strong>clusion assemblages (Fig. 1-3).<br />

Inherited zircon of middle Neoproterozoic age have<br />

variable trace element pattern that are considerably<br />

different from that of metamorphic zircon doma<strong>in</strong>s (Fig. 3).<br />

Based on CL, m<strong>in</strong>eral <strong>in</strong>clusion and U-Pb ages up to three<br />

phases of zircon growth or re-crystallisation can be<br />

identified <strong>in</strong> a s<strong>in</strong>gle sample (Fig. 2). The ages are<br />

<strong>in</strong>terpreted to date the time of (1) prograde and (2) UHP<br />

metamorphism dur<strong>in</strong>g subduction, and (3) later retrograde<br />

metamorphism dur<strong>in</strong>g exhumation.<br />

Metamorphic doma<strong>in</strong>s from a s<strong>in</strong>gle sample have often<br />

a uniform Hf isotope composition (and low 176 Lu/ 177 Hf -><br />

grt growth) <strong>in</strong>dicat<strong>in</strong>g isotope equilibration <strong>in</strong> the<br />

decimetre-scale dur<strong>in</strong>g the Middle Triassic UHP event<br />

(Fig. 3). This composition varies between different samples<br />

and is generally significantly more radiogenic than that of<br />

the <strong>in</strong>herited cores and thus the bulk rock. Its respective<br />

value is controlled by the percentage of dissolved or recrystallized<br />

<strong>in</strong>herited zircon, with low Lu/Hf and relatively<br />

unradiogenic 176 Hf/ 177 Hf, and the bulk rock composition.<br />

However, few samples have UHP zircon doma<strong>in</strong>s with<br />

scattered isotope composition (Fig. 3a), suggest<strong>in</strong>g no<br />

complete equilibration of the Lu-Hf system.<br />

Prelim<strong>in</strong>ary results show that there is a surpris<strong>in</strong>gly<br />

good correlation between the U-Pb and the Lu-Hf system<br />

and the Th/U for zircon of some samples (Fig. 4). Most<br />

analyses fall on mix<strong>in</strong>g l<strong>in</strong>es between magmatic cores and<br />

the homogeneous UHP doma<strong>in</strong>s, <strong>in</strong>dicat<strong>in</strong>g that most<br />

<strong>in</strong>herited zircon were affected by <strong>in</strong>complete recrystallization<br />

dur<strong>in</strong>g UHP metamorphism.<br />

Our new LA-ICP-MS ages together with the results from<br />

previous studies <strong>in</strong>dicate that metamorphic zircon doma<strong>in</strong>s<br />

formed or recrystallized dur<strong>in</strong>g Middle Triassic HP to UHP<br />

metamorphism at around 240-246 Ma and 233-225 Ma,<br />

respectively (Figs 5). Accord<strong>in</strong>g to Zheng et al. (2005) and<br />

Wu et al. (2006) these two events of zircon growth are

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

related to phases of fluid-availability dur<strong>in</strong>g UHP<br />

metamorphism; the first related to subduction and the<br />

second to <strong>in</strong>itial exhumation from the diamond to the<br />

coesite stability field.<br />

Recrystallized zircon rims, tips, and complete gra<strong>in</strong>s<br />

with ages of ~220-206 Ma (Fig. 5) are probably related to<br />

Late Triassic retrograde HP- and amphibolite-facies<br />

retrogression, respectively.<br />

206 Pb/ 238 U<br />

206 Pb/ 238 U<br />

206 Pb/ 238 U<br />

206 Pb/ 238 U<br />

0.14<br />

0.12<br />

0.10<br />

0.08<br />

0.06<br />

0.04<br />

150<br />

0.02<br />

0.1<br />

0.13<br />

0.11<br />

0.09<br />

0.07<br />

0.05<br />

0.03<br />

0.039<br />

0.035<br />

DS1, orthogneiss<br />

CCSD<br />

250<br />

350<br />

450<br />

550<br />

lower <strong>in</strong>tercept age<br />

230 ±10 Ma<br />

650<br />

750<br />

U.I. age<br />

787 ±17 Ma<br />

MSWD = 0.55<br />

0.12<br />

0.10<br />

0.08<br />

0.06<br />

0.04<br />

0.02<br />

0.3 0.5 0.7 0.9 1.1 1.3<br />

0.18 0.22 0.26 0.30 0.34 0.38<br />

0.16<br />

0.14<br />

0.12<br />

0.10<br />

0.08<br />

0.06<br />

Concordia age<br />

227.6 ±1.8 Ma<br />

MSWD C+E = 1.3<br />

7 spots<br />

P3c, Ph-Rt-eclogite<br />

CCSD: 326 m<br />

Concordia age<br />

226.6 ±3.5 Ma<br />

MSWD C+E = 0.87<br />

3 spots<br />

300<br />

UM-1, eclogite<br />

210<br />

220<br />

230<br />

240<br />

500<br />

250<br />

207 Pb/ 235 U<br />

700<br />

0.2 0.4 0.6 0.8 1.0 1.2<br />

350<br />

SG1, eclogite<br />

CCSD: m<br />

Concordia age<br />

796.9 ±4.8 Ma<br />

MSWD C+E = 1.9<br />

12 spots<br />

450<br />

550<br />

Intercepts at<br />

221 +13/-14 & 803 +23/-24 Ma<br />

MSWD = 0.97<br />

650<br />

data-po<strong>in</strong>t error ellipses are 2σ<br />

Concordia age<br />

231.9 ±1.8 Ma<br />

MSWD C+E = 1.6<br />

12 spots<br />

750<br />

850<br />

Intercepts at<br />

226 ± 30 & 799 ± 8 Ma<br />

MSWD = 0.86<br />

0.04<br />

0.3 0.5 0.7 0.9 1.1 1.3<br />

0.13<br />

0.11<br />

0.09<br />

0.07<br />

0.05<br />

0.03<br />

0.036<br />

0.034<br />

0.032<br />

0.030<br />

P6W, orthogneiss<br />

CCSD: 2873 m<br />

Concordia age<br />

228.9 ±3.2 Ma<br />

MSWD C+E = 1.1<br />

4 spots<br />

450<br />

250<br />

180<br />

350<br />

200<br />

550<br />

650<br />

0.028<br />

0.18 0.20 0.22 0.24 0.26<br />

0.12<br />

0.10<br />

0.08<br />

0.06<br />

0.04<br />

220<br />

750<br />

0.3 0.5 0.7 0.9 1.1<br />

PJ6, orthogneiss<br />

CCSD: 2625 m<br />

Concordia age<br />

228.5 ±2.1 Ma<br />

MSWD C+E = 1.5<br />

13 spots<br />

500<br />

300<br />

AG2a-1, Py-Rt-eclogite<br />

CCSD 452m<br />

Concordia age<br />

230.7 ±2.2 Ma<br />

MSWD C+E = 0.90<br />

12 spots<br />

450<br />

Fig. 1. U-Pb LA-ICP-MS dat<strong>in</strong>g of complex zircon from CCSD UHP rocks.<br />

250<br />

Thus the U-Pb zircon data imply that the metamorphic<br />

evolution of the Sulu-Dabie terrane lasted for at least 40<br />

Myr, with more than 25 Myr of HP to UHP metamorphism<br />

(Fig. 5).<br />

350<br />

lower <strong>in</strong>tercept age<br />

225 +12/-13 Ma<br />

550<br />

data-po<strong>in</strong>t error ellipses are 2σ<br />

Concordia age<br />

208.1 ±3.2 Ma<br />

MSWD C+E = 1.6<br />

5 spots<br />

650<br />

700<br />

Intercepts at<br />

226.1 ± 5.6 & 798 ± 13 Ma<br />

MSWD= 1.11<br />

0.2 0.4 0.6 0.8 1.0 1.2<br />

PJ6, orthogneiss<br />

late overgrowths<br />

CCSD: 2625 m<br />

750<br />

Intercepts at<br />

230 ±14 & 773 +29/-28 Ma<br />

MSWD = 0.83<br />

0.1 0.3 0.5 0.7 0.9 1.1<br />

207 Pb/ 235 U<br />

U.I. age<br />

779 +31/-33 Ma<br />

MSWD = 1.05<br />

55

56<br />

1000<br />

100<br />

10<br />

1<br />

0.1<br />

Sample/Chondrite 10000<br />

0.01<br />

0.001<br />

1000<br />

100<br />

10<br />

1<br />

0.1<br />

Sample/Chondrite 10000<br />

0.01<br />

0.001<br />

1000<br />

100<br />

10<br />

1<br />

0.1<br />

Sample/Chondrite 10000<br />

0.01<br />

0.001<br />

H3 Inherited (detrital) zircon<br />

Prograde zircon doma<strong>in</strong><br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

H3<br />

UHP zircon doma<strong>in</strong><br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

H3<br />

Retrograde zircon doma<strong>in</strong><br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

a<br />

c<br />

e<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

H4 Inherited (detrital) zircon<br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

H4<br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

H4<br />

Prograde zircon doma<strong>in</strong><br />

UHP zircon doma<strong>in</strong><br />

Retrograde zircon doma<strong>in</strong><br />

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu<br />

Fig. 2. Chondrite-normalized REE pattern of <strong>in</strong>herited magmatic zircon and that of three dist<strong>in</strong>ct metamorphic zircon<br />

doma<strong>in</strong>s, Dabie-Sulu terrane (Liu et al., 2006).<br />

Hf/ Hf (t)<br />

176 177<br />

176 177<br />

Hf/ Hf (t)<br />

.28295<br />

.28285<br />

.28275<br />

.28265<br />

.28255<br />

.28245<br />

.28235<br />

.28285<br />

.28280<br />

.28275<br />

.28270<br />

.28265<br />

.28260<br />

.28255<br />

.28250<br />

.28245<br />

.28240<br />

a<br />

176 177<br />

Lu/ Hf<br />

mix<strong>in</strong>g<br />

SH1, eclogite<br />

±2σ<br />

.28275<br />

.28270<br />

.28265<br />

.28260<br />

d<br />

Db3, orthogneiss<br />

retrograde rims<br />

.28215<br />

UHP overgrowths<br />

UHP overgrowths<br />

Inherited zircon cores<br />

magmatic variation<br />

.28210<br />

.28205<br />

partially recrystallized doma<strong>in</strong>s<br />

zircon cores (concordant U-Pb)<br />

1.E-05 1.E-04 1.E-03 1.E-02 1.E-05 1.E-04 1.E-03 1.E-02<br />

176 177<br />

Lu/ Hf<br />

c G13, amphibolite<br />

Inherited core<br />

UHP overgrowths<br />

Retrograde gra<strong>in</strong>s<br />

magmatic variation<br />

2σ<br />

1.E-05 1.E-04 1.E-03 1.E-02<br />

.28240<br />

.28235<br />

.28230<br />

.28225<br />

.28220<br />

b<br />

±2σ<br />

176 177<br />

Lu/ Hf<br />

G12, amphibolite<br />

mix<strong>in</strong>g<br />

.28255<br />

.28250<br />

Inherited cores<br />

UHP overgrowths<br />

Retrograde gra<strong>in</strong>s<br />

.28245<br />

Inherited zircon<br />

.28240<br />

(Zheng et al. 2006)<br />

magmatic variation<br />

1.E-05 1.E-04 1.E-03 1.E-02<br />

176 177<br />

Lu/ Hf<br />

Fig. 3. Initial 176 Hf/ 177 Hf vs 176 Lu/ 177 Hf of zircon from different UHP rocks from the CCSD, Sulu terrane. The data<br />

suggest that usually both, the <strong>in</strong>herited zircon and the UHP overgrowth doma<strong>in</strong>s, were homogenized dur<strong>in</strong>g formation.<br />

Scatter <strong>in</strong> the <strong>in</strong>herited zircon is due to partial recrystallization related to UHP metamorphism.<br />

b<br />

d<br />

f<br />

2σ

176 177<br />

Hf/ Hf (t)<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Th/U<br />

1.00<br />

0.10<br />

0.01<br />

.28245<br />

.28240<br />

.28235<br />

.28230<br />

.28225<br />

.28220<br />

.28215<br />

.28210<br />

.28205<br />

206 238<br />

apparent Pb/ U age<br />

200 300 400 500 600 700 800<br />

retrograde rims<br />

UHP overgrowths<br />

partially recrystallized doma<strong>in</strong>s<br />

zircon cores (concordant U-Pb)<br />

PJ6, orthogneiss<br />

250 350 450 550 650 750 850<br />

206 238<br />

apparent Pb/ U age<br />

Fig. 4. Plots of Th/U (log) and <strong>in</strong>itial 176 Hf/ 177 Hf vs apparent U-Pb age.<br />

Relative probability<br />

retrograde HP- &<br />

amphibolite-facies<br />

retrogression<br />

UHP zircon<br />

0<br />

200 210<br />

220 230 240 250<br />

U-Pb age<br />

HP/UHP<br />

zircon<br />

Fig. 5. B<strong>in</strong>ned frequency and probability density distribution plot of U-Pb ages of metamorphic zircon from Dabie-Sulu UHP rocks. The<br />

data show a bimodal distribution for HP-UHP zircon doma<strong>in</strong>s and a wide peak def<strong>in</strong>ed by late recrystallized zircon (rims, tips and whole<br />

gra<strong>in</strong>s) due to retrograde HP- to amphibolite-facies retrogression. (data source: this study; Liu F.L. et al. 2006a,b, 2007, <strong>in</strong> revision. Ayers<br />

et al. 2002; Hacker et al., 2000, 2006; Li et al. 2004, 2006; Li X.P. et al. 2004; Liu et al. 2004, 2006; Liu & Jian 2004; Liu D. et al. 2006;<br />

Okay et al. 1993,Wan et al. 2005; Webb et al., 1999; Wu et al. 2006; Xie et al. 2004; Xu Z.Q. et al. 2006; Zhao et al. 2006; Zheng et al.<br />

2005).<br />

11<br />

10<br />

9<br />

8<br />

7<br />

6<br />

5<br />

4<br />

3<br />

2<br />

1<br />

Number<br />

57

58<br />

<strong>ICDP</strong><br />

Magnetofabrics of eclogites and ultramafic<br />

rocks from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific<br />

Drill<strong>in</strong>g (CCSD) project: evidence for<br />

ultrahigh-pressure (UHP) texture <strong>in</strong>heritance<br />

throughout retrogression<br />

J.C. GRIMMER 1 , X. QI 2 , Z. XU 2<br />

1 Geologisches Institut, Universität Karlsruhe, Hertzstrasse 16,<br />

76187 Karlsruhe, Germany<br />

2 Institute of Geology, Ch<strong>in</strong>ese Academy of Geological Sciences,<br />

Baiwanzhuang Road 26, 10037 Beij<strong>in</strong>g, Ch<strong>in</strong>a<br />

Introduction<br />

In this study, we present data of the anisotropy of<br />

magnetic susceptibility (AMS) from variably retrogressed<br />

eclogites and ultramafic rocks from the uppermost 1000 m<br />

of the 5138 m deep drill hole of the Ch<strong>in</strong>ese Cont<strong>in</strong>ental<br />

Scientific Drill<strong>in</strong>g (CCSD) project (Fig. 1). In particular,<br />

Fe-rich mafic-ultramafic rocks provide a good control on<br />

retrograde reactions due to the <strong>in</strong>volvement of Fe- and Fe-<br />

Ti-oxides dur<strong>in</strong>g the retrograde eclogite to amphibolite and<br />

amphibolite to greenschist grade reactions. As<br />

magnetofabrics depend on both the magnetic m<strong>in</strong>eralogy<br />

and lattice- or shape-preferred orientations of m<strong>in</strong>erals the<br />

AMS-method is a promis<strong>in</strong>g tool to study exhumation<br />

related processes <strong>in</strong> terms of retrograde fluid-rock<br />

<strong>in</strong>teractions and ductile deformation. The CCSD ma<strong>in</strong>hole<br />

(MH) <strong>in</strong>tersected the steeply east-dipp<strong>in</strong>g Maobei eclogite<br />

body (Fig. 1). Based on geochemistry and petrography four<br />

units are dist<strong>in</strong>guished for the uppermost 1.2 km (Zhang et<br />

al. 2006a): unit 1 (100–530 m): quartz-rich eclogites,<br />

rutile-rich eclogites and th<strong>in</strong> gneiss layers; unit 2 (530–600<br />

m): rutile- and ilmenite-rich eclogites; unit 3 (600–680 m)<br />

serpent<strong>in</strong>ized ultramafic rocks with m<strong>in</strong>or <strong>in</strong>tercalations of<br />

eclogite and garnet pyroxenites layers and lenses; unit 4<br />

(680–1160 m) <strong>in</strong>terlayered paragneisses, eclogites, and<br />

retrograde eclogite (amphibolites) with a th<strong>in</strong> layer of<br />

ultramafic rocks at ca. 850 m.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Petrography and texture<br />

Eclogites consist of garnet and omphacite with variable<br />

contents of Fe-Ti-oxides, Fe-sulphides, and phengite<br />

represent<strong>in</strong>g peak UHP rock composition. The eclogites of<br />

all units show variable degrees of retrograde amphibolite to<br />

greenschist facies metamorphic overpr<strong>in</strong>t focused <strong>in</strong><br />

irregular ve<strong>in</strong>s. The retrograde m<strong>in</strong>eral phases comprise<br />

bluish-greenish amphiboles of pargasitic composition<br />

(Riemann & Oberhänsli 2007; Yang 2004), f<strong>in</strong>e-gra<strong>in</strong>ed<br />

amphibole-plagioclase-symplectites, titanite, epidote,<br />

biotite, and albitic feldspar. Retrograde pargasitic<br />

amphibole coronas with newly grown magnetite occur as<br />

<strong>in</strong>tergra<strong>in</strong> phases of non-isometric garnets. Magnetite<br />

seems to be limited to the pargasitic amphiboles and<br />

probably traces the former gra<strong>in</strong> boundaries of garnet. The<br />

ultramafic rocks are serpent<strong>in</strong>ized to various degrees.<br />

Serpent<strong>in</strong>ite ve<strong>in</strong>s and cracks separate relict oliv<strong>in</strong>e cores,<br />

which causes a typical mesh texture. Magnetite is enriched<br />

along former gra<strong>in</strong> boundaries of oliv<strong>in</strong>e, <strong>in</strong> serpent<strong>in</strong>ite<br />

cracks and ve<strong>in</strong>s and on th<strong>in</strong> rims around garnet.<br />

Magnetic m<strong>in</strong>eralogy<br />

The mean susceptibilities (Kmean) of the eclogites vary<br />

from 0.6x10-3 to 14.3x10-3 SI (Fig. 2). Low (Kmean < 10-<br />

3), <strong>in</strong>termediate (1 < Kmean < 5x10-3) and high (Kmean ><br />

5x10-3) susceptibilities <strong>in</strong>dicate variable contributions of<br />

ferrimagnetic m<strong>in</strong>erals with<strong>in</strong> the different eclogite<br />

samples and superposed para- and ferromagnetic fabrics.<br />

Except for one sample, which exceeded the measurement<br />

range (max. 250x10-3 SI) of the Kappabridge, Kmean of<br />

the ultramafic rocks varies from 17.5x10-3 to 232.7x10-3<br />

SI (Fig. 2).<br />

Magnetic susceptibility as a function of temperature<br />

was measured from representative lithologies from all<br />

sampled units for the temperature range of -192°C to<br />

700°C <strong>in</strong> order to identify the m<strong>in</strong>erals carry<strong>in</strong>g bulk<br />

susceptibility. K(T)-measurements are also helpful to<br />

calculate the relative proportion of the respective para- and<br />

ferrimagnetic m<strong>in</strong>erals.<br />

Figure 1: Overview map (<strong>in</strong>set upper left) of the Sulu UHP-metamorphic belt with border<strong>in</strong>g faults (XF: Xiangshui Fault; SJF: Shuyang-<br />

J<strong>in</strong>p<strong>in</strong>g fault;WYF: Wulian-Yantai-Fault). Geologic overview map displays major mafic-ultramafic bodies <strong>in</strong> the UHP-metamorphic<br />

nappes (`slices´), which are separated by ductile shear zones with top to NW k<strong>in</strong>ematics (e.g. Xu et al. 2006b) with barbs on hang<strong>in</strong>g wall<br />

(modified after Xu Z et al. 2006a). B) Cross section of the Maobei eclogite body (modified after Liu et al. <strong>2008</strong>) with sampl<strong>in</strong>g depths as<br />

<strong>in</strong>dicated by white squaeres.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Figure 2: Kmean-distribution diagram of eclogites and ultramafic rocks (modified from Qi et al. (submitted)).<br />

The calculated contribution of paramagnetic m<strong>in</strong>erals<br />

to the bulk susceptibility varies from 24 to 89%. However,<br />

the contribution of the ferromagnetic subfabric to the bulk<br />

susceptibility of eclogites with Kmean > 5x10-3 may<br />

approach 100%. The K(T)-curves of ultramafic rocks<br />

outl<strong>in</strong>e Ti-free and stoichiometric magnetite.<br />

Magnetic fabric<br />

The corrected degrees of anisotropy (P´) vary from 1 to<br />

1.53. The shape factors T vary from -0.83 to 0.68. T<br />

<strong>in</strong>creases strongly with decreas<strong>in</strong>g densities and thus seems<br />

to be very sensitive to retrogression. P´ correlates<br />

positively with Kmean and thus with <strong>in</strong>creas<strong>in</strong>g magnetite<br />

content. In the ultramafic rocks P´ varies from 1.34 to 1.98.<br />

The shape factors T vary from -0.68 to 0.78. Kmean<br />

<strong>in</strong>creases with <strong>in</strong>creas<strong>in</strong>g retrogression, but P´ decreases<br />

with <strong>in</strong>creas<strong>in</strong>g densities. This implies that more modal<br />

magnetite reduces the degree of anisotropy, which is<br />

caused by the serpent<strong>in</strong>ization process and related meshtexture<br />

formation.<br />

The low-field AMS measures the bulk fabric whereas<br />

the high-field AMS isolates the paramagnetic from the bulk<br />

fabric. Eclogites from all units outl<strong>in</strong>e paramagnetic or<br />

superposed para- and ferromagnetic fabrics. Therefore all<br />

oriented eclogite samples were measured <strong>in</strong> both a lowfield<br />

and a high-field with a torque magnetometer. The<br />

low-field AMS of all eclogites shows consistent N-Strend<strong>in</strong>g<br />

Kmax-axes with K <strong>in</strong>t- and K m<strong>in</strong>-axes distributed on<br />

an E-W-girdle (Fig. 3). The orientation of the N-S-trend<strong>in</strong>g<br />

Kmax-axis is <strong>in</strong>dependent of the primary eclogite<br />

composition, the degree of retrogression, and the highly<br />

variable P´-, K mean-, and T-values.<br />

The serpent<strong>in</strong>ized ultramafic rocks outl<strong>in</strong>e almost<br />

identical prolate ellipsoids with essentially N-S-trend<strong>in</strong>g<br />

subhorizontal Kmax-axes and a girdle distribution for the<br />

K<strong>in</strong>t- and K m<strong>in</strong>-axes (Fig. 3). An isolation of the<br />

paramagnetic subfabric was not possible due to the high<br />

susceptibilities, which produced torques that exceeded the<br />

sensitivity of the measurement device.<br />

Figure 3: Stereodiagrams (equal area, lower hemisphere) of the<br />

pr<strong>in</strong>cipal susceptibility axes (Km<strong>in</strong>, K<strong>in</strong>t, Kmax) of oriented eclogite<br />

and ultramafic rock samples show N-S-trend<strong>in</strong>g maximum<br />

susceptibility axes (Kmax) for both the eclogites and the ultramafic<br />

rocks and an E-W-girdle distribution for K<strong>in</strong>t and Km<strong>in</strong> axes<br />

imply<strong>in</strong>g a generally prolate fabric for both eclogites and<br />

ultramafic rocks (modified from Qi et al. (submitted)).<br />

Discussion and conclusions<br />

The eclogites of all units show different degrees and<br />

responses on retrograde metamorphic overpr<strong>in</strong>t, which is<br />

related to different primary modal and chemical<br />

composition, and variable degrees of fluid-rock <strong>in</strong>teraction.<br />

Superposed para- and ferromagnetic fabrics characterize<br />

the magnetofabrics of CCSD-eclogites from the uppermost<br />

1000m of the CCSD-MH. The eclogite texture, primary<br />

eclogite composition and the retrograde formation of<br />

pargasitic amphibole-magnetite coronas around garnet are<br />

the major parameters that control the magnetofabrics of the<br />

CCSD-eclogites. The magnetofabrics mimic the eclogite<br />

texture via retrograde magnetite growth around shapepreferred<br />

garnet. The consistently N-S-trend<strong>in</strong>g Kmax-axes -<br />

<strong>in</strong>dependent of variable primary eclogite composition, the<br />

different degrees of retrogression, and the highly variable<br />

P´-, T-, and Kmean-values also display texture <strong>in</strong>heritance.<br />

The serpent<strong>in</strong>ized ultramafic rocks are characterized by<br />

very high susceptibilities with magnetite as carrier of the<br />

susceptibility. Shape-preferred orientation of relict oliv<strong>in</strong>e<br />

and garnet and the formation of th<strong>in</strong> magnetite rim around<br />

garnet and of syn-serpent<strong>in</strong>ization magnetite growth with<strong>in</strong><br />

a mesh texture control the distribution of magnetite and<br />

thus the magnetofabrics of the ultramafic rocks <strong>in</strong>dicat<strong>in</strong>g<br />

texture <strong>in</strong>heritance as well.<br />

59

60<br />

At the th<strong>in</strong> section scale evidence for ductile shear<strong>in</strong>g is<br />

lack<strong>in</strong>g <strong>in</strong> the studied ve<strong>in</strong>s with a retrograde m<strong>in</strong>eral<br />

assemblage. Evidence for ductile shear<strong>in</strong>g <strong>in</strong> the ve<strong>in</strong>s is<br />

miss<strong>in</strong>g <strong>in</strong> both the CCSD. Irregular ve<strong>in</strong> geometries and<br />

boundaries at both th<strong>in</strong>-section and at the mesoscale also<br />

corroborate that the ve<strong>in</strong>s were not exploited as shear zones<br />

or – vice versa – exploited former shear zones. These ve<strong>in</strong>s<br />

thus may represent preserved primary retrograde features,<br />

which orig<strong>in</strong>ated from channelized fluid flow and<br />

synchronous m<strong>in</strong>eral decomposition. The retrograde<br />

coronas around garnet <strong>in</strong>dicate <strong>in</strong>itial fluid flow along<br />

former gra<strong>in</strong> boundaries and trace the former UHP texture.<br />

It is suggested that the mafic-ultramafic Maobei body<br />

behaved as a rigid body with<strong>in</strong> a ductilely deform<strong>in</strong>g<br />

quartzo-feldspathic matrix dur<strong>in</strong>g exhumation related<br />

retrogression. Internal stra<strong>in</strong> is restricted to brittle<br />

fractur<strong>in</strong>g, associated fluid circulation and ve<strong>in</strong> formation,<br />

which facilitated retrograde reactions <strong>in</strong> the maficultramafic<br />

rocks.<br />

Acknowledgements<br />

F<strong>in</strong>ancial support by the Deutsche<br />

Forschungsgeme<strong>in</strong>schaft (Project GR3193-1) and the<br />

Major State Basic Research Program of P.R. Ch<strong>in</strong>a (973;<br />

Grant No. 2003CB716504) is greatly acknowledged.<br />

References<br />

Qi X, Grimmer JC, Xu Z (submitted) Magnetofabrics of eclogites and<br />

ultramafic rocks from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g<br />

(CCSD) project: evidence for ultrahigh-pressure (UHP) texture<br />

<strong>in</strong>heritance throughout retrogression. Tectonophysics.<br />

Riemann A, Oberhänsli R (2007) Fluid <strong>in</strong>fluence on retrograde assemblage<br />

<strong>in</strong> UHP eclogites. Geochimica et Cosmochimica Acta 71/15, A843.<br />

Yang T (2004) Retrograded textures and associated mass transfer: evidence<br />

for aqueous fluid action dur<strong>in</strong>g exhumation of the Q<strong>in</strong>glongshan<br />

eclogite, Southern Sulu ultrahigh-pressure metamorphic terrane,<br />

eastern Ch<strong>in</strong>a. Journal of Metamorphic Geology 22: 653-669.<br />

Zhang Z, Xiao Y, Hoefs J, Liou J, Simon K (2006) Ultrahigh pressure<br />

metamorphic rocks from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g<br />

Project: I. Petrology and geochemistry of the ma<strong>in</strong> hole (0-2,050 m).<br />

Contributions to M<strong>in</strong>eralogy and Petrology 152/4: 421-441.<br />

<strong>IODP</strong><br />

Rapid changes <strong>in</strong> biogenic and siliciclastic<br />

sedimentation dur<strong>in</strong>g the last 1 Ma: results<br />

from North Atlantic <strong>IODP</strong> Sites U1313 and<br />

U1314<br />

J. GRÜTZNER 1 , S.M. HIGGINS 2 , R. STEIN 3 , G. ACTON 4 , G. WEFER 1<br />

1 MARUM, Bremen University, Bremen, Germany<br />

2 Jo<strong>in</strong>t Oceanographic Institutions, Wash<strong>in</strong>gton DC, U.S.A.<br />

3 Alfred-Wegener-Institute for Polar and Mar<strong>in</strong>e Research,<br />

Bremerhaven, Germany<br />

4 Department of Geology, University of California, Davis, U.S.A<br />

<strong>IODP</strong> Sites of the North Atlantic paleoceanography<br />

study (<strong>IODP</strong> Expeditions 303 and 306) provide new<br />

sedimentary archives that allow to determ<strong>in</strong>e the long-term<br />

evolution of millennial-scale variability <strong>in</strong> ice sheet<br />

stability and thermohal<strong>in</strong>e circulation over the last few<br />

million years. A major objective of our research project is<br />

to measure element <strong>in</strong>tensities (e.g. Al, Si, K, Ca, Ti, Fe,<br />

Sr, Ba) on Sites U1313 (41.0°N, 32.9°W) and U1314<br />

(56.4°N, 27.9°W) to derive cm-resolution records of<br />

terrigenous and biogenic sediment composition. Comb<strong>in</strong>ed<br />

with detailed age models these records characterize<br />

prom<strong>in</strong>ent millennial scale climate cycles of the last glacial<br />

period known as Dansgaard/Oeschger and He<strong>in</strong>rich events<br />

and help to study their possible occurrence <strong>in</strong> time <strong>in</strong>tervals<br />

prior to 100 ka BP.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Site U1313 constitutes a reoccupation of Deep Sea<br />

Drill<strong>in</strong>g Project (DSDP) Site 607 located at the base of the<br />

upper western flank of the Mid-Atlantic Ridge <strong>in</strong> a water<br />

depth of 3426 m, northwest of the Azores (Fig. 1). The<br />

carbonate rich sediment is composed of nannofossil ooze<br />

with vary<strong>in</strong>g amounts of foram<strong>in</strong>ifers and clay- to silt-sized<br />

terrigenous material. Based on evident orbital cyclicity <strong>in</strong><br />

sediment colour reflectance and other physical properties at<br />

Site U1313 it was possible to ref<strong>in</strong>e the shipboard bio- and<br />

magnetostratigraphic age models for the last 3.4 Ma<br />

already dur<strong>in</strong>g the cruise (Ste<strong>in</strong> et al., 2006). A prelim<strong>in</strong>ary<br />

age model was constructed by match<strong>in</strong>g sharp variations <strong>in</strong><br />

the L* lightness record with glacial and <strong>in</strong>terglacial<br />

term<strong>in</strong>ations <strong>in</strong> the global benthic oxygen isotope stack of<br />

Lisiecki and Raymo (2005).<br />

Site U1314 was drilled ~300 meters (complete splice<br />

down to 281 mcd) <strong>in</strong>to the southern Gardar Drift at a water<br />

depth of 2800 m (Fig. 1). The sediments consist of<br />

carbonate-rich (nannofossil oozes) and carbonate-poor<br />

(silty clay) <strong>in</strong>tervals that alternate on decimeter to meter<br />

scale. Sediment physical property records of Site U1314<br />

reveal a high similarity with the orbitally dated ODP Site<br />

983 (northern Gardar Drift). Thus a detailed correlation of<br />

colour reflectance and magnetic susceptibility data from<br />

both sites allowed deriv<strong>in</strong>g a new age model of orbital<br />

resolution for the last 1.8 Ma at Site U1314 (Grützner and<br />

Higg<strong>in</strong>s, submitted).<br />

Figure 1. General bathymetric map of the northern North Atlantic<br />

show<strong>in</strong>g the position of ODP/<strong>IODP</strong> Sites 980, 983, U1313 and<br />

U1314 (modified after Raymo et al., 2004). Arrows <strong>in</strong>dicate paths<br />

of major deep water flows (DSOW: Denmark Strait Overflow<br />

Water, ISOW: Iceland-Scotland Overflow Water, WTRO:<br />

Wyville-Thomson Ridge Overflow, LDW: Lower Deep Water,<br />

NWADW: North West Atlantic Deep Water, NEADW: North East<br />

Atlantic Deep Water).<br />

Both <strong>in</strong>vestigated sites exhibit pronounced sub-orbital<br />

scale variations <strong>in</strong> %CaCO3 and terrigenous provenance<br />

(<strong>in</strong>dicated by elemental ratios such as K/Ti or Si/Al)<br />

throughout the last 1.1 Ma. The amplitude of these<br />

millennial-scale changes is often ~40 to 70% of the<br />

maximum glacial/<strong>in</strong>terglacial range. These provenance<br />

changes are ma<strong>in</strong>ly controlled by the variability of deep<br />

circulation <strong>in</strong> the North Atlantic which is corroborated by<br />

the similarity between K/Ti and the deep sea δ 13 C record<br />

from ODP Site 607 (Raymo et al., 1990) on orbital time

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

scales. Low K/Ti ratios are typical for warmer <strong>in</strong>tervals<br />

with sediment delivery ma<strong>in</strong>ly through the ISOW from the<br />

Icelandic basaltic prov<strong>in</strong>ce. On the other hand glacials and<br />

stadials are characterized by higher K/Ti <strong>in</strong>dicat<strong>in</strong>g a<br />

dom<strong>in</strong>ance of acidic sediment sources which were likely<br />

transported by iceberg discharge or enhanced<br />

NEADW/LDW flow. Enhanced millennial scale variability<br />

<strong>in</strong> siliciclastic supply and deep hydrography at Site U1314<br />

occured dur<strong>in</strong>g ice growth phases when global benthic δ 18 O<br />

is with<strong>in</strong> a threshold range of 4.1 to 4.6 ‰. On the other<br />

hand peak glacial and <strong>in</strong>terglacial <strong>in</strong>tervals reveal very low<br />

variance <strong>in</strong> the sub-Milankovitch frequency band. An ice<br />

volume threshold for enhanced millennial scale variability<br />

was postulated by McManus et al. (1999) and Helmke et al.<br />

(2002) for the last 500 kyr and is now confirmed by our<br />

study (Fig. 2) for the last 1.1 Ma (Grützner and Higg<strong>in</strong>s,<br />

submitted).<br />

At Site U1313 sedimentation rates are lower (~4.7<br />

cm/kyr) then at Site U1314 but the sedimentation is very<br />

uniform such that spectral analyses are less biased by<br />

chang<strong>in</strong>g sedimentation rates. Prelim<strong>in</strong>ary spectral analyses<br />

reveal that significant suborbital variance with periods<br />

typical for the last 100 kyr can be detected with confidence<br />

for older <strong>in</strong>tervals also at this location. Suborbital variabilty<br />

<strong>in</strong> %CaCO3 at this location confirms the threshold level<br />

found at Site U1314 (Fig. 2). Furthermore our XRF core<br />

scann<strong>in</strong>g data from Site U1313 were used to identify<br />

He<strong>in</strong>rich events (enhanced Fe and Ti values) of the last 100<br />

kyr (Rashid et al., 2007), to constra<strong>in</strong> the age model for a 5<br />

Ma Record of extraterrestrial 3He flux (Higg<strong>in</strong>s et al.,<br />

2007) and to track times of Southern Ocean Water <strong>in</strong>flow<br />

(high Si/Al ratio) dur<strong>in</strong>g mar<strong>in</strong>e isotope stages 11 – 15<br />

(Voelker et al., <strong>in</strong> prep.)<br />

References:<br />

Grützner, J.and S.M. Higg<strong>in</strong>s (submitted). A 1.1 Ma long record of sediment<br />

provenance at the southern Gardar Drift reflects millennial-scale<br />

changes <strong>in</strong> deep water sources. Paleoceanography.<br />

Helmke, J. P., M. Schulz, and H. A. Bauch (2002), Sediment-Color Record<br />

from the Northeast Atlantic Reveals Patterns of Millennial-Scale<br />

Climate Variability dur<strong>in</strong>g the Past 500,000 Years, Quaternary<br />

Research, 57, 49-57.<br />

Higg<strong>in</strong>s, S.M., S.Mukhopadhyay, R. Ackert, and J. Grützner (2007). 5 Ma<br />

Record of extraterrestrial 3He flux, sediment provenance, and detrital<br />

fluxes at <strong>IODP</strong> Site 1313 <strong>in</strong> western North Atlantic. Fall Meet<strong>in</strong>g 2007,<br />

American Geophysical Union, San Francisco (Poster) Eos Trans. AGU,<br />

88(52), Fall Meet. Suppl., Abstract PP41C-0693.<br />

Lisiecki, L. E. and M. E. Raymo (2005), A Pliocene-Pleistocene stack of 57<br />

globally distributed benthic δ 18 Ο records, Paleoceanography, 20,<br />

doi:10.1029/2004PA001071.<br />

McManus, J. F., D. W. Oppo, and J. L. Cullen (1999), A 0.5-million-year<br />

reocrd of millenial-scale climate variability <strong>in</strong> the North Atlantic,<br />

Science, 283, 971-975.<br />

Rashid, H., J. Grützner, S. Lodestro, A. Voelker, B.P: Flower, and T.M.<br />

Qu<strong>in</strong>n (2007). Millennial-scale deep ocean ventilation and sea-surface<br />

variability dur<strong>in</strong>g the last four glacial cycles: a new assessment for the<br />

Northern Hemisphere ice-sheet growth. Fall Meet<strong>in</strong>g 2007, American<br />

Geophysical Union, San Francisco (Talk) Eos Trans. AGU, 88(52),<br />

Fall Meet. Suppl., Abstract PP44B-07.<br />

Raymo, M. E., W. F. Ruddiman, N. J. Shackleton, and D. W. Oppo (1990),<br />

Evolution of Atlantic Pacific Delta-C-13 Gradients Over the Last 2.5<br />

My, Earth Planet. Sci. Lett., 97, 353-368.<br />

Ste<strong>in</strong>, R., T. Kanamatsu, C.A. Alvarez Zarikian, S. Higg<strong>in</strong>s, J.E.T. Channell,<br />

E. Aboud, M. Ohno, G.D. Acton, K. Akimoto, I. Bailey, K.R.<br />

Bjørklund, H. Evans, S.H.H. Nielsen, N. Fang, P. Ferretti, J. Grützner,<br />

Y.J.B. Guyodo, K. Hag<strong>in</strong>o, R. Harris, K. Hatakeda, J. Hefter, S.A.<br />

Judge, D.K. Kulhanek, F. Nanayama, H. Rashid, F.J. Sierro Sanchez,<br />

A. Voelker, and Q. Zhai (2006). North Atlantic paleoceanography: the<br />

last 5 Million years. Eos 87 (13), p. 129, 133<br />

Voelker A.H.L., J. Grützner, and D. Hodell (<strong>in</strong> prep). Surface and Deep<br />

water hydrography <strong>in</strong> the mid-latitude North Atlantic dur<strong>in</strong>g Mar<strong>in</strong>e<br />

Isotope Stages 11 – 15: Insights from <strong>IODP</strong> sites U1313 and U1308.<br />

Mar<strong>in</strong>e Geology.<br />

Figure 2. A. Benthic oxygen isotope stack of Lisiecki and Raymo (2005) for the last 1 Ma.. The dashed horizontal l<strong>in</strong>e <strong>in</strong>dicates the<br />

threshold value of McManus et al. (1999) and Grützner and Higg<strong>in</strong>s (submitted) , above which larger amplitude millennial-scale climate<br />

variations are observed. B. High-pass-filtered (1/12 ka-1 cutoff frequency) %CaCO3 time series for Site U1313. C. High-pass-filtered<br />

time series of the Potassium to Titanium ratio for Site U1314. D. Time series of ice rafted detritus (IRD) from Site 980 (McManus eta l.<br />

1999). IRD is plotted as the number of detrital sediment gra<strong>in</strong>s (lithics), larger than 150 mm, per bulk sample weight. Maximum<br />

variability of all records shown <strong>in</strong> B-D occurs dur<strong>in</strong>g ice growth phases when δ18Ob is > 4.1 per mil.<br />

61

62<br />

<strong>ICDP</strong><br />

From land plants to anoxia - a pilot study of<br />

organic biomarkers gives <strong>in</strong>sight <strong>in</strong>to<br />

paleoclimate record of Lake El`gygytgyn<br />

S. HANISCH 1 , C. GEBHARDT 1 , O. JUSCHUS 2 , N. NOWACZYK 3<br />

1<br />

Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, Am<br />

Alten Hafen 26, D-27568 Bremerhaven;<br />

sab<strong>in</strong>e.hanisch@awi.de<br />

2<br />

University of Cologne, Institute for Geology and M<strong>in</strong>eralogy;<br />

Zuelpicher Str. 49a, D-50674 Cologne<br />

3<br />

GFZ-Geoforschungszentrum Potsdam, Telegrafenberg C321, D-<br />

14473 Potsdam<br />

With<strong>in</strong> the framework of <strong>ICDP</strong>, deep drill<strong>in</strong>g <strong>in</strong><br />

Siberian Lake El'gygytgyn is funded for the year 2009. The<br />

biomarker pilot study presented here was carried out on<br />

El'gygytgyn sediment core LZ1024, which was retrieved <strong>in</strong><br />

a previous cor<strong>in</strong>g campa<strong>in</strong> <strong>in</strong> 2003. The organic matter <strong>in</strong><br />

the lake sediments conta<strong>in</strong> a variety of organic molecules<br />

(biomarkers), which are here used to trace land plant <strong>in</strong>put<br />

and changes <strong>in</strong> lake bottom anoxia dur<strong>in</strong>g the last 345,000<br />

years of lake history.<br />

Previous studies have demonstrated that Lake<br />

El'gygytgyn sediments provide an excellent record of<br />

paleoclimatic conditions <strong>in</strong> the east Siberian Arctic. Melles<br />

et al. (2007) def<strong>in</strong>ed different climate modes for the past<br />

three glacial-<strong>in</strong>terglacial cycles based on geochemical<br />

analysis ((i) peak warm, (ii) warm, (iii) cold and dry, (iiii)<br />

cold and wet). Further key parameters for trac<strong>in</strong>g<br />

paleoclimatic or paleolimnological states are magnetic<br />

susceptibility (Nowaczyk et al., 2007) and pollen (Lozhk<strong>in</strong><br />

et al., 2007).<br />

For this biomarker study, sediment samples were<br />

scratched from the surface of the freshly split sediment<br />

core compris<strong>in</strong>g 10-20 cm depth <strong>in</strong>terval each (ca. 4 g dry<br />

sediment). To avoid mix<strong>in</strong>g of different climate modes,<br />

samples were taken based on the magnetic susceptibility<br />

record of LZ1024, which traces climate modes. Sediments<br />

were extracted with organic solvents and splitted <strong>in</strong>to 3<br />

fractions (hydrocarbon fraction, fatty acid fraction and<br />

polar fraction) and analysed with gas chromatography and<br />

mass spectrometry.<br />

All glacial modes are characterized by a suppression of<br />

terrestrial long-cha<strong>in</strong> alkanes (C27-C 31) compared to aquatic<br />

short-cha<strong>in</strong> alkanes (C 17 and C 19), <strong>in</strong>dicat<strong>in</strong>g a low <strong>in</strong>put of<br />

terrigenous matter as a consequence of perennial ice<br />

coverage of the lake. Aquatic short-cha<strong>in</strong> alkanes show<br />

highest concentrations (per g TOC) dur<strong>in</strong>g frozen periods<br />

<strong>in</strong>dicat<strong>in</strong>g a higher preservation rate for sensible<br />

compounds of the organic matter due to bottom water<br />

anoxia. Further <strong>in</strong>dicators for anoxia are the distribution<br />

patterns of hop-12(17)-ene (ma<strong>in</strong>ly derived from moss,<br />

lichen, microorganisms) and 17 (H), 21 (H)homohopane<br />

(bacteria), which also show high<br />

concentrations dur<strong>in</strong>g ice coverage and lower values dur<strong>in</strong>g<br />

warmer periods with seasonally open water.<br />

Peak warm and warm periods of the Eemian (MIS 5.5)<br />

and Holocene (MIS 1) are <strong>in</strong>dicated by significantly higher<br />

concentrations of olean-12-ene, a specific biomarker for<br />

dicotyle angiosperms (Sukh Dev, 1989). The biomarker<br />

data correlate with pollen data from Lozhk<strong>in</strong> et al. (2007)<br />

<strong>in</strong>dicat<strong>in</strong>g tree and shrub-dom<strong>in</strong>ated periods dur<strong>in</strong>g<br />

Holocene and Eemian. Due to the different transport<br />

mechanisms of pollen and biomarkers, a more detailed<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

biomarker record (<strong>in</strong>clud<strong>in</strong>g compound specific isotopes)<br />

could provide a valuable addition for the reconstruction of<br />

the local paleoenvironment. Biomarkers as <strong>in</strong>dicators of<br />

different algae (e.g. sterols) can provide a better <strong>in</strong>sight<br />

<strong>in</strong>to Lake El'gygytgyn paleoecology equilibrated to climate<br />

conditions <strong>in</strong> the terrestrial Arctic.<br />

References:<br />

Lozhk<strong>in</strong> A.V., Anderson P.M., Matrosova T.V., M<strong>in</strong>yuk P.S. (2007) The<br />

pollen record from El'gygytgyn Lake: implications from vegetation and<br />

climate histories of northern Chukotka s<strong>in</strong>ce the late middle<br />

Pleistocene. Journal of Paleolimnology 37, 135-153.<br />

Melles M., Brigham-Grette J., Glushkova O.Yu., M<strong>in</strong>yuk P.S., Nowaczyk<br />

N.R., Hubberten H.-W. (2007) Sedimentary geochemistry of core<br />

PG1351 from Lake El'gygytgyn - a sensitive record of climate<br />

variability <strong>in</strong> the East Siberian Arctic dur<strong>in</strong>g the past three glacial<strong>in</strong>terglacial<br />

cycles. Journal of Paleolimnology 37, 89-104.<br />

Nowaczyk N.R., Melles M., M<strong>in</strong>yuk P.S. (2007) A revised age model for<br />

core PG1351 from Lake El'gygytgyn, northeast Siberia, Russia:<br />

constra<strong>in</strong><strong>in</strong>g the tim<strong>in</strong>g of paleoenvironmental events for the past 200<br />

ka. Journal of Paleolimnology 37, 65-76.<br />

Sukh Dev (1989) Terpenoids. In: Rowe, J.W. (ed.): Natural products of<br />

woody plants I. Spr<strong>in</strong>ger, Berl<strong>in</strong>.<br />

<strong>IODP</strong><br />

Laser ablation ICP-MS as a tool for assess<strong>in</strong>g<br />

the preservation of fossil corals: Examples<br />

from deglacial Tahiti corals recovered by<br />

<strong>IODP</strong> Expedition 310<br />

ED C. HATHORNE 1 AND THOMAS FELIS 1<br />

1<br />

DFG-Research Center for Ocean Marg<strong>in</strong>s (RCOM), University of<br />

Bremen<br />

The chemistry of fossil coral skeletons, usually of the<br />

genus Porites, provide the unique opportunity to<br />

reconstruct environmental conditions at a sub-seasonal<br />

resolution (e.g. Felis et al. 2004). However, good<br />

preservation of fossil corals is essential to obta<strong>in</strong> reliable<br />

proxy records (e.g. Allison et al., 2005; Qu<strong>in</strong>n and Taylor,<br />

2006; Hendy et al., 2007). Diagenetic alteration is usually<br />

assessed rigorously us<strong>in</strong>g XRD analyses to scan for calcite<br />

and X-radiograph, SEM and petrography images to screen<br />

for dissolution and secondary aragonite (e.g. Qu<strong>in</strong>n and<br />

Taylor, 2006). This process is very time consum<strong>in</strong>g and as<br />

such can only be conducted on descrete regions of a fossil<br />

coral.<br />

Hier we present new high resolution Laser abalation<br />

ICP-MS analyses of degalcial Porites corals from Tahiti,<br />

recovered by <strong>IODP</strong> Expedition 310. These data reveal high<br />

fequency trace element variations similar to those found <strong>in</strong><br />

modern corals. Such high frequency trace element<br />

variations are likely to result from biom<strong>in</strong>eralization<br />

processes (e.g. S<strong>in</strong>clair 2005; Meibom et al., 2007) and<br />

their presence <strong>in</strong> these fossil corals <strong>in</strong>dicates the<br />

preservation of the origional trace element signal. Such<br />

analyses can be preformed relatively quickly and represent<br />

a powerful additional tool for assess<strong>in</strong>g the preservation of<br />

fossil corals.<br />

High resolution spot analyses (~15 microns diameter)<br />

on polished sections of fossil coral can target skeletal<br />

structures such as centres of calcification (COCs) which<br />

are often the focus of diagentic alteration and bias <strong>in</strong> proxy<br />

records (Allison et al., 2005). Such spatial resolution is<br />

comparable to that of Ion Microprobe techniques and can<br />

be used to analyse only prist<strong>in</strong>e skeleton <strong>in</strong> samples which<br />

are diagenetically altered (e.g. Cohen and Hart, 2004). LA-<br />

ICP-MS has the potential to produce long reliable proxy

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

records from fossil corals which would not be possible with<br />

other techniques.<br />

References:<br />

Allison et al. (2005). Geophyical Reearch Letters 32, L17609.<br />

Cohen and Hart (2004). Paleoceanography 19, PA4031.<br />

Felis et al. (2004). Nature 429, 164-168.<br />

Hendy et al. (2007). Paleoceanography 22, PA4101.<br />

Meibom et al. (2007). Geophyical Reearch Letters 34, L02601.<br />

S<strong>in</strong>clair (2005). Geochimica et Cosmochimica Acta 69, 3265-3284.<br />

Qu<strong>in</strong>n and Taylor (2006). Geophyical Reearch Letters 33, L04601.<br />

<strong>IODP</strong><br />

The Biomarker Inventory, Trace, and Source<br />

of He<strong>in</strong>rich Events and He<strong>in</strong>rich-type Layers<br />

(MIS 8-16) <strong>in</strong> the North Atlantic<br />

J. HEFTER 1 , R.. STEIN 1 , J. S. SINNINGHE DAMSTÉ 2<br />

1 Alfred-Wegener-Institute for Polar- and Mar<strong>in</strong>e Research, Am<br />

Alten Hafen 26, D-27568 Bremerhaven, Germany<br />

2 Royal Netherlands Institute for Sea Research (NIOZ), 1790 AB<br />

Den Burg, The Netherlands<br />

Multiple cores from different locations <strong>in</strong> the North<br />

Atlantic were recovered dur<strong>in</strong>g <strong>IODP</strong> Expeditions 303/306<br />

(Channell et al., 2006). We have <strong>in</strong>vestigated the biomarker<br />

distributions of identified/presumed He<strong>in</strong>rich layers (HL)<br />

and ambient glacial/<strong>in</strong>terglacial samples <strong>in</strong> proximity (Site<br />

U1305) to the former major iceberg discharge pathway<br />

derived via the Hudson Strait from the Laurentide-Ice-<br />

Shield (LIS) <strong>in</strong> order to:<br />

extend, <strong>in</strong> space and time, previous knowledge of<br />

biomarker <strong>in</strong>ventories from He<strong>in</strong>rich layers <strong>in</strong> the Labrador<br />

Sea (Rashid & Grosjean, 2006),<br />

narrow down or even identify the source(s) of organic<br />

matter deposited dur<strong>in</strong>g He<strong>in</strong>rich events, and<br />

explore and use the potential of biomarker f<strong>in</strong>gerpr<strong>in</strong>ts<br />

as chemical tracers for the occurrence and first appearance<br />

of He<strong>in</strong>rich event-like episodes even <strong>in</strong> the distal North<br />

Atlantic (Sites U1308, U1313).<br />

All He<strong>in</strong>rich layers present at Site U1305 (HL1, 2, 4)<br />

exclusively conta<strong>in</strong>ed a unique association of a multitude<br />

of “petrogenic” compounds such as benzohopanes, D-r<strong>in</strong>g<br />

monoaromatic 8,14-secohopanes, rearranged diasterenes,<br />

mono- and triaromatic steranes, isorenieratene-derivatives<br />

as well as characteristic pristane/n-C17 and<br />

pristane/phytane ratios.<br />

The occurrence of these compounds <strong>in</strong> samples<br />

deposited dur<strong>in</strong>g He<strong>in</strong>rich events is, from a chemical<br />

viewpo<strong>in</strong>t, unique because their structures clearly po<strong>in</strong>t<br />

towards an orig<strong>in</strong> either not compatible with the mar<strong>in</strong>e<br />

environmental conditions dur<strong>in</strong>g depositional times, or<br />

with the diagenetic state and age of the sediments under<br />

<strong>in</strong>vestigation. For example, the presence of C40isorenieratene<br />

derivatives suggests contributions from<br />

phototrophic green and purple sulfur bacteria <strong>in</strong>dicative of<br />

a highly stratified water column with photic-zone anoxia<br />

(e.g. Brocks & Summons, 2003), but such conditions are<br />

rather unlikely to have developed at the cor<strong>in</strong>g site. In<br />

addition, the presence of palaerenieratane po<strong>in</strong>ts towards a<br />

Paleozoic age of the organic matter from HL´s, because the<br />

known occurrence of this compound seems to be limited to<br />

the Paleozoic sedimentary rocks and oils spann<strong>in</strong>g today a<br />

geographically extensive portion of the North American<br />

cont<strong>in</strong>ent (Brown & Kenig, 2004).<br />

From the overall distribution of biomarker compounds<br />

<strong>in</strong> HL´s, a relatively immature, mar<strong>in</strong>e carbonate rock, that<br />

has been deposited <strong>in</strong> the Paleozoic under occasional<br />

photic zone anoxic conditions can be <strong>in</strong>ferred as potential<br />

source. Actually, upon re<strong>in</strong>vestigation of available geologic<br />

and organic-geochemical data (Macauley et al., 1990), it<br />

was even possible to narrow down this proposed source to<br />

an Ordovician oil shale, that is today outcropp<strong>in</strong>g close to<br />

Hudson Strait. Indeed, a strik<strong>in</strong>g concordance between<br />

biomarker distributions <strong>in</strong> a particular sample of that shale<br />

and the specific association of compounds from samples of<br />

He<strong>in</strong>rich Events is observed.<br />

As clearly <strong>in</strong>dicated by the downcore profile of Site<br />

U1305, the characteristic compound association ideally<br />

allows to dist<strong>in</strong>guish organic matter from HL compared to<br />

adjacent samples. Therefore, the above mentioned<br />

compounds can be regarded and be used as organicgeochemical<br />

tracers not only for the occurrence of He<strong>in</strong>rich<br />

Events of the last glacial cycle, but also for older He<strong>in</strong>richlike<br />

events. These geochemical tracers are highly selective<br />

because they <strong>in</strong>dicate the presence of Ordovician organic<br />

matter from rocks of the Hudson Bay area.<br />

The explored biomarker trace of last glacial He<strong>in</strong>rich<br />

events from the LIS-proximal Site U1305 could be<br />

followed up <strong>in</strong> the downcore sedimentary records of the<br />

distal Sites (U1308, U1313) <strong>in</strong> the central North Atlantic.<br />

We present a biomarker based high resolution record of<br />

such events dur<strong>in</strong>g a time <strong>in</strong>terval from about 320-460 kyr<br />

at Site U1313 (MIS 10-12) and an extended record (MIS 8-<br />

16) of He<strong>in</strong>rich-type events from Site U1308, i.e. from<br />

positions near the Mid-Atlantic Ridge and distal to the LIS.<br />

Brocks, J.J., Summons, R.E., (2003) Sedimentary hydrocarbons, biomarkers<br />

for early life, Treatise on Geochemistry, 8, pp. 63-115. Elsevier, New<br />

York.<br />

Brown, T.C., Kenig, F., (2004) Water column structure dur<strong>in</strong>g deposition of<br />

Middle Devonian-Lower Mississippian black and green/ gray shales of<br />

the Ill<strong>in</strong>ois and Michigan Bas<strong>in</strong>s; a biomarker approach.<br />

Palaeogeography, Palaeoclimatology, Palaeoecology, 215(1-2), 59-85.<br />

Channell, J.E.T., Sato, T., Kanamatsu, T., Ste<strong>in</strong>, R., Malone, M., Alvarez-<br />

Zarikian, C., and the <strong>IODP</strong> Expeditions 303 and 306 Scientists, (2006)<br />

<strong>IODP</strong> Expeditions 303 and 306 Monitor Miocene-Quaternary Climate<br />

<strong>in</strong> the North Atlantic. Scientific Drill<strong>in</strong>g, 2, 4-10.<br />

Macauley, G., Fowler, M.G., Goodarzi, F., Snowdon, L.R., and Stasiuk,<br />

L.D., (1990) Ordovician oil shale-source rock sediments <strong>in</strong> the central<br />

and eastern Arctic areas, and their significance for frontier exploration.<br />

Geological Survey of Canada, Paper 90-14.<br />

Rashid, H., Grosjean, E., (2006) Detect<strong>in</strong>g the source of He<strong>in</strong>rich layers: An<br />

organic geochemical study. Paleoceanography, PA3041,<br />

doi:10.1029/2005PA001240, 2006.<br />

<strong>ICDP</strong><br />

Geothermal <strong>in</strong>vestigations from well data of<br />

the Chesapeake Pen<strong>in</strong>sula, USA<br />

PHILIPP HEIDINGER 1 , HELMUT WILHELM 1 , JAN SAFANDA 2 , HANS<br />

BURKHARDT 3 , SIBYLLE MAYR 3 , YURI POPOV 4<br />

1<br />

Geophysical Institute of Karlsruhe, Germany<br />

2<br />

Geophysical Institute of Prague, Czech Republic<br />

3<br />

Institute of Applied Geosciences, Technical University of Berl<strong>in</strong>,<br />

Germany<br />

4<br />

Russian State Geological Prospect<strong>in</strong>g University, Moscow<br />

The Chesapeake Bay impact structure is a late Eocene<br />

complex crater which was excavated ~35 Ma ago by a<br />

comet or asteroid <strong>in</strong> a cont<strong>in</strong>ental shelf environment on the<br />

Atlantic marg<strong>in</strong> of Virg<strong>in</strong>ia. It is the largest impact crater <strong>in</strong><br />

the USA and the seventh largest on Earth. It has an average<br />

diameter of ~85 km around its centre near Cape Charles.<br />

The <strong>ICDP</strong> drill hole is situated on the central uplift of the<br />

crater.<br />

63

64<br />

Drill<strong>in</strong>g of the hole Eyreville-B started on September<br />

12, 2005 and ended on December 4, 2005 at 1766.3 m<br />

depth. After the mud circulation had stopped, first<br />

temperature measurements were recorded from the bottom<br />

of the hole upwards by the USGS logg<strong>in</strong>g tool. Then the<br />

Karlsruhe University logg<strong>in</strong>g tool, which had been shipped<br />

to Norfolk harbour <strong>in</strong> November 2005 and started high<br />

resolution temperature (HRT) measurements from the top<br />

downwards. The logg<strong>in</strong>g was <strong>in</strong>terrupted when the tool<br />

crashed at 780 m depth. After repair, a complete<br />

temperature profile was measured to 1400 m depth on<br />

December 6. In order to stop the artesian flow which had<br />

started immediately after the stop of circulation the well<br />

head was closed afterwards. On December 9 the well head<br />

pressure amounted to ~1.9 bar. After reopen<strong>in</strong>g of the well<br />

head, another temperature profile was recorded down to the<br />

end of the cas<strong>in</strong>g at 1130 m depth, because the lower open<br />

part was no longer accessible. After clos<strong>in</strong>g the well head<br />

the pressure raised to 2.13 bar. The temperature values of<br />

this campaign were heavily disturbed by outflow of<br />

artesian water and could only be used for an estimation of<br />

the depth where the fluid orig<strong>in</strong>ated.<br />

About 8.5 km away from the hole Eyre-B a test well<br />

STP2 has been drilled by USGS. The general lithology of<br />

this 823 m deep well and the resistivity and water sal<strong>in</strong>ity<br />

logs recorded <strong>in</strong> a 700 m deep groundwater observation<br />

well <strong>in</strong>stalled with<strong>in</strong> the test hole has been published <strong>in</strong><br />

EOS 85, no.39, 28 September 2004. Fortunately this hole<br />

was still accessible and not artesian. In this well the<br />

temperature could be recorded yield<strong>in</strong>g an undisturbed<br />

profile with an <strong>in</strong>terest<strong>in</strong>g feature near the surface, see<br />

figure 1 and 2. Below the depth of the annual perturbation<br />

an unusual rise of the temperature profile could be<br />

observed. This effect could be identified as a signature of<br />

anthropogenic structures <strong>in</strong> the subsurface temperature<br />

field <strong>in</strong> borehole surround<strong>in</strong>gs. The m<strong>in</strong>imum temperature<br />

was observed <strong>in</strong> 35 m, where the house and asphalt areas<br />

were built only seven years before the logg<strong>in</strong>g. Simulat<strong>in</strong>g<br />

these effects by solv<strong>in</strong>g numerically the heat conduction<br />

equation yielded a 3.3 °C temperature jump caused by the<br />

constructions and a diffusivity value of the upper<br />

subsurface of 0.64*10-6 m2/s.<br />

In order to measure an undisturbed temperature profile<br />

<strong>in</strong> the hole Eyre-B, a riser construction was created and a<br />

second logg<strong>in</strong>g campaign was set for 1.5.2006 – 8.5.2006.<br />

At the beg<strong>in</strong>n<strong>in</strong>g of the campaign the borehole still had an<br />

overpressure of 1.2 bars. The riser was connected to the<br />

wellhead of the borehole Eyre-B and was work<strong>in</strong>g f<strong>in</strong>e,<br />

prevent<strong>in</strong>g the outflow of the artesian water but still<br />

enabled the wire of the logg<strong>in</strong>g tool to pass through and we<br />

did the first successful measurement down to the end of the<br />

rema<strong>in</strong><strong>in</strong>g HQ-rods at 1100.3 m.<br />

After completion of the measurement Ward Sanford<br />

from USGS <strong>in</strong> Reston opened the well to let the artesian<br />

water flow out. His aim was to get as clear as possible<br />

water samples from the host rock not mixed with remnants<br />

of drill<strong>in</strong>g mud. Realiz<strong>in</strong>g that this several hours outflow of<br />

artesian water would be a heat pulse to the rocks above the<br />

pressurized layer, we decided to do more measurements<br />

after re-closure of the well <strong>in</strong> order to measure the<br />

relaxation process of the well. It was very surpris<strong>in</strong>g that at<br />

the next day, when Ward Sanford f<strong>in</strong>ished his work, the<br />

borehole Eyreville-B was not anymore artesian at all. The<br />

pressurised layer must have been limited. Dur<strong>in</strong>g the rest of<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

our stay on the Chesapeake Pen<strong>in</strong>sula we were able to do<br />

four more temperature measurements without the need of<br />

us<strong>in</strong>g the riser construction. The times of the measurements<br />

were 2 h, 20 h, 44 h and 98.5 h respectively after end of<br />

artesian water outflow. The riser construction yielded a<br />

measurement of the undisturbed temperature profile,<br />

afterwards we were able to measure the relaxation process<br />

of the borehole temperature towards the equilibrium.<br />

Boreholes drilled <strong>in</strong> impact structures are especially<br />

suited for <strong>in</strong>vestigations of the <strong>in</strong>fluence of heterogeneities<br />

on petrophysical properties and the thermal field. In the<br />

scientific well Eyreville-B drilled with<strong>in</strong> the frame of the<br />

International Cont<strong>in</strong>ental Deep Drill<strong>in</strong>g Program (<strong>ICDP</strong>)<br />

two high resolution temperature measurement campaigns<br />

were recorded. Additionaly a dense petrophysical profile<br />

measured on core samples at ~10 m depth <strong>in</strong>tervals was<br />

generated and offers a rare opportunity for geothermal<br />

<strong>in</strong>vestigations on the terrestrial heat flow densitiy (HFD).<br />

The registration of the relaxation process after some<br />

outflow of artesian water which heated the surround<strong>in</strong>g<br />

rock gave <strong>in</strong>sight to the <strong>in</strong>-situ values of the geothermal<br />

parameters. The results of these calculations could be<br />

compared with the parameters yielded on core samples <strong>in</strong><br />

the laboratory.<br />

To jo<strong>in</strong> this <strong>ICDP</strong> project all science team members<br />

and their associates had to agree to a moratorium on<br />

publication. At the end of the moratorium period, a jo<strong>in</strong>t<br />

publication will be the forum for all <strong>in</strong>itial publications and<br />

only afterwards papers, talks or posters conta<strong>in</strong><strong>in</strong>g<br />

scientific results can be presented by the members. This<br />

directive was confirmed on the 2007 GSA Denver Annual<br />

Meet<strong>in</strong>g 28 - 31 October, 2007 and the moratorium will be<br />

valid until this jo<strong>in</strong>t publication has the status <strong>in</strong>-press,<br />

which should be around fall <strong>2008</strong>. Therefore and <strong>in</strong><br />

concordiance with the moratorium no data and results of<br />

the Eyreville-B borehole are presented here. Only a general<br />

description of what have been performed to the data is<br />

written here, an exception is the temperature profile of the<br />

STP2 borehole and the results of these <strong>in</strong>vestigations<br />

because this well does not belong to the <strong>ICDP</strong> project.<br />

Comb<strong>in</strong><strong>in</strong>g the gradient of a temperature profile with<br />

the thermal conductivity yields the heat flow densitiy.<br />

Repeated determ<strong>in</strong>ations at all depths, where the thermal<br />

conductivity was determ<strong>in</strong>ed, produced a depth profile of<br />

the HFD. Because <strong>in</strong> a borehole only the vertical gradient<br />

of temperature is measured the results only represent the<br />

vertical component of the HFD as well. An averaged<br />

vertical HFD was calculated from 43 values and is<br />

identified as the terrestrial HFD on the well Eyreville-B.<br />

Significant variations of the vertical heat flow density can<br />

be expla<strong>in</strong>ed by:<br />

Additional convective heat transport caused by<br />

migrat<strong>in</strong>g fluids<br />

System is not <strong>in</strong> a steady-state geothermal condition,<br />

but transient due to i.e. paleoclimatic effects<br />

Potential depth error, because depths of samples are<br />

determ<strong>in</strong>ed with the drill<strong>in</strong>g rods (drill<strong>in</strong>g depth), whereas<br />

the temperature values are measured with a cable<br />

(measurement depth). The difference can be <strong>in</strong> range of ~<br />

decimeter up to a meter.<br />

Different scales, thermal conductivity measured with<br />

the non-contact optical scann<strong>in</strong>g method is done for<br />

centimeters only and heterogeneity can be high. The<br />

temperature profile, representative as the rock temperature

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

profile can be determ<strong>in</strong>ed only <strong>in</strong> range of at least ~ 20 cm<br />

due to averag<strong>in</strong>g effects of the fluid filled borehole.<br />

Incl<strong>in</strong>ed structures are diffract<strong>in</strong>g the terrestrial heat<br />

flow but only the vertical component can be determ<strong>in</strong>ed.<br />

Model calculations of this effect were performed by<br />

Wilhelm H. et al., 2005.<br />

The characteristics of the result<strong>in</strong>g profile could be<br />

simulated with a 2D f<strong>in</strong>ite element model us<strong>in</strong>g the<br />

FEMLAB code.<br />

The relaxation process measured after artesian water<br />

outflow depends on the thermal properties of the<br />

surround<strong>in</strong>g rocks. With the l<strong>in</strong>e source model the<br />

relaxation process is simulated by a superposition of<br />

analytical solutions for the heat<strong>in</strong>g/cool<strong>in</strong>g process<br />

(Bullard E. C., 1947). The correspond<strong>in</strong>g equation was<br />

fitted to the measured data us<strong>in</strong>g the Levenberg-Marquardt<br />

algorithm (Press W. H. et al., 1992). As a result of these<br />

calculations the undisturbed (equilibrated) temperature and<br />

a second <strong>in</strong>-situ parameter, the term qL/4/π/λ, i.e. the ratio<br />

of the heat<strong>in</strong>g power and the <strong>in</strong>-situ thermal conductivity,<br />

is determ<strong>in</strong>ed. If the heat<strong>in</strong>g power is known, the <strong>in</strong>-situ<br />

value of the thermal conductivity can be determ<strong>in</strong>ed. The<br />

heat<strong>in</strong>g power depends on the amount and temperature of<br />

the artesian water flown out of the well. We simulated the<br />

transient disturbance of the subsurface temperature field by<br />

solv<strong>in</strong>g numerically the heat convection-conduction<br />

equation <strong>in</strong> an axisymmetric geothermal model of the<br />

borehole and its surround<strong>in</strong>gs by the f<strong>in</strong>ite difference (FD)<br />

method. A simple two-layer model with thermal<br />

conductivities of the surround<strong>in</strong>g rocks was considered.<br />

The heat<strong>in</strong>g power of the artesian outflow was calculated<br />

as the horizontal conductive heat flow <strong>in</strong>to the surround<strong>in</strong>g<br />

rock at a distance of 1 cm from the borehole wall at each<br />

depth node at each time step. The average heat<strong>in</strong>g power<br />

was obta<strong>in</strong>ed by <strong>in</strong>tegration over the period of the outflow.<br />

Comb<strong>in</strong><strong>in</strong>g the results, the ratio qL/4/π/λ and the depth<br />

dependent heat<strong>in</strong>g power obta<strong>in</strong>ed by FD modell<strong>in</strong>g, the <strong>in</strong>situ<br />

thermal conductivity was calculated and compared<br />

with the thermal conductivity measured on saturated<br />

samples <strong>in</strong> the laboratory.<br />

Fig.1: Temperature profile of borehole STP-2<br />

Fig.2: Temperature profile of borehole STP-2, upper part and<br />

model results<br />

References<br />

Bullard E. C., 1947, The time necessary for a bore hole to atta<strong>in</strong> temperature<br />

equilibrium, Monthly Notices Roy. Astron. Soc. Geophys. Suppl. 5,<br />

127-130, 1947<br />

Press W. H. et al., 1992, Numerical Recipes, Second Edition 1992,<br />

Cambridge University Press, Chapter 15.5 Nonl<strong>in</strong>ear models<br />

Wilhelm H. et al., 2005, Heterogeneity effects <strong>in</strong> thermal borehole<br />

measurements <strong>in</strong> the Chicxulub impact crater, J. Geophys. Eng. 2<br />

(2005) 357-363<br />

65

66<br />

<strong>IODP</strong><br />

A late Miocene-early Pliocene deepwater<br />

record of cyclic iron reduction events<br />

(Antarctic Pen<strong>in</strong>sula Pacific marg<strong>in</strong>, ODP<br />

Site 1095)<br />

D.A. HEPP 1 , T. MÖRZ 2<br />

1<br />

Fachbereich Geowissenschaften, Universität Bremen<br />

2<br />

DFG-Forschungszentrum Ozeanränder (RCOM), Universität<br />

Bremen<br />

The Antarctic ice sheet is the largest ice sheet on Earth<br />

today. It acts as key component <strong>in</strong> the global climate<br />

regime s<strong>in</strong>ce the late Eocene. Ice volume variations<br />

<strong>in</strong>fluence the ocean thermohal<strong>in</strong>e circulation and control<br />

the eustatic sea level.<br />

The Pacific marg<strong>in</strong> off the Antarctic Pen<strong>in</strong>sula is very<br />

sensitive to climate and ice-sheet volume changes. Climatic<br />

variations on the Antarctic Pen<strong>in</strong>sula cont<strong>in</strong>ental shelf<br />

control regional sedimentary processes and foster the buildup<br />

of giant deep-sea sediment drifts. These drifts represent<br />

the most proximal cont<strong>in</strong>uous sedimentary recorders for<br />

West Antarctic ice evolution and glacial-<strong>in</strong>terglacial<br />

cyclicity.<br />

Sediment physical, geochemical records and X-ray<br />

images derived from Drift 7 (ODP Site 1095, 3840 m water<br />

depth) were used to identify pattern <strong>in</strong> glacial-<strong>in</strong>terglacial<br />

cyclicity and associated sedimentary and diagenetic<br />

processes dur<strong>in</strong>g late Miocene and early Pliocene. Two<br />

boundary types divid<strong>in</strong>g half-cycles have been recognized:<br />

(1) <strong>in</strong>terglacial-to-glacial transitions are characterized by a<br />

sharp boundary and abrupt change <strong>in</strong> lithology; (2) glacialto-<strong>in</strong>terglacial<br />

transitions can described as a gradual change<br />

from a full glacial to a full <strong>in</strong>terglacial stage. A prom<strong>in</strong>ent<br />

feature of the glacial-to-<strong>in</strong>terglacial transition is the loss of<br />

the magnetic susceptibility signal.<br />

Late Miocene to early Pliocene was a period of global<br />

evidence for enhanced primary productivity and<br />

accumulation of biogenetic components <strong>in</strong> the sediment<br />

(‘Biogenic bloom’ hypothesis). At that time warm climate<br />

conditions were characterized by reduced sea ice cover and<br />

overall reduced ice volume. ODP Site 1095 was with<strong>in</strong> a<br />

southward-shifted or generally enhanced opal depocentre.<br />

It experienced exceptional opal and organic carbon fluxes<br />

comparable to those at the modern opal belt.<br />

Late Miocene to early Pliocene ice sheet dynamics<br />

<strong>in</strong>volved frequent advances and retreats of the <strong>in</strong>land ice<br />

sheet and led to more pronounced ice sheet collapses and<br />

meltwater pulses dur<strong>in</strong>g deglaciations. The discharge of<br />

large amounts of meltwater to the Antarctic surface waters<br />

caused stratification of the water column and shoal<strong>in</strong>g of<br />

the pycno- and nutricl<strong>in</strong>e <strong>in</strong>to the photic zone, promot<strong>in</strong>g<br />

high export productivity from the lower photic zone. Water<br />

column stratification weakened the Aantarctic bottom<br />

water formation and convection. Export productivity pulses<br />

(Short lived diatom blooms) <strong>in</strong> nearly stagnant deep water<br />

conditions led to reduc<strong>in</strong>g conditions <strong>in</strong> the sediment with<br />

sulfate reduction close to the sediment water <strong>in</strong>terface. This<br />

temporary suboxic to anoxic sediment conditions caused<br />

diagenetic alteration and demagnetization of magnetic iron<br />

m<strong>in</strong>erals (Loss of the magnetic susceptibility signal).<br />

Similar redox processes are described for organic carbon<br />

rich Madeira abyssal pla<strong>in</strong> turbidites and Mediterranean<br />

sapropels, but are uncommon for vented Circum-Antarctic<br />

deep-sea sediments<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Follow<strong>in</strong>g the meltwater pulses the reduction of the<br />

supply of nutrients that had been bound <strong>in</strong> the ice led to a<br />

rapid decl<strong>in</strong>e of export productivity. The break-up of water<br />

stratification allowed the re-establishment of bottom water<br />

formation, circulation and ventilation, affect<strong>in</strong>g of the<br />

upper sediment column.<br />

On long time-scales the <strong>in</strong>tensity and duration of<br />

diagenesis reflect major trends <strong>in</strong> global paleoceanographic<br />

and climatic change and consequently the variability <strong>in</strong><br />

primary export production. After Antarctic ice sheet<br />

stabilization, between 3.3 to 2.3 Ma, the flux of organic<br />

matter and sedimentation rates fell below a threshold level<br />

prevent<strong>in</strong>g development of reduc<strong>in</strong>g conditions <strong>in</strong> the<br />

surface sediments.<br />

The mapp<strong>in</strong>g and documentation of losses of magnetic<br />

susceptibility <strong>in</strong> sixty-four zones (late Miocene to early<br />

Pliocene period) of sediment cores from ODP Site 1095<br />

provide the first long term record of cyclic meltwater<br />

pulses and high export productivity events result<strong>in</strong>g <strong>in</strong><br />

reduc<strong>in</strong>g conditions <strong>in</strong> the near surface sediments <strong>in</strong> the<br />

high latitud<strong>in</strong>al Southern Ocean.<br />

Meltwater events orig<strong>in</strong>ate<strong>in</strong>g <strong>in</strong> the Antarctic may<br />

have had a major impact on the global thermohal<strong>in</strong>e<br />

overturn<strong>in</strong>g strength. Further, <strong>in</strong>creased carbon burial <strong>in</strong> the<br />

high latitudes dur<strong>in</strong>g extensive green-house conditions may<br />

have been a negative feed-back to atmospheric CO2<br />

concentrations.<br />

The processes of early diagenesis described here are a<br />

function of the environmental factors of the local regime<br />

and reflect changes along the West Antarctic Pen<strong>in</strong>sula;<br />

they may be more widespread <strong>in</strong> the Antarctic region.<br />

Although early diagenesis may obliterate primary proxies<br />

and processes, it can also serve as evidence of unusual<br />

oceanic conditions that otherwise might be obscured and<br />

overlooked <strong>in</strong> geological records.<br />

References:<br />

Hepp, D.A., Mörz, T. and Grützner, J., 2006. Pliocene glacial cyclicity <strong>in</strong> a<br />

deep-sea sediment drift (Antarctic Pen<strong>in</strong>sula Pacific Marg<strong>in</strong>).<br />

Palaeogeography, Palaeoclimatology, Palaeoecology, 231(1-2): 181-<br />

198.<br />

Hepp, D.A. et al., submitted. A late Miocene-Pliocene Antarctic deepwater<br />

record of cyclic iron reduction events. Paleoceanography.<br />

<strong>IODP</strong><br />

Geochemical evolution of the Early Aptian<br />

Oceanic Anoxic Event 1a <strong>in</strong> the tropical<br />

Atlantic, ODP Site 641C Galicia Marg<strong>in</strong>.<br />

P. HOFMANN 1 , T. WAGNER 2<br />

1 Universität zu Köln, Institut für Geologie und M<strong>in</strong>eralogie,<br />

Zülpicher Str. 49a, 50674 Köln<br />

2 Newcastle University, Civil Engeneer<strong>in</strong>g and Geoscience,<br />

Newcastle Upon Tyne NE 1 7RU, UK<br />

A key mechanism which controls rapid climate change<br />

dur<strong>in</strong>g greenhouse periods of the Mesozoic climate system<br />

appears to be the catastrophic release of methane from gas<br />

hydrates to the oceanic and atmospheric carbon reservoirs.<br />

Excess CO2 liberated from gas hydrate desiccation is<br />

expected to result <strong>in</strong> the <strong>in</strong>tensification of greenhouse<br />

conditions lead<strong>in</strong>g to an acceleration of the hydrological<br />

cycle, <strong>in</strong>tensified weather<strong>in</strong>g conditions, an elevated supply<br />

of nutrients to the ocean and extensive black shale<br />

deposition.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

The most prom<strong>in</strong>ent example for rapid climate change<br />

related to the release of CO2 from gas hydrates <strong>in</strong> the<br />

Cretaceous is thought to be represented by an abrupt and<br />

stepped negative carbon-isotope excursion at the base of<br />

the Early Aptian Oceanic Anoxic Event 1a (OAE 1a, Selli-<br />

or Niveau Goguel-Event). Aim of this project is to<br />

reconstruct the cha<strong>in</strong> of processes affect<strong>in</strong>g the Early<br />

Aptian land-ocean-atmosphere system <strong>in</strong> tropical regions<br />

of the Atlantic <strong>in</strong>duced by the release of CO2 exemplified<br />

by ODP Site 641C Galicia Marg<strong>in</strong>, based on high<br />

resolution proxy data e.g., for the development of sea<br />

surface temperatures (Tex 86), carbon burial and<br />

preservation and the isotopic evolution of the ocean and<br />

atmosphere (δ 13 C values from long cha<strong>in</strong> n-alkanes and<br />

steranes).<br />

Here we present data of the first phase of <strong>in</strong>vestigation<br />

which focused on the identification of the OAE 1a and its<br />

characteristics at Site 641C. Bulk carbon isotope data from<br />

carbonates and organic matter allow identify<strong>in</strong>g the onset<br />

of OAE 1a at Site 641C at the bottom of core 9R. The base<br />

of the event is marked by a negative δ 13 C shift of 1.25 per<br />

mil recorded bulk carbonates associated with an <strong>in</strong>crease <strong>in</strong><br />

TOC values from 0.5 to more than 2%. The <strong>in</strong>itial negative<br />

carbon isotope excursion is followed by sudden drop <strong>in</strong><br />

carbonate content to 0-10% CaCO3 from more than 40%.<br />

Carbonate values rema<strong>in</strong> low throughout core 9R, while<br />

TOC values fluctuate between 0.5 and 3.5%. A drop to<br />

TOC values below 1% <strong>in</strong> core 8R is associated with a 3 per<br />

mil <strong>in</strong>crease <strong>in</strong> δ 13 C car values and a gradual return to<br />

carbonate values between 20 and 40%.<br />

The comparison of our data with records from the<br />

Vocontian Bas<strong>in</strong> (France) and Northern and Central Italy<br />

shows, that key feature of OAE 1a which can be<br />

recognized worldwide were recovered at ODP Site 641C,<br />

despite considerable core losses. The <strong>in</strong>itial negative<br />

carbon isotope excursion which has been <strong>in</strong>terpreted as the<br />

result of CO2 liberated from gas hydrate desiccation is<br />

present <strong>in</strong> an approximately 1m thick <strong>in</strong>terval and will be<br />

the focus of our further <strong>in</strong>vestigations.<br />

<strong>IODP</strong><br />

Pacific circulation dur<strong>in</strong>g the middle Miocene<br />

climate transition:Monitor<strong>in</strong>g ocean<br />

overturn<strong>in</strong>g and the east-west hydrographic<br />

gradient<br />

A. HOLBOURN 1 , W. KUHNT 1 , B. HALEY 2 , M. REGENBERG 1 , A.<br />

MIX 3 , N. ANDERSEN 4<br />

1 Institute of Geosciences, Christian-Albrechts-University,<br />

Olshausenstr, 40, D-24118 Kiel, Germany<br />

2 Leibniz Institute of Mar<strong>in</strong>e Sciences IFM-GEOMAR,<br />

Wischhofstr. 13, D-24148 Kiel, Germany<br />

3 College of Oceanic and Atmospheric Sciences, Oregon State<br />

University, 104 COAS Adm<strong>in</strong> Bldg, Corvallis, OR 97331-<br />

5503, USA<br />

4 Leibniz Laboratory for Radiometric Dat<strong>in</strong>g and Stable Isotope<br />

Research, Christian-Albrechts-University, Max-Eyth-Str. 11-<br />

13, D-24118, Kiel, Germany<br />

MOTIVATION<br />

About 13.9 million years ago, the Earth’s climate<br />

cooled dramatically after an extended period of relative<br />

warmth. This key transition <strong>in</strong> Earth’s climatic and biotic<br />

evolution, which marked the f<strong>in</strong>al stage of stepwise<br />

Cenozoic cool<strong>in</strong>g, rema<strong>in</strong>s one of the most enigmatic<br />

episodes <strong>in</strong> Earth’s Cenozoic climate history. While there<br />

is evidence that <strong>in</strong>solation forc<strong>in</strong>g and CO2 variations<br />

<strong>in</strong>fluenced climate evolution, the role of the ocean’s<br />

circulation as enhancer or driver of climate change rema<strong>in</strong>s<br />

unclear. The Pacific Ocean represents a key region to<br />

decipher middle Miocene climatic evolution: today, this<br />

huge ocean plays a crucial role <strong>in</strong> the transmission of<br />

global climate change and <strong>in</strong> the middle Miocene it must<br />

have exerted an enormous <strong>in</strong>fluence on global climate, as it<br />

was even larger then. Our primary goals with<strong>in</strong> this project<br />

are to <strong>in</strong>vestigate water mass distribution patterns and<br />

circulation changes <strong>in</strong> the Pacific dur<strong>in</strong>g the middle<br />

Miocene climate optimum and through the major climatic<br />

transition culm<strong>in</strong>at<strong>in</strong>g with global cool<strong>in</strong>g at ~ 13.9 Ma.<br />

Our project focuses on the evolution of the upper water<br />

column, ocean-atmosphere <strong>in</strong>teractions and rates of ocean<br />

overturn<strong>in</strong>g to test the hypothesis that global cool<strong>in</strong>g and<br />

ice-sheet expansion co<strong>in</strong>cided with an <strong>in</strong>tensification of<br />

hydrographic gradients, the <strong>in</strong>itiation of a West Pacific<br />

Warm Pool (and SE Asian Monsoon) system and a<br />

fundamental re-organization <strong>in</strong> Pacific <strong>in</strong>termediate and<br />

deep water circulation.<br />

METHODS<br />

Our study is based on high resolution (3-5 kyr) samples<br />

from NW Pacific Sites 806 (Ontong Java Plateau, 2531 m<br />

water depth) and 1146 (South Ch<strong>in</strong>a Sea, 2092 m water<br />

depth) and SE Pacific Sites 1236 and 1237 (1323 m and<br />

3212 m water depth, respectively) cover<strong>in</strong>g the <strong>in</strong>terval<br />

16.5 to 12.5 Ma, which were previously analysed for<br />

benthic isotopes at Kiel University (Project Ku649/18).<br />

New paleoclimate proxy records generated with<strong>in</strong> the<br />

current project are also <strong>in</strong>tegrated with high resolution data<br />

available from SW Pacific Sites 588 and 1171 (Flower and<br />

Kennett, 1993; Shevenell and Kennett, 2004; Shevenell et<br />

al., 2004, <strong>2008</strong>) <strong>in</strong> order to broaden latitud<strong>in</strong>al coverage.<br />

Orbitally-tuned chronologies, developed dur<strong>in</strong>g Project<br />

Ku649/18 for Sites 588, 806, 1146, 1236, 1237 and 1171<br />

provide a high resolution, consistent chronological<br />

framework that allows highly detailed correlations of<br />

multiproxy data across the Pacific.<br />

Stable isotope analysis:<br />

Approximately 12-20 specimens of the surface<br />

dwell<strong>in</strong>g planktonic foram<strong>in</strong>ifer Globiger<strong>in</strong>oides ruber or<br />

its immediate precursor Globiger<strong>in</strong>oides subquadratus<br />

(250-350 µm) are used for stable carbon and oxygen<br />

isotope analysis. Tests are broken <strong>in</strong>to large fragments,<br />

then cleaned <strong>in</strong> alcohol <strong>in</strong> an ultrasonic bath and dried at<br />

40°C. Measurements are made with the F<strong>in</strong>nigan MAT 251<br />

mass spectrometer at the Leibniz Laboratory, Kiel<br />

University. The <strong>in</strong>strument is coupled on-l<strong>in</strong>e to a Carbo-<br />

Kiel Device (Type I). Replicate measurements <strong>in</strong> samples<br />

conta<strong>in</strong><strong>in</strong>g sufficient numbers of <strong>in</strong>dividuals <strong>in</strong>dicate mean<br />

reproducibility of ±0.1 ‰ for δ18O and δ13C. The highresolution<br />

planktonic record (3-4 kyr) generated <strong>in</strong> South<br />

Ch<strong>in</strong>a Sea Site 1146 allows us to capture precessional<br />

variability <strong>in</strong> surface water δ18O.<br />

Mg/Ca analysis:<br />

Approximately 40 tests of the surface dweller Gs. ruber<br />

or subquadratus (250-350 µm), weigh<strong>in</strong>g ~ 0.3-0.5 mg per<br />

sample, are measured for Mg/Ca. Tests are gently crushed<br />

and cleaned follow<strong>in</strong>g the standard procedure with<br />

reductive step detailed <strong>in</strong> Mart<strong>in</strong> and Lea (2002). Samples<br />

are analyzed with the ICP-OES (Spectro Ciros SOP) with<br />

cooled cyclonic spraychamber and microconcentric<br />

67

68<br />

nebulization (200 µl m<strong>in</strong> -1 ) at the Institute of Geosciences,<br />

Kiel University. Intensity ratio calibration follows the<br />

method of de Villiers et al. (2002). Mg/Ca values are then<br />

converted to temperatures us<strong>in</strong>g equations developed by<br />

Anand et al. (2003). High resolution planktonic Mg/Ca <strong>in</strong><br />

South Ch<strong>in</strong>a Sea Site 1146 allows us to reconstruct<br />

temperature <strong>in</strong>dependent δ18Oseawater variations, which<br />

may be related to changes <strong>in</strong> monsoonal <strong>in</strong>tensity.<br />

Nd isotope analysis:<br />

Our method is based on the technique of Gutjahr et al.<br />

(2007), which was shown to be successful for the leach<strong>in</strong>g<br />

of Fe-Mn oxyhydroxide coat<strong>in</strong>gs <strong>in</strong> bulk mar<strong>in</strong>e sediments<br />

(<strong>in</strong>clud<strong>in</strong>g coarse fraction residues over 63 µm) through<br />

use of a a reduc<strong>in</strong>g reagent (hydroxylam<strong>in</strong>e). The fractions<br />

of this leach<strong>in</strong>g procedure are collected and analysed, and<br />

the Nd is separated from elemental <strong>in</strong>terferences dur<strong>in</strong>g<br />

mass spectrometry us<strong>in</strong>g established chromatographic<br />

techniques. Measurements of Pb, Nd and Sr isotopes are<br />

made with the Multicollector ICPMS at the Leibniz<br />

Institute of Mar<strong>in</strong>e Sciences IFM-GEOMAR. This method<br />

allows for the first time to study Miocene changes <strong>in</strong> water<br />

masses with a temporal resolution resolv<strong>in</strong>g orbital-scale<br />

variability.<br />

INITIAL RESULTS<br />

We used benthic and planktonic foram<strong>in</strong>iferal δ 13 C and<br />

δ 18 O, planktonic Mg/Ca together with Nd isotopes and<br />

deep-water ventilation proxies (benthic foram<strong>in</strong>iferal<br />

accumulation rates, proportion of coarse fraction > 63 μm<br />

and XRF Fe) <strong>in</strong> four ODP cores from the northwestern,<br />

central and southeastern Pacific to monitor sea surface<br />

temperature and sal<strong>in</strong>ity gradients and to track circulation<br />

changes across the Pacific dur<strong>in</strong>g the middle Miocene<br />

climate transition (16.5-12.5 Ma).<br />

Pacific surface hydrography and monsoon evolution<br />

dur<strong>in</strong>g the middle Miocene:<br />

Stable isotope and Mg/Ca measurements <strong>in</strong> surface<br />

dwell<strong>in</strong>g planktonic foram<strong>in</strong>ifers from Site 1146 (South<br />

Ch<strong>in</strong>a Sea) provide new <strong>in</strong>sights <strong>in</strong>to tropical sea surface<br />

variability and the evolution of Pacific hydrographic<br />

gradients dur<strong>in</strong>g the middle Miocene climate transition.<br />

Our high resolution (3-4 kyr) planktonic record from Site<br />

1146 exhibits high amplitude variability as well as<br />

significant power <strong>in</strong> the 21 and 19 kyr precessional bands<br />

(Fig. 1), suggest<strong>in</strong>g that a monsoonal regime already<br />

became established <strong>in</strong> the South Ch<strong>in</strong>a Sea <strong>in</strong> the middle<br />

Miocene. When benthic δ 18 O values <strong>in</strong>creased sharply after<br />

14.6 and 13.9 Ma dur<strong>in</strong>g two successive episodes of ice<br />

expansion, planktonic δ 18 O values strik<strong>in</strong>gly decreased,<br />

amplitude variations <strong>in</strong> planktonic δ 18 O <strong>in</strong>creased and the<br />

Δδ 18 O benthic-planktonic <strong>in</strong>tensified markedly (Fig. 1). Sea<br />

surface temperature (SST) estimates derived from Mg/Ca<br />

measurements also <strong>in</strong>dicate that these decreases <strong>in</strong> surface<br />

δ 18 O co<strong>in</strong>cided with a rise <strong>in</strong> tropical SST and freshen<strong>in</strong>g<br />

of surface waters. In contrast, Mg/Ca temperature estimates<br />

from the high southern latitudes (Tasman Rise Site 1171)<br />

reveal that surface cool<strong>in</strong>g occurred after the major ice<br />

expansion at ~ 13.9 Ma. Thus, our <strong>in</strong>itial results suggest<br />

that Middle Miocene ice expansion overall concurred with<br />

the (1) onset of steeper latitud<strong>in</strong>al temperature gradients,<br />

(2) expansion of a proto West Pacific Warm Pool and (3)<br />

<strong>in</strong>tensification of the SE Asian Summer monsoon.<br />

Nd and δ 13 C as tracers of water masses evolution and<br />

ocean overturn<strong>in</strong>g:<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Results from our Nd isotopes pilot study <strong>in</strong> Sites 1236<br />

and 1237 (1323 m and 3212 m water depths, respectively)<br />

<strong>in</strong>dicate that the composition of Pacific subtropical<br />

<strong>in</strong>termediate waters altered substantially on relatively short<br />

timescales dur<strong>in</strong>g the major re-organization <strong>in</strong> the climateocean<br />

system. Three ma<strong>in</strong> phases of evolution can be<br />

dist<strong>in</strong>guished (Fig. 2): (1) Nd values rema<strong>in</strong> quite negative<br />

until the major ice volume <strong>in</strong>crease at ~ 13.9 Ma; (2) Nd<br />

values became markedly more radiogenic dur<strong>in</strong>g CM6<br />

(13.9-13.5 Ma), represent<strong>in</strong>g the last and most pronounced<br />

δ13C maxima with<strong>in</strong> the „Monterey Excursion“; (3) Nd<br />

values reached slightly more negative values after 13.5 Ma.<br />

In parallel to Nd changes, the δ 13 C gradient between<br />

<strong>in</strong>termediate and deep waters showed <strong>in</strong>creas<strong>in</strong>g<br />

divergence with time (Fig. 2), suggest<strong>in</strong>g that the<br />

stratification of the upper ocean <strong>in</strong>tensified and<br />

<strong>in</strong>termediate waters became better ventilated, especially<br />

after 13.5 Ma. Deep-water ventilation proxies (benthic<br />

foram<strong>in</strong>iferal accumulation rates, proportion of coarse<br />

fraction > 63 μm and XRF Fe) also <strong>in</strong>dicate that ice<br />

expansion after 13.9 Ma was assiocated with a major<br />

deepen<strong>in</strong>g of the Calcite Compensation Depth and the<br />

establishment of a more vigorous deep water ventilation<br />

(Holbourn et al., 2005; 2007). Therefore, our results<br />

<strong>in</strong>dicate that middle Miocene climate change was<br />

associated with a major reorganization of both deep and<br />

<strong>in</strong>termediate water circulation <strong>in</strong> the Pacific.<br />

OUTLOOK<br />

In the last phase of our project, our aim will be to<br />

complement our prelim<strong>in</strong>ary Mg/Ca and Nd <strong>in</strong>vestigation.<br />

We will seek <strong>in</strong> particular to deconvolve the temperature<br />

and/or sal<strong>in</strong>ity (precipitation) components <strong>in</strong> planktonic<br />

δ18O variations <strong>in</strong> West Pacific Site 1146 by us<strong>in</strong>g an<br />

<strong>in</strong>dependent high resolution temperature record that<br />

captures orbital frequencies. To this effect, we will <strong>in</strong>crease<br />

the resolution of the 1146 Mg/Ca record to 4-12 kyr,<br />

focus<strong>in</strong>g over the <strong>in</strong>terval ~ 15-13 Ma, which marked the<br />

most fundamental re-organization <strong>in</strong> the climate-ocean<br />

system. To constra<strong>in</strong> the amplitude and tempo of Pacific<br />

circulation changes, we plan to generate a cont<strong>in</strong>uous, high<br />

resolution (10-20 kyr) Nd isotope record <strong>in</strong> Site 1236 (SE<br />

Pacific, 1323 mwd), which is ideally located to monitor the<br />

variability of subtropical <strong>in</strong>termediate water, <strong>in</strong> particular<br />

the mix<strong>in</strong>g history of northern and southern component<br />

water masses over the <strong>in</strong>terval ~ 15-13 Ma. We will<br />

additionally analyse Nd isotopes <strong>in</strong> NW Pacific Site 806,<br />

SE Pacific Site 1237 and SW Pacific Site 1171 <strong>in</strong> order to<br />

characterize Pacific deep water masses and to track the<br />

long-term mix<strong>in</strong>g history of northern, Equatorial and<br />

southern deep water masses <strong>in</strong> the Pacific. Our<br />

<strong>in</strong>vestigation will ultimately provide a synthesis of ocean<br />

chemistry proxies that will allow detailed correlation of<br />

paleoceanographic and climatic events <strong>in</strong> different regions<br />

of the Pacific and will help constra<strong>in</strong> model<strong>in</strong>g studies of<br />

past and future climate.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

References:<br />

Anand, P., Elderfield, H., Conte, M.H. Calibration of Mg/Ca thermometry <strong>in</strong><br />

planktonic foram<strong>in</strong>ifera from a sediment trap time series.<br />

Paleoceanography 18 (2), 1050, doi: 10.1029/2002PA000846 (2003).<br />

de Villiers, S., Greaves, M., Elderfield, H. An <strong>in</strong>tensity ratio calibration<br />

method for the accurate determ<strong>in</strong>ation of Mg/Ca and Sr/Ca of mar<strong>in</strong>e<br />

carbonates by ICP-AES. Geochemistry Geophysics Geosystems (G3) 3<br />

(1), 1001, doi:10.1029/2001GC000169 (2002).<br />

Flower, B.P. and Kennett, J.P. Middle Miocene ocean-climate transition:<br />

high resolution oxygen and carbon isotopic records from DSDP Site<br />

588A, southwest Pacific. Paleoceanography, 8, 811-843 (1993).<br />

Gutjahr, M., Frank, M., Stirl<strong>in</strong>g, C.H., Klemm, V., van de Flierdt, T. and<br />

Halliday, A.N. Reliable extraction of a deepwater trace metal isotope<br />

signal from Fe-Mn oxyhydroxide coat<strong>in</strong>gs of mar<strong>in</strong>e sediments.<br />

Chemical Geology, 242, 351-370 (2007).<br />

Holbourn, A.E., Kuhnt, W. and Schulz, M. and Erlenkeuser, H. Impacts of<br />

orbital forc<strong>in</strong>g and atmospheric CO2 on Miocene ice-sheet expansion.<br />

Nature, 438(7067), 483-487, doi:10.1038/nature04123 (2005).<br />

Holbourn, A.E., Kuhnt, W., Schulz, M., Flores, J.-A. and Andersen, N.<br />

Orbitally-paced climate evolution dur<strong>in</strong>g the middle Miocene<br />

“Monterey” carbon-isotope excursion. Earth Planetary Science Letters,<br />

261, 534-550. http://dx.doi.org/10.1016/j.epsl.2007.07.026 (2007).<br />

Mart<strong>in</strong>, P.A., Lea, D.W. A simple evaluation of clean<strong>in</strong>g procedures on<br />

fossil benthic foram<strong>in</strong>iferal Mg/Ca, Geochemistry Geophysics<br />

Geosystems (G3) 3 (10), 8401, doi: 10.1029/2001GC000280 (2002).<br />

Shevenell, A. E. and Kennett, J. P. Paleoceanographic change dur<strong>in</strong>g the<br />

middle Miocene climate revolution: An Antarctic stable isotope<br />

perspective. In The Cenozoic Southern Ocean: Tectonics,<br />

Sedimentation and Climate Change between Australia and Antarctica,<br />

edited by Exon, N., Kennett, J.P. Malone, M., 235-252 (Geophys.<br />

Monog. Ser., 151, AGU, Wash<strong>in</strong>gton, DC, 2004).<br />

Shevenell, A. E., Kennett, J. P. and Lea, D. W. Middle Miocene ice sheet<br />

dynamics, deep-sea temperatures, and carbon cycl<strong>in</strong>g: A Southern<br />

Ocean perspective. Geochemistry Geophysics Geosystems (G3) (<strong>in</strong><br />

press).<br />

Shevenell, A. E., Kennett, J. P. and Lea, D. W. Middle Miocene Southern<br />

Ocean Cool<strong>in</strong>g and Antarctic Cryosphere expansion. Science, 305,<br />

1766-1770 (2004).<br />

Figure 1. Comparison of high resolution benthic and planktonic δ 18 O records <strong>in</strong> Site 1146. Planktonic δ18O overall exhibits high<br />

amplitude precessional variability and significant power <strong>in</strong> the 21 and 19 kyr precessional bands (along with other Milankovitch<br />

periodicities), suggest<strong>in</strong>g that a monsoonal regime already became established <strong>in</strong> the South Ch<strong>in</strong>a Sea <strong>in</strong> the middle Miocene. In<br />

contrast, benthic δ 18 O only shows pronounced variability <strong>in</strong> the 41, 100 and 400 kyr bands (Holbourn et al., 2007). Planktonic δ18O<br />

values strik<strong>in</strong>gly decreased and the Δδ 18 Obenthic-planktonic <strong>in</strong>tensified markedly after 14.6 and 13.9 Ma dur<strong>in</strong>g phases of ice<br />

expansion and high latitudes cool<strong>in</strong>g.<br />

69

70<br />

<strong>IODP</strong><br />

On the role of temperature on the stress state<br />

of underthrust sediments at the Nankai<br />

marg<strong>in</strong><br />

A. HÜPERS 1 , A. KOPF 1<br />

1 DFG-Research Center Ocean Marg<strong>in</strong>s, University of Bremen,<br />

P.O. Box 330440, 28334 Bremen, Germany. E-mail:<br />

ahuepers@uni-bremen.de, Fax: +4942121865810<br />

Along the Nankai convergent marg<strong>in</strong> (Japan), a wide<br />

accretionary prism is built up by offscrap<strong>in</strong>g of <strong>in</strong>com<strong>in</strong>g<br />

sediments from the downgo<strong>in</strong>g Phillip<strong>in</strong>e Sea plate. While<br />

these sediments undergo fault<strong>in</strong>g and accretion, subduct<strong>in</strong>g<br />

sediments beneath the plate boundary largely suffer<br />

compaction. The stress state of these underthrust sediments<br />

is important for the location of the ma<strong>in</strong> plate boundary<br />

(i.e. decollement) and the onset of unstable slid<strong>in</strong>g<br />

behaviour at the updip limit of the seismogenic zone.<br />

Based on several DSDP, ODP and <strong>IODP</strong> deep-sea drill<strong>in</strong>g<br />

expeditions, a number of studies focused therefore on the<br />

stress state of the underthrust sediments. Although it is<br />

generally assumed that underthrust sediments are<br />

overpressured as function of rapid load<strong>in</strong>g by the overly<strong>in</strong>g<br />

prism and poor dra<strong>in</strong>age, documented physical properties<br />

and mechanical strength for underthrust sediments at the<br />

Nankai marg<strong>in</strong> are not fully understood.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Figure 2. Initial Nd results from our pilot study <strong>in</strong> Sites 1236 and 1237 (1323 m and 3212 m water depths, respectively) <strong>in</strong>dicate that SE<br />

Pacific <strong>in</strong>termediate waters changed significantly <strong>in</strong> composition follow<strong>in</strong>g ice growth at ~ 13.9 Ma. Three ma<strong>in</strong> phases of Nd<br />

evolution can be identified <strong>in</strong> parallel with changes <strong>in</strong> the δ 13 C gradient between <strong>in</strong>termediate and deep waters. These changes suggest<br />

that the stratification of the upper ocean <strong>in</strong>tensified and <strong>in</strong>termediate waters became better ventilated, especially after 13.5 Ma.<br />

Even though <strong>in</strong>-situ temperatures have been discovered<br />

to be up to ~110°C, thermal effects on the consolidation<br />

state of these sediments have been neglected <strong>in</strong> the<br />

abovementioned studies. To overcome this shortcom<strong>in</strong>g,<br />

we carried out isothermal uniaxial tests to characterize the<br />

<strong>in</strong>fluence of temperature effects on the mechanical<br />

properties of subduct<strong>in</strong>g sediments. Disaggregated samples<br />

of the ma<strong>in</strong> lithologies <strong>in</strong> the Nankai Trough (smectite-,<br />

illite- and quartz/tephra-rich) were loaded up to 70MPa at<br />

20°C, 100°C and 150°C. Compar<strong>in</strong>g consolidation states at<br />

similar loads and different temperatures, we found that the<br />

pore space is be<strong>in</strong>g reduced with <strong>in</strong>creas<strong>in</strong>g temperature.<br />

This thermally <strong>in</strong>duced consolidation is more pronounced<br />

for the clay-rich samples than for coarser-gra<strong>in</strong>ed<br />

lithologies. On this basis we exam<strong>in</strong>ed <strong>in</strong>-situ physical<br />

properties curves at different drill sites along the Nankai<br />

marg<strong>in</strong>. The thermal states serve to expla<strong>in</strong> unsolved key<br />

features such as high compression <strong>in</strong>dices of <strong>in</strong>-situ<br />

consolidation curves as well as observed offsets between<br />

consolidation curves of the drill sites. We conclude from<br />

our data that consolidation states are a comb<strong>in</strong>ation of<br />

mechanical load, thermal state and excess fluid pressure.<br />

We further estimated temperature corrected excess pore<br />

pressures for drill sites 1174 and 808 at the deformation<br />

front of the Nankai accretionary prism. Maximum excess<br />

pressures are found to be 1.8 – 3.3MPa at site 1174 and<br />

3.4-4.5MPa for site 808, suggest<strong>in</strong>g underconsolidated<br />

stress states for both holes. Although maximum

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

overpressures are ~0.7-1.3MPa smaller than previously<br />

believed, our data are <strong>in</strong> agreement with the assumption<br />

that pore pressure <strong>in</strong>creases with depth along the<br />

subduction thrust. Together with low basal friction, the<br />

pore pressures estimated from our data may responsible for<br />

the small taper angle along parts of the Nankai marg<strong>in</strong>.<br />

Further down-dip, it may be speculated that the<br />

observed temperature-dependent consolidation behaviour<br />

has implications for the onset of the seismogenic zone.<br />

Temperature-dependent test<strong>in</strong>g may therefore become<br />

important to understand physical property data from deep<br />

drill<strong>in</strong>g of the riser-vessel Chikyu to the seismogenic zone<br />

with<strong>in</strong> the <strong>IODP</strong>.<br />

<strong>IODP</strong><br />

Ve<strong>in</strong><strong>in</strong>g history of abyssal peridotites from a<br />

detachment fault sett<strong>in</strong>g (ODP Leg 209):<br />

from melt impregnations to low-temperature<br />

alteration<br />

N. JÖNS 1 , W. BACH 1 , T. SCHROEDER 2 , M. ROSNER 1,3<br />

1 Department of Geosciences, University of Bremen, 28359<br />

Bremen, Germany<br />

2 Environmental Earth Science Department, Eastern Connecticut<br />

State University, Willimantic CT06226, U.S.A.<br />

3 present address: Bundesanstalt für Materialforschung und –<br />

prüfung, 12205 Berl<strong>in</strong>, Germany<br />

Serpent<strong>in</strong>ization of abyssal peridotites result<strong>in</strong>g from<br />

<strong>in</strong>teraction with seawater is an important process<br />

<strong>in</strong>fluenc<strong>in</strong>g the properties of the oceanic lithosphere (e. g.<br />

composition, rheology, gravity, seismic structure).<br />

Furthermore, hydrogen and methane are released, which<br />

feed microbial communities at ultramafic-hosted<br />

hydrothermal systems. However, alteration of peridotites is<br />

a complex multistage process, rang<strong>in</strong>g from <strong>in</strong>teraction<br />

with gabbroic/plagiogranitic melts at high temperatures to<br />

low-temperature alteration at seafloor pressure-temperature<br />

conditions. The key to an understand<strong>in</strong>g of these processes<br />

is the ve<strong>in</strong><strong>in</strong>g history of abyssal peridotites.<br />

Abyssal peridotites are found at oceanic core<br />

complexes, the occurrence of which is generally bound to<br />

low-angle detachment faults at mid-ocean ridges. Our work<br />

focuses on samples from ODP Leg 209, which is located at<br />

the Mid-Atlantic Ridge, <strong>in</strong> the vic<strong>in</strong>ity of the 15°20’N<br />

fracture zone.<br />

All studied samples are strongly serpent<strong>in</strong>ized<br />

harzburgites. Relics of oliv<strong>in</strong>e (XMg= 0.87–0.91), Crbear<strong>in</strong>g<br />

sp<strong>in</strong>el (XCr= 0.47–0.55) and, <strong>in</strong> rare cases,<br />

orthopyroxene (XEn= 0.83–0.91) are locally preserved. To<br />

a large extent, these primary m<strong>in</strong>erals have been replaced<br />

by late-stage serpent<strong>in</strong>e and magnetite form<strong>in</strong>g mesh (after<br />

oliv<strong>in</strong>e) and bastite textures (after orthopyroxene). Samples<br />

are furthermore crosscut by several generations of ve<strong>in</strong>s:<br />

The oldest ve<strong>in</strong>s are bound to small-scale semi-brittle<br />

shear zones and show dist<strong>in</strong>ct m<strong>in</strong>eralogy. They conta<strong>in</strong><br />

brownish magnesiohornblende (XMg= 0.86–0.96) that is<br />

surrounded by coronas of act<strong>in</strong>olite/tremolite. The<br />

amphibole is situated <strong>in</strong> a matrix of chlorite (cl<strong>in</strong>ochlore).<br />

Accessory m<strong>in</strong>eral phases are apatite (XOH= 0.55–0.57,<br />

XCl= 0.35–0.39, XF= 0.05–0.08) and zircon. Ti-<strong>in</strong>-zircon<br />

thermometry applied to magmatically-zoned zircon gives<br />

temperatures of 720–830 °C, <strong>in</strong>terpreted as crystallization<br />

temperature of magmatic melt impregnations. These<br />

temperatures are too low to be expla<strong>in</strong>ed by crystallization<br />

from a gabbroic magma and we propose that the ve<strong>in</strong>s<br />

represent strongly altered plagiogranitic melts. This<br />

<strong>in</strong>terpretation is supported by Fe-rich orthopyroxene<br />

(XEn= 0.73) that is found as t<strong>in</strong>y <strong>in</strong>clusion <strong>in</strong> zircon.<br />

Chlorite thermometry po<strong>in</strong>ts to alteration of these melt<br />

impregnations at temperatures of ca. 200 °C.<br />

Ve<strong>in</strong>s consist<strong>in</strong>g of isotropic serpent<strong>in</strong>e (picrolite)<br />

crosscut the altered melt portions. There is textural<br />

evidence that growth of these ve<strong>in</strong>s <strong>in</strong>volved multiple<br />

open<strong>in</strong>g and fluid transport; however, from major and trace<br />

elements no clear dist<strong>in</strong>ction can be made between these<br />

different growth stages.<br />

Carbonate-bear<strong>in</strong>g ve<strong>in</strong>s generally formed later or<br />

coeval with picrolite ve<strong>in</strong>s. There are at least three different<br />

types: Some ve<strong>in</strong>s consist of euhedral dolomite crystals<br />

(XMgCO3= 0.87–0.91) <strong>in</strong> a matrix of calcite (XMgCO3=<br />

0.04–0.09). Other ve<strong>in</strong>s are pure dolomite ve<strong>in</strong>s<br />

(XMgCO3= 0.84–0.93); pure calcite ve<strong>in</strong>s are also present.<br />

The Sr and Li isotope compositions of the calcite ve<strong>in</strong>s are<br />

similar to those of 350 °C hot vent fluids from the nearby<br />

Logatchev hydrothermal area, suggest<strong>in</strong>g that the<br />

detachment faults have been migration pathways for fluids<br />

of similar nature. The O isotopes of the calcite ve<strong>in</strong>s,<br />

however, <strong>in</strong>dicate lower temperatures (90–185 °C,<br />

assum<strong>in</strong>g a fluid d18 of 1.5). One possible <strong>in</strong>terpretation of<br />

these data is that the fluids underwent significant amounts<br />

of conductive cool<strong>in</strong>g upon upward migration with<strong>in</strong> the<br />

detachment fault. U-Th and radiocarbon dat<strong>in</strong>g of lowtemperature<br />

(

72<br />

geochemical data of syn- to postk<strong>in</strong>ematic calcite ve<strong>in</strong>s<br />

may suggest large amounts of conductive cool<strong>in</strong>g,<br />

<strong>in</strong>dicat<strong>in</strong>g that fluid flow was likely not vigorous enough<br />

for convective heat transport to dom<strong>in</strong>ate.<br />

<strong>ICDP</strong><br />

The warm stages with<strong>in</strong> the 340 ka sediment<br />

record of Lake El´gygytgyn/NE Siberia– a<br />

comparison<br />

O. JUSCHUS 1 , M. MELLES 1 AND LAKE EL´GYGYTGYN SCIENTIFIC<br />

PARTY<br />

1 Universität zu Köln, Institut für Geologie und M<strong>in</strong>eralogie,<br />

Zülpicher 49a, 50674 Köln, E-Mail: olaf.juschus@unikoeln.de<br />

Lake El´gygytgyn, located on Chukchi pen<strong>in</strong>sula/NE<br />

Siberia, is a nearly circular lake with a diameter of 12 km<br />

and a water depth of 170 m. It was formed by an impact<br />

about 3.6 million years ago. Despite the fact that the lake is<br />

situated north of the Arctic Circle, geomorphological<br />

evidence suggests that the crater was never glaciated<br />

dur<strong>in</strong>g the entire Late Cenozoic. Thus, a full-length<br />

sediment core from Lake El´gygytgyn would yield a<br />

complete record of Arctic climate evolution, back one<br />

million years prior to the first major glaciation of the<br />

Northern Hemisphere.<br />

Dur<strong>in</strong>g the last decade the sedimentary record of the<br />

lake has become a major focus of multi-discipl<strong>in</strong>ary mult<strong>in</strong>ational<br />

paleoclimatic research. The International<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g Program (<strong>ICDP</strong>) has<br />

provided fund<strong>in</strong>g for drill<strong>in</strong>g operations on the lake and <strong>in</strong><br />

its permafrost catchment <strong>in</strong> <strong>2008</strong>/2009. Additionally, the<br />

project became <strong>in</strong>volved <strong>in</strong> the IPY under the umbrella of<br />

APEX and BIPOMAC. Pre-site surveys carried out <strong>in</strong> 1998<br />

and 2003 recovered two 12.9 m and 16.6 m long sediment<br />

cores from the deepest part of the lake. They revealed a<br />

basal age of approximately 250 ka and 340 ka respectively<br />

and confirmed the lack of glacial erosion.<br />

Presented here is a comparison of the ma<strong>in</strong> warm<br />

stages with<strong>in</strong> the 16.6 m long sediment record of core<br />

Lz1024 which was recovered <strong>in</strong> 2003. To establish an age<br />

model for core Lz1024, selected sedimentological<br />

parameters (mag. susceptibility, total organic carbon, TiO2,<br />

and biogenic silica) were systematically tuned to the<br />

northern hemisphere <strong>in</strong>solation. The tun<strong>in</strong>g yielded an age<br />

of 343 ka for the base of the composite core. Down to 200<br />

ka sediment age the tun<strong>in</strong>g is confirmed by the results of<br />

IRSL dat<strong>in</strong>g.<br />

Sediment successions correlated with the mar<strong>in</strong>e<br />

isotope stages (MIS) 1, 3, 5.5, 7.1, 7.5, and 9.3 represent<br />

the ma<strong>in</strong> warm phases with<strong>in</strong> the sediment record of core<br />

Lz1024. Compare to the sediments settled dur<strong>in</strong>g cold<br />

phases, the warm stage sediments are usually massive with<br />

comparably high susceptibility values. This <strong>in</strong>dicates an<br />

ice-free season dur<strong>in</strong>g the summer with complete mix<strong>in</strong>g of<br />

the water body. The lake bottom and the uppermost<br />

sediments were oxygenated which allowed bioturbation<br />

and oxygenation.<br />

The warm stage sediment units are subdivided <strong>in</strong>to<br />

three different types.<br />

Type 1: The sediments of the first type are<br />

characterised by biogeochemical parameters which <strong>in</strong>dicate<br />

comparably low bioproductivity with<strong>in</strong> the lake and a<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

strong decomposition of organic matter at the watersediment<br />

transition. Low shrub and arboreal pollen values<br />

provide evidence of at least relatively cold summer<br />

conditions. High susceptibility values and TiO2 contents<br />

give <strong>in</strong>dications for a complete meltout of the ice cover<br />

dur<strong>in</strong>g the summer and mix<strong>in</strong>g of the water body. This<br />

pattern is valid for the sediments settled dur<strong>in</strong>g MIS 3 and<br />

7.5.<br />

Type 2: Both the organic and <strong>in</strong>organic geochemical<br />

data of this sediment type are comparable to those from<br />

Type 1 with a low bioproductivity. The susceptibility<br />

values seem to be a little bit higher. The remarkably higher<br />

contents of arboreal pollen are the ma<strong>in</strong> difference and<br />

<strong>in</strong>dicate better grow<strong>in</strong>g conditions dur<strong>in</strong>g this time. These<br />

conditions prevailed dur<strong>in</strong>g MIS 1 and 7.1.<br />

Type 3: Especially the organic geochemistry data differ<br />

from the first two types by remarkable higher contents of<br />

organic carbon and biogenic silica, reflect<strong>in</strong>g much higher<br />

bioproductivity with<strong>in</strong> the water column. Due to<br />

postdepositional dissolution processes the susceptibility<br />

values decreased to lower levels. The high amount of<br />

arboreal and shrub <strong>in</strong>dicates relatively warm summers. The<br />

occurrence of these peak warm sediment successions is<br />

restricted to MIS 5.5 and especially 9.3. The latter one<br />

represents the time period dur<strong>in</strong>g the last 340 ka with the<br />

highest bioproductivity with<strong>in</strong> the lake.<br />

<strong>IODP</strong><br />

The rapid constriction of the Indonesian<br />

Gateway across 3.4-3 Ma as a ma<strong>in</strong><br />

contribut<strong>in</strong>g factor for global climate change<br />

C. KARAS 1 , D. NÜRNBERG 2 , A. GUPTA 3 , K. MOHAN 2 , R.<br />

TIEDEMANN 3<br />

1 IFM-GEOMAR, Kiel, Deutschland<br />

2 Indian Institute of Technology, Kharagpur, Indien<br />

3 Alfred-Wegener-Institut für Polar- und Meeresforschung,<br />

Bremerhaven, Deutschland<br />

The mid-Pliocene climate transition across 4-3 Ma<br />

marks a global cool<strong>in</strong>g <strong>in</strong> l<strong>in</strong>e with the onset of the<br />

Northern Hemisphere Glaciation and most dist<strong>in</strong>ctly, with<br />

the shoal<strong>in</strong>g of the global thermocl<strong>in</strong>e. It is still a major<br />

scientific issue whether these changes are related to<br />

variations <strong>in</strong> the North Atlantic thermohal<strong>in</strong>e circulation<br />

connected with the constriction of the Central American<br />

Seaway, or are rather amplified by the narrow<strong>in</strong>g of the<br />

Indonesian Gateway. Here, we present sea-(sub)surface<br />

foram<strong>in</strong>iferal Mg/Ca-temperature and sal<strong>in</strong>ity data from the<br />

tropical eastern Indian Ocean (DSDP Site 214) for the time<br />

period from 6.8 to 2.4 Ma to reconstruct changes <strong>in</strong> the<br />

Indonesian Throughflow (ITF). Accord<strong>in</strong>g to the strik<strong>in</strong>g<br />

hypothesis of Cane and Molnar (2001), the chang<strong>in</strong>g plate<br />

tectonic constellation across 4-3 Ma caused a switch <strong>in</strong> the<br />

source of the ITF waters from warm/sal<strong>in</strong>e S-Pacific<br />

towards cool/fresh N-Pacific waters enter<strong>in</strong>g the Indian<br />

Ocean. In response, cool<strong>in</strong>g of the tropical Indian Ocean<br />

caused droughts <strong>in</strong> Africa, and Northern Hemisphere<br />

Glaciation (NHG) <strong>in</strong>tensified. For the critical time period<br />

of 3.4-3 Ma, we observe a pronounced freshen<strong>in</strong>g and<br />

cool<strong>in</strong>g (ca. 4°C) of subsurface waters and hence, a<br />

shoal<strong>in</strong>g of the thermocl<strong>in</strong>e. We regard these changes to<br />

reflect an <strong>in</strong>creas<strong>in</strong>g <strong>in</strong>fluence of N-Pacific subsurface<br />

waters <strong>in</strong> the throughflow area, imply<strong>in</strong>g that the plate

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

tectonic reorganization <strong>in</strong> the ITF region rather affected<br />

subsurface than surface water masses. Hence, the<br />

constriction of the Indonesian Gateway significantly<br />

contributed to the global cool<strong>in</strong>g of the thermocl<strong>in</strong>e, which<br />

presumably term<strong>in</strong>ated permanent El Niño conditions at<br />

that time.<br />

<strong>ICDP</strong><br />

Lake <strong>in</strong>ternal depositional dynamics as<br />

revealed by the areal distribution of surface<br />

sediments <strong>in</strong> Laguna Potrok Aike (Southern<br />

Patagonia, Argent<strong>in</strong>a) – a prelim<strong>in</strong>ary study<br />

<strong>in</strong> the framework of the <strong>ICDP</strong> project<br />

PASADO<br />

STEPHANIE KASTNER 1 , CHRISTIAN OHLENDORF 1 , TORSTEN<br />

HABERZETTL 2 , ANDREAS LÜCKE 3 , NORA I. MAIDANA 4 , CHRISTOPH<br />

MAYR 5 , FRANK SCHÄBITZ 6 , BERND ZOLITSCHKA 1<br />

1 University of Bremen, Institute of Geography (Geopolar), 28359<br />

Bremen, Germany (steka@uni-bremen.de)<br />

2 Sedimentology and Environmental Geology, Geoscience Center,<br />

University of Gött<strong>in</strong>gen, 37077 Gött<strong>in</strong>gen, Germany<br />

3 Institute for Chemistry and Dynamics of the Geosphere (ICG) V:<br />

Sedimentary Systems, Research Center Jülich, 52425 Jülich,<br />

Germany<br />

4 Departement of Biodiversity and Experimental Biology,<br />

University of Buenos Aires, C1428EHA Buenos Aires,<br />

Argent<strong>in</strong>a<br />

5 GeoBio-CenterLMU and Dept. of Earth & Environmental<br />

Sciences, University of Munich, 80333 Munich, Germany<br />

6 Sem<strong>in</strong>ar for Geography and Education, University of Cologne,<br />

50931 Cologne, Germany<br />

In an area sensitive to variations <strong>in</strong> southern<br />

hemispheric w<strong>in</strong>d and pressure systems, a high potential as<br />

a paleolimnological key site for the reconstruction of<br />

terrestrial paleoclimate conditions has been ascribed to<br />

Laguna Portok Aike (51°58’S, 70°23’W). This lake is a<br />

100 m deep and ca. 770 ka old maar <strong>in</strong> the dry steppe<br />

environment of south-eastern Patagonia. Interdiscipl<strong>in</strong>ary<br />

multi-proxy studies as well as a climate modell<strong>in</strong>g<br />

approach document a unique lacustr<strong>in</strong>e record of<br />

paleoclimatic and paleoecological variability. For this<br />

reason the lake was chosen as an <strong>ICDP</strong> drill<strong>in</strong>g site <strong>in</strong> <strong>2008</strong><br />

with<strong>in</strong> the “Potrok Aike maar lake sediment archive<br />

drill<strong>in</strong>g project” (PASADO). Geochemical, palynological,<br />

diatomological and isotopic <strong>in</strong>vestigations were carried out<br />

with high temporal resolution on long sediment records<br />

cover<strong>in</strong>g the last 16 ka (Haberzettl et al., 2007; Mayr et al.,<br />

subm.; Wille et al., 2007). Changes <strong>in</strong> the lake´s<br />

hydrological budget related to the variability of the<br />

Southern Hemispheric Westerlies are expressed by several<br />

sediment proxies as well as by subaerial and subaquatic<br />

lake level terraces (Mayr et al., 2007). To improve the<br />

<strong>in</strong>terpretation of the long sediment record to be recovered<br />

with<strong>in</strong> the project PASADO, it is vital to develop an<br />

understand<strong>in</strong>g of modern processes and hence the<br />

dynamics that control the spatial distribution and the<br />

characteristics of the sediments <strong>in</strong> Laguna Potrok Aike.<br />

Therefore, a survey of the sediment distribution was carried<br />

out <strong>in</strong> 2005 by us<strong>in</strong>g 46 gravity cores of up to 49 cm <strong>in</strong><br />

length. This dense grid of cores covers a water depth range<br />

from 9 to 100 m.<br />

The age model established <strong>in</strong> Haberzettl et al. (2005) is<br />

transferred from a sediment short core of the deep central<br />

lake bas<strong>in</strong> and is based on four AMS radiocarbon ages.<br />

New cores were correlated to this record us<strong>in</strong>g Ca and Ti<br />

data obta<strong>in</strong>ed by XRF and magnetic susceptibility scans <strong>in</strong><br />

1 and 4 mm spatial resolution, respectively. A successful<br />

core correlation prior to the 2005 sediment surface was<br />

achieved for cores from water depths exceed<strong>in</strong>g 45 m.<br />

Thus surface samples were taken from all 46 cores while<br />

subsampl<strong>in</strong>g of selected past time w<strong>in</strong>dows (AD 1960,<br />

1800, 1610, 1500, 1380) was only possible for 25 well<br />

correlated cores. These time slices were chosen to cover<br />

paleoenvironmentally dist<strong>in</strong>ctive <strong>in</strong>tervals with known<br />

hydrological (i.e., lake level) variations. First results of<br />

XRF and magnetic susceptibility scann<strong>in</strong>g as well as<br />

element concentrations (C, N, S), pollen, stable isotope<br />

(δ 13 C, δ 15 N) and diatom analyses are presented by<br />

distribution maps which reproduce modern dynamics at the<br />

sediment surface, i.e., at a sediment depth of 0-1 cm<br />

(represent<strong>in</strong>g the last approx. 20 years). These maps reveal<br />

pronounced differences between the littoral cores down to<br />

45 m water depth and the lake´s profundal cores separated<br />

from each other by steep slopes. In general, sediments from<br />

the deep bas<strong>in</strong> represent lowest values for all analysed<br />

parameters but with discernable variations throughout the<br />

deep central pla<strong>in</strong>. A conspicuous m<strong>in</strong>imum of C/N-ratios<br />

and total <strong>in</strong>organic carbon values is apparent near the<br />

south-eastern slope of the lake and <strong>in</strong> the deep bas<strong>in</strong>. This<br />

pattern seems to be l<strong>in</strong>ked to a canyon-like structure which<br />

is deeply <strong>in</strong>cised <strong>in</strong> the south-eastern subaerial lake level<br />

terraces and which most probably cont<strong>in</strong>ues subaquatically.<br />

After all, sedimentation with<strong>in</strong> this term<strong>in</strong>al lake seems to<br />

be sensitive not only to changes <strong>in</strong> the hydrological regime.<br />

Probably lake <strong>in</strong>ternal currents, differences <strong>in</strong> basement<br />

geology or ephemeral surface and groundwater <strong>in</strong>flows can<br />

affect the sediment distribution as well. Hence, exist<strong>in</strong>g<br />

analyses of representative s<strong>in</strong>gle sediment cores from the<br />

deepest part of the lake should be complemented by<br />

<strong>in</strong>formation obta<strong>in</strong>ed from the areal sediment distribution<br />

study.<br />

Prelim<strong>in</strong>ary results of the short core survey presented<br />

here visualise a spatial variation of sediment parameters<br />

that have been analysed with high resolution on s<strong>in</strong>gle long<br />

cores. Comb<strong>in</strong>ed with high resolution seismic data the<br />

evaluation of this spatial <strong>in</strong>formation (1) improves the preconditions<br />

to make a decision about the best possible<br />

drill<strong>in</strong>g location with an undisturbed and representative<br />

sediment succession, (2) fosters the understand<strong>in</strong>g of recent<br />

processes concern<strong>in</strong>g sediment distribution and (3)<br />

improves the capabilities for a better <strong>in</strong>terpretation of the<br />

anticipated long sediment record. The two dist<strong>in</strong>guishable<br />

areas of deposition - the central bas<strong>in</strong> and the slopes<br />

<strong>in</strong>clud<strong>in</strong>g submerged terrace levels - will both be the target<br />

of the scheduled <strong>ICDP</strong> deep drill<strong>in</strong>g project PASADO.<br />

References:<br />

Haberzettl, T. et al., (2005) Climatically <strong>in</strong>duced lake level changes dur<strong>in</strong>g<br />

the last two millennia as reflected <strong>in</strong> sediments of Laguna Potrok Aike,<br />

southern Patagonia (Santa Cruz, Argent<strong>in</strong>a). Journal of Paleolimnology<br />

33: 283-302.<br />

Haberzettl, T. et al. (2007) Lateglacial and Holocene wet-dry cycles <strong>in</strong><br />

southern Patagonia: chronology, sedimentology and geochemistry of a<br />

lacustr<strong>in</strong>e record from Laguna Potrok Aike, Argent<strong>in</strong>a. The Holocene,<br />

17: 297-310.<br />

Mayr, C. et al. (2007) Holocene variability of the Southern Hemisphere<br />

westerlies <strong>in</strong> Argent<strong>in</strong>ean Patagonia (52°S). Quaternary Science<br />

Reviews, 26: 579-584.<br />

Mayr, C. et al. (subm.) Isotopic and geochemical f<strong>in</strong>gerpr<strong>in</strong>ts of<br />

environmental changes dur<strong>in</strong>g the last 16,000 years on lacustr<strong>in</strong>e<br />

organic matter from Laguna Potrok Aike (southern Patagonia,<br />

Argent<strong>in</strong>a). Chemical Geology.<br />

Wille, M. et al. (2007) Vegetation and climate dynamics <strong>in</strong> southern South<br />

America: The microfossil record of Laguna Potrok Aike, Santa Cruz,<br />

Argent<strong>in</strong>a. Review of Palaeobotany and Palynology 146: 234-246.<br />

73

74<br />

<strong>IODP</strong><br />

Pliocene Changes <strong>in</strong> the Composition of<br />

Mediterranean Outflow Water at DSDP Site<br />

548 and ODP Site 978<br />

N. KHELIFI 1 , M. SARNTHEIN 1 , M. FRANK 2 , M. WEINELT 1 , N.<br />

ANDERSEN 3 , D. GARBE-SCHÖNBERG 1<br />

1 Institut für Geowissenschaften, Christian-Albrechts-Universität zu<br />

Kiel, Deutschland (nk@gpi.uni-kiel.de)<br />

2 Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR),<br />

Christian-Albrechts-Universität zu Kiel, Deutschland<br />

3 Leibniz-Labor für Altersbestimmung und Isotopenforschung,<br />

Christian-Albrechts-Universität zu Kiel, Deutschland<br />

Pliocene changes <strong>in</strong> the Mediterranean Outflow (3.6 –<br />

2.5 Ma) were studied at East Atlantic DSDP Site 548<br />

which lies today with<strong>in</strong> the depth range of modern<br />

Mediterranean Outflow Water (MOW; 1251 m w.d.). This<br />

site provided a largely cont<strong>in</strong>uous benthic record of bottom<br />

water variability with millennial-scale resolution from 3.68<br />

Ma (MIS Gi01) to 2.56 Ma (MIS 101; tuned to age scale<br />

LR04). We assume that MOW spilled this Site 548 almost<br />

cont<strong>in</strong>uously over the whole <strong>in</strong>terval studied, s<strong>in</strong>ce Nd<br />

isotopes rema<strong>in</strong>ed constant at e = -10.3±0.3 to -9.5±0.3, a<br />

range characteristic of Mediterranean waters. Mg/Ca-based<br />

bottom water temperatures show a major <strong>in</strong>crease near 3.46<br />

to 3.38 Ma – for reasons yet unknown – from an average of<br />

6°–8°C up to a plateau of 8°–11.5°C, which lasted until<br />

2.95 Ma (MIS G17). Subsequently, bottom water<br />

temperatures displayed a unique short-last<strong>in</strong>g drop down to<br />

3°C at MIS G10 (2.82 Ma), a drop coeval with the f<strong>in</strong>al<br />

closure of Central American Seaways and the onset of<br />

major Northern Hemisphere Glaciation (NHG; Bartoli et<br />

al., 2005). After MIS G10 bottom water temperatures<br />

returned to 6°–8°C, a level characteristic of modern MOW<br />

and be<strong>in</strong>g traced until 2.56 Ma (MIS 101). S<strong>in</strong>ce icevolume<br />

corrected benthic δ18O values do not reflect any of<br />

these immense changes, the long-term temperature rise of<br />

3°–4° C also implies a major <strong>in</strong>crease of bottom water<br />

sal<strong>in</strong>ity by 1.5 to 2.0 p.s.u. Accord<strong>in</strong>gly, the plateau reflects<br />

<strong>in</strong>tensified advection of MOW and salt discharge to the<br />

northern North Atlantic, that may have strengthened North<br />

Atlantic THC and thus preconditioned the onset of NHG.<br />

Only after 2.95 Ma, dur<strong>in</strong>g the f<strong>in</strong>al closure of the Central<br />

American Seaways, the high Mediterranean salt <strong>in</strong>put was<br />

replaced by salt discharge from the Caribbean. S<strong>in</strong>ce this<br />

time epibenthic δ13C values <strong>in</strong>dicate slightly improved<br />

ventilation of MOW, that came close to the modern-to-Late<br />

Pleistocene level. In contrast to the outl<strong>in</strong>ed high level of<br />

temperature and sal<strong>in</strong>ity MOW ventilation was somewhat<br />

reduced prior to 3 Ma, suggest<strong>in</strong>g mid-Pliocene<br />

Mediterranean climates and <strong>in</strong> particular, a regime of<br />

cont<strong>in</strong>ental wetness that was significantly different from<br />

today. – The multiproxy records DSDP Site 548 need to be<br />

supplemented by Pliocene paleoceanographic records from<br />

the Mediterranean source region to study Pliocene<br />

variations <strong>in</strong> the composition of Mediterranean<br />

Intermediate Water prior to its mix<strong>in</strong>g with North Atlantic<br />

<strong>in</strong>termediate water masses. To reach this goal, we started<br />

analyz<strong>in</strong>g ODP Site 978 from the Alboran Sea.<br />

References:<br />

Bartoli, G., Sarnthe<strong>in</strong>, M., We<strong>in</strong>elt, M., Erlenkeuser, H., Garbe-Schönberg,<br />

D., Lea, D.W., 2005. F<strong>in</strong>al closure of Panama and the onset of northern<br />

hemisphere glaciation. Earth and Planetary Science Letters 237, 33-44.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Kerogen-bound organic matter <strong>in</strong> sediments<br />

represent<strong>in</strong>g the Oceanic Anoxic Event 1a<br />

B. KLEIN 1 , S.C. BRASSELL 2 , J. RULLKÖTTER 1<br />

1 Institute of Chemistry and Biology of the Mar<strong>in</strong>e Environment<br />

(ICBM), Carl von Ossietzky University of Oldenburg, PO<br />

Box 2503, D-26111 Oldenburg<br />

2 Biogeochemical Laboratories, Department of Geological<br />

Sciences, Indiana University, Bloom<strong>in</strong>gton, IN 47405-1403,<br />

USA<br />

Organic matter <strong>in</strong> sediments occurs both as free lowmolecular-weight<br />

molecules and bound by functional<br />

groups <strong>in</strong>to the <strong>in</strong>soluble kerogen. The proportion of free<br />

organic molecules which are amenable via solvent<br />

extraction depends on the maturity of the organic matter.<br />

The analysis of the kerogen-bound fraction requires<br />

treatment to liberate the low-molecular-weight compounds<br />

from the more complex matrix. This is possible by either<br />

chemical degradation or pyrolytical methods.<br />

Hopanoids - both methylated at C-2 and demethylated -<br />

are a class of molecules which can be <strong>in</strong>corporated <strong>in</strong>to the<br />

kerogen via their side-cha<strong>in</strong> conta<strong>in</strong><strong>in</strong>g diverse functional<br />

groups. They serve as a biomarkers for bacteria and<br />

cyanobacteria, of which the latter are known to be the only<br />

producer of significant amounts of 2-methylhopanoids<br />

(Summons et al., 1999). The ratio of hopanoids to 2methylhopanoids<br />

(2-methylhopanoid <strong>in</strong>dex, 2-MeH <strong>in</strong>dex)<br />

allows an estimation of cyanobacterial <strong>in</strong>fluence on<br />

bioproductivity <strong>in</strong> certa<strong>in</strong> time <strong>in</strong>tervals of the geological<br />

past.<br />

In this study we focus on a sediment succession<br />

recovered dur<strong>in</strong>g ODP Leg 198 <strong>in</strong> the Pacific Ocean. The<br />

sediment samples drilled on Shatsky Rise cover an age<br />

range of the Cretaceous through the Paleogene. With<strong>in</strong> this<br />

sediment succession, together with several other abrupt<br />

climatic change events, the Oceanic Anoxic Event 1a <strong>in</strong> the<br />

early Aptian (120 Ma) is represented (Bralower et al.,<br />

2006). Organic matter is enriched and organic carbon<br />

content may exceed 30 %. Previous geochemical analyses<br />

suggest that a high phytoplanktonic productivity<br />

significantly contributed to this high amount of organic<br />

matter (Dumitrescu & Brassell, 2005).<br />

As mentioned above the 2-MeH-<strong>in</strong>dex is used to<br />

<strong>in</strong>vestigate the cyanobacterial contribution to the<br />

sedimentary organic matter. Beside this <strong>in</strong>dex, nitrogen<br />

isotopic data of the sediments are another important tool<br />

for the evaluation of microbial activity because nitrogen<br />

fixation – which is an important function of some<br />

cyanobacteria – leads to a change <strong>in</strong> the isotopic values.<br />

The mechanism of nitrogen fixation allows some<br />

microorganisms to thrive if nitrate as major nutrient is<br />

limited. Due to sluggish ocean circulation conditions<br />

dur<strong>in</strong>g the OAE 1a or high microbial activity a lack of<br />

nitrogen supply may have occurred. The ratio of<br />

methylated to demethylated hopanoids with<strong>in</strong> the<br />

succession – obta<strong>in</strong>ed from total lipid extracts – shows a<br />

good correlation with the nitrogen isotopic data (Fig. 1).

565,6<br />

565,7<br />

565,8<br />

565,9<br />

566,0<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

0<br />

10<br />

30<br />

20<br />

C org (%)<br />

60<br />

50<br />

40<br />

30<br />

20<br />

10<br />

0<br />

50<br />

40<br />

2-MeH-Index (C 27 + C 31 + C 33 )<br />

-2,2<br />

-2,4<br />

-2,6<br />

-2,8<br />

-3,0<br />

-3,2<br />

-3,4<br />

-3,6<br />

δ15 δ N (‰) 15N (‰)<br />

Fig. 1. Depth profiles of total organic carboncontent, 2-MeH-<strong>in</strong>dex<br />

(derived from total lipid extracts) and nitrogen isotopic data (from<br />

left to right).<br />

The higher the 2-MeH-<strong>in</strong>dex is, the lower are the δ 15 N<br />

values. This strengthens the assumption that nitrogen fix<strong>in</strong>g<br />

cyanobacteria significantly contributed to the sedimentary<br />

organic matter.<br />

Due to these results offl<strong>in</strong>e-pyrolysis at 500 °C for one<br />

hour under an <strong>in</strong>ert atmosphere was performed with the<br />

samples to set free the kerogen-bound proportion of the<br />

hopanoids. Figure 2 shows mass chromatograms<br />

representative of hopanoids (a and c) and 2methylhopanoids<br />

(b and d) (m/z 191 and m/z 205,<br />

respectively).<br />

All chromatograms were obta<strong>in</strong>ed for a sediment<br />

sample taken at Site 1207B and comprise both kerogen and<br />

the correspond<strong>in</strong>g total lipid extract. The mass<br />

chromatograms labelled a and b represent the portion of<br />

molecules amenable via solvent extraction and hence are<br />

only a small part compared to the total amount.<br />

Pyrolysis of the untreated sediment releases a greater<br />

variety (Fig. 2 c and d) of compounds and hence allows the<br />

analysis of the overall composition of hopanes and 2methylhopanes<br />

regardless of any maturity effects and thus<br />

a new calculation of the 2-MeH <strong>in</strong>dex. Furthermore, gaps<br />

<strong>in</strong> the 2-MeH <strong>in</strong>dex for samples where neither hopanoids<br />

nor 2-methylhopanoids were detectable <strong>in</strong> the extracts may<br />

be closed due to the availability of the comprehensive<br />

pyrolysis data.<br />

Relative Abundance<br />

100<br />

0<br />

100<br />

a)<br />

b)<br />

m/z 191<br />

m/z 205<br />

0<br />

56 58 60 62 64 66 68 70 72 74 76 78 80 82 84<br />

Time (m<strong>in</strong>)<br />

*<br />

Relative Abundance<br />

100<br />

0<br />

100<br />

0<br />

c)<br />

d)<br />

References<br />

Bralower, T.J., Premoli Silva, I., and Malone, M.J., 2006. Leg 198<br />

synthesis: a remarkable 120-m.y. record of climate and oceanography<br />

from Shatsky Rise, northwest Pacific Ocean. In Bralower, T.J., Premoli<br />

Silva, I., and Malone, M.J. (Eds.), Proc. ODP, Sci. Res., 198: College<br />

Station, TX (Ocean Drill<strong>in</strong>g Program), 1–47.<br />

doi:10.2973/odp.proc.sr.198.101.2006<br />

Dumitrescu, M., Brassell, S.C., 2005. Biogeochemical assessment of<br />

sources of organic matter and paleoproductivity dur<strong>in</strong>g the early Aptian<br />

Oceanic Anoxic Event at Shatsky Rise, ODP Leg 198. Organic<br />

Geochemistry, 36, 1002-1022.<br />

Summons, R.E., Jahnke, L.L., Hope, J.M., Logan, G.A., 1999. 2-<br />

Methylhopanoids as biomarkers for cyanobacterial oxygenic<br />

photosynthesis. Nature, 400, 554-557.<br />

m/z 191<br />

m/z 205<br />

56 58 60 62 64 66 68 70 72 74 76 78 80 82 84<br />

Time (m<strong>in</strong>)<br />

Fig. 2. Comparison of mass chromatograms from total lipid extracts (a and b) and pyrolysates (c and d).<br />

Asterisks mark signals of m/z 205 result<strong>in</strong>g from the C31 hopane.<br />

*<br />

*<br />

*<br />

75

76<br />

<strong>ICDP</strong><br />

Effects on magnetization <strong>in</strong> basalts from<br />

fluid-rock <strong>in</strong>teractions <strong>in</strong> volcanic geothermal<br />

systems<br />

A. KONTNY, B. OLIVA URCIA<br />

Geologisches Institut, Strukturgeologie und Tektonophysik,<br />

Universität Karlsruhe, Hertzstrasse 16, 76187 Karlsruhe<br />

Aeromagnetic surveys from geothermal areas <strong>in</strong> hotspot<br />

related volcanic regions <strong>in</strong>dicate a significant decrease<br />

or variation <strong>in</strong> magnetic field strength. One example is the<br />

high-temperature Krafla geothermal field <strong>in</strong> NE Iceland,<br />

situated with<strong>in</strong> the caldera of the Krafla central volcano.<br />

The study of the magnetic properties of volcanic rocks<br />

affected by hydrothermal alteration <strong>in</strong> active geothermal<br />

systems is significant to understand magnetic anomalies<br />

related to MORB and its tectonic implications. Furtheron it<br />

may contribute to our understand<strong>in</strong>g of the complex<br />

dynamic processes act<strong>in</strong>g <strong>in</strong> geothermal systems. Our study<br />

focuses <strong>in</strong> an area where the fluid-rock <strong>in</strong>teractions <strong>in</strong><br />

fissure-related subaerial lavas dim<strong>in</strong>ishes the magnetization<br />

and <strong>in</strong>creases the magnetic susceptibility. The samples that<br />

are shown here were taken from KH-1 (200 m depth) and<br />

KH-3 (400 m depth) drill cores, from the rim of the Krafla<br />

caldera. The magnetic high <strong>in</strong> the area, which was<br />

measured dur<strong>in</strong>g an aeromagnetic survey, (Leo<br />

Kristjánsson, pers.com.) corresponds to the Mt. Krafla, and<br />

the magnetic low co<strong>in</strong>cides with the caldera bottom (where<br />

the Krafla geothermal field is). The standard samples show<br />

low values of NRM (< 5 A/m) but a wide range of<br />

magnetic susceptibility (0.2-140x10-3 SI). The high values<br />

<strong>in</strong> susceptibility suggest a high content <strong>in</strong> ferromagnetic<br />

m<strong>in</strong>erals, while the low values <strong>in</strong> NRM <strong>in</strong>dicate gra<strong>in</strong> sizes<br />

<strong>in</strong> the multidoma<strong>in</strong> range. However, to better understand<br />

this behavior, low temperature magnetic maesurements at<br />

the Institute of Rock Magnetism, M<strong>in</strong>neapolis, USA (Oliva<br />

& Kontny, 2007) and textural observations from the<br />

magnetic phases were done. The magnetic properties allow<br />

to dist<strong>in</strong>guish different degrees of hydrothermal alteration<br />

between the samples. Our f<strong>in</strong>d<strong>in</strong>gs show how effective low<br />

temperature measurements are for prob<strong>in</strong>g the orig<strong>in</strong>s of<br />

differently magnetized basaltic crust.<br />

Due to different processes, the orig<strong>in</strong>al tmt60<br />

(titanomagnetite with an ulvösp<strong>in</strong>el component of 60%;<br />

e.g. Bleil and Petersen, 1982) can oxidize at high and low<br />

temperatures (deuteric oxidation and maghemitization)<br />

produc<strong>in</strong>g a Ti-poor titanomagnetite/maghemite. The<br />

oxidation leads to texture modifications of the primary tmt<br />

gra<strong>in</strong>s (see e.g. Fig. 11 <strong>in</strong> Vahle et al., 2007) and an<br />

<strong>in</strong>crease <strong>in</strong> Curie temperature is expected with <strong>in</strong>creas<strong>in</strong>g<br />

degree of oxidation. However, this Ti-maghemite is not<br />

stable and forms, especially <strong>in</strong> older basalts, an <strong>in</strong>tergrowth<br />

of Ti-poor titanomagnetite and ilmenite (Readman and<br />

O´Reilly, 1972; Moskowitz, 1987). In the very young<br />

basalts from the Icelandic rift zones, different stages of<br />

these reactions can be seen. In most cases the reactions are<br />

not yet completed, but they affect the rock magnetic<br />

properties significantly. For the reactions <strong>in</strong>volv<strong>in</strong>g the<br />

magnetic m<strong>in</strong>erals, fluid composition seems to be critical.<br />

Sulfuric magmatic fluids are able to dissolve the<br />

titanomagnetite/maghemite on expense of pyrite formation,<br />

while more oxidiz<strong>in</strong>g meteoric fluids seem to be more<br />

responsible for the maghemitization. Therefore, the<br />

textures can show different stages but when the alteration is<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

extreme, only relicts of the primary titanomagnetite gra<strong>in</strong><br />

rema<strong>in</strong> (we call it “ghost-textures”) and the magnetization<br />

decreases significantly compared to the orig<strong>in</strong>ally high<br />

values of 10-20 A/m for the young fissure-related basaltic<br />

lava flows from the surface. We were able to dist<strong>in</strong>guish<br />

different degrees of alteration us<strong>in</strong>g -T curves (Fig. 1)<br />

and we further <strong>in</strong>vestigated some samples us<strong>in</strong>g the <strong>in</strong> and<br />

out-of-phase magnetic susceptibility, zero field and field<br />

cooled SIRM and cool<strong>in</strong>g–heat<strong>in</strong>g cycles of room<br />

temperature SIRM <strong>in</strong> the temperature range 10-300 K (Fig.<br />

2).<br />

The <strong>in</strong>vestigated drill cores consist of altered f<strong>in</strong>egra<strong>in</strong>ed<br />

basalts. Plagioclase phenocrysts occur <strong>in</strong> prismatic<br />

shapes with a range of gra<strong>in</strong> sizes vary<strong>in</strong>g from 100-300<br />

m (exceptionally up to 3 mm) and laths of 20-100 m <strong>in</strong><br />

the matrix. Altered pyroxenes can be identified <strong>in</strong> polarized<br />

light. From X-ray diffraction chlorite/smectite, albite,<br />

quartz and zeolite are identified, <strong>in</strong>dicat<strong>in</strong>g a pervasive<br />

alteration for the KH-1 and KH-3 drill cores <strong>in</strong> the chlorite<br />

zone. Chlorite, quartz and calcite have been observed<br />

microscopically <strong>in</strong> vesicules and voids but also <strong>in</strong> the<br />

matrix, where chlorite is associated with sphene and pyrite,<br />

which both form on the expense of the magnetic Fe-Ti<br />

m<strong>in</strong>erals. The total abundance of opaque m<strong>in</strong>erals was<br />

estimated from th<strong>in</strong>-section observations and it varies from<br />

5 to 20% vol. As opaque m<strong>in</strong>erals titanomagnetite,<br />

sulphides, sphene, ilmeno-hematite and rutile were<br />

identified. The textures observed <strong>in</strong> the drill cores <strong>in</strong>dicate<br />

both, slow and quick orig<strong>in</strong>al cool<strong>in</strong>g of the lava with<br />

large, idiomorphic titanomagnetite gra<strong>in</strong>s and small<br />

cruciform and skeletal shapes, respectively (Fig. 2a and d).<br />

Exsolution lamellae due to high-temperature oxidation<br />

occur <strong>in</strong> both cores at different depths. Accord<strong>in</strong>g to<br />

Haggerty (1991) they <strong>in</strong>dicate C3 state of oxidation.<br />

Further oxidation steps can take place <strong>in</strong> a discont<strong>in</strong>uous<br />

manner and at lower temperatures (250-350 °C) dur<strong>in</strong>g the<br />

hydrothermal alteration. The most altered samples are the<br />

ones show<strong>in</strong>g “ghost textures”, very low<br />

NRM/susceptibility and irreversible -T curves (Fig. 1b).<br />

Intermediate stages of alteration are seen <strong>in</strong> gra<strong>in</strong>s with<br />

patchy textures due to the reaction of the titanomagnetite to<br />

other non-magnetic phases (sphene), but titanomaghemite<br />

is still present (Fig. 2a). The oxide gra<strong>in</strong>s often show<br />

cracks due to low-temperature oxidation (maghemitization;<br />

Fig. 2a and d). The cracks form as a result of the decrease<br />

<strong>in</strong> lattice parameters (Petersen and Vali, 1987).<br />

The temperature dependent magnetic susceptibility<br />

curves are used to identify magnetic phases. The Curie<br />

temperature is sensitive to composition and is the<br />

temperature that def<strong>in</strong>es the transition from ferromagnetic<br />

to paramagnetic order<strong>in</strong>g. The degree of reversibility of the<br />

heat<strong>in</strong>g and cool<strong>in</strong>g runs <strong>in</strong> air and <strong>in</strong> argon atmosphere<br />

<strong>in</strong>dicate the stability of the orig<strong>in</strong>al magnetic phases (Vahle<br />

et al., 2007). Surface samples from Krafla show reversible<br />

� � , which <strong>in</strong>dicate very little (if any) lowtemperature<br />

oxidation. On the contrary, all samples but one<br />

from the Krafla drill cores show non-reversible<br />

� � <strong>in</strong>dicat<strong>in</strong>g different degrees of<br />

maghemitization (Fig. 1).<br />

At the Verwey transition (TV) magnetite transforms<br />

from monocl<strong>in</strong>ic to cubic sp<strong>in</strong>el structure. Any deviat<strong>in</strong><br />

from stoichiometry <strong>in</strong> magnetite <strong>in</strong>fluences TV (e.g.<br />

Özdemir and Dunlop, 1993) and only m<strong>in</strong>or Ti-substitution<br />

also supresses TV (Moskowitz et al., 1998). While high-

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

temperature oxidation mostly causes low degrees of<br />

nonstoichiometry (oxidation parameter z less than 0.1),<br />

larger degrees of oxidation can be achieved at low<br />

temperatures, ultimately result<strong>in</strong>g <strong>in</strong> the formation of<br />

maghemite (z=1). For maghemite, TV is supressed. In our<br />

study, we found that the degree of oxidation is higher <strong>in</strong><br />

small (titano)magnetite gra<strong>in</strong>s without previous hightemperature<br />

oxidation (Fig. 2d, e, f) compared to larger<br />

gra<strong>in</strong>s with previous high-temperature oxidation (Fig. 2a,<br />

b, c). Our study shows that the irreversibility of -T curves<br />

<strong>in</strong> the temperature range 77 – 970 K comb<strong>in</strong>ed with TV<br />

observations is a sensitive probe for detect<strong>in</strong>g lowtemperature<br />

oxidation of titanomagnetite/magnetite.<br />

The rock magnetic analyses and texture observations<br />

allows to differentiate a higher degree of alteration <strong>in</strong> KH-1<br />

with respect to KH-3:<br />

Cation-deficient magnetite with Verwey transition and<br />

oxidized titanomagnetite dom<strong>in</strong>ate <strong>in</strong> KH-3 Oxidized<br />

titanomagnetite without Verwey transition dom<strong>in</strong>ates <strong>in</strong><br />

KH-1<br />

Magnetic m<strong>in</strong>eral textures are similar <strong>in</strong> both cores, but<br />

<strong>in</strong> KH-1 the “ghost texture” occurs more often<br />

The higher degree of alteration is seen <strong>in</strong> -T curves <strong>in</strong><br />

the temperature range 77 –970 K and can even better be<br />

characterized by low-temperature experiments<br />

Despite strong alteration, the orientation of NRM<br />

vector follows the expected <strong>in</strong>cl<strong>in</strong>ation (as seen <strong>in</strong> other<br />

studies from basalts).<br />

References:<br />

Bleil, U., and N. Petersen (1982): Magnetic properties of natural m<strong>in</strong>erals,<br />

<strong>in</strong>: Numerical Data and Functional Relationships <strong>in</strong> Science and<br />

Technology, Group V: Geophysics and Space Research, edited by G.<br />

Angenheister. 308– 365, Spr<strong>in</strong>ger, New York.<br />

Haggerty, 1991. Oxide textures- a m<strong>in</strong>i-atlas, <strong>in</strong>: Oxide M<strong>in</strong>erals: Petrologic<br />

and magnetic significance. Ed: D. H. L<strong>in</strong>dsley. M<strong>in</strong>eralogical Society<br />

of America, Reviews <strong>in</strong> m<strong>in</strong>eralogy vol 25: 129-219. Michigan, USA.<br />

Moskowich, B. (1987): Towards resolv<strong>in</strong>g the <strong>in</strong>consistencies <strong>in</strong><br />

characteristic physical properties of synthetic titanomagliemitesLowtemperature<br />

magnetic behavior titanomagnetites. Earth and Planetary<br />

Science Letters, 46: 173-183.<br />

Özdemir, Ö., D.J. Dunlop (1993): The effect of oxidation on the Verwey<br />

transition im magnetite. Geophysical Research Letters, 20, 16, 1671-<br />

1674.<br />

Oliva, B., A. Kontny, (2007): Crustal magnetization and magnetic petrology<br />

from hot-spot related basalts – an approach from low-T magnetic<br />

measurements and magnetic force microscopy. The IRM Quarterly,<br />

117, 13,3-4.<br />

Petersen, N. and Vali, H. (1987): Observation of shr<strong>in</strong>kage cracks <strong>in</strong> ocean<br />

floor titanomagnetite. Physics of Earth and Planetary Interiors, 46, 197-<br />

205.<br />

Readman, P.W. and O´Really, W. (1972): Magnetic properties of oxidized<br />

(cation-deficient) titanomagnetites (Fe, Ti,)3O4. Journal of<br />

Geomagnetism and Geoelectricity, 69-90.<br />

Vahle et al., Kontny, A., Gunnlaugsson, H.P. and Kristjansson, L. (2007):<br />

The Stardalur magnetic anomaly revisited—New <strong>in</strong>sights <strong>in</strong>to a<br />

complex cool<strong>in</strong>g and alteration history. Physics of the Earth and<br />

Planetary Interiors, 164: 119-141.<br />

Acknowledgements:<br />

Fund<strong>in</strong>g for this project comes from DFG grant number: KO 1514/3. V.<br />

Zibat is acknowledged for his support <strong>in</strong> the laboratory for electron<br />

microscopy <strong>in</strong> Karlsruhe. Many thanks to Anja Schleicher for XRD<br />

analyses.<br />

Fig. 1. Characteristic -T curves measured <strong>in</strong> an argon atmosphere for the KH-1 drill cores from the Krafla geothermal field. (a) A weak<br />

expression of the Verwey transition at 110 K, a Curie temperature between 450 and 550°C and a strong irreversibility of the heat<strong>in</strong>g and<br />

cool<strong>in</strong>g curve are <strong>in</strong>dicative of Ti-maghemite. This type or similar types of curves are the most abundant ones. Fig. 2 shows low temperature<br />

measurements for two examples with the same -T curve, but different textures. (b) Paramagnetic behavior at low temperature, a Curie<br />

temperature at about 580 °C and the formation of pyrrhotite from pyrite (py) <strong>in</strong> the cool<strong>in</strong>g curve is typical for samples with ghost-textures<br />

(see <strong>in</strong>lay).<br />

77

78<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 2. Low temperature measurements of two samples with -T curves as it is shown <strong>in</strong> Fig. 1a. (a) and (d) BSE images show<strong>in</strong>g the<br />

different textures of titanomaghemites. NRM and for sample KH-3-380.4 is 2.1 A/m and 135x 10-3 SI and for sample KH-1-68.9 it<br />

is 0.1 A/m and 0.85 x 10-3 SI. For Fig. 2a textures, (b) frequency-dependent out of phase susceptibility measured between10 and 300 K<br />

show a Verwey transition at 110 K. The decrease by 10 K is due to Ti substitution and cation-deficiency. For Fig. 2b textures, the<br />

Verwey transition is not clear but a decrease of susceptibility between 150 and 50 K is observed, due to a higher degree of vacancies.<br />

Field cooled (FZ) and zero field cooled (ZFC) SIRM shows a complex behavior with two phases, an ilmeohematite and<br />

titanomaghemite phase. The irreversible behavior of the heat<strong>in</strong>g and cool<strong>in</strong>g run for room temperature SIRM <strong>in</strong>dicates multidoma<strong>in</strong><br />

behavior of the magnetic gra<strong>in</strong>s, which is <strong>in</strong> accordance with microscopic observations.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Deep Biosphere Quantification <strong>in</strong><br />

Chesapeake Bay Impact Structure Sediments<br />

GERRIT KÖWEKER, ANNA BLAZEJAK AND AXEL SCHIPPERS<br />

Bundesanstalt für Geowissenschaften und Rohstoffe (BGR),<br />

Referat Geomikrobiologie, Stilleweg 2, 30655 <strong>Hannover</strong><br />

The Chesapeake Bay Impact Structure (CBIS) is one of<br />

the world’s largest crater formation caused by a meteor<br />

crash<strong>in</strong>g to the late Eocene ocean shelf on today’s Virg<strong>in</strong>ia<br />

(VA) coastal l<strong>in</strong>e. One objective of the CBIS project is to<br />

study the abundance and vitality of microorganisms with<br />

the aim to understand the <strong>in</strong>fluence of the impact scenario<br />

and its consequences on the biosphere. The BGR subproject<br />

studies exclusively the deep biosphere of the postimpact<br />

sediments while all other microbiologists of the<br />

CBIS deep biosphere team focus on the impact sediment<br />

and breccia layers. In May/June 2006, biological samples<br />

were taken from the <strong>in</strong>ner crater zone <strong>in</strong> Eyreville (VA)<br />

from the upper 140 m of the 444 m thick post-impact<br />

sediment zone. For contam<strong>in</strong>ation control fluorescent beads<br />

of bacterial size were used. Samples were checked for the<br />

abundance and vitality of microorganisms by SybrGreen<br />

direct count<strong>in</strong>g and catalyzed reporter deposition –<br />

fluorescence <strong>in</strong> situ hybridization (CARD-FISH). In<br />

addition, DNA was extracted from deep-frozen material for<br />

quantification analysis of microbial genes us<strong>in</strong>g real-time<br />

PCR (Q-PCR) target<strong>in</strong>g 16S or 18S rDNA gene as<br />

phylogenetic marker and functional genes (mcrA, dsrA) as<br />

physiological markers. Microorganisms could be found<br />

throughout all depths. Total cell numbers decreased from<br />

109 to 106 cells per g dry weight (dw) with<strong>in</strong> the first five<br />

meters of depth. Up to 100 meters depth, cell numbers<br />

slowly decreased to about 105 cells per g dw. Below that<br />

po<strong>in</strong>t, cell numbers slightly <strong>in</strong>creased aga<strong>in</strong>. Due to the<br />

relative low cell numbers different cell detachment<br />

protocols were tested for better statistics and compared to<br />

the standard protocol for total cell numbers. The general<br />

depth trend of total cell numbers could be confirmed<br />

although overall lower cell numbers were obta<strong>in</strong>ed by<br />

us<strong>in</strong>g detachment protocols. CARD-FISH data suggested<br />

that only a very small fraction of the cells, both Bacteria<br />

and Archaea, were active. Bacterial cell numbers calculated<br />

from the Q-PCR data mostly ranged <strong>in</strong> the same order of<br />

magnitude than the total cell numbers. Archaea were<br />

equally abundant <strong>in</strong> the top 5 m but scarcely detectable <strong>in</strong><br />

deeper layers us<strong>in</strong>g Q-PCR. Eukaryotic 18 rDNA was<br />

detected up to 50 m depth. So far, there was no evidence<br />

for sulfate-reducers <strong>in</strong> the samples as there couldn´t be<br />

found any copies of the dsrA gene. The copy number for<br />

mcrA, a key gene <strong>in</strong>volved <strong>in</strong> methanogenesis, was also<br />

under the detection limit. In the uppermost section,<br />

Geobacteriacae were found. This bacterial family is known<br />

for Fe(III)-and Mn(IV)-reduction. Geochemical data also<br />

revealed a potential for microbial Fe(III)-reduction <strong>in</strong> these<br />

layers as reactive iron species could be detected. Overall,<br />

the post-impact sediments of Chesapeake Bay are more<br />

densely colonized by microorganisms than the impact<br />

sediment and breccia layers <strong>in</strong> greater depth.<br />

<strong>ICDP</strong><br />

Evolutionary, Geological, and Environmental<br />

History of Lake Ohrid (EGEL):<br />

A new <strong>ICDP</strong> <strong>in</strong>itiative<br />

S. KRASTEL 1 , B. WAGNER 2 , K. REICHERTER 3 , G. DAUT 4 , M.<br />

WESSELS 5 , T. WILKE 6<br />

1<br />

Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR),<br />

Kiel, skrastel@ifm-geomar.de<br />

2<br />

Institut für Geologie und M<strong>in</strong>eralogie, Universität zu Köln<br />

3<br />

Neotektonik und Georisiken, RWTH Aachen<br />

4<br />

Institut für Geographie der Friedrich Schiller Universität Jena<br />

5<br />

Institut für Seenforschung; Langenargen<br />

6<br />

Tierökologie und Spezielle Zoologie, Justus-Liebig-Universität<br />

Giessen<br />

The Balkan Lake Ohrid at the Macedonian/Albanian<br />

border is likely the oldest cont<strong>in</strong>uously exist<strong>in</strong>g lake <strong>in</strong><br />

Europe and was tectonically formed probably dur<strong>in</strong>g the<br />

Tertiary. The exact age of the formation of the lake, total<br />

accumulated sediment thickness, and the structural context<br />

are not known. The proposed cont<strong>in</strong>uous existence s<strong>in</strong>ce<br />

the Tertiary, however, makes Lake Ohrid an excellent<br />

archive of environmental changes <strong>in</strong> the central northern<br />

Mediterranean region. Because of its geographic position<br />

and its presumed old age, Lake Ohrid represents an<br />

important l<strong>in</strong>k between climatic and environmental records<br />

from the Mediterranean Sea and the adjacent cont<strong>in</strong>ents.<br />

Moreover, with more than 200 endemic species, the lake is<br />

a unique aquatic ecosystem of worldwide importance. This<br />

importance was emphasized, when the lake was declared<br />

UNESCO World Heritage Site <strong>in</strong> 1979, and <strong>in</strong>cluded as a<br />

target area of the International Cont<strong>in</strong>ental Scientific<br />

Drill<strong>in</strong>g Program (<strong>ICDP</strong>) already <strong>in</strong> 1993. Based on<br />

numerous sedimentological, biological, and first<br />

geophysical <strong>in</strong>vestigations an <strong>in</strong>ternational group of<br />

scientists submitted an <strong>ICDP</strong>-workshop proposal <strong>in</strong><br />

January <strong>2008</strong>.<br />

Prelim<strong>in</strong>ary DNA work and molecular clock analyses<br />

of endemic faunal elements <strong>in</strong>dicate that the vast majority<br />

of biodiversity <strong>in</strong> Lake Ohrid evolved <strong>in</strong>tralacustr<strong>in</strong>e and<br />

that the evolutionary effective age of most taxa (i.e., the<br />

age s<strong>in</strong>ce when these groups cont<strong>in</strong>uously existed <strong>in</strong> Lake<br />

Ohrid) lies between 2 and 3 Ma. This suggested age would<br />

also set the temporal framework for the proposed <strong>ICDP</strong><br />

campaign (also see the contribution of Wilke et al. dur<strong>in</strong>g<br />

this colloquium).<br />

Extant sedimentary records from Lake Ohrid were<br />

recovered dur<strong>in</strong>g field campaigns <strong>in</strong> 1973 and, more<br />

recently, between 2001 and 2007. These records cover,<br />

except for some short hiatuses, the past glacial/<strong>in</strong>terglacial<br />

cycle and reveal that Lake Ohrid is a valuable archive of<br />

volcanic ash dispersal and climate change <strong>in</strong> the central<br />

northern Mediterranean region. However, with respect to<br />

the extraord<strong>in</strong>ary high endemism <strong>in</strong> the lake, these records<br />

are too short to provide <strong>in</strong>formation about the age and<br />

orig<strong>in</strong> of the lake and to unravel the mechanisms<br />

controll<strong>in</strong>g the evolutionary development.<br />

A first shallow seismic survey was carried out <strong>in</strong> spr<strong>in</strong>g<br />

2004 us<strong>in</strong>g a high-resolution parametric sediment<br />

echosounder. Penetration was strongly dependent on<br />

lithological and physical properties and reaches up to 50 m.<br />

The high-resolution hydroacoustic profiles of Lake Ohrid<br />

demonstrate well the <strong>in</strong>terplay between sedimentation and<br />

active tectonics. Due to relatively constant sedimentation<br />

rates the tectonic block movements can be reconstructed<br />

79

80<br />

ma<strong>in</strong>ly along normal faults on the E and W coast of the<br />

lake. Multiple sets of normal faults have their impr<strong>in</strong>t on<br />

the structural style of the lake borders, partly with roll over<br />

anticl<strong>in</strong>es or back-tilted halfgrabens.<br />

A multichannel seismic pilot study was carried out <strong>in</strong><br />

September 2007. Four days were used for survey<strong>in</strong>g the<br />

Macedonian part of the lake with a M<strong>in</strong>i-GI-Gun (0.25l) as<br />

source and a 100 m 16- channel streamer for receiv<strong>in</strong>g the<br />

acoustic energy. In total we shot 17 profiles with a total<br />

length of ~150 km, which impressively prove the potential<br />

of Lake Ohrid for an <strong>ICDP</strong> drill<strong>in</strong>g. The lacustr<strong>in</strong>e slope<br />

areas show very complex structures <strong>in</strong>clud<strong>in</strong>g heavily<br />

faulted areas, numerous slides, and foresets. In contrast,<br />

undisturbed sedimentary sequences are imaged <strong>in</strong> the<br />

central bas<strong>in</strong>. The basement - though partly overla<strong>in</strong> by<br />

multiples - is clearly visible on the seismic profile. The<br />

maximal sediment thickness reaches ~720 ms TWT<br />

correspond<strong>in</strong>g to ~570 m us<strong>in</strong>g an average sound velocity<br />

of 1600 m/s. No unconformities or erosional features are<br />

found <strong>in</strong> this part of the lake <strong>in</strong>dicat<strong>in</strong>g that this sequence is<br />

complete. Fund<strong>in</strong>g by the Deutsche<br />

Forschungsgeme<strong>in</strong>schaft for a systematic seismic pre-site<br />

survey of and structural work around Lake Ohrid just<br />

started. Field work is scheduled for summers <strong>2008</strong> and<br />

2009.<br />

<strong>IODP</strong><br />

Helium, neon and argon isotope systematics<br />

of the Hawaiian hotspot<br />

T. KRÜSMANN, S. NIEDERMANN, N.A. STRONCIK, J. ERZINGER<br />

GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473<br />

Potsdam, Germany<br />

Noble gases, especially helium, are used as tracers for<br />

mantle reservoirs, based on the assumption that high<br />

3 He/ 4 He ratios (>8 RA, where R A is the atmospheric<br />

3 He/ 4 He ratio of 1.39×10 –6 ) represent material from the<br />

deep, supposedly less degassed mantle whereas lower<br />

ratios with<strong>in</strong> the MORB range (~ 8 RA) are thought to<br />

represent the upper mantle. In this study we determ<strong>in</strong>ed the<br />

noble gas systematics of samples from several Hawaiian<br />

volcanoes. The studied volcanoes <strong>in</strong>clude Mauna Kea,<br />

from which we ma<strong>in</strong>ly <strong>in</strong>vestigated drill core samples from<br />

the Hawaii Scientific Drill<strong>in</strong>g Project (HSDP), Mauna Loa,<br />

Kilauea and Kohala (all located on the Island of Hawaii) as<br />

well as Haleakala, Maui. He ratios from this study show a<br />

variation from 7-18 RA. It is known that OIBs show a wide<br />

range of He ratios, from MORB-like values up to as much<br />

as 35 R A. A few samples of this study show elevated<br />

20 Ne/ 22 Ne and 21 Ne/ 22 Ne ratios with respect to the<br />

atmospheric value, up to 11.14±0.49 and 0.0365±0.0062,<br />

respectively, thereby support<strong>in</strong>g the theory of a partly less<br />

degassed source region for the Hawaiian hotspot with<br />

solar-like He and Ne isotopic compositions deep <strong>in</strong> the<br />

mantle. When us<strong>in</strong>g Ne as a tracer for a less degassed<br />

source of the Hawaiian mantle plume, one has to be aware<br />

that atmospheric contam<strong>in</strong>ation is a severe problem. By the<br />

technique of stepwise heat<strong>in</strong>g however, this problem can<br />

partly be circumvented. 40 Ar/ 36 Ar ratios are predom<strong>in</strong>antly<br />

close to the atmospheric value of 296, but a few samples<br />

show higher values up to 3790.<br />

Follow<strong>in</strong>g the approach of Honda et al. (1993), the<br />

expected He isotopic composition can be calculated from a<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

given Ne isotopic composition. Calculated He ratios for<br />

samples of this study, however, do not correlate well with<br />

the measured He ratios. This feature can be expla<strong>in</strong>ed by a<br />

preferential loss of He from the magma source. Calculated<br />

4 He/ 40 Ar * , 3 He/ 22 Nes and 4 He/ 21 Ne * ratios for the sample<br />

suite (where * denotes radiogenic and nucleogenic<br />

components and S means the primordial “solar”<br />

component) are lower than the respective production and<br />

primordial ratios, support<strong>in</strong>g a preferential loss of He.<br />

20 Ne/ 22 Ne<br />

13.0<br />

12.0<br />

11.0<br />

10.0<br />

Air<br />

Solar<br />

Loihi-Kilauea l<strong>in</strong>e<br />

0.03 0.04 0.05 0.06<br />

21Ne/ 22Ne The figure shows a neon three-isotope plot for oliv<strong>in</strong>e<br />

phenocrysts from Mauna Loa, Mauna Kea, and Kilauea<br />

volcanoes studied <strong>in</strong> this work. The MORB and Loihi-<br />

Kilauea correlation l<strong>in</strong>es, respectively, are mix<strong>in</strong>g l<strong>in</strong>es<br />

between atmospheric Ne and Ne components typical for<br />

the MORB and Hawaiian plume source, respectively.<br />

Despite large uncerta<strong>in</strong>ties (2σ), it is evident that Ne data<br />

plot along the Loihi-Kilauea l<strong>in</strong>e despite He isotope ratios<br />

partly with<strong>in</strong> the MORB range. The solar Ne composition<br />

is shown for reference.<br />

References:<br />

M. Honda, I. McDougall, D. Patterson (1993) Solar noble gases <strong>in</strong> the Earth;<br />

the systematics of helium-neon isotopes <strong>in</strong> mantle derived samples,<br />

Lithos 30, 257–265.<br />

<strong>IODP</strong><br />

Middle Miocene changes <strong>in</strong> the Southern<br />

Ocean deep-water carbonate chemistry<br />

H. KUHNERT 1 , T. BICKERT1, 2<br />

MORB<br />

l<strong>in</strong>e<br />

Mauna Loa<br />

Mauna Kea<br />

Kilauea<br />

1<br />

Universität Bremen, Forschungszentrum Ozeanränder, 28359<br />

Bremen<br />

2<br />

Universität Bremen, MARUM, 28359 Bremen<br />

hkuhnert@uni-bremen.de<br />

The middle Miocene cool<strong>in</strong>g was one of the most<br />

prom<strong>in</strong>ent climate shifts dur<strong>in</strong>g the Neogene, expressed <strong>in</strong><br />

the drastic decrease of global temperatures and the<br />

expansion of the East Antarctic Ice Sheet. While the<br />

general picture of the cool<strong>in</strong>g is well-known, the role of the<br />

mar<strong>in</strong>e carbonate system and atmospheric CO2 are not fully<br />

understood. Global anomalies <strong>in</strong> mar<strong>in</strong>e stable carbon<br />

isotopes ("Monterey carbon isotope excursion") precede<br />

and partially accompany the cool<strong>in</strong>g. These anomalies have<br />

been <strong>in</strong>terpreted to reflect periods of massive organic<br />

carbon burial (V<strong>in</strong>cent and Berger, 1985) and/or <strong>in</strong>creased<br />

cont<strong>in</strong>ental weather<strong>in</strong>g (Raymo, 1994), where both

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

mechanisms draw down atmospheric CO 2, <strong>in</strong> l<strong>in</strong>e with<br />

pCO2 reconstructions (Pagani et al., 1999, 2005). The<br />

<strong>in</strong>creas<strong>in</strong>g ventilation of <strong>in</strong>termediate water masses <strong>in</strong> the<br />

Southern Ocean has been proposed as an additional factor<br />

<strong>in</strong> chang<strong>in</strong>g the state of the global carbon cycle dur<strong>in</strong>g the<br />

middle Miocene (Shevenell et al., 2004). We want to<br />

<strong>in</strong>vestigate the mutual <strong>in</strong>fluences of pCO2, hydrographic<br />

changes, and the state of the oceanic carbonate system by<br />

reconstruct<strong>in</strong>g the carbonate ion saturation (Δ[CO32-]) and<br />

alkal<strong>in</strong>ity of the Southern Ocean deep-water.<br />

We use Ba/Ca and B/Ca from benthic foram<strong>in</strong>ifera<br />

from ODP site 1092 (46.4°S, 7.1°E, Atlantic sector of the<br />

Southern Ocean) to <strong>in</strong>fer past ocean alkal<strong>in</strong>ity and Δ[CO3 2-<br />

], respectively. Initial data cover<strong>in</strong>g the time from 14.2 to<br />

13 Ma (<strong>in</strong>clud<strong>in</strong>g the Mi 3 and CM 6 events) show a<br />

general correlation between alkal<strong>in</strong>ity and δ 13 C. Alkal<strong>in</strong>ity<br />

<strong>in</strong>creases dur<strong>in</strong>g Mi 3 (~13.9 Ma), the most prom<strong>in</strong>ent<br />

<strong>in</strong>terval of cool<strong>in</strong>g and/or ice sheet expansion. A<br />

cont<strong>in</strong>uous decrease commences at 13.6 Ma. The<br />

magnitude of change (up to 100 µEq/kg) cannot be<br />

expla<strong>in</strong>ed by the exchange of the local water mass. Dur<strong>in</strong>g<br />

the middle Miocene cool<strong>in</strong>g NADW was largely absent<br />

(Wright and Miller, 1996) reduc<strong>in</strong>g the potential alkal<strong>in</strong>ity<br />

contrast. Furthermore, chang<strong>in</strong>g water masses would lead<br />

to a negative correlation between Δ[CO3 2- ] and alkal<strong>in</strong>ity,<br />

which is not present <strong>in</strong> our data. This suggests that<br />

alkal<strong>in</strong>ity at Site 1092 reflects global changes <strong>in</strong> the carbon<br />

cycle and is potentially causal <strong>in</strong> driv<strong>in</strong>g atmospheric pCO2<br />

variations.<br />

Future work will <strong>in</strong>clude the extension of the proxy<br />

record back <strong>in</strong> time to cover the transition to the Miocene<br />

climatic optimum, and the analysis of Pacific sites.<br />

References:<br />

Pagani, M., Arthur, M. A., and Freeman, K. H., 1999. Miocene evolution of<br />

atmospheric carbon dioxide. Paleoceanography 14, 273-292.<br />

Pagani, M., Zachos, J. C., Freeman, K. H., Tipple, B., and Bohaty, S., 2005.<br />

Marked decl<strong>in</strong>e <strong>in</strong> atmospheric carbon dioxide concentrations dur<strong>in</strong>g<br />

the Paleogene. Science 309, 600-603.<br />

Raymo, M. E., 1994. The Himalayas, organic carbon burial, and climate <strong>in</strong><br />

the Miocene. Paleoceanography 9, 399-404.<br />

Shevenell, A. E., Kennett, J. P., and Lea, D. W., 2004. Middle Miocene<br />

Southern Ocean cool<strong>in</strong>g and Antarctic cryosphere expansion. Science<br />

305, 1766-1770.<br />

V<strong>in</strong>cent, E. and Berger, W. H., 1985. Carbon dioxide and polar cool<strong>in</strong>g <strong>in</strong><br />

the Miocene: The Monterey hypothesis. In: Sundquist, E. T. and<br />

Broecker, W. S. Eds.), The carbon cycle and atmospheric CO2: Natural<br />

variations Archean to present. AGU, Wash<strong>in</strong>gton, pp. 455-468.<br />

Wright, J. D. and Miller, K. G., 1996. Control of North Atlantic Deep Water<br />

circulation by the Greenland-Scotland Ridge. Paleoceanography 11,<br />

157-170.<br />

<strong>IODP</strong><br />

Cenozoic trends <strong>in</strong> size and silica use <strong>in</strong> low<br />

and high latitude radiolarian faunas:<br />

evidence for co-evolution between diatoms<br />

and radiolarians and <strong>in</strong>creas<strong>in</strong>g competition<br />

for dissolved biogenic silicia<br />

DAVID LAZARUS (1), BEN KOTRC (2), GERWIN WULF (3) AND<br />

DANIELA N. SCHMIDT (4)<br />

1-Museum f. Naturkunde, Invalidenstrasse 43, 10115 Berl<strong>in</strong>,<br />

Germany<br />

2-Botanical Museum, Harvard University, 26 Oxford street,<br />

Cambridge, MA 02138 USA<br />

3-Bauernreihe 62b, 21709 Burweg, Germany<br />

4-Department of Earth Sciences, University of Bristol, Queens<br />

Road, Bristol, BS8 1RJ UK<br />

Harper and Knoll (1975) proposed that a Cenozoic<br />

trend towards lower shell weights <strong>in</strong> radiolaria documented<br />

by Moore (1969) reflected selective pressure to use less<br />

silica, due to <strong>in</strong>creas<strong>in</strong>g removal of dissolved silica <strong>in</strong><br />

ocean water <strong>in</strong> the Cenozoic caused by the evolutionary<br />

rise of mar<strong>in</strong>e diatoms. More recently, Schmidt (2004) and<br />

F<strong>in</strong>kel et al. (2005, 2007) have documented Cenozoic<br />

changes <strong>in</strong> mean size <strong>in</strong> planktonic foram<strong>in</strong>ifera, diatoms<br />

and d<strong>in</strong>oflagellates. These authors attribute size change <strong>in</strong><br />

these groups <strong>in</strong>stead to other factors, such as <strong>in</strong>creas<strong>in</strong>g<br />

water column stratification. Moore’s data for radiolarians<br />

could thus reflect (water stratification driven) size change,<br />

diatom evolution driven change <strong>in</strong> silica efficiency, or<br />

both.<br />

To <strong>in</strong>vestigate which mechanism(s) are most likely<br />

responsible for Cenozoic trends <strong>in</strong> radiolarian shell weight,<br />

we have measured both size and silica use/unit cell volume<br />

<strong>in</strong> series of Ceonozic radiolarian populations from both low<br />

and high latitudes. Modern low latitude surface waters<br />

often have extremely low concentrations of dissolved silica<br />

due to efficient removal by planktonic diatoms. In high<br />

latitude oceans by contrast, deep mix<strong>in</strong>g renews nutrients<br />

and surface water silica is often not fully removed by<br />

plankton growth, suggest<strong>in</strong>g that <strong>in</strong> high latitudes, silica<br />

availability driven changes <strong>in</strong> radiolarian faunas should<br />

also be reduced. Our results are based on >5000<br />

specimens, taken from 26 low latitude samples rang<strong>in</strong>g<br />

from 61 to 0 Ma from the Indian, Pacific and Atlantic<br />

Oceans, and 9 samples rang<strong>in</strong>g from 60 to 1 Ma from the<br />

Southern Ocean. The Berl<strong>in</strong> radiolarian MRC provided<br />

many of the slides used <strong>in</strong> our study. All samples were<br />

controlled for dissolution of shells which can bias results.<br />

Length, width; shell porosity and thickness were measured<br />

for each specimen when possible. Simple geometric<br />

models were used to calculate cell volume and silica<br />

use/unit volume for the two ma<strong>in</strong> groups of fossil<br />

radiolarians (Spumellaria -spheres, Nassellaria-cones).<br />

Our results show a clear unidirectional trend towards<br />

greater silica efficiency <strong>in</strong> low latitude radiolarian faunas<br />

over the Cenozoic, with however a significant shift<br />

occurr<strong>in</strong>g near the Eocene-Oligocene boundary. High<br />

latitude radiolarian faunas by contrast show only a m<strong>in</strong>imal<br />

trend towards greater silica efficiency. Size shows no net<br />

change <strong>in</strong> radiolarian faunas over the Cenozoic and the one<br />

major feature ( a peak <strong>in</strong> the Early-Mid Eocene) is not<br />

correlated to size change records of other groups. These<br />

results support the hypothesis of Harper and Knoll that<br />

removal (by diatoms) of silica from Cenozoic oceans has<br />

<strong>in</strong>fluenced the evolution of radiolarians, driv<strong>in</strong>g a trend<br />

towards <strong>in</strong>creased efficiency <strong>in</strong> the use of silica <strong>in</strong><br />

radiolarian shells.<br />

<strong>IODP</strong><br />

Early Paleogene deep-water overturn<strong>in</strong>g <strong>in</strong><br />

the South Atlantic (EPASA) - A progress<br />

report -<br />

D.C. LEUSCHNER 1<br />

1 Universität Leipzig, Institut für Geophysik und Geologie,<br />

Talstraße 35, 04103 Leipzig<br />

The aim of the EPASA project is to reconstruct the<br />

circulation of deep- and bottom-water masses <strong>in</strong> the eastern<br />

South Atlantic dur<strong>in</strong>g the Cenozoic us<strong>in</strong>g gra<strong>in</strong> size and<br />

81

82<br />

clay m<strong>in</strong>eralogical studies of sediments from the Walvis<br />

Ridge (Leg 208). Particular attention is laid on the nature<br />

and behavior of the deep-water masses dur<strong>in</strong>g extreme<br />

climatic situations and on their response to abrupt<br />

environmental and climatic changes <strong>in</strong> the late Paleocene<br />

to early Eocene. This time <strong>in</strong>terval is characterized by short<br />

climatic excursions overrid<strong>in</strong>g a long-term warm<strong>in</strong>g trend.<br />

These short last<strong>in</strong>g climatic extremes had a significant<br />

impact on the oceans, e.g. a rapid acidification of the ocean<br />

dur<strong>in</strong>g the Paleocene/Eocene Thermal Maximum (PETM;<br />

Zachos et al., 2005). This change <strong>in</strong> the ocean waters<br />

chemistry is associated with a massive shoal<strong>in</strong>g of the<br />

calcite compensation depth (CCD) of more than 2000 m <strong>in</strong><br />

the Walvis Ridge region (Kroon et al., 2007). A<br />

comparable but less pronounced perturbation is accociated<br />

with the Early Eocene Thermal Maximum 2 (ETM2; also<br />

known as ELMO event; Lourens et al., 2005; Sluijs et al.,<br />

2007), which was first described dur<strong>in</strong>g Leg 208. The<br />

Paleogene sediments recovered dur<strong>in</strong>g ODP Leg 208 at<br />

Walvis Ridge allow detailed reconstructions of the tim<strong>in</strong>g<br />

and <strong>in</strong>tensity of such perturbations and the result<strong>in</strong>g<br />

reorganization of the deep- and bottom water masses over a<br />

paleodepth range of more than 2000 m.<br />

In our study we comb<strong>in</strong>e sedimentological and clay<br />

m<strong>in</strong>eralogical data and is carried out <strong>in</strong> two phases. First, a<br />

lower resolution study performed on sediments tfrom the<br />

Sites 1265 and 1267 <strong>in</strong> order to reconstruct the long-term<br />

trend <strong>in</strong> the development <strong>in</strong> the oceanic circulation. This<br />

provides the background <strong>in</strong>formation on the changes<br />

associated with the transition from an <strong>in</strong>termediate<br />

Paleogene climate to the Eocene greenhouse, the<br />

subsequent cool<strong>in</strong>g <strong>in</strong>to the Oligocene ice-house and<br />

Miocene cool<strong>in</strong>g events. The knowledge of the long-term<br />

processes is crucial to evaluate the significance of the<br />

extreme climatic events <strong>in</strong> the early Paleogene. For this<br />

purpose a total number of 415 samples were taken and<br />

processed (separation of gra<strong>in</strong> size fractions, sample<br />

preparation of the clay fraction and XRD analysis). Some<br />

results from Site 1265 are shown <strong>in</strong> Fig. 2.<br />

In the second Phase, higher resolution studies of the<br />

late Paleocene to the early Eocene <strong>in</strong>terval were performed<br />

at five Sites (1262, 1267, 1266, 1265 and 1263) spann<strong>in</strong>g<br />

the whole depth range of the Leg 208 transect. Standard<br />

sampl<strong>in</strong>g resolution was one sample per 50 cm. The<br />

sampl<strong>in</strong>g resolution was <strong>in</strong>creased across critical <strong>in</strong>tervals<br />

(PETM, ETM2) <strong>in</strong> order to resolve these events. The total<br />

amount of samples processed <strong>in</strong> this <strong>in</strong>vestigation is about<br />

880. So far the sampl<strong>in</strong>g for this part of the project has<br />

been carried out on four sites. All of these sample sets<br />

already passed the laboratory preparation process and XRD<br />

measurements were completely performed on the entire<br />

sample sets from sites 1265, 1266 and 1267 cover<strong>in</strong>g a<br />

water depth range of almost 1300m <strong>in</strong> the central part of<br />

the depth transect.<br />

Both, Site 1265 and 1266 (Fig. 3) clay m<strong>in</strong>eral records<br />

show that illite and smectite are the major components of<br />

the terrigenous clay fraction, form<strong>in</strong>g almost a twocomponent<br />

system dur<strong>in</strong>g the entire Cenozoic record at site<br />

1265. Therefore, the records of the two m<strong>in</strong>erals show an<br />

oppos<strong>in</strong>g trend. Kaol<strong>in</strong>ite and chlorite are almost absent <strong>in</strong><br />

the late Paleocene to early Eocene. These m<strong>in</strong>erals start to<br />

become abundant at the end of the early Eocene to the<br />

middle Eocene, with an <strong>in</strong>creas<strong>in</strong>g and persistent trend<br />

throughout the younger Paleogene and Neogene.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Associated with the <strong>in</strong>crease <strong>in</strong> kaol<strong>in</strong>ite and chlorite a<br />

m<strong>in</strong>imum abundance of illite and a maximum abundance of<br />

smectite can be observed. These changes <strong>in</strong> sediment<br />

composition at the end of the early Eocene likely reflect the<br />

most severe changes <strong>in</strong> oceanic circulation at the northern<br />

Walvis Ridge dur<strong>in</strong>g the studied period. A change <strong>in</strong><br />

oceanic currents is probably associated with the <strong>in</strong>cise of a<br />

channel structure <strong>in</strong> he study area across the Walvis Ridge<br />

start<strong>in</strong>g to develop between 50 and 40 mio. years ago<br />

(Bartels et al., 2007). Surpris<strong>in</strong>gly, the warm period at the<br />

end of the Paleocene <strong>in</strong>to the Early Eocene Climatic<br />

Optimum (EECO) is characterized by a broad maximum <strong>in</strong><br />

illite abundance and low smectite values. The abundance of<br />

smectite than beg<strong>in</strong>s to rise with the transition <strong>in</strong>to cooler<br />

climates of the late Paleogene. The nature of such<br />

developments and detailed <strong>in</strong>vestigations on the short and<br />

abrupt events that are overrid<strong>in</strong>g these long-term trends are<br />

subject to the ongo<strong>in</strong>g <strong>in</strong>vestigation.<br />

References:<br />

Bartels, T., Krastel, S., and Spiess, V., 2007. Correlation of High-Resolution<br />

Seismic Data with ODP Leg 208 Borehole Measurements. In Kroon,<br />

D., Zachos, J.C., and Richter, C. (Eds.), Proc.ODP, Sci. Results, 208:<br />

College Station, TX.<br />

Kroon, D., Zachos, J.C., and Leg 208 Scientific Party, 2007. Leg 208<br />

Synthesis: Cenozoic Climate Cycles and Excursions. In Kroon, D.,<br />

Zachos, J.C., and Richter, C. (Eds.), Proc.ODP, Sci. Results, 208:<br />

College Station, TX.<br />

Lourens, L.J., Sluijs, A., Kroon, D., Zachos, J.C., Thomas, E., Röhl, U.,<br />

Bowles, J., and Raffi, I., 2005. Astronomical pac<strong>in</strong>g of the late<br />

Palaeocene to early Eocene global warm<strong>in</strong>g events, Nature, 435: 1083-<br />

1087.<br />

Sluijs, A., Br<strong>in</strong>khuis, H., Schouten, S., Bohaty, S.M., John, C.M., Zachos,<br />

J.C., S<strong>in</strong>n<strong>in</strong>ghe Damsté, J.S., Crouch, E.M., and Dickens, G.R., 2007.<br />

Environmental precursors to rapid light carbon <strong>in</strong>jection at the<br />

Paleocene/Eocene boundary, Nature, 450: 1218-1221.<br />

Zachos, J.C., Röhl, U., Schellenberg, S.A., Sluijs, A., Hodell, D.A., Kelly,<br />

D.C., Thomas, E., Nicolo, M., Raffi, I., Lourens, L.J., McCarren, H.,<br />

and Kroon, D., 2005. Rapid Acidification of the Ocean dur<strong>in</strong>g the<br />

Paleocene-Eocene Thermal Maximum, Science, 308: 1611-1615.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1: Core sites and sampl<strong>in</strong>g strategy carried out <strong>in</strong> the EPASA project<br />

83

84<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 2: Clay m<strong>in</strong>eralogy of core 1265 (3060 m water depth, 28°50.10’S, 2.38.35’E). Core recovery at Site 1265, relative<br />

abundance of illite, smectite, kaol<strong>in</strong>ite and chlorite <strong>in</strong> the terrigenous clay size fraction, lithostratigraphic units,<br />

chronostratigraphic units.<br />

Fig. 3: Clay m<strong>in</strong>eralogy of core 1266 (3798 m water depth, 28°32.55’S, 2.20.61’E). Core recovery at Site 1266, relative abundance<br />

of illite, smectite, kaol<strong>in</strong>ite and chlorite <strong>in</strong> the terrigenous clay size fraction, lithostratigraphic units, chronostratigraphic units.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Distribution of Prokaryotic Biomass <strong>in</strong> the<br />

Deep Biosphere<br />

JULIUS S. LIPP 1 , YUKI MORONO 2 , FUMIO INAGAKI 2 & KAI-UWE<br />

HINRICHS 1<br />

1 Organic Geochemistry Group, Department of Geosciences and<br />

Research Center Ocean Marg<strong>in</strong>s (RCOM), University of<br />

Bremen, PO Box 330 440, 28334 Bremen, Germany<br />

2 Geomicrobiology Group, Kochi Institute for Core Sample<br />

Research, Japan Agency for Mar<strong>in</strong>e-Earth Science and<br />

Technology (JAMSTEC), Monobe B200, Nankoku, Kochi<br />

783-8502, Japan<br />

The deep biosphere conta<strong>in</strong>s up to one third of the total<br />

carbon <strong>in</strong> live cells of our planet (Parkes et al., 2000;<br />

Whitman et al., 1998). This vast ecosystem has become<br />

the research focus of microbiologists and geochemists to<br />

address key questions like: What types of microbes thrive<br />

<strong>in</strong> deeply buried sediments? And, what are the processes<br />

they are mediat<strong>in</strong>g? Recent studies have provided<br />

<strong>in</strong>formation on metabolic activities and quantities of deeply<br />

buried prokaryotic cells (e.g. Biddle et al., 2006; Inagaki et<br />

al., 2006), while fundamental questions regard<strong>in</strong>g the<br />

taxonomic composition rema<strong>in</strong> unresolved. For example,<br />

various techniques appear to disagree already at the doma<strong>in</strong><br />

level on who actually dom<strong>in</strong>ates this ecosystem. Molecular<br />

biological methods like catalyzed reporter deposition -<br />

fluorescent <strong>in</strong> situ hybridization (CARD-FISH) and<br />

quantitative polymerase cha<strong>in</strong> reaction (Q-PCR) suggest a<br />

predom<strong>in</strong>ance of bacterial over archaeal cells (Schippers et<br />

al., 2005; Inagaki et al., 2006). On the other hand FISH<br />

and <strong>in</strong>tact polar lipids (IPL) suggest a predom<strong>in</strong>ance of<br />

archaea among live prokaryotes (Biddle et al., 2006).<br />

We analyzed IPLs, a marker for live prokaryotic cells<br />

<strong>in</strong> a set of sediment samples from a depth range of 0.01 to<br />

367 mbsf from sites <strong>in</strong> the Black Sea, Nankai Trough, Peru<br />

marg<strong>in</strong>, Cascadia Marg<strong>in</strong>, Demerara Rise, and Equatorial<br />

Pacific (RV Logatchev TTR15, RV Kairei KY04-11, RV<br />

Sonne SO147, ODP Legs 201, 204, 207, and <strong>IODP</strong><br />

Expeditions 301 and 311). The observed IPL<br />

concentrations cover more than three orders of magnitude<br />

from 4 to 16,000 ng mL-1 sediment and display a similar<br />

concentration-depth relationship as observed <strong>in</strong> a global<br />

compilation of direct counts of active cells (cf. Parkes et<br />

al., 2000). Surface sediments are clearly dom<strong>in</strong>ated by<br />

bacterial IPLs with possible admixtures of eukaryotic<br />

lipids. The major bacterial IPLs identified comprise<br />

phosphatidylglycerol (PG), phosphatidylethanolam<strong>in</strong>e<br />

(PE), and phosphatidylchol<strong>in</strong>e (PC) diacylglycerides with<br />

C16 and C18 acyl groups. The major archaeal lipids are<br />

mono- and diglycosidic derivatives of archaeol and<br />

glyceroldibiphytanylglyceroltetraether (GDGT) lipids.<br />

Concentrations of bacterial lipids decl<strong>in</strong>e rapidly with<strong>in</strong> the<br />

first 10 cmbsf to levels significantly lower than those of<br />

their archaeal counterparts. In deeply buried horizons,<br />

diglycosyl GDGTs are dom<strong>in</strong>ant and lipid distributions are<br />

less diverse than <strong>in</strong> surface sediments.<br />

The sedimentary IPLs can be used as a proxy for the<br />

quantity of live microbial biomass <strong>in</strong> subsurface<br />

environments. We observed a double logarithmic<br />

relationship between concentrations of IPLs and total<br />

organic carbon (TOC), extend<strong>in</strong>g over more than two and<br />

four orders of magnitude <strong>in</strong> TOC and IPL concentration,<br />

respectively, and testify<strong>in</strong>g to the heterotrophic nature of<br />

the subsurface ecosystem. The relationship further<br />

<strong>in</strong>dicates that the quantity of fossil organic matter is an<br />

important controll<strong>in</strong>g factor for the amount of prokaryotic<br />

biomass and can be used to derive an estimate of the global<br />

<strong>in</strong>ventory of biomass <strong>in</strong> mar<strong>in</strong>e subsurface sediments from<br />

well constra<strong>in</strong>ed concentrations of TOC. We estimate an<br />

amount of 8 Pg IPL <strong>in</strong> habitable subsurface sediments,<br />

which can be converted <strong>in</strong>to 95 to 114 Pg carbon units <strong>in</strong><br />

prokaryotic biomass.<br />

Improved protocols of DNA extraction and<br />

purification, and modified quantification protocols of slotblot<br />

hybridization and quantitative polymerase cha<strong>in</strong><br />

reaction (Q-PCR) of samples from the Peru Marg<strong>in</strong> (ODP<br />

Leg 201) and the Juan de Fuca Ridge Flank (<strong>IODP</strong><br />

Expedition 301) support the lipid-based results and <strong>in</strong>dicate<br />

that previous molecular biology-based analyses of similar<br />

and identical samples largely underestimated archaeal<br />

biomass.<br />

Our comb<strong>in</strong>ed evidence suggests a vast ecosystem, <strong>in</strong><br />

which Archaea contribute a major fraction to the stand<strong>in</strong>g<br />

stock of biomass. In comb<strong>in</strong>ation with estimates of the<br />

relative contributions of the two prokaryotic doma<strong>in</strong>s to<br />

water column biomass (Karner et al., 2001), our data imply<br />

that <strong>in</strong> the mar<strong>in</strong>e realm, Archaea are more abundant than<br />

Bacteria.<br />

References:<br />

Biddle J.F., Lipp J.S., Lever M.A., Lloyd K.G., Sørensen K.B., Anderson<br />

R., Fredricks H.F., Elvert M., Kelly T.J., Schrag D.P., Sog<strong>in</strong> M.L.,<br />

Brenchley J.E., Teske A., House C.H., and H<strong>in</strong>richs K.-U. (2006).<br />

Heterotrophic Archaea dom<strong>in</strong>ate sedimentary subsurface ecosystems<br />

off Peru. Proc. Natl. Acad. Sci.USA 103, 3846-3851.<br />

Inagaki F., Nunoura T., Nakagawa S., Teske A., Lever M.A., Lauer A.,<br />

Suzuki M., Takai K., Delwiche M., Colwell F.S., Nealson K.H.,<br />

Horikoshi K., D’Hondt S., and Jørgensen B.B. (2006). Biogeographical<br />

distribution and diversity of microbes <strong>in</strong> methane hydrate-bear<strong>in</strong>g deep<br />

mar<strong>in</strong>e sediments on the Pacific Ocean Marg<strong>in</strong>. Proc. Natl. Acad.<br />

Sci.USA 103, 2815-2820.<br />

Karner, M.B., DeLong, E.F., Karl, D.M. (2001). Archaeal dom<strong>in</strong>ance <strong>in</strong> the<br />

mesopelagic zone of the Pacific Ocean. Nature 409, 507-510.<br />

Parkes R.J., Cragg B.A., and Wellsbury P. (2000). Recent studies on<br />

bacterial populations and processes <strong>in</strong> subseafloor sediments: A review.<br />

Hydrogeol. J. 8, 11-28.<br />

Schippers, A., Neret<strong>in</strong>, L.N., Kallmeyer, J., Ferdelman, T.G., Cragg, B.A.,<br />

Parkes, R.J., Jørgensen, B.B., 2005. Prokaryotic cells of the deep subseafloor<br />

biosphere identified as liv<strong>in</strong>g bacteria. Nature 433, 861-864.<br />

Whitman W.B., Coleman D.C., and Wiebe W.J. (1998). Prokaryotes: The<br />

unseen majority. Proc. Natl. Acad. Sci.USA 95, 6578-6583.<br />

<strong>ICDP</strong><br />

Direct observation of blast<strong>in</strong>g triggered<br />

geogas transport through an <strong>in</strong>active fault<br />

system at 3.6km depth, Tautona gold m<strong>in</strong>e,<br />

SA<br />

J. LIPPMANN-PIPKE 1,2 , J. ERZINGER 2 , M. ZIMMER 2 , C. KUJAWA 2 , E.<br />

VAN HEERDEN 3 , A. BESTER 3 , H. MOLLER 4 , M. BOETTCHER 5 , Z.<br />

RECHES 6<br />

1 Institute of Interdiscipl<strong>in</strong>ary Isotope Research (IIF), Leipzig,<br />

Germany (lippmann@iif-leipzig.de)<br />

2 GeoForschungsZentrum Potsdam (GFZ), Germany<br />

3 University of the Free State (UFS), Bloemfonte<strong>in</strong>, South Africa<br />

4 Tautona Gold M<strong>in</strong>e, Charletonville, South Africa<br />

5 United Stated Geological Survey (USGS), Menlo Park, CA,<br />

United States of America<br />

6 Oklahoma University, United States of America<br />

A highly sensitive gas monitor<strong>in</strong>g device enables the<br />

direct observation of blast<strong>in</strong>g triggered geogas transport<br />

from fluid reservoirs <strong>in</strong>to a dry borehole that crosses<br />

85

86<br />

through the <strong>in</strong>active Pretorious Fault System at 3.6km<br />

depth, Tautona gold m<strong>in</strong>e, South Africa (DAFGAS 1 ). The<br />

sensitivity of our experimental set-up allows to observe the<br />

geogas transport through open fractures triggered by the<br />

daily blast<strong>in</strong>g operations <strong>in</strong> nearby stopes. Beside this<br />

sensitivity to gas compositional changes <strong>in</strong> the borehole,<br />

the analytical system, <strong>in</strong>clud<strong>in</strong>g a mass specetometer, is<br />

relative sophisticated and suffers under the harsh<br />

environment undergound. A series of technical problems<br />

caused long last<strong>in</strong>g data gaps <strong>in</strong> the time series and,<br />

therefore, made us miss just all of the m<strong>in</strong><strong>in</strong>g <strong>in</strong>duced<br />

seismic events dur<strong>in</strong>g the last 12 month. Still, we are<br />

encouraged to carry on with the gas monitor<strong>in</strong>g <strong>in</strong> this<br />

deepest produc<strong>in</strong>g m<strong>in</strong>e on earth <strong>in</strong> order to f<strong>in</strong>ally<br />

accomplish our orig<strong>in</strong>al goal: the monitor<strong>in</strong>g and<br />

quantification of gases released dur<strong>in</strong>g m<strong>in</strong><strong>in</strong>g <strong>in</strong>duced<br />

seismic events at magnitudes from –2 to above +2.<br />

At first, the composition of the major gas components<br />

<strong>in</strong> the borehole (N2, O2, 40Ar) is, expectedly, similar to<br />

that of the atmosphere. The trace concentrations of CH4,<br />

4He, CO2 and 222Rn cont<strong>in</strong>uously decl<strong>in</strong>ed <strong>in</strong> the course<br />

of the monitor<strong>in</strong>g experiment from <strong>in</strong>ital concentrations of<br />

about 900, 40, 3 and 18 times atmosperic levels,<br />

respectively.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Displayed is a time series for the period March 26th through April 1st, 2007. The measured concentration of H2 <strong>in</strong> the borehole gas<br />

(vol.%) (wiggled data with clear peaks, left axis) is jo<strong>in</strong>tly displayed with the cumulative moment release (Nm) from the nearest<br />

seismic station (step-function like graph, right axis,). The correlation of the tim<strong>in</strong>g of the events is strik<strong>in</strong>g and clearly identifies the<br />

blasts as the trigger for the spontaneous daily <strong>in</strong>crease of the H2 concentration <strong>in</strong> the borehole. Unfortunately, the seismic system<br />

did stop deliver<strong>in</strong>g data on Thursday, March 29th. On Sundays, no blast<strong>in</strong>g operations are performed. This is <strong>in</strong> agreement with the<br />

miss<strong>in</strong>g H2 peak on Sumday, April 1st, 2007.<br />

1<br />

DAFGAS: Drill<strong>in</strong>g Active Faults <strong>in</strong> South African M<strong>in</strong>es, DFG-<br />

<strong>ICDP</strong> funded project (Li872/3)<br />

We assume that the observed lower geogas concentrations<br />

after some weeks represent dynamic equilibrium<br />

concentrations caused by the cont<strong>in</strong>uous pump<strong>in</strong>g of gas<br />

(6 L per hour) from the borehole <strong>in</strong>to our analytical device<br />

and cont<strong>in</strong>uous recharge at the same rate (6 L per hour).<br />

This recharged gas is <strong>in</strong>terpreted to be a mixture that of air<br />

and geogas from the formation. The equilibrium<br />

concentrations of the trace gases <strong>in</strong> the borehole amount to<br />

about 640 ppm CO2, 190 ppm CH4, 60 ppm H2 and 18<br />

ppm 4He (weekly average of the week follow<strong>in</strong>g March,<br />

23rd, 2007).<br />

The particular sensitivity of our monitor<strong>in</strong>g devices to<br />

blast<strong>in</strong>g triggered geogas transport through an otherwise<br />

<strong>in</strong>active fault system is explicitely attestable by the<br />

significant correlation between CO2 and H2 peaks that<br />

show up simultaneously to the seismic signal measured at a<br />

nearby seismic station (≤ 4 m apart) <strong>in</strong>stalled and<br />

ma<strong>in</strong>ta<strong>in</strong>ed by the NELSAM 2 team. The strong correlation<br />

between the daily H2 peaks and the cumulative seismic<br />

moment release (Nm) is shown <strong>in</strong> the figure below.<br />

2 NELSAM: Natural Earthquake Laboratory <strong>in</strong> South African<br />

M<strong>in</strong>es, NSF-funded project (EAR0

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

231 Pa/ 230 Th from Atlantic Ocean sediments - a<br />

proxy for deep water circulation over the past<br />

30,000 years<br />

J. LIPPOLD 1 , M. CHRISTL 2 , A. HOFMANN 1 , F. BERNSDORFF 1 , Y.<br />

LAHAYE 3 , J. GRÜTZNER 4 , G. MOLLENHAUER 4 , A. MANGINI 1<br />

1<br />

Heidelberger Akademie der Wissenschaften, Heidelberg<br />

2<br />

Institute of Particle Physics, Laboratory of Ion Beam Physics,<br />

ETH Zurich<br />

3<br />

Institut für Geowissenschaften, Universität Frankfurt<br />

4<br />

Institut für Geowissenschaften, Universität Bremen<br />

231 Pa and 230 Th are produced at a constant activity rate<br />

of 0.093 <strong>in</strong> Ocean water. However, the 231 Pa/ 230 Th ratio<br />

recorded <strong>in</strong> Atlantic sediments is subject to temporal and<br />

spatial variations. Recently, 231 Pa/ 230 Th has been used as a<br />

proxy for the strength of the Atlantic meridional<br />

overturn<strong>in</strong>g (AMOC) and recent studies suggest that times<br />

of shifted 231 Pa/ 230 Th ratios are related with prom<strong>in</strong>ent<br />

cool<strong>in</strong>g or warm<strong>in</strong>g events support<strong>in</strong>g the conclusion that<br />

variations <strong>in</strong> the AMOC may <strong>in</strong>cite climate changes<br />

[McManus et al., 2004].<br />

However, there are still significant gaps <strong>in</strong> our<br />

understand<strong>in</strong>g of this proxy. In particular the impact of<br />

changes <strong>in</strong> particle flux and particle composition<br />

significantly alters the sedimentary 231 Pa/ 230 Th ratio<br />

limit<strong>in</strong>g the applicability of 231 Pa/ 230 Th as a proxy for the<br />

strength of the AMOC [Siddall et al., 2007] [Keigw<strong>in</strong> and<br />

Boyle, <strong>2008</strong>].<br />

For example, The relevance of the large upwell<strong>in</strong>g regions<br />

off North- and Southwest Africa as an additional s<strong>in</strong>k for<br />

231 Pa is not well understood, and the impact of boundary<br />

scaveng<strong>in</strong>g on the Atlantic 231 Pa/ 230 Th ratio is still a great<br />

matter of discussion. In response to a weaker AMOC, 231 Pa<br />

would reside longer <strong>in</strong> the ocean bas<strong>in</strong> and thus could be<br />

more efficiently trapped <strong>in</strong> the upwell<strong>in</strong>g regions. To<br />

approach this question we are measur<strong>in</strong>g sedimentary<br />

231 Pa/ 230 Th profiles from the open North- (ODP 983),<br />

West- (ODP 1063) and South-(ODP 1089) Atlantic Ocean.<br />

These records will be compared with those from three sites<br />

located at the West-African marg<strong>in</strong>s (GeoB 1711-4, GeoB<br />

3722-2 and GeoB 9508-5).<br />

Here we present first results from the ODP cores<br />

represent<strong>in</strong>g a North South transect across the open<br />

Atlantic Ocean. The 231 Pa data is obta<strong>in</strong>ed by ICP-MS and<br />

AMS, which to the first time was applied to measure 231 Pa<br />

[Christl et al., 2007].<br />

References:<br />

Christl, M., L. Wacker, J. Lippold and M. Suter (2007). "Protact<strong>in</strong>ium-231,<br />

a new radionuclide for AMS." NIM B 262.<br />

Keigw<strong>in</strong>, L. D. and E. A. Boyle (<strong>2008</strong>). "Did north Atlantic overturn<strong>in</strong>g halt<br />

17,000 years ago?" Paleoceanography <strong>in</strong> press.<br />

McManus, J. F., R. Francois, J. M. Gherardi, L. D. Keigw<strong>in</strong> and S. Brown-<br />

Leger (2004). "Collapse and rapid resumption of Atlantic meridional<br />

circulation l<strong>in</strong>ked to deglacial climate change." Nature 428.<br />

Siddall, M., T. F. Stocker, G. M. Henderson, F. Joos, M. Frank, N. R.<br />

Edwards, S. P. Ritz and S. A. Müller (2007). "Modell<strong>in</strong>g the<br />

relationship between 231Pa/230Th distribution <strong>in</strong> North Atlantic<br />

sediment and Atlantic meridional overturn<strong>in</strong>g circulation."<br />

Paleoceanography 22.<br />

231 Pa/ 230 Th at three ODP Sites 983 (Gardar Drift), 1063 (Bermuda Rise, compared to GGC5) and 1089 (Cape Bas<strong>in</strong>). ODP 1089 shows only low<br />

variability at low 231 Pa/ 230 Th levels dur<strong>in</strong>g the last 30 kyrs caused by Antarctic Pa-depleted waters prevail<strong>in</strong>g this location. In contrast ODP<br />

1063 (as do GGC5) displays <strong>in</strong>creased 231 Pa/ 230 Th dur<strong>in</strong>g He<strong>in</strong>rich-Stadials po<strong>in</strong>t<strong>in</strong>g at a weakened AMOC [McManus et al., 2004] or <strong>in</strong>creased<br />

<strong>in</strong>put of Si-rich southern waters [Keigw<strong>in</strong> and Boyle, <strong>2008</strong>]. Whereas ODP 983 <strong>in</strong>dicates high 231 Pa import dur<strong>in</strong>g the Holocene.<br />

87

88<br />

<strong>ICDP</strong><br />

Environmental response to volcanic and<br />

climatic events <strong>in</strong> NE Anatolia dur<strong>in</strong>g the last<br />

20,000 years based on annually lam<strong>in</strong>ated<br />

sediments from Lake Van<br />

T. LITT 1 , G. HEUMANN 1 , H-U. SCHMINCKE 2 , M. SUMITA 2<br />

1<br />

Paleontology, University of Bonn, Nussallee 8, 53115 Bonn<br />

2<br />

IFM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel<br />

Tephra layers drilled <strong>in</strong> 400 m-deep Lake Van<br />

(Anatolia) <strong>in</strong> 2004 have been studied structurally,<br />

texturally and compositionally for correlation between drill<br />

sites and with volcanic deposits on land<br />

(Schm<strong>in</strong>cke/Sumita). Analysis of equivalent deposits on<br />

the historically active caldera volcano Nemrut, the major<br />

supplier of tephra, will allow reconstruct<strong>in</strong>g larger volcanic<br />

events (Pl<strong>in</strong>ian fallout, pyroclastic flows and flank<br />

collapses), magma evolution and environmental impacts<br />

such as tsunamis. High-resolution pollen analyses based on<br />

the annually lam<strong>in</strong>ated lacustr<strong>in</strong>e sediments should reflect<br />

the impact of volcanic events on paleoenvironment<br />

(Litt/Heumann). The comparison between volcanic and<br />

climatically <strong>in</strong>duced vegetation changes will be analyzed.<br />

The goals of the paleoecological part of the project fall<br />

<strong>in</strong>to 3 major categories:<br />

Environmental impact of volcanic events <strong>in</strong> the lake<br />

Van region based on high-resolution pollen analysis;<br />

Environmental impact of climatic events especially<br />

dur<strong>in</strong>g the Weichselian Lateglacial based on highresolution<br />

pollen analysis;<br />

Comparison of both effects on vegetation with respect<br />

to rate of change, reaction and regeneration.<br />

Short-term effects of volcanic eruptions on vegetation<br />

can only be traced with a very f<strong>in</strong>e stratigraphical<br />

resolution. The lake Van records with their annually<br />

lam<strong>in</strong>ated lacustr<strong>in</strong>e sediments provide an extremely high<br />

time resolution. Thus, the sediment sequence with the<br />

<strong>in</strong>tercalated volcanic ash layers is an excellent archive for<br />

such an approach. However, episodic tephra <strong>in</strong>put from<br />

adjacent volcanoes <strong>in</strong>to Lake Van took place also dur<strong>in</strong>g<br />

the climatically <strong>in</strong>stable Lateglacial, which encompasses<br />

the time span between the Last Glacial Maximum and the<br />

Holocene (ca. 14,500 – 11,500 cal BP). Therefore,<br />

observed changes <strong>in</strong> pollen assemblages may have been<br />

also the result of Lateglacial climatic changes. The<br />

question on how cont<strong>in</strong>ental ecosystems, as reflected <strong>in</strong> the<br />

pollen record of lake Van, respond to high-amplitude and<br />

high-frequency climate changes dur<strong>in</strong>g the Lateglacial, will<br />

be answered based on event stratigraphy (biotic responses<br />

to the isotopic shifts). An additional aim of the proposed<br />

project is to extend the correlation and synchronization of<br />

Lateglacial sediment profiles from Europe towards the<br />

Near East <strong>in</strong>clud<strong>in</strong>g the varved sediments from Lake Van.<br />

Based on our ongo<strong>in</strong>g pollen analyses we have<br />

substantially <strong>in</strong>creased the sample resolution for the<br />

Lateglacial sequence and especially for the basal and top<br />

contacts of the tephra layers. Before the deposition of a<br />

tephra layer each sample conta<strong>in</strong> a known number of<br />

annual layers, usually c. 20 varves whereas after a tephra<br />

deposition each sample <strong>in</strong>cludes a known time span of c. 5-<br />

10 varves, because recent studies of the environment<br />

follow<strong>in</strong>g the Mt. St. Helens eruption on May 18, 1980,<br />

have shown that the affected vegetation outside the actual<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

blast zone recovers rapidly with<strong>in</strong> years. Additional<br />

sampl<strong>in</strong>g is required for the stable isotopes to obta<strong>in</strong> the<br />

same resolution as the pollen samples for the Lateglacial<br />

sequence.<br />

<strong>IODP</strong><br />

A Neogene Stratigraphic and<br />

Paleoenvironmental Transect across the<br />

Fram Strait (Arctic Ocean)<br />

MICHAEL SCHRECK, JENS MATTHIESSEN<br />

Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research (AWI),<br />

Am Alten Hafen 26, D-27568 Bremerhaven, Germany<br />

(Jens.Matthiessen@awi.de /Fax +49-47148311923 / Phone +49-<br />

471-4831-1568)<br />

(Michael.Schreck@awi.de /Fax +49-47148311923 /Phone +49-<br />

471-4831-1232)<br />

Despite sucessfully drill<strong>in</strong>g Neogene sediments dur<strong>in</strong>g<br />

ODP Legs 151 and 162 and <strong>IODP</strong> Expedition 302, the<br />

Neogene paleoenvironmental evolution <strong>in</strong> the cold water<br />

doma<strong>in</strong> of the Atlantic sector of the high northern latitudes<br />

is virtually unknown. This is partly due to a problematic<br />

chronostratigraphy of the largely biogenic carbonate and<br />

silica free hemipelagic sediments. Initial shipboard and<br />

shore-based studies have shown that organic-walled<br />

palynomorphs (d<strong>in</strong>oflagellate cysts, chlorophytes,<br />

acritarchs etc.) are a useful microfossil group but a<br />

consistent palynostratigraphy for high latitude sediments is<br />

still not available. To overcome this obstacle, a transect<br />

from the seasonally-ice covered Nordic Seas to the<br />

perennial ice-covered Arctic Ocean, consist<strong>in</strong>g of Sites<br />

907, 909, and M2A, is studied to calibrate<br />

palynostratigraphic datums versus magnetostratigraphy and<br />

apply this data on paleoenvironmental reconstructions for<br />

the period between ~16 and 3 Ma years. Numerous<br />

potentially valuable palynomorph datums have been<br />

identified but comparison with occurrences at other high<br />

latitude sites is presently hampered by taxonomically<br />

problematic taxa and an <strong>in</strong>consistent stratigraphic<br />

framework of ODP holes from the Atlantic sector of the<br />

high northern latitudes. A number of taxa must be restudied<br />

and age models of ODP holes must be revised and adjusted<br />

to ATNTS2004 before palynomorph datums can be<br />

calibrated and a comprehensive and consistent zonation for<br />

the polar doma<strong>in</strong>s can be established. These specific<br />

problems of high latitude palynostratigraphy are illustrated<br />

by describ<strong>in</strong>g the biogeographic and stratigraphic<br />

distribution of a number of palynomorph taxa and by<br />

discuss<strong>in</strong>g the implications of revised datums for high<br />

latitude chronostratigraphy.<br />

<strong>ICDP</strong><br />

Formation and characteristics of impact<br />

glasses - the Lake Bosumtwi and Chesapeake<br />

cases<br />

S. LUETKE 1 , A. DEUTSCH 1 , F. LANGENHORST 2 , R. SKALA 2<br />

1 Institut f. Planetologie, WWU Münster, Wilhelm-Klemm-Str. 10,<br />

D-48149 Münster; deutsca@uni-muenster.de<br />

2 Institut f. Geowissenschaften, FSU Jena, D-07749 Jena;<br />

falko.langenhorst@uni-jena.de<br />

Introduction: Various types of m<strong>in</strong>eral and rock melts<br />

orig<strong>in</strong>ate <strong>in</strong> crater<strong>in</strong>g events. Their orig<strong>in</strong> is still not

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

understood <strong>in</strong> detail despite <strong>in</strong>tense geochemical<br />

<strong>in</strong>vestigations and model<strong>in</strong>g attempts [1]. Glassy material<br />

(and their alteration products) may occur <strong>in</strong> different<br />

geological sett<strong>in</strong>gs <strong>in</strong> and around impact craters. In general,<br />

their composition reflects (i) the target composition, and<br />

(ii) the formation processes. This term <strong>in</strong>cludes orig<strong>in</strong> by<br />

melt<strong>in</strong>g or condensation after vaporization, peak<br />

temperatures, redox conditions, and variable cool<strong>in</strong>g rates.<br />

The Lake Bosumtwi crater, Ghana, W. Africa, as well<br />

as the buried Chesapeake Bay impact structure, VA,<br />

U.S.A., represent model cases for the <strong>in</strong>vestigation of the<br />

different impact-related melt lithologies: • Bosumtwi (age<br />

1.07 Ma, diameter D ~10 km) is the source crater for Ivory<br />

Coast (IVC) tektites and related microtektites, the fall-out<br />

suevites carry glass fragments, and the <strong>ICDP</strong> drill<strong>in</strong>g<br />

revealed a nearly unique cm-thick layer of glassy fall-back<br />

particles on top of the impact breccias [2-4]. • Chesapeake<br />

(late Eocene ~35 Ma, D <strong>in</strong>ner crater ~40 km, D brim ~80<br />

km [5]) is source of the North American tektite strewn<br />

field, and the Eyreville core of the <strong>ICDP</strong>-USGS drill<strong>in</strong>g<br />

project yielded <strong>in</strong> part glass-rich suevites <strong>in</strong> the depth<br />

<strong>in</strong>terval 1397 to 1474 m, and a variety of possible precursor<br />

rocks (granite, schist, pegmatite, mafics) <strong>in</strong> the lithic<br />

breccias below and above this layer [6]. Here we present<br />

results of a systematic geochemical and m<strong>in</strong>eralogical<br />

study of the different glasses.<br />

• Bosumtwi. Regard<strong>in</strong>g major and trace elements, tektites<br />

have a quite restricted, microtektites and fallback particles,<br />

and especially glass shards <strong>in</strong> the suevites a wider<br />

compositional range. These characteristics reflect <strong>in</strong> part<br />

the different precursor materials, for example Al-rich<br />

staurolith schists for some glass particles <strong>in</strong> the suevites.<br />

Other variations, e.g., <strong>in</strong> sodium content, may <strong>in</strong>dicate loss<br />

of more volatile elements related to the formation<br />

processes (Figure 1). A significant contribution of the up to<br />

25 m thick tropical soil layer to the IVC tektites – as<br />

requested by model<strong>in</strong>g - is evident from Sr-Nd systematics<br />

[7]. All glass types display similar REE patterns (Figure 2),<br />

which <strong>in</strong> turn compare well with the REE distribution <strong>in</strong><br />

phyllites-slates (the major precursor lithology [4]), while<br />

meta-graywackes, another important rock type <strong>in</strong> the target<br />

have lower REE contents. The IVC tektites are<br />

characterized by particularly high concentrations of the<br />

refractory elements Ba, Zr, and Nb.<br />

Figure 1. Alum<strong>in</strong>um and sodium vs.<br />

SiO2 <strong>in</strong> glassy materials that orig<strong>in</strong>ated<br />

<strong>in</strong> the Bosumtwi impact event.<br />

Analytical technique: JEOL JXA<br />

8900M Superprobe operat<strong>in</strong>g at 15 kV<br />

acceleration voltage, 5 nA sample<br />

current, and 5 µm defoc. beam, us<strong>in</strong>g a<br />

Moldavite tektite as <strong>in</strong>ternal standard.<br />

Figure 2. Average REE distribution patterns, normalized to the average upper cont<strong>in</strong>al crust (data by [8]), for (left) IVC tektites,<br />

microtektites, fallback particles, and target rocks (meta-graywackes and phyllites-slates) from <strong>ICDP</strong> drill core LB-08, and (right)<br />

three Bediasites (= belong to the North American tektite strewn field) specimen. The nearly complete overlap of the data reflects the<br />

high degree of homogeneity <strong>in</strong> this tektite group. Analytical technique: Element2 LA-ICP-MS (5Hz, 8-9J/cm2; Inst. f. M<strong>in</strong>eralogie,<br />

WWU Münster) us<strong>in</strong>g Si as <strong>in</strong>ternal, and NIST 612 as external standard. For tektites, 3 spots (ø 60 µm), and for microtektites and<br />

fallback particles 1 spot (ø 35 µm) per sample were measured.<br />

89

90<br />

Chesapeake. Suevite glasses show large chemical<br />

heterogeneity at the µm scale, <strong>in</strong>dicat<strong>in</strong>g <strong>in</strong>complete<br />

mix<strong>in</strong>g dur<strong>in</strong>g melt<strong>in</strong>g of precursor rocks. In addition,<br />

totals on the order of 92-97 wt.% <strong>in</strong>dicate the onset of<br />

hydratisation although the glass is isotropic on the scale of<br />

the optical microscope. Crystallization of pyroxene and<br />

feldspar microliths occurs rather frequently <strong>in</strong> the<br />

schlieren-rich glass (Figure 3a).<br />

MgO (wt. %)<br />

5<br />

4<br />

3<br />

2<br />

1<br />

0<br />

mafic component?<br />

schist<br />

Bediasites<br />

pegmatite<br />

20 40 60 80 100 120<br />

SiO 2 (wt. %)<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Chemical variations <strong>in</strong> the glasses from suevites can be<br />

largely expla<strong>in</strong>ed by variations <strong>in</strong> the analysed target rocks<br />

(schist, granite, pegmatite), but an additional mafic<br />

component is required as precursor material (Figure 3b-d)<br />

to expla<strong>in</strong> Mg-Ti-rich and Si-poor glasses. The Bediasites<br />

(North American tektites), <strong>in</strong> contrast, are very<br />

homogeneous – <strong>in</strong>ternally as well as the whole group, as<br />

illustrated <strong>in</strong> Figure 2 for REE, and <strong>in</strong> Figures 3b-d for<br />

major elements.<br />

40<br />

30<br />

20<br />

SiO 2<br />

50<br />

50<br />

0 10 20 30 40 50<br />

a<br />

CaO + MgO<br />

Al2O3 + FeO<br />

b<br />

TiO 2 (wt. %)<br />

8<br />

6<br />

4<br />

2<br />

0<br />

10<br />

0<br />

schist<br />

100<br />

20 40 60 80 100 120<br />

SiO 2 (wt. %)<br />

c d<br />

90<br />

80<br />

70<br />

Ti-rich<br />

component<br />

Bediasites<br />

pegmatite<br />

Figure 3. Glassy material that orig<strong>in</strong>ated <strong>in</strong> the Chesapeake impact event. (a) Schlieren-rich glass particle with crystallites and<br />

partly hydrated areas, suevite ADE 38 CB depth 1428 m; // nicols. (b-d) Geochemical correlation diagrams <strong>in</strong> wt.% for Bediasites<br />

(red) and various glasses <strong>in</strong> suevites from core Eyreville B; XRF Philips PW 2400 and EMP Cameca SX50 data.<br />

60

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

The formation temperature of melts that now form the glass<br />

particles <strong>in</strong> the suevites, exceeded <strong>in</strong> some cases 1850°C<br />

(melt<strong>in</strong>g T of rutile) as examplified by the presence of<br />

m<strong>in</strong>ute titania phases that crystallized from melt (Figure 4).<br />

These high-temperature estimates for impact glasses are<br />

also <strong>in</strong> accordance with the occurrence of corroded zircons<br />

on impact melt melt breccias of the <strong>ICDP</strong> Chicxulub drill<br />

core YAX-1 [9].<br />

50 µm<br />

bubbles<br />

burst<br />

26 ppm H2O<br />

FeO<br />

#4<br />

#5<br />

#6 pseudo-<br />

#7 brookite<br />

#12<br />

ilmenite<br />

ulvösp<strong>in</strong>el<br />

860 ppm H2O<br />

TiO 2<br />

rutile<br />

magnetite<br />

Figure 4. Titanium-rich phases <strong>in</strong> suevitic glasses (left) back scatter electron image of sample FSU-CB012 depth 1407 m perlitic<br />

cracks; and (right) ternary diagram show<strong>in</strong>g the composition of titanium phases <strong>in</strong> suevitic glasses from Eyreville B.<br />

decomposition<br />

of carbonates<br />

Figure 5. Bediasite (left) H2O release at high T; suevite glass (center) H2O, and (right) CO and CO2 release. The tektite is<br />

exceptional dry, requir<strong>in</strong>g flash heat<strong>in</strong>g to extreme temperature. The glass fragment <strong>in</strong> the suevite didn’t loose all volatiles<br />

<strong>in</strong>dicat<strong>in</strong>g a lower formation temperature. Analytical technique: Direct coupled Evolved Gas Analysis System (DEGAS,<br />

FSU Jena), a comb<strong>in</strong>ation of thermogravimetry and quadrupole mass spectrometry with stepwise heat<strong>in</strong>g of samples up to<br />

1500°C, allow<strong>in</strong>g simultaneous detection of 28 masses between m/z = 1 to 200.<br />

CO 2<br />

release<br />

from<br />

glass<br />

91<br />

Fe 2 O 3

92<br />

The formation temperature of tektites is considered to be<br />

even higher. This case is strengthened by the new gas<br />

release data for Bediasites (Figure 5) and IVC tektites. The<br />

H2O and CO 2 contents <strong>in</strong> Bediasites (20-30 ppm H 2O) are<br />

dist<strong>in</strong>ctly lower than those of fresh suevitic glass (0.1 wt.%<br />

H2O); moreover, this H 2O content <strong>in</strong> Bediasites is 1 order<br />

of magnitude less than previously reported. Bediasite<br />

releases gases at much higher T than suevite glass,<br />

<strong>in</strong>dicat<strong>in</strong>g a different type of bond<strong>in</strong>g. In addition,<br />

Bediasites conta<strong>in</strong> reduced gas species (e.g., CO). These<br />

results match closely those reported by [10] for Bosumtwi<br />

related glasses, namely glass shards <strong>in</strong> suevites and IVC<br />

tektites. The glass shards are relatively rich <strong>in</strong> volatile<br />

components: The ~3 % wt.% H2O are released ma<strong>in</strong>ly <strong>in</strong><br />

the low temperature (< 300 °C) regime from clay m<strong>in</strong>erals<br />

which l<strong>in</strong>e bubbles, and which hence, can not be<br />

considered as glass alteration product. In addition, these<br />

glasses contaion CO2 (0.28 %) and SOx. The IVC tektites<br />

are like Bediasites extremely depleted <strong>in</strong> gases; they<br />

conta<strong>in</strong> only H 2O (~100 ppm), CO 2 and CO (<strong>in</strong> higher<br />

conc. than CO2) <strong>in</strong> trace amounts. The detection of CO <strong>in</strong><br />

Bediasites and IVC tektites is the first report of this gas<br />

species <strong>in</strong> tektites.<br />

The presence of CO, the total lack of ferric iron, and<br />

the extremely low volatile content underl<strong>in</strong>e the conclusion<br />

that tektites are formed at very high temperatures under<br />

highly reduc<strong>in</strong>g conditions followed by fast quench<strong>in</strong>g.<br />

Chemical homogeneity probably reflect more the<br />

melt/ejection process than homogeneity of the precursor<br />

materials. The compositional variance of glass shards <strong>in</strong> the<br />

suevites obviously is a corollary of heterogeneities <strong>in</strong> the<br />

target. Melt<strong>in</strong>g occurs also at quite high temperatures, yet<br />

<strong>in</strong>complete loss of volatiles as well as the presence of<br />

crystallites po<strong>in</strong>t to a different T-t path. The groups of<br />

fallback melt particles and microtektites show more<br />

compositional variations although <strong>in</strong>dividual spherules are<br />

composed quite homogeneously; the variations are ascribed<br />

to properties of the precursor materials. Both groups of<br />

spherules may have been formed by condensation, the<br />

presence of dendritic crystals <strong>in</strong> the microtektites <strong>in</strong>dicate a<br />

slighlty slower cool<strong>in</strong>g process <strong>in</strong> comparison to the<br />

fallback material.<br />

We appreciate support by DFG grants De 401/19-1, La<br />

830/7-1 (Bosumtwi), De 401/21-1, and La 830/12-1<br />

(Chesapeake). Skillful sample preparation was carried out<br />

by U. Heitmann (Münster); J. Berndt (Münster) is<br />

acknowledged for help with the microprobe and LA-ICP-<br />

MS analyses.<br />

References:<br />

[1] Artemieva, N. (2002) In: Impacts <strong>in</strong> Precambrian Shields (eds. J. Plado<br />

and L.J. Pesonen) Spr<strong>in</strong>ger, Berl<strong>in</strong> – Heidelberg, 257-276.<br />

[2] Deutsch, A. et al. (2007), MAPS, 42, 635-654.<br />

[3] Koeberl, C. et al. (2007) MAPS, 42, 709-729.<br />

[4] Ferrière, L. et al. (2007) MAPS, 42, 667-688.<br />

[5] Coll<strong>in</strong>s, G.S., Wünnemann K. (2005) Geology, 33, 925 - 928, ISSN:<br />

0091-7613.<br />

[6] Gohn, G. et al. (2006) EOS, 87(35), 349-360.<br />

[7] Luetke, S. et al. (2007) Abstract <strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> Potsdam 2007,<br />

Abstract vol. 88.<br />

[8] Rudnick, R.L. and Gao, S. (2004) In: Treatise on Geochemistry (ed.<br />

H.D. Holland) Elsevier, Amsterdam, 1-56.<br />

[9] Deutsch, A. and Langenhorst, F. (2007) GFF 129, 155-160.<br />

[10] Langenhorst, F. et al. (2007) Abstract <strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong><br />

Potsdam 2007, Abstract vol. 88.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Investigation of microbial <strong>in</strong>dicators at the<br />

mound base of Challenger mound <strong>in</strong> the<br />

Belgica carbonate mound prov<strong>in</strong>ce<br />

(Porcup<strong>in</strong>e bas<strong>in</strong>, offshore Ireland)<br />

K. MANGELSDORF 1 , R. DI PRIMIO 1 , B. CRAGG 2 , B. HORSFIELD 1<br />

AND <strong>IODP</strong> EXPEDITION 307 SCIENTIFIC PARTY<br />

1<br />

GeoForschungsZentrum Potsdam, Telegrafenberg B423, 14473<br />

Potsdam, e-mail: K.Mangelsdorf@gfz-potsdam.de<br />

2<br />

School of Earth, Ocean and Planetary Sciences, University of<br />

Cardiff, PO Box 914, Cardiff, CF10 3YE, UK<br />

Cold water corals occur along the north-eastern<br />

Atlantic cont<strong>in</strong>ental marg<strong>in</strong>s form<strong>in</strong>g small isolated<br />

colonies to giant mound structures. In May 2005 sediment<br />

material drilled dur<strong>in</strong>g <strong>IODP</strong> Leg 307 on and adjacent to<br />

the Challenger mound <strong>in</strong> the Belgica carbonate mound<br />

prov<strong>in</strong>ce (Porcup<strong>in</strong>e bas<strong>in</strong>) provided a rare opportunity to<br />

ga<strong>in</strong> a first <strong>in</strong>sight <strong>in</strong>to the <strong>in</strong>itiation and growth of this<br />

remarkable deep water carbonate formations.<br />

In a previous study (the Geomound project) Naeth et al.<br />

(2005) revealed <strong>in</strong> a computer simulations of the bas<strong>in</strong><br />

history, undertaken at GFZ Potsdam, that below the<br />

carbonate mounds <strong>in</strong> the Belgica mound prov<strong>in</strong>ce<br />

(Porcup<strong>in</strong>e bas<strong>in</strong>, offshore Ireland) specific sandstones<br />

from Cretaceous and Tertiary sequences represent<br />

important migration pathways for natural gases to the<br />

surface. Hydrocarbon gases migrat<strong>in</strong>g to the surface can<br />

form a food source for microbial communities stimulat<strong>in</strong>g<br />

microbial activity at the sediment water <strong>in</strong>terface. Microbes<br />

oxidiz<strong>in</strong>g methane (aerobically and anaerobically) might<br />

have formed carbonate crusts be<strong>in</strong>g potential areas for cold<br />

water coral colonisation.<br />

Prelim<strong>in</strong>ary results show that microbial populations<br />

with<strong>in</strong> the mound <strong>in</strong>terval are only below the average<br />

prediction l<strong>in</strong>e of the trend observed <strong>in</strong> other <strong>IODP</strong> or ODP<br />

sites (Parkes et al., 2000). In contrast to this, at and below<br />

the mound base the cell counts together with the number of<br />

divid<strong>in</strong>g cells are <strong>in</strong>creas<strong>in</strong>g and plot above the average<br />

prediction l<strong>in</strong>e <strong>in</strong>dicat<strong>in</strong>g population growth at this<br />

sedimentary <strong>in</strong>terval. Low numbers of liv<strong>in</strong>g microbes are<br />

also <strong>in</strong>dicated by traces of phospholipids be<strong>in</strong>g only stable<br />

<strong>in</strong> <strong>in</strong>tact cell over geological times. Concomitantly, the<br />

<strong>in</strong>crease <strong>in</strong> cells is accompanied with the significant<br />

occurrence of methane and a decrease <strong>in</strong> pore water<br />

sulphate, suggest<strong>in</strong>g methane oxidation is tak<strong>in</strong>g place at<br />

this depth. However, the overlap of these two gradients is<br />

very broad (about 30 m) <strong>in</strong>dicat<strong>in</strong>g very low metabolic<br />

rates. Gas wetness and carbon as well as hydrogen isotope<br />

<strong>in</strong>vestigations of methane po<strong>in</strong>t to a mixed gas from<br />

biogenic and thermogenic sources suggest<strong>in</strong>g that at least a<br />

part of the migrat<strong>in</strong>g gas is from a thermogenic much<br />

deeper source. Microbiological labell<strong>in</strong>g experiments<br />

<strong>in</strong>dicate that the biogenic gas was not generated <strong>in</strong> situ and,<br />

therfore, must migrate also from a deeper source. Oil<br />

hydrocarbons were not detected <strong>in</strong> the <strong>in</strong>vestigated<br />

sediments. In sediment samples from the upper few meters<br />

below the mound base an H2S smell was recognized<br />

<strong>in</strong>dicat<strong>in</strong>g the reduction of sulphate. Microbial biomarkers<br />

(hopanoids) are low <strong>in</strong> the mound section, but <strong>in</strong>crease<br />

significantly below the mound base <strong>in</strong>dicat<strong>in</strong>g at least a<br />

higher proportion of dead microbial biomass at this<br />

<strong>in</strong>terval. Very light isotopic carbon signatures of <strong>in</strong>dividual<br />

microbial compounds, <strong>in</strong>dicat<strong>in</strong>g the assimilation of

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

methane carbon dur<strong>in</strong>g methanotrophy, were not detected<br />

up to now.<br />

Seismic profiles show that the mound base consists of a<br />

plane and an slope section. Cores were only obta<strong>in</strong>ed from<br />

the slope part. The mound base identified <strong>in</strong> the drilled<br />

cores is an erosional surface above middle Miocene<br />

sediments. The base is <strong>in</strong>deed firm but not a lithified hard<br />

ground, where coral would be able to settle on. Therefore,<br />

it seems that the nucleus of the mound <strong>in</strong>itiation was not<br />

drilled dur<strong>in</strong>g Leg 307. Thus, it is still unclear what the<br />

start<strong>in</strong>g po<strong>in</strong>t of the carbonate mound is: carbonate hard<br />

crusts, drop stones, mussel beds etc. In case of challenger<br />

mound it is suggested that the nucleus is located <strong>in</strong> the<br />

plane section of the mound base.<br />

References:<br />

EN.REFLISTNaeth, J. et al., 2005. Hydrocarbon seepage and carbonate<br />

mound formation: a bas<strong>in</strong> modell<strong>in</strong>g study from the Porcup<strong>in</strong>e Bas<strong>in</strong><br />

(offshore Ireland). Journal of Petroleum Geology 28 (2), 43-62.<br />

<strong>IODP</strong><br />

A simplified transfer function to estimate 2D<br />

mar<strong>in</strong>e gas hydrate <strong>in</strong>ventories<br />

M. MARQUARDT 1 , T. HENKE 2 , R. GEHRMANN 3 , C. HENSEN 1 , C.<br />

MÜLLER 2 , K. WALLMANN 1<br />

1<br />

IFM-Geomar, Wischhofstrasse 1-3, 24148 Kiel<br />

2<br />

Federal Institute for Geosciences and Natural Resources (BGR),<br />

Stilleweg 2, 30655 <strong>Hannover</strong><br />

3<br />

University of Leipzig, Talstrasse 35, 04103 Leipzig<br />

Offshore gas hydrate (GH) <strong>in</strong>ventories have been<br />

quantified so far either by the use of available pore water<br />

data (usually restricted to ODP drill sites) or by the<br />

<strong>in</strong>terpretation of seismic records. The results derived from<br />

these two methods very often revealed <strong>in</strong>deed significant<br />

differences <strong>in</strong> terms of quantity and distribution.<br />

In the project HYDRA a complementary approach has<br />

been developed us<strong>in</strong>g geochemical reactive-transport<br />

models and geophysical rock physics modell<strong>in</strong>g to quantify<br />

regional GH <strong>in</strong>ventories. Our prelim<strong>in</strong>ary result presented<br />

here is a simplified general transfer function which can be<br />

used to calculate 2D GH volumes. Derivation of the<br />

transfer function required a thorough sensitivity analysis of<br />

the most important control parameters <strong>in</strong> a transportreaction<br />

model (Figure 1). The six most important control<br />

parameters are the sedimentation rate, water depth, sea<br />

bottom temperature, thermal gradient, depth of anaerobic<br />

methane oxidation (AOM) and the potential GH occurrence<br />

zone (GHOZ). The GHOZ limited either by the end of the<br />

sediment column or by the GH stability field.<br />

In addition, six geochemical transport-reaction models<br />

constra<strong>in</strong>ed on DSDP/ ODP drill Sites 685, 1230, 1233,<br />

1040, 1041 and 1043 (Costa Rica, Peru and Chile) have<br />

been developed to obta<strong>in</strong> the natural variance of the<br />

different parameters and respective the result<strong>in</strong>g GH<br />

concentrations (Figure 2).<br />

In order to derive the general simplified transfer<br />

function, the six control parameters and the respective<br />

result<strong>in</strong>g GH concentration from each model have been<br />

used to set up <strong>in</strong> an ord<strong>in</strong>ary differential equation system<br />

(ODE). Six coefficients (u, v, w, x, z) result from solv<strong>in</strong>g<br />

the ODE, which will be multiplied by the regional<br />

parameters to obata<strong>in</strong> gas hydrate concentrations. The<br />

transfer function is given as:<br />

GH = u * Sedimentationrate + v * Thermal-gradient +<br />

w * AOM-depth + x * Waterdepth + y * Potential-GHOZ +<br />

z * Surfacetemperature<br />

GH is the maximum potential of average GH<br />

concentration <strong>in</strong> vol.% <strong>in</strong> the GH occurrance zone.<br />

u, v, w, x, y, z are the respective determ<strong>in</strong>ed<br />

coefficients of parameters.<br />

Apply<strong>in</strong>g the general function requires <strong>in</strong>corporation of<br />

aforementioned regional parameters i.e. water depth,<br />

sediment thickness (potential GHOZ), sedimentation rate,<br />

thermal gradient, sea bottom temperature, and AOM data.<br />

AOM depth and sedimentation rate have to be obta<strong>in</strong>ed by<br />

sediments and pore water from gravity cores.<br />

Interpretations of seismic records yield waterdepth, thermal<br />

gradient and sediment thickness. Therefore a velocity<br />

analysis calculat<strong>in</strong>g the seismic velocities vp and vs from<br />

the elastic moduli and the rock density (effective medium<br />

theory), planar <strong>in</strong>formation of sediment thickness, and the<br />

thermal gradient have been applied. Sensitive parameters <strong>in</strong><br />

the geophysical model (e.g. porosity) were calibrated<br />

aga<strong>in</strong>st the geochemical model <strong>in</strong> order to ma<strong>in</strong>ta<strong>in</strong> two<br />

coherent and valid models.<br />

The project aims at the accurate estimation of marg<strong>in</strong>wide<br />

GH <strong>in</strong>ventories. First results are a 2D distribution<br />

transect of gas hydrate concentration along the seismic l<strong>in</strong>e<br />

BGR99-44 across ODP sites 1040 and 1041 on the<br />

cont<strong>in</strong>ental slope (Figure 3). Along that profile a dense data<br />

mesh exists from the cruises M-54, SO-173 and BGR-99.<br />

The appliccation of the transfer function on that profile<br />

has been done <strong>in</strong> 625m <strong>in</strong>tervals. For every s<strong>in</strong>gle <strong>in</strong>terval<br />

all control parameters had to be determ<strong>in</strong>ed. Pore water<br />

data from the gravity cores along that profile have been<br />

used to determ<strong>in</strong>e the AOM depth by <strong>in</strong>terpolation along<br />

the profile. Sedimentation rate is assumed to be constant<br />

and has been published by Kimura et al. (1997). The<br />

thermal gradient is determ<strong>in</strong>ed from Langseth and Silver<br />

(1996). The sediment thickness and the visible BSR-depth<br />

of the profile have been calculated by the aforementioned<br />

velocity analysis. The result<strong>in</strong>g GH concentrations are<br />

vary<strong>in</strong>g between 0 and 3 vol.% of porespace. Figure 4<br />

shows the distribution along the marg<strong>in</strong>.<br />

As the gas hydrate zone widens with <strong>in</strong>creas<strong>in</strong>g<br />

sediment thickness and a subsid<strong>in</strong>g BSR the potential of<br />

gas hydrate formation <strong>in</strong>creases significantly. Towards the<br />

upper slope the concentration is also <strong>in</strong>creas<strong>in</strong>g <strong>in</strong>dicated<br />

by the shallower AOM depth (shallow AOM depth means<br />

high POC degradation rate).<br />

Integration of the GH bear<strong>in</strong>g sediments along the<br />

seismic profile and subsequent extrapolation onto 1 km of<br />

cont<strong>in</strong>ental marg<strong>in</strong> yield a potential of 31.4 10 12 g CH 4 /<br />

km.<br />

References:<br />

Kimura G., Silver E., Blum P., et al., (1997): Proc. ODP, Init. Repts., 170:<br />

College Station, TX (Ocean Drill<strong>in</strong>g Program).<br />

Langseth and Silver (1996): The Nicoya convergent marg<strong>in</strong> - a region of<br />

exceptionally low heat flow. Geophysical Research Letters, Vol 23, S.<br />

891 - 894.<br />

Marquardt, M., Henke, T., Gehrmann, R., Hensen, M., Müller, C.: Gas<br />

hydrate quantification: A general function allow<strong>in</strong>g for regional<br />

conditions to estimate 2D–gas hydrate <strong>in</strong>ventories by means of<br />

comb<strong>in</strong>ed geochemical and geophysical modell<strong>in</strong>g. In prep.<br />

93

94<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Figure 1: The effect of chang<strong>in</strong>g <strong>in</strong>dividual model parameters on GH concentration. Six parameters have been chosen to determ<strong>in</strong>e the<br />

transfer function. The AOM depth has been selected <strong>in</strong>stead of the POC degradation because AOM depth is easier to determ<strong>in</strong>e.<br />

Figure 2: Three of the six ODP Sites have been used for the derivation of the transfer function. The profiles show the measured data (red<br />

dots) and the model concentrations (black l<strong>in</strong>es). The blue l<strong>in</strong>e shows the maximum solubility of dissolved CH4 <strong>in</strong> porewater. GH starts to<br />

precipitate below the depth of saturation.<br />

ODP Sites 1040, 1041<br />

BGR 99-44<br />

Figure 3: Map of Costa Rica with the seismic profile BGR-99-44 (blue l<strong>in</strong>e) and the ODP Sites 1040 and 1041 (blue arrow). It shows the<br />

exist<strong>in</strong>g data mesh: heatflow data (black dots), seismic profiles (red l<strong>in</strong>es) and gravity cores (coloured dots).<br />

Depth [m] Depth [m]

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Redox sensitivity of P and Fe cycl<strong>in</strong>g dur<strong>in</strong>g<br />

Late Cretaceous black shale formation<br />

C. MÄRZ 1, 2 , S.W. POULTON 3 , B. BECKMANN 4, 5 , K. KÜSTER 1 , T.<br />

WAGNER 3 1, 6<br />

, S. KASTEN<br />

1<br />

Department of Geosciences,University of Bremen, Klagenfurter<br />

Str., 28359 Bremen, Germany (*correspond<strong>in</strong>g author: Email:<br />

cmaerz@uni-bremen.de, Tel.: +421 218 3927)<br />

2<br />

Microbiogeochemistry, ICBM, University of Oldenburg, Carlvon-Ossietzky-Strasse<br />

9-11, 26129 Oldenburg, Germany<br />

(cmaerz@icbm.de, Tel.: +441 798 3627)<br />

3<br />

School of Civil Eng<strong>in</strong>eer<strong>in</strong>g and Geosciences, University of<br />

Newcastle, NE1 7RU, Newcastle upon Tyne, UK<br />

4<br />

Institute for Geology and M<strong>in</strong>eralogy, University of Cologne,<br />

Zülpicher Str. 49a, 50674 Cologne, Germany<br />

5<br />

Federal Institute for Geosciences and Natural Resources,<br />

Stilleweg 2, 30655 <strong>Hannover</strong>, Germany<br />

6<br />

Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, Am<br />

Handelshafen 12, 27570 Bremerhaven, Germany<br />

Widespread deposition of organic-rich, often<br />

metalliferous mar<strong>in</strong>e sediments, usually referred to as black<br />

shales, is generally believed to have occurred under very<br />

special oceanic conditions. Dur<strong>in</strong>g ODP Leg 207 to<br />

Demerara Rise, a thick Mid- to Late Cretaceous black shale<br />

succession, <strong>in</strong>clud<strong>in</strong>g the Oceanic Anoxic Events (OAEs) 2<br />

and 3, was recovered. We <strong>in</strong>vestigated OAE 3 sediments<br />

(Santonian-Coniacian) conta<strong>in</strong><strong>in</strong>g between 3-12 wt% TOC<br />

from Sites 1259 and 1261 <strong>in</strong> high resolution by means of<br />

<strong>in</strong>organic geochemical analysis (major and m<strong>in</strong>or elements,<br />

P and Fe speciation). The focus of this <strong>in</strong>vestigation is the<br />

cycl<strong>in</strong>g of the important nutrient P <strong>in</strong> the water column and<br />

sediment, especially its sensitivity to chang<strong>in</strong>g redox<br />

conditions and its coupl<strong>in</strong>g to the cycles of Fe and organic<br />

matter. From records of the redox-sensitive trace metals<br />

Cd, Mn, Mo, Ni, V and Zn, it is evident that at both studied<br />

sites the redox conditions of bottom waters and sediments<br />

were highly variable. The redox state ranged from sulfidic<br />

to anoxic, non-sulfidic, while fully oxic conditions at the<br />

sea floor were never reached dur<strong>in</strong>g the respective time<br />

period. The observed fluctuations of the redox state<br />

obviously followed an astronomically forced cyclicity,<br />

which is also visible <strong>in</strong> the bulk P record. Although P is<br />

generally depleted <strong>in</strong> the studied sediments – a well-known<br />

phenomenon <strong>in</strong> anoxic sett<strong>in</strong>gs, result<strong>in</strong>g <strong>in</strong> C/P ratios of<br />

up to 300 -, there are marked P peaks that are paralleled by<br />

lowest TOC/Al, S/Al values and lowest trace element<br />

enrichments. Thus, these P peaks were obviously formed<br />

dur<strong>in</strong>g periods of less reduc<strong>in</strong>g conditions, i.e. anoxic, nonsulfidic<br />

bottom waters. Sequential extractions of P and Fe<br />

species reveal that most of the P <strong>in</strong> these peaks is bound to<br />

authigenic apatite, but also to Fe (oxyhydr)oxides. Based<br />

on these observations, we draw a schematic model of the<br />

redox development of bottom waters and sediments dur<strong>in</strong>g<br />

deposition of the <strong>in</strong>vestigated black shale <strong>in</strong>tervals.<br />

<strong>IODP</strong><br />

Physical Rock Properties of the Chesapeake<br />

Bay Impact Structure<br />

SIBYLLE I. MAYR 1 , YURI POPOV 2 , HANS BURKHARDT 1 , DENIS N.<br />

GOROBTSOV 2 , RAISA A. ROMUSHKEVICH 2 . HELMUT WILHELM 3 ,<br />

PHILIPP HEIDINGER 3 ,<br />

1 Fachgebiet Angewandte Geophysik, Institut für Angewandte<br />

Geowissenschaften Technische Universität Berl<strong>in</strong><br />

2 Russian State Geological Prospect<strong>in</strong>g University, Russia.<br />

3 Geophysikalisches Institut Universität Karlsruhe (TH)<br />

The borehole Eyreville was drilled <strong>in</strong> 2005 <strong>in</strong>to the<br />

Chesapeake Bay Impact Structure (Gohn et al 2006). It is<br />

located <strong>in</strong> the moat of the central crater that surrounds the<br />

central uplift and is totally cored from 127 to the f<strong>in</strong>al<br />

depth (1766 m). The aim of our projects is the physical<br />

characterisation of the cored lithology and to supply basic<br />

data for geophysical field <strong>in</strong>vestigations. Furthermore the<br />

project contributes to a better understand<strong>in</strong>g of correlation<br />

between petrophysical properties and both the<br />

m<strong>in</strong>eralogical composition and the texture of the rocks, and<br />

by this the <strong>in</strong>fluence of an impact on petrophysical<br />

properties. The project is based on a previous project<br />

deal<strong>in</strong>g with the Chicxulub impact crater (Popov et<br />

al.2004, Mayr et al. 2007, Mayr et al., forthcom<strong>in</strong>g)<br />

Figure 1: Top: Thermal conductivity parallel to bedd<strong>in</strong>g<br />

(TC par) versus porosity. Bottom: P-wave velocity<br />

perpendicular to core axis (~ parallel to bedd<strong>in</strong>g) versus<br />

porosity.Porosity is measured on dry samples: (post<br />

impact clay, Exmore Sediment Breccia) and saturated<br />

samples (granite, suevite and lithic breccia, schist and<br />

pegmatite).<br />

95

96<br />

Approx. 330 samples cover<strong>in</strong>g the complete cored depth<br />

<strong>in</strong>terval with equidistant sampl<strong>in</strong>g (approximately 5 m)<br />

were chosen for the determ<strong>in</strong>ation of thermal parameters<br />

(thermal conductivity, anisotropy and <strong>in</strong>homogeneity and<br />

thermal diffusivity tensor components), density and<br />

porosity. Ultrasonic P- and S-wave velocity was measured<br />

on a subgroup of samples: all mechanically stable samples<br />

and samples that were geometrically suitable for the<br />

measurement cell without further preparation. For most<br />

granites (1096 m – 1371 m) and selected suevites, breccia<br />

(1391 m – 1557 m), schists and pegmatites (below 1557 m)<br />

the measurements were performed under dry and fully<br />

saturated conditions. Measurements on sedimentary postimpact<br />

clay (127 - 444 m) and Exmore sediment Breccia<br />

(444 m - 1096 m) were performed only on vacuum dry<br />

samples due to possible des<strong>in</strong>tegration of samples dur<strong>in</strong>g<br />

saturation.<br />

Figure 1 shows that <strong>in</strong> general the porosity is the most<br />

dom<strong>in</strong>ant factor that <strong>in</strong>fluences the physical properties. For<br />

the <strong>in</strong>dividual lithological units this trend is partly obscured<br />

by additional <strong>in</strong>fluence of m<strong>in</strong>eralogical composition and<br />

texture. In post-impact sediments the highest porosities are<br />

found, lead<strong>in</strong>g to low thermal conductivities and velocities.<br />

Rocks of the Exmore sediment-clast breccia and Exmore<br />

sediment megablocks have lower porosities.<br />

The cluster<strong>in</strong>g of data for samples from below 1096 m<br />

(granite, suevite and lithic breccia, basement rocks: schist<br />

and pegmatite) <strong>in</strong> lithological groups is h<strong>in</strong>dered by the<br />

<strong>in</strong>fluence of m<strong>in</strong>eral content and texture (e.g. micro-cracks)<br />

too, and does not allow a clear dist<strong>in</strong>ction between the<br />

s<strong>in</strong>gle groups.<br />

For the correlation between seismic velocity and<br />

thermal conductivity there is <strong>in</strong> a general positive trend<br />

(Figure 2), but due to data scatter<strong>in</strong>g no applicable<br />

correlation function is appropriate. Some peculiarities can<br />

be seen: for <strong>in</strong>stance post-impact sediments can be<br />

dist<strong>in</strong>guished from Exmore Breccia due to relatively low<br />

velocities and higher thermal conductivity.<br />

Figure 2: P-wave velocity versus thermal conductivity (TC)<br />

dry.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

In the post impact sedimentary rocks low bulk densities<br />

of dry rocks are measured (Figure 3). A dist<strong>in</strong>ct m<strong>in</strong>imum<br />

is observed <strong>in</strong> the depth range from ~250 to ~350 m (below<br />

1 g/cm 3 ). This can be expla<strong>in</strong>ed by the existence of<br />

siliceous shells, Diatoms (R. Bussert, L. Edwards pers.<br />

communication) lead<strong>in</strong>g to closed porosity. In the Exmore<br />

sediments the density of solid material ρmtx is more or less<br />

constant (approximately 2.6 g/cm 3 ). The P-wave velocities<br />

<strong>in</strong> the high porosity (27% - 67%) post-impact and Exmore<br />

sediments above 1100 m lie between 1.2 and 3 km/s (dry<br />

rocks), Figure 3 (5).<br />

The partly high <strong>in</strong>homogeneity Figure 3 (4) <strong>in</strong> sample<br />

scale (up to 60%) of thermal conductivity for post-impact<br />

clays is due to layer<strong>in</strong>g (lead<strong>in</strong>g to fractures <strong>in</strong> dry rocks!).<br />

The high <strong>in</strong>homogeneity of thermal conductivity of<br />

Exmore sediments is due to variations <strong>in</strong> m<strong>in</strong>eralogical<br />

composition (Breccia). In the measured temperature<br />

gradient, the post-impact unit can be del<strong>in</strong>eated from the<br />

Exmore sediments, see Figure 3 (6). Regions with higher<br />

temperature gradient (~650 m - ~750 m) correlate with<br />

units of oxidised clay and silt. A slightly lower temperature<br />

gradient is observed <strong>in</strong> the sandstone units.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Figure 3: Selected logs of measured data: (1) dry bulk density ρdry and density of solid material ρmtx, (2) porosity Φ bmeasured <strong>in</strong> dry<br />

sedimentary (unstable) and saturated stable samples, (3) thermal conductivity par to bedd<strong>in</strong>g (λdry and λsat), (4) Thermal<br />

<strong>in</strong>homogeneity, (5) P-wave velocity perpendicular to core axis (~par to bedd<strong>in</strong>g) dry and saturated and (5) Logs of reduced measured<br />

temperature, (Temp - 22°-0.024°/m * Depth), measured May 2006 under +/- stationary conditions. The temperature-gradient<br />

(calculated us<strong>in</strong>g Δz = 1.4m). No temperature log is available below 1100 m.<br />

97

98<br />

In the Granitic section P-wave velocities between 5.8 and<br />

6.5 km/s are found (saturated rocks), typical for low<br />

porosity granite. The thermal conductivity and the density<br />

reflect the vary<strong>in</strong>g m<strong>in</strong>eralogical content (biotite, quartz,<br />

feldspar, pers. com. R.L. Gibson, and chemical analysis by<br />

R. Bussert). Furthermore the gra<strong>in</strong> size of the granite<br />

differs. The physical properties (density, thermal<br />

conductivity, P- and S-wave velocity) are <strong>in</strong> correlation<br />

with this gra<strong>in</strong> size. The reason for this has to be further<br />

<strong>in</strong>vestigated.<br />

In the suevite-lithic breccia section and the schistpegmatite<br />

section the P-velocities are significantly lower<br />

(2.8 - 5.8 km/s) whereas density of solid material is partly<br />

higher than <strong>in</strong> the granites due to different m<strong>in</strong>eral content<br />

(amphibolite, pyrite, muscovite, pers. com W. U. Reimold,<br />

and chemical analysis by Robert Bussert). The velocity<br />

values can be expla<strong>in</strong>ed by both, higher porosity (up to 22<br />

%) and higher amount of micro-cracks <strong>in</strong> the rocks.<br />

Thermal <strong>in</strong>homogeneity is significant <strong>in</strong> most cases and<br />

reaches up to 70 %. This is an <strong>in</strong>dication for the complex<br />

structure of the rocks (breccia). In the suevite-lithic breccia<br />

section the porosities are higher than <strong>in</strong> the granites above<br />

and the schist-pegmatite section below, lead<strong>in</strong>g to lower<br />

thermal conductivity and P-wave velocity. In the schistpegmatite<br />

section the variation of velocity and thermal<br />

conductivity is high due to fractur<strong>in</strong>g of both types of<br />

rocks.<br />

The <strong>in</strong>ternal surface reflects the different type of rocks<br />

with different micro-morphology (not shown). Internal<br />

surface of clay is significantly higher than that of sandstone<br />

due to lamellar structure of clay m<strong>in</strong>erals. Internal surface<br />

of granite is <strong>in</strong> general lower than of rocks of the suevite<br />

and the schist-pegmatite section. The differences have to be<br />

further <strong>in</strong>vestigated by analysis of SEM-images.<br />

Conclusions<br />

S<strong>in</strong>ce no logs (besides gamma and temperature) are<br />

available, laboratory measurements present the only<br />

possibility of obta<strong>in</strong><strong>in</strong>g <strong>in</strong>formation about velocity, density<br />

and thermal conductivity for the <strong>in</strong>terpretation of<br />

geophysical field data.<br />

The physical properties allow a dist<strong>in</strong>ction between the<br />

lithological units.<br />

A complete analysis of all parameters (<strong>in</strong>clud<strong>in</strong>g the<br />

analysis of the microstructure) on the same samples has to<br />

be performed. Furthermore these data are necessary for the<br />

application of e. g. mix<strong>in</strong>g models, petrophysical model<strong>in</strong>g<br />

c.f. Mayr and Burkhardt, 2006.<br />

Dense sampl<strong>in</strong>g is necessary especially <strong>in</strong> the f<strong>in</strong>e<br />

layered Exmore Breccia and Cretaceous Sediment<br />

megablock as well as <strong>in</strong> the suevite and basement<br />

(thickness of units is partly below 1 m).<br />

Measurements on rocks of boreholes from the outer<br />

part of the impact structure are necessary for the<br />

comparison with rocks that are not <strong>in</strong>fluenced by the<br />

impact.<br />

References:<br />

Gohn, G.S., Koeberl, C., Miller, K.G., Reimold, W.U., Cockell, C.S.,<br />

Horton Jr., J.W., Sanford, W.E., Voytek, M.A. (2006): Chesapeake<br />

Bay Impact Structure Drilled. EOS, 87(35):349,355.<br />

Mayr, S. I., and H. Burkhardt (2006), Ultrasonic Properties of Sedimentary<br />

Rocks: Effect of Pressure, Saturation, Frequency and Microcracks.<br />

Geophys. J. Int., 164, 246-258.<br />

Mayr, S., Burkhardt, H., Popov, Y., Romushkevich, R., Bayuk, I.,<br />

Wittmann, A., Heid<strong>in</strong>ger P. and H. Wilhelm: (forthcom<strong>in</strong>g) Integrated<br />

Interpretation of Physical Properties of Rocks of the Borehole<br />

YAXCOPOIL-1 (Chicxulub impact crater). Accepted with m<strong>in</strong>or<br />

changes by JGR (Manuscript under revision)<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Mayr, S., Burkhardt, H., Popov, Y., Wittmann, A., (2007): Estimation of<br />

hydraulic permeability consider<strong>in</strong>g the micro morphology of rocks of<br />

the borehole YAXCOPOIL-1 (Impact crater Chicxulub, Mexico). Int J<br />

Earth Sci (Geol Rundsch), DOI : 10.1007/s00531-007-0227-6<br />

Popov, Y., Romushkevich, R., Bayuk, L., Korobkov, D., Mayr, S.,<br />

Burkhardt, H. & Wilhelm, H. (2004): Physical properties of rocks from<br />

the upper part of the Yaxcopoil-1 drill hole, Chicxulub crater.<br />

Meteoritics & Planetary Science 39, 700-812.<br />

<strong>IODP</strong><br />

Vegetation and climate development dur<strong>in</strong>g<br />

the Cenozoic <strong>in</strong> Antarctica. Future drill<strong>in</strong>g of<br />

cont<strong>in</strong>ental marg<strong>in</strong> sections: ANDRILL,<br />

<strong>IODP</strong> and <strong>ICDP</strong>?<br />

B.A.R. MOHR 1 & ANDRILL COMMUNITY<br />

1 Museum of Natural History, Invalidenstr. 43, 10115<br />

Berl<strong>in</strong>, Germany; e-mail: barbara.mohr@rz.hu-berl<strong>in</strong>.de<br />

Understand<strong>in</strong>g Antarctica’s palaeovegetation dur<strong>in</strong>g<br />

the last 100 Ma. is crucial for any global studies on climate<br />

change. Furthermore, vegetation studies, ma<strong>in</strong>ly based on<br />

palynological results, will also shed light on the evolution<br />

of land animals, ma<strong>in</strong>ly mammals of the southern<br />

hemisphere dur<strong>in</strong>g the Cenozoic.<br />

Earlier publications described the development of<br />

floras through the Cenozoic <strong>in</strong> West Antarctica based on<br />

data from land sections on Seymour, Snow and K<strong>in</strong>g<br />

George Islands and ODP Leg 113 (Ask<strong>in</strong>, 1988; Mohr<br />

2001). Drill holes of the Cape Roberts Project recovered<br />

Miocene through Late Eocene sections <strong>in</strong> the southwestern<br />

Ross Sea, however with large gaps (Ra<strong>in</strong>e and Ask<strong>in</strong>,<br />

2001). These miss<strong>in</strong>g time <strong>in</strong>tervals may have been now<br />

partly recovered by the ANDRILL program. Two sites MIS<br />

and SMS were drilled, the latter dur<strong>in</strong>g 2007 and is now<br />

under <strong>in</strong>vestigation. Besides the cool to cold adapted low<br />

diversity floras of angiosperm-moss-liverwort assemblages<br />

that may reflect a herb-moss tundra, warmer pulses with<br />

forest and heather vegetation (Epacridaceae) have been<br />

recovered from the Early and mid-Miocene.<br />

The temperate early Tertiary floras are dom<strong>in</strong>ated by<br />

various gymnosperms, ma<strong>in</strong>ly Araucariaceae and<br />

Podocarpaceae, a half dozen species of the southern beech<br />

Nothofagus and several fern and angiosperm taxa of<br />

Proteaceae (Lomatia; Gevu<strong>in</strong>a) plus Myricaceae,<br />

Myrtaceae, Gunneraceae, Aquifoliaceae, W<strong>in</strong>teraceae,<br />

Rubiaceae and Rosaceae and Anacardiaceae. The fern<br />

component <strong>in</strong>cludes remnants of tree ferns, and various<br />

taxa found today <strong>in</strong> South America, such as Lophosoria.<br />

Oligocene and Miocene strata have been recovered <strong>in</strong> CRP<br />

3, one of the few sections <strong>in</strong> Antarctica where Early<br />

Oligocene palynofloras have been studied, but extended<br />

Oligocene sections need still to be drilled. ANDRILL’s<br />

proposal to drill at Coulman High aims to recover sections<br />

with high high sedimentation rates reflect<strong>in</strong>g Oligocene to<br />

Miocene climate cycles and the Eocene–Oligocene<br />

transition. The planned <strong>IODP</strong> cruise Leg 323 to Wilkes<br />

Land, East Antarctica, will set out with the goal to recover<br />

pre-Eocene strata <strong>in</strong> order to understand the early<br />

development of ice on the Antarctic cont<strong>in</strong>ent and the<br />

consequences for life history <strong>in</strong> southern high latitudes.<br />

Even though our knowledge on Cenozoic vegetation on<br />

the Antarctic cont<strong>in</strong>ent has grown dur<strong>in</strong>g the last decades,<br />

it still rema<strong>in</strong>s patchy, because the recovered material<br />

comes from scattered localities along the cont<strong>in</strong>ental<br />

marg<strong>in</strong>. Thus, for the future, it must be our goal to try to

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

understand better the early part of the Palaeogene, with<br />

special emphasis on organic and palaeontological studies<br />

from West (and East) Antarctica. This goal could be<br />

potentially reached by drill<strong>in</strong>g <strong>in</strong>to one of the West<br />

Antarctic Islands, namely Seymour Island with its extended<br />

Palaeogene and Late Cretaceous sections.<br />

References:<br />

Ask<strong>in</strong>, R.A. 1988. Campanian to Paeocene palynological succession of<br />

Seymour and adjacent islands, northeastern Antarctic Pen<strong>in</strong>sula. Geol.<br />

Soc. America, Memoir 169: 131-153.<br />

Mohr, B.A.R. 2001. The development of Antarctic fern floras dur<strong>in</strong>g the<br />

Tertiary, and palaeoclimatic and palaeobiogeographic implications.<br />

Palaeontographica, B 259: 167-208.<br />

Ra<strong>in</strong>e, J.I. and Ask<strong>in</strong>, R.A. 2001 Terrestrial palynology of Cape Roberts<br />

Project Drillhole CRP-3, Victoria Land Bas<strong>in</strong>, Antarctica. Terra<br />

Antartica, 8(4): 389-400.<br />

<strong>IODP</strong><br />

Short-term variability of surface-water<br />

characteristics <strong>in</strong> the Late Neogene North<br />

Atlantic Ocean: Prelim<strong>in</strong>ary results of a<br />

biomarker record from <strong>IODP</strong> Site U1313<br />

B.D.A. NAAFS 1 , J. HEFTER 1 , R. STEIN 1 AND G.H. HAUG 2<br />

1 Alfred-Wegener-Institut for Polar and Mar<strong>in</strong>e Research,<br />

Columbusstrasse, 27568 Bremerhaven, Germany<br />

2 Geologisches Institut, ETH Zürich, Universitätstrasse 16, 8092<br />

Zürich, Switserland<br />

We use samples from North Atlantic <strong>IODP</strong> Site 1313<br />

(Leg 306), which is a re-drill of DSDP Site 607, to<br />

construct a high-resolution record of short-term variability<br />

<strong>in</strong> sea-surface temperature and productivity <strong>in</strong> the late<br />

Neogene North Atlantic Ocean us<strong>in</strong>g organic-geochemical<br />

(biomarker) proxies. Of special <strong>in</strong>terest is the relationship<br />

between sea surface temperatures (SST’s) and<br />

environmental change (e.g. ice sheet <strong>in</strong>stabilities).<br />

Determ<strong>in</strong>ation of the long-term evolution of millennialscale<br />

variability <strong>in</strong> surface characteristics can provide clues<br />

to the mechanisms responsible for abrupt climate change,<br />

which are still poorly understood <strong>in</strong> detail. Prelim<strong>in</strong>ary<br />

results show alkenone based SST’s at Site 1313 vary<strong>in</strong>g<br />

between 7 and 21 o C dur<strong>in</strong>g the time <strong>in</strong>terval between MIS<br />

9 and 16 (~0.5 kyr resolution). Dur<strong>in</strong>g MIS 10, 12, 14, 15<br />

and 16, dist<strong>in</strong>ct maxima <strong>in</strong> alkenones (<strong>in</strong>terpreted as proxy<br />

for primary production) co<strong>in</strong>cide with m<strong>in</strong>ima <strong>in</strong> SST’s.<br />

These results are the first of a high-resolution record that<br />

will span the period from 0-6 Ma. It will be the first longterm<br />

high-resolution alkenone based SST and productivity<br />

record from the North Atlantic that will extend back to the<br />

late Miocene, the period before the development of largescale<br />

Northern Hemisphere ice-sheets.<br />

<strong>IODP</strong><br />

Habitats of Globiger<strong>in</strong>oides ruber (d’Orbigny)<br />

<strong>in</strong> the eastern Mediterranean Sea s<strong>in</strong>ce the<br />

Mar<strong>in</strong>e Isotopic Stage 12<br />

L. NUMBERGER 1 , CH. HEMLEBEN 1 , R. HOFFMANN 1 , A.<br />

MACKENSEN 2 , H. SCHULZ 1 , M. KUCERA 1<br />

1<br />

Eberhard-Karls-University, Sigwartstr. 10, 72076 Tüb<strong>in</strong>gen,<br />

Germany<br />

2<br />

Alfred Wegener Institute, Columbusstrasse, 27568 Bremerhaven,<br />

Germany<br />

The chemical composition of shells of planktonic<br />

foram<strong>in</strong>ifera, e.g. Globiger<strong>in</strong>oides ruber (d’Orbigny,<br />

white), is frequently used to determ<strong>in</strong>e past sea surface<br />

conditions. Recently, it has been shown that arbitrarily<br />

def<strong>in</strong>ed morphotypes with<strong>in</strong> this species exhibit different<br />

chemical and isotopic signatures. These results imply either<br />

that the morphotypes represent cryptic species which<br />

possess different ecological preferences or that the species<br />

produces predictable morphological aberrations under<br />

different ecological conditions. At any rate, the l<strong>in</strong>k<br />

between shell chemistry and morphology <strong>in</strong> G. ruber<br />

implies an as yet poorly understood but potentially<br />

powerful factor that could be used to better <strong>in</strong>terpret<br />

paleoenvironmental data obta<strong>in</strong>ed from this species. Here<br />

we <strong>in</strong>vestigate the presence and distribution through time<br />

of morphological types of G. ruber (white) <strong>in</strong> late<br />

Quaternary and Holocene sediments of the eastern<br />

Mediterranean. In 115 samples from MIS 12-9 and MIS 2-<br />

1 at ODP Site 964 and the piston core GeoTü-SL96, we<br />

have def<strong>in</strong>ed four arbitrary morphological types with<strong>in</strong> the<br />

species, determ<strong>in</strong>ed their relative abundance and stable<br />

isotopic composition. We show that the abundance of the<br />

morphotypes changes significantly between glacials and<br />

<strong>in</strong>terglacials and that the isotopic composition of the types<br />

differs. A multivariate analysis of the abundances of the<br />

different morphotypes of G. ruber <strong>in</strong>dicates a systematic<br />

variation at both sites between warm stages, which are<br />

characterised by high abundances of the “normal”<br />

morphotype and cold stages, which show higher<br />

proportions of the type “platys”. An exception to this is<br />

observed <strong>in</strong> MIS 12, which is dist<strong>in</strong>guished by the higher<br />

abundance of the “elongate” type. The three abundant<br />

morphotypes of G. ruber show significant offsets <strong>in</strong> their<br />

stable isotopic composition. These offsets are consistent<br />

with<strong>in</strong> <strong>in</strong>dividual glacial and <strong>in</strong>terglacial stages and show<br />

predictable reversal patterns between glacials and<br />

<strong>in</strong>tergalcials, except for MIS10 which is thus characterised<br />

not only by a unique composition of G. ruber morphotypes,<br />

but also by a unique pattern of isotopic offset among them.<br />

Interest<strong>in</strong>gly, the sign of the offset <strong>in</strong> the stable isotopic<br />

composition of <strong>in</strong>dividual morphotypes is systematically<br />

reversed between the two Sites, except of MIS10,<br />

<strong>in</strong>dicat<strong>in</strong>g a more uniform upper water column structure<br />

and/or seasonal production pattern with<strong>in</strong> the central<br />

Mediterranean at that time. This <strong>in</strong>terpretation is consistent<br />

with other proxy evidence for anomalously warm surface<br />

waters <strong>in</strong> the eastern Mediterranean dur<strong>in</strong>g the MIS 10<br />

glacial. S<strong>in</strong>ce the isotopic shifts among the three G. ruber<br />

morphotypes are systematic and often exceed 1 per mill,<br />

their understand<strong>in</strong>g is essential for the <strong>in</strong>terpretation of all<br />

G. ruber – based proxy records for the paleoceanographic<br />

development of the Mediterranean dur<strong>in</strong>g the late<br />

Quaternary.<br />

99

100<br />

<strong>ICDP</strong><br />

Chacterization of a pre-Holocene lake level<br />

high stand <strong>in</strong> Laguna Potrok Aike<br />

(Argent<strong>in</strong>a) – project POTROK<br />

C. OHLENDORF 1 , M. FEY 1 , T. HABERZETTL 2 , S. JANSSEN 3 , A.<br />

LÜCKE 4 , C. MAYR 5 , G. OLIVA 6 , F. SCHÄBITZ 3 , M. WILLE 3 , B.<br />

ZOLITSCHKA 1<br />

1 GEOPOLAR, Institute of Geography, University of Bremen,<br />

Celsiusstr. FVG-M, D-28359 Bremen, Germany (ohlen@unibremen.de)<br />

2 Geoscience Center, University of Gött<strong>in</strong>gen, Goldschmidtstr. 3,<br />

D-37077 Gött<strong>in</strong>gen, Germany<br />

3 Sem<strong>in</strong>ar for Geography and Education, University of Cologne,<br />

Gronewaldstr. 2, D-50931 Cologne, Germany<br />

4 Institute of Chemistry and Dynamics of the Geosphere, ICG V:<br />

Sedimentary Systems, Research Center Jülich, D-52425<br />

Jülich, Germany<br />

5 GeoBio-CenterLMU and Dept. of Earth and Environmental<br />

Sciences, University of Munich, Richard-Wagner-Str. 10, D-<br />

80333 Munich, Germany<br />

6 Estación Experimantal Agropecuaria Santa Cruz (INTA), Chacra<br />

45, CC 332, AR-9400 Río Gallegos, Argent<strong>in</strong>a<br />

The southernmost <strong>ICDP</strong> project dedicated to terrestrial<br />

paleoclimatic reconstructions, the “Potrok Aike maar lake<br />

sediment archive drill<strong>in</strong>g project” (PASADO), is a GLAD<br />

800 deep drill<strong>in</strong>g scheduled for the second half of <strong>2008</strong> <strong>in</strong><br />

the maar lake Laguna Potrok Aike (52°S, 70°W; 113 m<br />

a.s.l.; diameter: 3.5 km) <strong>in</strong> southern Patagonia, Argent<strong>in</strong>a.<br />

The sedimentary record of this term<strong>in</strong>al lake is well suited<br />

to trace temporal changes <strong>in</strong> the hydrological cycle because<br />

evidently large lake level variations occurred <strong>in</strong> the<br />

Holocene and Late Glacial periods. In order to provide a<br />

more process related <strong>in</strong>terpretation of the sedimentary<br />

record a monitor<strong>in</strong>g program was established at Laguna<br />

Potrok Aike <strong>in</strong> 2002 which was ma<strong>in</strong>ta<strong>in</strong>ed <strong>in</strong> the<br />

framework of the DFG-<strong>ICDP</strong> project POTROK. Us<strong>in</strong>g a<br />

cont<strong>in</strong>uous collection of environmental data<br />

(meteorological parameters, lake level, water temperature,<br />

etc.) we have the opportunity to develop an understand<strong>in</strong>g<br />

of how observed lake volume changes may be translated<br />

<strong>in</strong>to synoptic scale processes. This knowledge can then be<br />

applied to past lake volume changes of known magnitude<br />

and age. Ow<strong>in</strong>g to the relatively simple, pot-shaped,<br />

bathymetry of Laguna Potrok Aike, water volume changes<br />

for lake levels lower than present day can be <strong>in</strong>ferred from<br />

terraces visible on geo-referenced seismic profiles. The<br />

occurrence of past lake levels higher than present day is<br />

witnessed by several subaerial lake level terraces. For these<br />

terraces high precision differential GPS measurements of<br />

position and altitude were carried out dur<strong>in</strong>g a field survey<br />

<strong>in</strong> 2006.<br />

A comb<strong>in</strong>ation of the levell<strong>in</strong>g and the bathymetric<br />

dataset of Laguna Potrok Aike yields a total of 10,433 data<br />

po<strong>in</strong>ts. Based on this available dataset a 3D-modell of the<br />

lake and its catchment area was created. A colour coded<br />

surface plot clearly shows that an overflow must have<br />

existed at the north-western corner of the lake at an<br />

elevation of 21 m above the present day lake level. The<br />

level<strong>in</strong>g data confirms that this is the only place around the<br />

entire lake bas<strong>in</strong> where a break through the surround<strong>in</strong>g<br />

mora<strong>in</strong>e deposits which form the aquiclud<strong>in</strong>g frame of the<br />

lake exists. Support<strong>in</strong>g evidence for the existence of such<br />

an overflow comes from a shallow open pit NNE of the<br />

Potrok Aike meteorological station where fluvial gravel has<br />

been discovered. Based on the evidence from a profundal<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

and a marg<strong>in</strong>al lacustr<strong>in</strong>e sediment record it has been<br />

proposed that this overflow might have been active dur<strong>in</strong>g<br />

pre-Holocene times potentially dur<strong>in</strong>g the Late-Glacial<br />

period (Haberzettl et al., 2007, <strong>2008</strong>). Moreover, it is<br />

conceivable that a bypass situation of the ma<strong>in</strong> <strong>in</strong>flow<strong>in</strong>g<br />

tributary might have existed <strong>in</strong> the past because the<br />

position of the ma<strong>in</strong> <strong>in</strong>flow that today enters the lake<br />

episodically via a cataract <strong>in</strong> a bay on the western shore of<br />

the lake is very close to the position of the anticipated<br />

overflow. The altitud<strong>in</strong>al difference between <strong>in</strong>- and<br />

outflow today is only less than 2 m and even decreases<br />

further to the west. Additionally, a bay like structure that is<br />

visible on the eastern side of the lake at the same elevation<br />

as the overflow might have formed. Clues to the reasons<br />

for this <strong>in</strong>ferred pre-Holocene lake level high stand can be<br />

obta<strong>in</strong>ed from the lake level and meteorological monitor<strong>in</strong>g<br />

study. These <strong>in</strong>dicate that decreas<strong>in</strong>g lake levels occur<br />

dur<strong>in</strong>g periods of persistently high w<strong>in</strong>d speed from<br />

westerly directions which are l<strong>in</strong>ked to a strengthen<strong>in</strong>g of<br />

the Southern Hemispheric Westerlies. On the other hand<br />

<strong>in</strong>creases of the lake level occur dur<strong>in</strong>g periods with a more<br />

frequent occurrence of precipitation br<strong>in</strong>g<strong>in</strong>g easterly<br />

w<strong>in</strong>ds that today prevail dur<strong>in</strong>g situations where zonal flow<br />

is temporarily blocked. The analysis of recent lake level<br />

and meteorological data <strong>in</strong>dicates that the latter situation<br />

might be l<strong>in</strong>ked to the ENSO periodicity.<br />

References:<br />

Haberzettl, T., H. Corbella, M. Fey, S. Janssen, A. Lücke, C. Mayr, C.<br />

Ohlendorf, F. Schäbitz, G. Schleser, M. Wille, S. Wulf and B.<br />

Zolitschka (2007). Lateglacial and Holocene wet-dry cycles <strong>in</strong> southern<br />

Patagonia: chronology, sedimentology and geochemistry of a lacustr<strong>in</strong>e<br />

sediment record from Laguna Potrok Aike (Argent<strong>in</strong>a).- The Holocene<br />

17, 297-311.<br />

Haberzettl, T., B. Kück, S. Wulf, F. Anselmetti, D. Ariztegui, H. Corbella,<br />

M. Fey, S. Janssen, A. Lücke, C. Mayr, C. Ohlendorf, F. Schäbitz, G.<br />

Schleser, M. Wille and B. Zolitschka (<strong>2008</strong>). Hydrological variability<br />

<strong>in</strong> southeastern Patagonia and explosive volcanic activity <strong>in</strong> the<br />

southern Andean Cordillera dur<strong>in</strong>g Oxygen Isotope Stage 3 and the<br />

Holocene <strong>in</strong>ferred from lake sediments of Laguna Potrok Aike,<br />

Argent<strong>in</strong>a. Palaeogeography, Palaeoclimatology, Palaeoecology,<br />

doi:10.1016/j.palaeo.2007.10.008.<br />

<strong>IODP</strong><br />

Modern ostracodes from Lago Petén Itzá and<br />

lakes of the Península Yucatán as <strong>in</strong>dicators<br />

of environmental and climate change<br />

L. PÉREZ 1 , B. SCHARF 1 , R. V. GELDERN 2 , P. STEEB 1 , D. SAMOL 1 , J.<br />

LORENSCHAT 1 , A. SCHWALB 1<br />

1 Institut für Umweltgeologie, Technische Universität<br />

Braunschweig, Braunschweig, Germany<br />

2 Leibniz Institut für Geowissenschaftliche<br />

Geme<strong>in</strong>schaftsaufgaben, <strong>Hannover</strong>, Germany<br />

Introduction<br />

The Yucatán Península, located <strong>in</strong> the northern lowland<br />

Neotropics, is characterized by humid tropical climate and<br />

a steep N-S precipitation gradient and is thus an ideal<br />

region to study species preferences and distribution<br />

patterns. Lago Petén Itzá is the third largest lake <strong>in</strong><br />

Guatemala, 20 km long and 3-4 km wide, and the deepest<br />

lake of the Yucatán Península with a maximum depth of<br />

165 m (Anselmetti et al. 2006, Hodell et al. 2006).<br />

Sediments conta<strong>in</strong> abundant ostracodes, one of the most<br />

useful groups of bio<strong>in</strong>dicators used for the reconstruction<br />

of past climates and environments. Our project is a<br />

contribution to the Lake Petén Itzá (Guatemala) Scientific<br />

Drill<strong>in</strong>g Project (PISDP). A total of 1327 m of sediment

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

cores from 7 sites were retrieved us<strong>in</strong>g the GLAD 800 <strong>in</strong><br />

2006 <strong>in</strong> order to study the 1) paleoclimatic history of the<br />

northern lowland Neotropics; the 2) paleoecology and<br />

biogeography of the tropical lowland forest and the 3)<br />

subsurface biogeochemistry. The sampl<strong>in</strong>g party for<br />

bio<strong>in</strong>dicators took place at the LacCore, University of<br />

M<strong>in</strong>nesota <strong>in</strong> 2007.<br />

Methods<br />

We retrieved surface and littoral samples from a total<br />

of 18 lakes across the Yucatán Península (Guatemala,<br />

Belize and Mexico) between N 15°27’ and 20°39’ and W<br />

89°06’ and 89°13’. Water samples were retrieved at the<br />

deepest part of each lake <strong>in</strong> order to characterize physicochemical<br />

properties. To better understand preferences,<br />

tolerances and habitats of modern ostracode species, we<br />

took surface sediment samples at different water depths<br />

along a N-S transect <strong>in</strong> Lago Petén-Itzá. In the northern<br />

part of the lake, surface sediment samples were retrieved<br />

every 5 m from 5 to 30 m water depth, and then every 20 m<br />

to a max depth of 160 m. Additionally two about 40 cm<br />

long short cores (PI-SC-1-10 m and PI-SC-2-40 m) were<br />

retrieved <strong>in</strong> order to reconstruct the recent environmental<br />

history of the lake. Short cores were 210 Pb and 137 Cs dated.<br />

Ostracodes were separated from the sediments by siev<strong>in</strong>g,<br />

and taxonomical identification was carried out us<strong>in</strong>g both<br />

valves characteristics and soft parts of liv<strong>in</strong>g specimen.<br />

Results<br />

Water geochemistry<br />

Analysis of ma<strong>in</strong> elements shows that sulfate,<br />

hydrogencarbonate and chloride dom<strong>in</strong>ate the waters of the<br />

Yucatán lake systems. Major cations <strong>in</strong> the lake waters are<br />

Na, Ca and Mg. Waters with high sulfate concentrations<br />

(max. 2295 mgL-1) are: Chichancanab, Milagros and<br />

Bacalar. Lakes Izabal, Perdida, Yaxhá and Belize 2 have<br />

waters dom<strong>in</strong>ated by hydrogencarbonate (max. conc. 214<br />

mgL-1). Lakes with high seawater <strong>in</strong>trusion are Cenote<br />

and Almond Hill (max. chloride concentration 1652 mgL-<br />

1).�The 18O values <strong>in</strong> the waters range from +4 and +5 ‰<br />

for 18O, and -14 and – 1 ‰ for 13CDIC, reflect<strong>in</strong>g the<br />

effects of evaporation, groundwater <strong>in</strong>put and productivity.<br />

Enrichment of 18O by evaporation is high <strong>in</strong> the “closed<br />

lakes” Petén Itzá, Yaxhá, Macanché, Chichancanab and<br />

Yalahau. Negative 18O values (-9.14 ‰) were measured<br />

<strong>in</strong> Lake Bacalar, where groundwater is be<strong>in</strong>g received at a<br />

rapid rate. Laguna Perdida is eutrophic, which is reflected<br />

by a low secchi depth, high dissolved oxygen and the<br />

presence of the highest 13CDIC values (-1.27 ‰) of the<br />

entire data set.<br />

Ostracodes from Yucatán lakes<br />

Species assemblages consist of the benthic species<br />

Cytheridella ilosvayi, Cyprideis spp., Darw<strong>in</strong>ula<br />

stevensoni, Fabaeformiscandona sp., Limnocythere sp. and<br />

Perissocytheridea cribosa, and the nektic species<br />

Cypridopsis okeechobei, Eucypris sp., Heterocypris<br />

punctata, Physocypria globula, P. pustulosa, P. xanabanica,<br />

Stenocypris malcolmsoni, Strandesia <strong>in</strong>trepida and<br />

Thalassocypria sp. Because carapaces of Cypretta sp. and<br />

Potamocypris sp. were lack<strong>in</strong>g soft parts, we have not yet<br />

been able to def<strong>in</strong>itively conclude whether they are benthic<br />

or nektic species. Some species are restricted to a specific<br />

type of environment or waters and thus present excellent<br />

bio<strong>in</strong>dicators. We identified, for example, Potamocypris sp.<br />

as typical of the lakes <strong>in</strong> the dry northwest of Yucatán,<br />

Laguna Yalahau, where the precipitation is only 450 mm<br />

101<br />

yr-1. Stenocypris malcolmsoni was found <strong>in</strong> waters with<br />

low conductivity (192-215 µScm-1) and low dissolved<br />

oxygen (5.8-7.6 mgL-1). Ostracodes characteristic of<br />

brackish waters (max. sal<strong>in</strong>ity 5960 µScm-1) are Cyprideis<br />

spp., Perissocytheridea cribosa and Thalassocypria sp., C.<br />

okeechobei. Fabaeformiscandona sp., D. stevensoni and C.<br />

ilosvayi are widely distributed and thus less suited to<br />

def<strong>in</strong>e specific preferences and environments.<br />

Ostracodes from Lago Petén Itzá<br />

Lago Petén Itzá presents 8 species <strong>in</strong>clud<strong>in</strong>g the<br />

benthic species C. ilosvayi, D. stevensoni, Limnocythere<br />

sp., Fabaeformiscandona sp., and the nektic species C.<br />

okeechobei, P. globula, H. punctata and Strandesia<br />

<strong>in</strong>trepida (Fig. 1). Species found only <strong>in</strong> littoral samples<br />

were Strandesia <strong>in</strong>trepida and H. punctata. H. punctata was<br />

found only <strong>in</strong> the southern littoral (0.1 and 0.7 m water<br />

depth) while Strandesia <strong>in</strong>trepida was found <strong>in</strong> both,<br />

northern (0.5 m water depth) and southern littoral samples.<br />

The presence of these species <strong>in</strong> long cores from the deep<br />

bas<strong>in</strong> may thus be <strong>in</strong>dicative of low lake levels dur<strong>in</strong>g drier<br />

climates. P. globula is a nektic species and seems to prefer<br />

deep waters. Their carapaces often conta<strong>in</strong>ed soft parts at a<br />

water depth of about 60 m. This suggests that these<br />

ostracodes are liv<strong>in</strong>g close to this water depth. A water<br />

column profile from the deepest part of Lago Péten Itzá<br />

shows a decrease of dissolved oxygen and a thermocl<strong>in</strong>e<br />

located between 30 and 40 m. Ostracodes are abundant and<br />

diverse between 0 and 40 m, and less abundant below 40 m<br />

water depth (Fig. 2).<br />

Recent environmental change recorded <strong>in</strong> Lago Petén<br />

Itzá sediments<br />

Short core PI-SC-1-10m has a sedimentation rate of<br />

0.96 mm yr-1 and an extrapolated total age of 550 years.<br />

The upper 10 cm consists of light olive gray silty clays and<br />

the rema<strong>in</strong>der of the core down to a depth of 40 cm<br />

consists of yellowish gray silty clays. Short core PI-SC-2-<br />

40m is characterized by olive gray silty clays and a high<br />

sedimentation rate (3.77 mm yr-1) suggest<strong>in</strong>g a maximum<br />

age of only 155 years.. Both short cores conta<strong>in</strong> 6<br />

ostracodes species: P. globula, Limnocythere sp.,<br />

Cytheridella ilosvayi, Cypridopsis okeechobei, Darw<strong>in</strong>ula<br />

stevensoni and Fabaeformiscandona sp. In PI-SC-1-10m<br />

Limnocythere sp. is the most abundant ostracode while <strong>in</strong><br />

PI-SC-2-40m the dom<strong>in</strong>ant species is P. globula. This<br />

confirms that P. globula prefers deeper water (40 m) <strong>in</strong><br />

comparison to other ostracodes species. Also, high<br />

abundances of P. globula <strong>in</strong> the upper olive gray, organicrich<br />

sediments suggest that this species can be used as<br />

<strong>in</strong>dicator of eutrophication. Species found <strong>in</strong> yellowish<br />

gray sediments (lower eutrophication level) are C. ilosvayi,<br />

C. okeechobei and Limnocythere sp. The effects of<br />

population growth lead<strong>in</strong>g to eutrophication of the lake,<br />

drastic lake level changes and heavy ra<strong>in</strong> seasons <strong>in</strong> the<br />

1940's <strong>in</strong> the area of Lago Petén Itzá.<br />

Conclusions and Outlook<br />

Our prelim<strong>in</strong>ary results present a first sweep<strong>in</strong>g<br />

overview of ostracode species assemblages, detailed<br />

taxonomy and ecological valences of species that is<br />

significantly improv<strong>in</strong>g the role of ostracodes from<br />

Yucatán aquatic systems as <strong>in</strong>dicators of environmental<br />

change. This is also confirmed by the results from the short<br />

cores that clearly show how the recent environmental<br />

change at Lago Petén Itzá has been recorded by ostracode<br />

species assemblages. This <strong>in</strong>formation will now be applied

102<br />

to species assemblages from long cores compris<strong>in</strong>g the past<br />

approximately 85,000 years (Hodell, personal<br />

communication).<br />

Acknowledgements<br />

We thank D. Hodell, M. Brenner and J. Curtis<br />

(University of Florida), M. Dix, M. Palmieri, M.<br />

Maldonado, G. Alfaro, M. Orozco, S. Ramirez and J.<br />

Blijdenste<strong>in</strong> (Universidad del Valle de Guatemala),<br />

CONAP (Guatemala), SRE, CONAPESCA and G. Islebe<br />

(ECOSUR-Chetumal, Mexico) for facilitat<strong>in</strong>g field work<br />

and their support.<br />

References<br />

Anselmetti, F. S., D. Ariztegui, D. A. Hodell, M. B. Hillesheim, M. Brenner,<br />

A. Gilli, J. A. McKenzie, and A. D. Mueller. 2006. Late Quaternary<br />

climate-<strong>in</strong>duce lake level variations <strong>in</strong> Lake Petén Itzá, Guatemala,<br />

<strong>in</strong>ferred from seismic stratigraphic analysis. Palaeogeography,<br />

palaeoclimatology, palaeoecology 230:52-69.<br />

Hodell, D., F. Anselmetti, M. Brenner, D. Ariztegui, and t. P. S. Party. 2006.<br />

The Lake Petén Itzá Scientific Drill<strong>in</strong>g Project. Scientific Drill<strong>in</strong>g.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1. Ostracode valves and carapaces from Lago Petén Itzá. Nektic species: A. Cypridopsis okeechobei, B. Heterocypris punctata,<br />

C. Physocypria globula, D. Strandesia <strong>in</strong>trepida. Benthic species: E. Cytheridella ilosvayi, F. Fabaeformiscandona sp., G. Limnocythere<br />

sp., H. Darw<strong>in</strong>ula stevensoni.<br />

Physocypria globula<br />

Cypridopsis okeechobei<br />

Limnocythere opesta<br />

Cytheridella ilosvayi<br />

Fabaeformiscandona sp.<br />

Darw<strong>in</strong>ula stevensoni<br />

Heterocypris punctata<br />

Stra ndesia itre pid a<br />

H’<br />

0 mN 40 mN 80 mN 120 mN 160 m 120 mS 80 mS 40 mS 0 mS<br />

Fig. 2. Distribution and diversity (H’) of 8 ostracode species <strong>in</strong> Lago Petén Itzá along a N-S transect from the littoral of the northern shore<br />

across the lake and maximum water depth of 160 m to the littoral of the southern shore. Ostracode species are given <strong>in</strong> percentages.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Assess<strong>in</strong>g the accuracy of SST and<br />

δ 18 Osw/sal<strong>in</strong>ity estimates from Tahiti corals<br />

us<strong>in</strong>g Monte Carlo simulations: implications<br />

for the <strong>in</strong>terpretation of fossil corals<br />

M. PFEIFFER 1 , S.Y. CAHYARINI 2 , W.-C. DULLO 3 , M. WEBER 1 , T.<br />

FELIS 4 , W. RICKEN 1<br />

1<br />

Institut für Geologie und M<strong>in</strong>eralogie, Universität zu Köln,<br />

Germany<br />

2<br />

Research Centre for Geotechnology, Indonesian Institute of<br />

Sciences (LIPI), Bandung, Indonesia<br />

3<br />

IFM-GEOMAR, Kiel, Germany<br />

4<br />

DFG-Research Center for Ocean Marg<strong>in</strong>s (RCOM) & MARUM,<br />

University of Bremen, Bremen, Germany<br />

Paired measurements of δ 18 O and Sr/Ca <strong>in</strong> coral<br />

aragonite are rout<strong>in</strong>ely used for deriv<strong>in</strong>g estimates of SST,<br />

δ 18 O sw and, by extension, sea surface sal<strong>in</strong>ity variations<br />

from fossil corals. However, <strong>in</strong> practice, the accuracy (or<br />

the error) of these estimates is often difficult to assess.<br />

Here, we use simulated proxy data and Monte-Carlo<br />

simulations to <strong>in</strong>vestigate the accuracy of SST and δ 18 O sw<br />

estimates from paired coral δ 18 O and Sr/Ca measurements.<br />

First, we estimate expected values of coral Sr/Ca and δ 18 O<br />

from <strong>in</strong>strumental or reanalysis data of sea surface<br />

temperature (SST) and sea surface sal<strong>in</strong>ity (SSS). We then<br />

add the typical analytical errors onto the expected Sr/Ca<br />

(δ 18 O) data as random numbers and compute Sr/Ca +error and<br />

δ 18 O sw+error from the noisy proxy data for a 1000 sample<br />

Monte Carlo. From this simple Monte Carlo simulation, the<br />

range of correlation coefficients between Sr/Ca+error<br />

(δ 18 O sw+error) and expected Sr/Ca (δ 18 O sw) is estimated. As<br />

expected, we f<strong>in</strong>d that this range ma<strong>in</strong>ly depends on the<br />

magnitude of the actual SST and SSS variations at a given<br />

site, as well as on the slope of the δ 18 Osw-SSS relationship.<br />

A comparison with real coral-based SST and δ 18 O sw<br />

reconstructions from Tahiti <strong>in</strong>dicates that correlations<br />

between reconstructed SST (δ 18 O sw) and <strong>in</strong>strumental SST<br />

(SSS) fall with<strong>in</strong> the range of correlation coefficients<br />

predicted based on our Monte-Carlo simulation. Thus, our<br />

simple simulation exercise may help to assess the<br />

feasibility of SST, δ 18 O sw and sal<strong>in</strong>ity reconstructions from<br />

Tahiti corals. This will provide a basel<strong>in</strong>e for the<br />

<strong>in</strong>terpretation of fossil corals from Tahiti.<br />

<strong>IODP</strong><br />

Drift-Analysis of ocean bottom pressure<br />

measurements<br />

A. POLSTER 1 , H. VILLINGER 1 , M. FABIAN 1 , H.-H. GENNERICH 1<br />

1 Universität Bremen, Fachbereich 5 Geowissenschaften,<br />

Meersetechnik/Sensorik, Klagenfurter Straße GEO, Raum<br />

4310, 28359 Bremen, Germany<br />

S<strong>in</strong>ce the 1980s, the Paroscientific Digi-Quarz sensor is<br />

deployed by deep ocean bottom pressure measurements.<br />

The NOAA (National Oceanic and Atmospheric<br />

Adm<strong>in</strong>istration) use the sensors for there DART (Deepocean<br />

Assessment and Report<strong>in</strong>g of Tsunamis) System<br />

s<strong>in</strong>ce 1986. Here the mobile sensors repeatedly deployed<br />

on the ocean bottom. The present <strong>IODP</strong> (Integrated Ocean<br />

Drill<strong>in</strong>g Program) also <strong>in</strong>stalled the sensors <strong>in</strong> there CORK<br />

(Circulation Obviation Retrofit Kit) System s<strong>in</strong>ce 1992.<br />

Here the sensors will fix <strong>in</strong> the stationary CORK-Stations<br />

103<br />

for some years on the ocean bottom. For the Paroscientific<br />

Digi-Quars sensors doesn’t exist longtime drift analysis,<br />

because mostly deployment are only s<strong>in</strong>gle measurements<br />

for one year. Now it is possible to analys<strong>in</strong>g the longtime<br />

drift of the mobile DART and stationary CORK sensors<br />

and view there contrast. The ambition <strong>in</strong> this analysis is to<br />

view the limit and range of the drift.<br />

Before the drift can be analyses, the dom<strong>in</strong>ant tidal<br />

signals should be reduce. Therefore two programs were<br />

available, the program T-Tide and ETERNA. Both<br />

programs don’t have reduce all periodic signals <strong>in</strong> the<br />

frequency range of the tides, for this reason a Notch filter<br />

was designed for filter<strong>in</strong>g the frequency range of the tides<br />

<strong>in</strong> the raw data.<br />

All <strong>in</strong> all 79 datasets of 33 mobile sensors from the<br />

NOAA DART-Stations and 46 datasets of 18 stationary<br />

sensors from the <strong>IODP</strong> CORK-Stations were available.<br />

The mobile sensors of the DART-Stations show<br />

different l<strong>in</strong>ear drift on their deployments, the stationary<br />

sensors of the CORK-Stations show different l<strong>in</strong>ear drift<br />

partly with exponential part <strong>in</strong> the beg<strong>in</strong>n<strong>in</strong>g. All sensors<br />

together don’t show <strong>in</strong> the drift a dependence on depth.<br />

For the reduction of the drift, all sensors and<br />

deployments have to be reckon<strong>in</strong>g <strong>in</strong>dividually. After the<br />

present analysis, it is not possible to give a prognosis of the<br />

drift with one ore more sensors.<br />

<strong>IODP</strong><br />

Middle to late Miocene (12-9 Ma) carbonate<br />

preservation and accumulation changes <strong>in</strong><br />

the Atlantic (Céara Rise Sites) and Pacific<br />

(Site 1237)<br />

I. PREIß-DAIMLER 1 , R. HENRICH 1<br />

1 Department of Geosciences- University of Bremen<br />

Klagenfurter Str., 28359 Bremen, Germany<br />

correspond<strong>in</strong>g author ipd@uni-bremen .<br />

To study of the causes of the Miocene Carbonate Crash<br />

events is one of the ma<strong>in</strong> goals of this work. The drop of<br />

carbonate content has been reported for several Atlantic,<br />

Caribbean and Pacific Sites <strong>in</strong> the <strong>in</strong>terval of middle to late<br />

Miocene transition (12-9Ma). Three ma<strong>in</strong> causes have been<br />

attributed to the phenomenon, that are (1) dilution of<br />

sediments by non-calcareous material, (2) dissolution and<br />

(3) changes <strong>in</strong> the productivity of the carbonate build<strong>in</strong>g<br />

organisms. In order to study the carbonate preservation and<br />

accumulation of Miocene sediments we selected time slices<br />

from different ODP sites <strong>in</strong> the Atlantic and Pacific. In<br />

these sediments short-term perturbations are common.<br />

Our data sets comprise carbonate concentration, silt<br />

gra<strong>in</strong> size distribution (e.g. calcareous silt, terrigenous silt<br />

and sortable silt), fragmentation <strong>in</strong>dices and component<br />

analysis of the coarse fraction. Based on these data we<br />

calculated accumulation rates of the ma<strong>in</strong> carbonate<br />

builders as well as for the terrigenous material.<br />

In the equatorial Atlantic records short-termed<br />

carbonate reductions are recognised that can be traced over<br />

the depth transect of drill sites (ODP Sites 926, 927, 928).<br />

The carbonate content at the three sites varies between 40%<br />

and 90 % wt., with m<strong>in</strong>ima around 60% at the shallow Site<br />

926, and around 40 % at the deep Site 928. W<strong>in</strong>now<strong>in</strong>g <strong>in</strong><br />

comb<strong>in</strong>ation with improvement of preservation is<br />

suggested to expla<strong>in</strong> the <strong>in</strong>crease of coarse fraction

104<br />

recorded at 9.9 Ma at Site 926, and 0.3 myrs later at Site<br />

928. We propose that these trends towards better<br />

preservation are related to a stronger NADW circulation.<br />

In the Pacific at all sites of Leg 202, cover<strong>in</strong>g the<br />

equatorial and southern Pacific, m<strong>in</strong>ima <strong>in</strong> carbonate<br />

accumulation rates are registered around 12 Ma to 9 Ma.<br />

This may <strong>in</strong>dicate a common cause for these carbonate<br />

reductions. Dur<strong>in</strong>g this time <strong>in</strong>terval, Site 1237 was<br />

cont<strong>in</strong>uously mov<strong>in</strong>g towards the South American<br />

Cont<strong>in</strong>ent thus approach<strong>in</strong>g the costal upwell<strong>in</strong>g zone.<br />

Consequently the <strong>in</strong>fluence of w<strong>in</strong>ds <strong>in</strong>creased recognised<br />

by <strong>in</strong>creased supply of dust and volcanic ashes to this site<br />

position. Hence, here short-term carbonate reductions are<br />

likely l<strong>in</strong>ked to a comb<strong>in</strong>ation of ash <strong>in</strong>put and dissolution.<br />

Currently sediments from the North Atlantic Site 982<br />

display<strong>in</strong>g high carbonate contents are under <strong>in</strong>vestigation.<br />

From the results we expect more <strong>in</strong>formation about the<br />

history of <strong>in</strong>termediate water circulation at this critical<br />

position of the Atlantic circulation loop.<br />

<strong>ICDP</strong><br />

Thermo-hydraulic conditions <strong>in</strong> a seismically<br />

active zone (Gulf of Cor<strong>in</strong>th, Greece)<br />

D. RETTENMAIER 1 , A. FÖRSTER 2 , H. HÖTZL 1<br />

1 University of Karlsruhe, Department of Applied Geology (AGK)<br />

2 GeoForschungsZentrum Potsdam (GFZ)<br />

In this project work the thermo-hydraulic conditions of<br />

a seismically active zone have been <strong>in</strong>vestigated by means<br />

of surface and subsurface <strong>in</strong>vestigations, borehole studies<br />

and numerical model<strong>in</strong>g. European research activities <strong>in</strong><br />

the Gulf of Cor<strong>in</strong>th have been targeted for obta<strong>in</strong><strong>in</strong>g data<br />

on earthquake sources and fault mechanics and for<br />

<strong>in</strong>vestigat<strong>in</strong>g the role of faults on fluid flow <strong>in</strong> this<br />

seismically active area. In this context, the DFG funded a<br />

project aimed at the exploration of the thermo-hydraulic<br />

conditions <strong>in</strong> the area near Aigion and the southern graben<br />

shoulder of the northern Peloponnesus <strong>in</strong>clud<strong>in</strong>g the<br />

determ<strong>in</strong>ation of surface heat flow <strong>in</strong> a 1000 m deep<br />

borehole, which is the scope of this work.<br />

First, due to a lack of geological <strong>in</strong>formation, a detailed<br />

<strong>in</strong>vestigation of the geological and tectonical situation was<br />

made. Secondly, the hydraulic parameters of the different<br />

lithological formations and of the hydraulic behavior of<br />

normal faults were determ<strong>in</strong>ed.<br />

Based on the field studies, hydraulic test<strong>in</strong>g,<br />

petrophysical well-log analysis, optical-fiber temperature<br />

sens<strong>in</strong>g, and laboratory measurement of thermal<br />

conductivity, a hydrogeological conceptual model was<br />

prepared. This conceptual model formed the basis for a<br />

numerical 2-D model of the hydraulic conditions at<br />

regional scale at the southern Cor<strong>in</strong>th graben shoulder.<br />

Different simulation scenarios were <strong>in</strong>vestigated to search<br />

for the best-fit model to known parameters.<br />

Coupled numerical model<strong>in</strong>g of groundwater flow and<br />

heat transport was then used to get <strong>in</strong>sights <strong>in</strong> the processes<br />

that may be typical for the study area. In the case of the<br />

Cor<strong>in</strong>th area, model calibration, as well as sensitivity and<br />

plausibility checks allow a prediction on how the thermohydraulic<br />

system <strong>in</strong> this seismically active zone is<br />

characterized and how the hydraulic conditions affect the<br />

heat flow. Surface heat-flow density was unknown <strong>in</strong> the<br />

northern Peloponnesus prior this study. Also unknown was<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

whether the water flow <strong>in</strong> aquifers results <strong>in</strong> strong heat<br />

advection signals <strong>in</strong> the temperature field.<br />

The coupl<strong>in</strong>g of temperature and geothermal<br />

parameters to the calibrated hydraulic flow model has<br />

shown that some of the <strong>in</strong>tervals are affected by heat<br />

advection due to fluid flow, affect<strong>in</strong>g the temperature<br />

gradient and hence the heat flow. In a pure conduction heat<br />

regime the measured temperature of 32°C from 750 m<br />

depth would be <strong>in</strong>crease to 37°C. At the lower model<br />

boundary of 1155 m depth the maxima temperature <strong>in</strong> the<br />

conductive 1-D temperature profile is 45°C which is<br />

approximately 4.5°C higher than <strong>in</strong> the coupled thermohydraulic<br />

flow model. The exam<strong>in</strong>ation of coupled<br />

model<strong>in</strong>g runs has shown that conductive heat flow of the<br />

crust is about 55 mW/m².<br />

F<strong>in</strong>ally, it is clear that the quality of <strong>in</strong>put data is<br />

play<strong>in</strong>g a major role for the best fitt<strong>in</strong>g of a numerical<br />

model. Otherwise it was also shown that sometimes<br />

generalization is necessary when general restrictions from<br />

the model<strong>in</strong>g software are required. Undoubtedly, the fault<br />

zones of the Gulf of Cor<strong>in</strong>th are represent<strong>in</strong>g one case of<br />

seismic zones and similar model approaches can be<br />

extended to other hydraulic systems with similar tectonical<br />

arrangements.<br />

References:<br />

Bauer, E., 2004. Europäische Erdbebenzone Golf von Kor<strong>in</strong>th: Geologischhydrogeologische<br />

Untersuchungen <strong>in</strong> der Region Aigion im Umfeld<br />

der Kont<strong>in</strong>entalen Tiefbohrung AIG10 (NW-Peleponnes,<br />

Griechenland). Unpubl. Diploma Thesis, Dept. of Applied Geology,<br />

University of Karlsruhe, 160 pp.<br />

Förster, A., Hötzl, H., Rettenmaier, D. & Kück, J., 2006. Petrophysical and<br />

temperature logg<strong>in</strong>g <strong>in</strong> the <strong>ICDP</strong> AIG10 borehole (Greece). Scientific<br />

Drill<strong>in</strong>g Database. doi: 10.1594 /GFZ. SDDB.1091<br />

().<br />

Giurgea, V., Rettenmaier, D., Pizz<strong>in</strong>o, L., Hötzl, H., Förster, A.,<br />

Quattrocchi, F.& Nikas, K., 2003. Hydrogeological conditions of the<br />

Aigion-Eliki seismic active region based on borehole observations and<br />

hydraulic tests. 2nd-Cor<strong>in</strong>th Rift Laboratory Workshop Aigion<br />

(Greece), Abstracts.<br />

Giurgea, V., Rettenmaier, D., Pizz<strong>in</strong>o, L., Unkel, I., Hötzl, H., Förster, A.&<br />

Quattrochi, F., 2004. Prelim<strong>in</strong>ary hydrogeological <strong>in</strong>terpretation of the<br />

Aigion area from the AIG10 borehole data. C. R. Geoscience, 336,<br />

467-475.<br />

Nikas, K., 2001a. Hydrogeological research project „Investigation-<br />

Evaluation of water resources <strong>in</strong> north Peloponnesus“. Subproject of<br />

Achaia Prefecture, maps 7, 11, 18, I.G.M.E. (Institute of Geological &<br />

M<strong>in</strong>eralogical Exploration).<br />

Nikas, K., 2001b. Hydrology of the tectonically active zone of North<br />

Achaia, Cor<strong>in</strong>th Rift. Laboratory Aigion Workshop, Greece.<br />

Rettenmaier, D., 2002. Europäische Erdbebenzone Golf von Kor<strong>in</strong>th:<br />

Geologisch-tektonische und hydrogeologische Untersuchungen <strong>in</strong> der<br />

Region Egion und Klokos (NW-Peloponnes, Griechenland). Unpubl.<br />

Diploma Thesis, Dept. of Applied Geology, University of Karlsruhe,<br />

116 pp.<br />

Rettenmaier, D., 2003. Geological conditions <strong>in</strong> the AIG10 borehole and<br />

technical aspects of drill<strong>in</strong>g through the Aigion seismic active fault<br />

zone. 2nd-Cor<strong>in</strong>th Rift Laboratory Workshop Aigion (Greece),<br />

Abstracts, Institut Physique du Globe Paris, p. 24.<br />

Rettenmaier, D., Giurgea, V. & Hötzl, H., 2002b. Darstellung und<br />

Bewertung der geologisch-tektonischen und hydrogeologischen<br />

Verhältnisse im Bereich der Egion-Tiefbohrung AIG 10 für die<br />

geplanten Bohrarbeiten. Report; Dept. of Applied Geology, University<br />

of Karlsruhe, 22 pp.<br />

Rettenmaier, D., Giurgea, V., Förster, A. & Hötzl, H., 2006. Thermohydraulic<br />

conditions <strong>in</strong> the area of the “Gulf of Cor<strong>in</strong>th Deep<br />

Geodynamic Laboratory”: Interpretation from well-logg<strong>in</strong>g and<br />

model<strong>in</strong>g. - DFG/<strong>IODP</strong>-<strong>ICDP</strong> Jo<strong>in</strong>t Colloquium Greifswald, scientific<br />

program and abstracts.<br />

Rettenmaier, D., Giurgea, V., Hötzl, H. & Förster, A., 2004. The AIG10<br />

drill<strong>in</strong>g project (Aigion, Greece): <strong>in</strong>terpretation of the litho-log <strong>in</strong> the<br />

context of regional geology and tectonics. C. R. Geoscience Vol. 336,<br />

p. 415-423.<br />

Rettenmaier, D., Giurgea, V., Hötzl, H., Förster, A. & Nikas, K., 2002a.<br />

Geological mapp<strong>in</strong>g and hydrogeological test<strong>in</strong>g of the block-faulted<br />

system <strong>in</strong> the h<strong>in</strong>terland of Egion. 27th General Assembly Europ.<br />

Geophys. Soc., Nice, (France), CD.<br />

Rettenmaier, D., Wohlgemuth, L., Kück, J., Borm, G. & Harms, U., 2003.<br />

Drill<strong>in</strong>g, cor<strong>in</strong>g, test<strong>in</strong>g and <strong>in</strong>strumentation of the AIG10 borehole,

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Aigion, Gulf of Cor<strong>in</strong>th, Greece. <strong>ICDP</strong> Newsletter, Vol. 5,<br />

GeoForschungsZentrum Potsdam, 20-23.<br />

Unkel, I., 2003. Europäische Erdbebenzone Golf von Kor<strong>in</strong>th: Geologischhydrogeologische<br />

Untersuchungen <strong>in</strong> der Region Aigion im Umfeld<br />

der kont<strong>in</strong>entalen Tiefbohrung AIG10 (NW-Peloponnes,<br />

Griechenland). Unpubl. Diploma Thesis, Dept. of Applied Geology,<br />

University of Karlsruhe, 153 pp.<br />

<strong>ICDP</strong><br />

Retrograde zircons <strong>in</strong> fluid zones<br />

A. RIEMANN, R. OBERHÄNSLI<br />

Universität Potsdam, Institut für Geowissenschaften<br />

Introduction<br />

The Dabie-Sulu region <strong>in</strong> east-central Ch<strong>in</strong>a is one of<br />

the largest and most coherent ultrahigh pressure (UHP) and<br />

high pressure (HP) metamorphic belts <strong>in</strong> the world, and has<br />

attracted a great deal of worldwide attention. A large<br />

number of contributions concern<strong>in</strong>g the petrology,<br />

geochemistry, geochronology, metamorphic P-T paths, and<br />

large-scale conceptual tectonic evolution models for the<br />

creation and exhumation of the UHP and HP metamorphic<br />

rocks <strong>in</strong> the region. Central to resolv<strong>in</strong>g the physical and<br />

chemical processes <strong>in</strong>volved <strong>in</strong> the genesis and exhumation<br />

of UHP terranes is constra<strong>in</strong><strong>in</strong>g the sequence of events.<br />

Simple questions like the follow<strong>in</strong>g rema<strong>in</strong> poorly<br />

answered: ‘‘How rapid was cont<strong>in</strong>ental subduction?’’<br />

‘‘How many metamorphic events were recorded?’’ ‘‘How<br />

long did these events last?’’ In the specific case of the giant<br />

Q<strong>in</strong>l<strong>in</strong>g-Dabie-Sulu UHP terrane, we know that it<br />

developed dur<strong>in</strong>g northward subduction of the Yangtze<br />

Craton beneath the S<strong>in</strong>o-Korean Craton <strong>in</strong> the Triassic<br />

(Hacker et al., 2000), but important controversies <strong>in</strong>clude<br />

the follow<strong>in</strong>g: Were UHP subduction and exhumation<br />

coeval everywhere along the length of the orogen, imply<strong>in</strong>g<br />

a short-lived subduction and exhumation event of regional<br />

extent, or were they diachronous? Are some of the<br />

eclogites assumed to be Triassic actually remnants of early<br />

(U)HP metamorphic events? (Hacker et al 2006)<br />

The drill site of the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific<br />

Drill<strong>in</strong>g (CCSD) is located near Maobei village (N34° 25’,<br />

E118° 40’), about 17 km southwest of Donghai <strong>in</strong> the<br />

southern segment of the Sulu UHP terrane. Major goals of<br />

the CCSD, as outl<strong>in</strong>ed by Xu et al. (1998), <strong>in</strong>clude to<br />

reveal the crustal structure of convergent plate boundaries,<br />

to provide constra<strong>in</strong>ts on crust–mantle <strong>in</strong>teractions and<br />

mantle behavior dur<strong>in</strong>g deep subduction of cont<strong>in</strong>ental<br />

crust, and to <strong>in</strong>vestigate fluid evolution dur<strong>in</strong>g UHP<br />

metamorphism (Zhang et al 2006). The drill core obta<strong>in</strong>ed<br />

from the ma<strong>in</strong> hole of CCSD consists ma<strong>in</strong>ly of eclogites,<br />

ortho- and paragneisses, ultramafics, and some schists and<br />

quartzite. A number of petrographic and isotopic studies<br />

have shown that all of the Dabie-Sulu UHP rocks<br />

underwent prograde metamorphism related to plate<br />

subduction, with subsequent decompressionrecrystallization<br />

related to exhumation of the subducted<br />

plate and consequent amphibolite-facies retrograde<br />

metamorphism (Zhang et al. 1995; Wawrzenitz et al 2006,<br />

Romer et al 2003 ).<br />

The rocks from the CCSD ma<strong>in</strong> hole conta<strong>in</strong> many<br />

zircons. There exist zircon studies of the Dabie Sulu region<br />

– age datas and <strong>in</strong>clusion studies. Three different<br />

metamorphic events were determ<strong>in</strong>ed: A 244-236 Ma<br />

“precursor” UHP event, was followed by a 230-220 Ma<br />

“ma<strong>in</strong>” UHP event, which was itself term<strong>in</strong>ated by a 220-<br />

105<br />

205 Ma amphibolite facies overpr<strong>in</strong>t (Hacker et al. 2006,).<br />

Although there are many studies about <strong>in</strong>clusions <strong>in</strong> zircon<br />

and their relevance for the PT-path, little is known about<br />

the zircon growth itself and the ma<strong>in</strong> driv<strong>in</strong>g forces.<br />

The core samples show the whole range of<br />

metamorphism from UHP to greenschist metamorphism<br />

with<strong>in</strong> few centimetres. The comb<strong>in</strong>ation of texture and <strong>in</strong>situ<br />

age <strong>in</strong>formation allows to get new <strong>in</strong>formations about<br />

the Dabie-Sulu orogen evolution<br />

This study reports a detailed microstructural analysis<br />

and <strong>in</strong>ductively coupled plasma mass spectrometry (ICP)<br />

<strong>in</strong>-situ experiments on zircon <strong>in</strong> a fluid <strong>in</strong>fluenced shear<br />

zone. This research is aimed to: (1) document the<br />

petrological evolution of dist<strong>in</strong>ct zones <strong>in</strong> eclogite, (2) l<strong>in</strong>k<br />

the appearance of fluid and zircons <strong>in</strong> the Sulu region, (3)<br />

get a better resolution of the post peak evolution.<br />

Textural observation of newly grown zircon <strong>in</strong><br />

retrograde eclogite<br />

Transition fresh to retrograde eclogite<br />

The eclogite sample (Fig.1a) conta<strong>in</strong>s zones with<br />

retrograde assemblages range from UHP to greenschist<br />

facies. These form <strong>in</strong> centimetre wide zones that can be<br />

subdivided <strong>in</strong>to a transition zone and a strongly altered<br />

<strong>in</strong>ner part. While the fluid <strong>in</strong>clusion bear<strong>in</strong>g assemblage<br />

garnet-omphacite-coesite-phengite-rutile reflects UHP<br />

conditions, albite-cl<strong>in</strong>opyroxene symplectites appear <strong>in</strong> the<br />

first stage of retrogression as a response to post peak<br />

decompression. Garnet <strong>in</strong> the transition zone is cracked and<br />

rimmed by amphibole, signaliz<strong>in</strong>g fluid <strong>in</strong>fluence <strong>in</strong> the<br />

amphibolite facies. Fluid also triggers the breakdown of<br />

garnet and omphacite to symplectite II and <strong>in</strong>tergrowth of<br />

rutile and newly formed ilmenite. Phengite adjacent to<br />

omphacite breaks down to biotite, albite and white mica.<br />

The <strong>in</strong>ner part of the retrograde zone is a epidote, aeger<strong>in</strong>e<br />

bear<strong>in</strong>g greenschist facies assemblage. We observed two<br />

different types of zircons across the zone of retrogression.<br />

Zircons <strong>in</strong> the fresh eclogite<br />

Zircon I: In the fresh UHP eclogite the amount of<br />

zircon is very low. The few zircons are small (less than 30<br />

μm ). They have a magmatic core and a th<strong>in</strong> yellow<br />

metamorphic rim. The host m<strong>in</strong>erals are garnet and<br />

omphacite. The zircon <strong>in</strong>clusions <strong>in</strong> garnet and omphacite<br />

form clusters of up to ten small zircons.<br />

Zircons <strong>in</strong> the retrograde eclogite<br />

Across the sample the zircon amount and size grow<br />

obviously where the retrogression takes place. The size of<br />

this type II zircon (Fig 1b) lies between 30 to 150 μm.<br />

Some of a them sit directly on gra<strong>in</strong> c<br />

garnet-garnet<br />

boundaries, but often they are located at the boundary<br />

between garnet- phengite and symplectite. Zircons b located<br />

<strong>in</strong> symplectites conta<strong>in</strong> many <strong>in</strong>clusions. In the <strong>in</strong>ner part<br />

of the retrogression zone the late host m<strong>in</strong>erals phengite,<br />

garnet (II), quartz have zircon <strong>in</strong>clusions. In many cases,<br />

zircons with oscillatory zon<strong>in</strong>g are altered, exhibit<strong>in</strong>g<br />

blurr<strong>in</strong>g and broaden<strong>in</strong>g of primary oscillatoy zon<strong>in</strong>g,<br />

probably related to zircon recrystallisation. Some of the<br />

metamorphic rims are irregular and complex, <strong>in</strong>dicate to an<br />

complex and multistage history. At some gra<strong>in</strong> boundaries<br />

the zircons grow parallel to the the gra<strong>in</strong> boundary but no<br />

<strong>in</strong>tergrowth are observed.

106<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1 a) Eclogite sample with <strong>in</strong>creas<strong>in</strong>g retrogression from right to left, boxes mark the th<strong>in</strong> section area, b) Concordia diagram, c) Zircon<br />

from the most retrogressive part<br />

Geochronology<br />

Based on CL images, three doma<strong>in</strong>s can be <strong>in</strong>dentified<br />

<strong>in</strong> most zircons, i.e. bright-lum<strong>in</strong>escent cores, lower<br />

lum<strong>in</strong>escent <strong>in</strong>ner-,mantle (rim I), small light rim II (not on<br />

every zircon visible). The cores preserve oscillator<strong>in</strong>g,<br />

some with irregular patterns, whereas the rims are more or<br />

less homogeneous. N<strong>in</strong>ety-two spots were analysed from<br />

35 zircons of the alterated <strong>in</strong>ner part of the eclogite sample.<br />

The core analyses give a discordia that <strong>in</strong>tersects at 784 ±<br />

20 and 207.6 ± 6.8 Ma (Fig. 1c). Data from the cores yield<br />

apparent 206Pb/238U ages from 221 to 728 with Th/U<br />

ratios of 0.04-1.12. Some of these Data po<strong>in</strong>ts lie on the<br />

boundary of rim and core, so these are mixed ages. 22<br />

analyses of the rims are concordant with<strong>in</strong> the analytical<br />

uncerta<strong>in</strong>ty. The ages ranges from 180 to 213 Ma with a<br />

weighted mean age 207 ± 2 Ma.<br />

Questions: Why does the young zircon grow <strong>in</strong> dist<strong>in</strong>ct<br />

zones? Which factors are relevant for the growth of zircon<br />

<strong>in</strong> these zones? What are the ma<strong>in</strong> factors for zircon growth<br />

and transport?<br />

The appearance of fluids is frequently reported from<br />

Dabie-Sulu samples (Xiao et al. 2000; Franz et al. 2001).<br />

The <strong>in</strong>vestigations show that fluid <strong>in</strong>clusions occur ma<strong>in</strong>ly<br />

<strong>in</strong> UHP rocks from the depth <strong>in</strong>tervals of 100 to 1250 m,<br />

and 2150 to 2720 m; whereas their abundance <strong>in</strong> the other<br />

depth <strong>in</strong>tervals are low (Zhang 2006). Previous workers<br />

have established relationships between fluid <strong>in</strong>clusions <strong>in</strong><br />

Sulu UHP rocks and successive stages of metamorphism.<br />

Several authors identified fluid <strong>in</strong>clusions <strong>in</strong> CCSD<br />

retrograde m<strong>in</strong>erals and <strong>in</strong> zircons with low grade m<strong>in</strong>eral<br />

<strong>in</strong>clusions.<br />

The evidences for fluid <strong>in</strong> this sample are given by<br />

fluid <strong>in</strong>clusions, water-bear<strong>in</strong>g m<strong>in</strong>erals and ve<strong>in</strong>s. We<br />

suggest fluid plays a significant role <strong>in</strong> the formation of<br />

zircon <strong>in</strong> this retrogressed eclogite sample. The fluid<br />

triggers zirconium host<strong>in</strong>g m<strong>in</strong>eral reactions and the<br />

solution/ precipitation of zircon. Therefore the amphibolite<br />

to greenschist facies event at 207 Ma is most likely l<strong>in</strong>ked<br />

to a fluid event.<br />

References:<br />

Hacker et al. 2000 Exhumation of ultrahigh-pressure cont<strong>in</strong>ental crust <strong>in</strong><br />

east central Ch<strong>in</strong>a: Late Triassic-Early Jurassic tectonic unroof<strong>in</strong>g,<br />

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 105, NO. B6,<br />

PAGES 13,339–13,364, 2000<br />

Hacker et al 2006 High-temperature geochronology constra<strong>in</strong>ts on the<br />

tectonic<br />

history and architecture of the ultrahigh-pressure Dabie-Sulu Orogen,<br />

TECTONICS, VOL. 25, TC5006<br />

Zhang et al 2006 Ultrahigh pressure metamorphic rocks from the Ch<strong>in</strong>ese<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g Project: I. Petrology and geochemistry<br />

of the ma<strong>in</strong> hole (0–2,050 m), Contrib M<strong>in</strong>eral Petrol 152:421–441<br />

Zhang et al. 1995; Petrology, metamorphic process and genesis of the<br />

Dabie-Sulu eclogite belt, east-central Ch<strong>in</strong>a, Acta Geologica S<strong>in</strong>ica.<br />

Vol. 69, no. 4, pp. 306-325. Nov. 1995<br />

Wawrzenitz et al 2006 Dat<strong>in</strong>g of subduction and differential exhumation of<br />

UHP rocks from the Central Dabie Complex (E-Ch<strong>in</strong>a): Constra<strong>in</strong>ts<br />

from microfabrics, Rb–Sr and U–Pb isotope systems, Lithos, Volume<br />

89, Issues 1-2, June 2006, Pages 174-201<br />

R.L.Romer,N.Wawrzenitz,R.Oberhänsli(2003)Anomalous unradiogenic<br />

87Sr//86Sr ratios <strong>in</strong> ultrahigh-pressure crustal carbonates - evidence for<br />

fluid <strong>in</strong>filtration dur<strong>in</strong>gdeepsubduction? Terra Nova 15 (5), 330–336.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Pleistocene changes <strong>in</strong> terrigenous sediment<br />

<strong>in</strong>put to the eastern tropical Pacific based on<br />

ODP Sites 1237 and 1239<br />

D. RINCON MARTINEZ 1 , C. SAUKEL 1 , F. LAMY 1 , S. STEPH 1 , A.<br />

STURM 1 , R. TIEDEMANN 1<br />

1 Alfred-Wegener-Institute for Polar and Mar<strong>in</strong>e Research, Am<br />

Alten Hafen 26, 27568 Bremerhaven, Germany;<br />

daniel.r<strong>in</strong>con.mart<strong>in</strong>ez@awi.de; frank.lamy@awi.de<br />

One of the fundamental miss<strong>in</strong>g l<strong>in</strong>ks <strong>in</strong> understand<strong>in</strong>g<br />

Pleistocene changes <strong>in</strong> southeast Pacific oceanography,<br />

productivity and El Niño behavior as well as associated<br />

variations <strong>in</strong> thermocl<strong>in</strong>e depth, upwell<strong>in</strong>g and dust<br />

fertilisation is the knowledge of changes <strong>in</strong> southeast trade<br />

w<strong>in</strong>d strength and dust transport on millennial and orbital<br />

time scales. Our study aims to reconstruct changes <strong>in</strong> South<br />

American cont<strong>in</strong>ental aridity, dust supply and trade w<strong>in</strong>d<br />

strength at ODP Sites 1237 and 1239.<br />

Site 1237 was drilled <strong>in</strong> the easternmost flank of the<br />

Nazca Ridge, about 140 km off the coast of southern Peru<br />

west of the deep-sea trench. This site is located below the<br />

modern path of eolian sediment <strong>in</strong>put <strong>in</strong> an area of high<br />

biological productivity supplied by the divergence-driven<br />

upwell<strong>in</strong>g associated with the regional trade-w<strong>in</strong>d system<br />

(Fig. 1). Site 1239, on the other hand, was drilled on the<br />

Carnegie Ridge, about 120 km off the coast of Ecuador, <strong>in</strong><br />

an area that presently receives fluvial sediment <strong>in</strong>put from<br />

the Guayas River that is the largest river of tropical South<br />

America flow<strong>in</strong>g <strong>in</strong>to the Pacific Ocean (Fig. 1).<br />

We present high resolution geochemical records for the<br />

past 2 Ma. The records were measured with an Avaatech<br />

XRF Core Scanner at the AWI Bremerhaven <strong>in</strong> millennial<br />

to centennial-scale resolution and cover the uppermost ca.<br />

40 mcd at Site 1237 and ca. 110 mcd at Site 1239. Our<br />

geochemical measurements <strong>in</strong>clude semi-quantitative<br />

records of major and m<strong>in</strong>or elements cover<strong>in</strong>g the suite of<br />

elements between Al and Ba. For the changes <strong>in</strong><br />

terrigenous sediment <strong>in</strong>put we concentrate on primarily<br />

terrigenous element records like Fe, Ti, K, and Al. The<br />

obta<strong>in</strong>ed records show pronounced orbital-scale variability<br />

with a clear antiphas<strong>in</strong>g between Sites 1237 and 1239. At<br />

site 1237, near the arid coast of Peru, high (low)<br />

accumulation of terrigenous elements is evidenced dur<strong>in</strong>g<br />

glacial (<strong>in</strong>terglacial) times, whereas the conversed pattern<br />

is observed at Site 1239. Prelim<strong>in</strong>arily, we <strong>in</strong>terpret this<br />

antiphased pattern as enhanced supply of eolian terrigenous<br />

material to Site 1237 dur<strong>in</strong>g glacials and at the same time<br />

reduced fluvial sediment supply to Site 1239. This<br />

<strong>in</strong>terpretation would be consistent with enhanced trade<br />

w<strong>in</strong>d strength and reduced tropical ra<strong>in</strong>fall dur<strong>in</strong>g glacials<br />

as suggested by some other records. Further studies<br />

<strong>in</strong>clud<strong>in</strong>g a more detailed chronostratigraphy, gra<strong>in</strong>-size<br />

analyses, and oxygen isotope studies <strong>in</strong> order to reconstruct<br />

thermocl<strong>in</strong>e depth reconstructions are currently underway.<br />

Fig. 1. SEC=South Equatorial Current, NECC=North<br />

Equatorial Countercurrent, EUC=Equatorial<br />

Undercurrent, PCC=Peru-Chile Current, PCCC=Peru-<br />

Chile Countercurrent, CC=Coastal Current,<br />

GU=Gunther Undercurrent. Modern mean annual seasurface<br />

temperatures (<strong>in</strong>°C) after Ocean Climate<br />

Laboratory, 1999 (Tiedemann & Mix, 2007). Yellow<br />

arrows <strong>in</strong>dicate prevalent w<strong>in</strong>d direction.<br />

Fig. 2. Comparison of Fe content changes at Sites 1237 and<br />

1239 over the past 1.5 Ma show<strong>in</strong>g antiphased changes on<br />

orbital time-scales. Benthic 18O curve of Liesicki & Raymo<br />

(2005) below for reference. Gray bars mark glacials.<br />

107

108<br />

<strong>ICDP</strong><br />

The electrical conductivity structure between<br />

the transitional (near SAFOD) and locked<br />

(SE of Cholame) segments of the San<br />

Andreas Fault, <strong>in</strong>clud<strong>in</strong>g the source region of<br />

the non-volcanic tremors<br />

O. RITTER 1 , M. BECKEN 1 , U. WECKMANN 1 , P. A. BEDROSIAN1, T.<br />

RYBERG 1 , C. HABERLAND 1 .<br />

1 GeoForschungsZentrum, Telegrafenberg, 14473 Potsdam<br />

2 US Geological Survey, Denver, USA<br />

The <strong>ICDP</strong>/<strong>IODP</strong> DFG-SPP funded magnetotelluric<br />

(MT) experiment DeepRoot near the San Andreas Fault<br />

(SAF) Observatory at Depth (SAFOD) revealed a steeplydipp<strong>in</strong>g<br />

upper crustal high electrical conductivity zone<br />

flank<strong>in</strong>g the seismically def<strong>in</strong>ed SAF to the NE, widen<strong>in</strong>g<br />

<strong>in</strong>to the lower crust where it appears to be connected to a<br />

broad anomaly <strong>in</strong> the upper mantle. Becken et al. (<strong>2008</strong>)<br />

suggested that the high conductivity represents a deeprooted<br />

channel for crustal and/or mantle fluid ascent,<br />

consistent with the fluid chemistry of the SAFOD<br />

(Wiersberg & Erz<strong>in</strong>ger, 2007). Both the geochemical data<br />

and the resistivity model agree <strong>in</strong> suggest<strong>in</strong>g that a deeprooted<br />

fluid channel penetrates the entire crust. However,<br />

results from DeepRoot show that the upper crustal branch<br />

of the fluid conduit is located NE of the seismicallydef<strong>in</strong>ed<br />

SAF. This suggests that the fault does not provide a<br />

major pathway for fluids. This <strong>in</strong>terpretation is supported<br />

by the position and orientation of the high-conductivity<br />

zones <strong>in</strong> the upper crust and by recent studies with<strong>in</strong> the<br />

SAFOD ma<strong>in</strong> hole, which <strong>in</strong>dicate that (i) pore pressures<br />

with<strong>in</strong> the core of the SAF zone are not anomalously high<br />

(Zoback, 2006), (ii) mantle-derived fluids are m<strong>in</strong>or<br />

constituents <strong>in</strong> the fault-zone fluid composition, (Wiersberg<br />

& Erz<strong>in</strong>ger, 2007) and (iii) both the mantle content and the<br />

fluid pressure <strong>in</strong>crease towards the NE of the SAF<br />

(Zoback, 2006; Wiersberg & Erz<strong>in</strong>ger, 2007). All of these<br />

observations are consistent with a deep rooted (<strong>in</strong> the<br />

mantle or lower crust) source of fluids generat<strong>in</strong>g the<br />

observed high fluid pressures NE of the fault but not with<strong>in</strong><br />

the SAF.<br />

Analysis of triggered event data from the borehole<br />

High Resolution Seismic Network (HRSN) at Parkfield,<br />

California, revealed tremor-like signals orig<strong>in</strong>at<strong>in</strong>g to the<br />

south with<strong>in</strong> the Cholame Valley, approximately 40 km SE<br />

of Parkfield. Their locations <strong>in</strong>dicate that, with<strong>in</strong> the search<br />

radius, the tremors are conf<strong>in</strong>ed to a ~25-km segment of<br />

the SAF and occur at depths of between ~20 and 40 km.<br />

Nadeau & Dolenc (2005) suggested that either fluids are<br />

not important for the SAF tremors or an alternative fluid<br />

source (when compared with subduction zones) exists<br />

below the seismogenic zone <strong>in</strong> this area. Ellsworth et al.<br />

(2005) confirmed the observation of non-volcanic tremors<br />

<strong>in</strong> May 2005 dur<strong>in</strong>g the deployment of a multi-level<br />

borehole seismic array <strong>in</strong> the SAFOD ma<strong>in</strong> hole. An<br />

apparent correlation between tremor and local microearthquake<br />

rates at Cholame (Nadeau and Dolenc, 2005)<br />

suggests that deep deformation associated with the<br />

Cholame tremors may be stress<strong>in</strong>g the shallower<br />

seismogenic zone <strong>in</strong> this area. Further evidence for stresscoupl<strong>in</strong>g<br />

between the deep tremor zone and the<br />

seismogenic SAF is observed <strong>in</strong> the correlation between<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

tremor and the 2004, M6 Parkfield earthquake,<br />

approximately 10 km NW of Cholame.<br />

Near Cholame, earlier MT work found evidence for a<br />

resistive crust beneath the SAF (Park & Biasi, 1991) which<br />

could be <strong>in</strong>dicative of a dry zone capable of trapp<strong>in</strong>g fluids<br />

<strong>in</strong> the lower crust and/or the upper mantle. This hypothesis<br />

would be consistent with low mantle derived He content <strong>in</strong><br />

the Jack-Ranch Highway-46 Well (Kennedy et al., 1997)<br />

near Cholame and <strong>in</strong> support of a locally well-conf<strong>in</strong>ed<br />

source region for the non-volcanic tremors (Nadeau &<br />

Dolenc, 2005). It would mean, however, that the geological<br />

and / or rheological situation near Cholame is markedly<br />

different from Parkfield, where the resistivity model and<br />

the fluid chemistry (Kennedy et al., 1997; Wiersberg &<br />

Erz<strong>in</strong>ger, 2007) suggest a pathway for fluids <strong>in</strong>to the brittle<br />

regime of the SAF system.<br />

All of the above observations suggest that tremors (and<br />

possibly associated fluids) appear to be closely l<strong>in</strong>ked to<br />

fundamental processes govern<strong>in</strong>g both the deep roots and<br />

the seismogenic zone of large fault zones. The presence or<br />

absence of NVT could co<strong>in</strong>cide with the transition of the<br />

SAF from be<strong>in</strong>g locked (Cholame) to <strong>in</strong>termediate creep<br />

(SAFOD) and could reflect significant structural changes<br />

affect<strong>in</strong>g the deep hydraulic system along this portion of<br />

the SAF which <strong>in</strong> turn could be detectable with MT. Tests<br />

based on constra<strong>in</strong>ed <strong>in</strong>versions of the DeepRoot MT data<br />

across the SAFOD clearly show that a resistive lower crust<br />

is <strong>in</strong>consistent with the data (Becken et al., <strong>2008</strong>). This also<br />

means however, that we could resolve a resistive lower<br />

crust if it should exist beneath the Cholame segment of the<br />

SAF. Furthermore, if migration of fluids from the lower<br />

<strong>in</strong>to the upper crust is blocked by an impermeable seal, the<br />

upper crust should be more resistive. In fact, the eastern<br />

conductor (EC) which we <strong>in</strong>terpret as the upper crustal<br />

branch of the fluid channel near the SAFOD appears to be<br />

absent <strong>in</strong> prelim<strong>in</strong>ary <strong>in</strong>version models of the southernmost<br />

short profile of Unsworth et al. (unpublished), located just<br />

5 km NW of Cholame.<br />

To address these questions we have been cont<strong>in</strong>u<strong>in</strong>g<br />

our research activities with the TremorMT (GFZ-funded)<br />

and ELSAF (DFG+GFZ fund<strong>in</strong>g) projects to image an<br />

entire segment of the SAF with a network of MT stations,<br />

deployed from the Pacific Ocean <strong>in</strong>to the Great Valley,<br />

cross<strong>in</strong>g the SAFOD near Parkfield and the NVT source<br />

region beneath the SAF near Cholame. In autumn 2007, we<br />

measured MT data along a 130 km long profile across the<br />

Coast Ranges and centred above the source region of nonvolcanic<br />

tremors near Cholame (project TremorMT). We<br />

extended the exist<strong>in</strong>g DeepRoot profile to a length of 130<br />

km to better constra<strong>in</strong> lower crustal and upper mantle<br />

conductivity structure. Furthermore, four small-aperture<br />

seismic arrays (SASA) were deployed <strong>in</strong> cooperation with<br />

the USGS <strong>in</strong> the vic<strong>in</strong>ity of Cholame to test if the location<br />

accuracy of the NVT-events (<strong>in</strong> particular the depth<br />

estimate) could be improved. Prelim<strong>in</strong>ary results of the<br />

SASA work, which was carried out <strong>in</strong> cooperation with W.<br />

Ellsworth from the USGS, are very promis<strong>in</strong>g as we<br />

observed numerous tremor-type signals <strong>in</strong> a record<strong>in</strong>g time<br />

of only 6 weeks. We are currently analyz<strong>in</strong>g these data.<br />

With ELSAF we will cont<strong>in</strong>ue to collect MT data <strong>in</strong> spr<strong>in</strong>g<br />

<strong>2008</strong> with an array of MT sites connect<strong>in</strong>g the highresolution<br />

profiles across the SAFOD and the Cholame<br />

Valley. With the 3D array of MT sites we can resolve<br />

along-strike variations between the Colame and Parkfield

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

segments of the SAF (see Fig. 1 for exist<strong>in</strong>g and planned<br />

MT sites).<br />

Fig. 1: Proposed and exist<strong>in</strong>g MT sites <strong>in</strong> the Cholame-Parkfield area <strong>in</strong> Central California. Blue asterisks and red dots <strong>in</strong>dicate the<br />

proposed new comb<strong>in</strong>ed long-period(LMT)/broad-band(BB) and BB-only sites, respectively, white asterisks and green dots <strong>in</strong>dicate<br />

exist<strong>in</strong>g MT sites, acquired by the GFZ Potsdam and the UC Riverside <strong>in</strong> 2005/6 and by Unsworth et al. (1997). Additional MT data<br />

recently gathered <strong>in</strong> the NE part by S. Park (collaborator <strong>in</strong> DeepRoot) are shown as green squares. The SAFOD site near Parkfield<br />

is marked with a yellow star and the region of the non-volcanic tremors near Cholame is <strong>in</strong>dicated by a yellow rectangle. Phase I of<br />

the project (TremorMT, GFZ funded) as successfully completed <strong>in</strong> fall 2007 with data acquisition along the 130 km long profile<br />

(CHO) and extend<strong>in</strong>g the exist<strong>in</strong>g 50km long MT/seismic profile of the DeepRoot project from the Pacific coast <strong>in</strong>to the San Joaqu<strong>in</strong><br />

Valley (profile PKD). In phase II of the project (<strong>ICDP</strong>, ELSAF) profiles CHO and PKD will be connected spatially with an array of<br />

LMT/BB and BB magnetotelluric sites, as <strong>in</strong>dicated with blue asterisks and red dots. Gray triangles <strong>in</strong>dicate the locations of the<br />

seismic m<strong>in</strong>i-arrays (phase I); the solid black l<strong>in</strong>e and black asterisks <strong>in</strong>dicate the location of the exist<strong>in</strong>g seismic<br />

refraction/reflection l<strong>in</strong>e SJ-6 (Murphy & Walter, 1984).<br />

Furthermore, our research activities onshore will be<br />

extended offshore <strong>in</strong> a collaborative research effort with<br />

our colleagues from Scripps Institution of Oceanography,<br />

UCSD. Brent Wheelock, Kerry Key, and Steven Constable<br />

will be extend<strong>in</strong>g our land profiles with their Scripps<br />

funded “Deep San Andreas Fault Boundary Structure from<br />

Mar<strong>in</strong>e MT” experiment. The offshore data will be<br />

collected <strong>in</strong> autumn <strong>2008</strong>. The comb<strong>in</strong>ation of onshore and<br />

offshore data will help us to see the whole picture as<br />

modell<strong>in</strong>g shows that important parts of the San Andreas<br />

Fault structure, e.g. a deep rooted source of fluids <strong>in</strong> the<br />

upper mantle, can only be fully imaged by extend<strong>in</strong>g the<br />

MT array offshore.<br />

109<br />

References:<br />

Becken M, Ritter, O., Park, S., Bedrosian, P., Weckmann, U., and Weber,<br />

M., <strong>2008</strong>. A deep crustal fluid channel <strong>in</strong>to the San Andreas Fault<br />

system near Parkfield, . Geophys. J Int.,(submitted), Manuscript under<br />

moderate revision – <strong>in</strong>cluded as an attachment to this proposal.<br />

Ellsworth, W. L., Luetgert J. H., Oppenheimer D. H., 2005. Borehole Array<br />

Observations of Non-Volcanic Tremor at SAFOD, AGU fall meet<strong>in</strong>g,<br />

San Francisco.<br />

Kennedy, B. M., Kharaka, Y. K., Evans, W. C., Ellwood, A., DePaolo, D. J.,<br />

Thordsen, J., Ambats, G. and Mar<strong>in</strong>er, R. H., 1997. Mantle fluids <strong>in</strong> the<br />

San Andreas Fault System, California. Science, 278, 1278-1281.<br />

Nadeau, M. N., and Dolenc, D., 2005, Nonvolcanic Tremors Deep Beneath<br />

the San Andreas Fault. Science, 307, 389.<br />

Park, S.K., Biasi, G.P., Mackie, R.L., Madden, T.R., 1991. Magnetotelluric<br />

evidence for crustal suture zones bound<strong>in</strong>g the southern Great Valley,<br />

California. J. Geophys. Res., 96(B1), p. 353-376.<br />

Wiersberg, T. and Erz<strong>in</strong>ger, J. 2007. A helium isotope cross-section study<br />

through the San Andreas Fault at seismogenic depths, Geochemistry,<br />

Geophysics, Geosystems, 8, Q01002<br />

Zoback, M.; Hickman, S.; Ellsworth, W., 2006. Structure and properties of<br />

the San Andreas fault <strong>in</strong> central California: Prelim<strong>in</strong>ary results from the<br />

SAFOD experiment, Geophysical Research Abstracts, 8, EGU

110<br />

<strong>IODP</strong><br />

The plat<strong>in</strong>um group element and osmium<br />

isotope <strong>in</strong>ventory of Atlantis Massif<br />

M. ROSNER 1,3 , B. PEUCKER-EHRENBRINK 2 , W. BACH 3<br />

1 Bundesanstalt für Materialforschung und –prüfung formerly<br />

Universität Bremen, Petrologie der Ozeankruste,<br />

mart<strong>in</strong>.rosner@bam.de<br />

2 Woods Hole Oceanographic Institution, Mar<strong>in</strong>e Chemistry &<br />

Geochemistry, Woods Hole, MA 02543<br />

3 Universität Bremen, Petrologie der Ozeankruste, Klagenfurter<br />

Straße, GEO Geb., 28334 Bremen<br />

Dur<strong>in</strong>g <strong>IODP</strong> Expeditions 304/305 a 1400m thick<br />

section of ultramafic to gabbroic oceanic crust was<br />

recovered from the Atlantis Massif. The massif is an<br />

Oceanic Core Complex that formed <strong>in</strong> the past 1.5-2.0 Ma<br />

at the <strong>in</strong>tersection of the Mid-Atlantic Ridge and the<br />

Atlantis fracture zone. Hole U1309D was drilled <strong>in</strong> the<br />

central part of the Core Complex, and gabbros and<br />

troctolites are the dom<strong>in</strong>ant rock type (92%), followed by<br />

ultramafic (~5%) and basaltic (~3%) rocks. Hole U1309D<br />

is the third deepest drill hole <strong>in</strong> oceanic crust and the<br />

recovered section is believed to be a common endmember<br />

of ocean crust from at slow spread<strong>in</strong>g mid ocean ridge<br />

sett<strong>in</strong>gs. We <strong>in</strong>itiate a plat<strong>in</strong>um group element and osmium<br />

isotope project to characterize the PGE <strong>in</strong>ventory of ocean<br />

crust of this reference section and study chemical fluxes<br />

dur<strong>in</strong>g late-stage alteration processes related to the uplift of<br />

the crust.<br />

To characterize the drilled section we selected MORBs<br />

(from the top of the massif) and diabases (<strong>in</strong>trusive <strong>in</strong><br />

gabbros) as well as gabbros (gabbros to oliv<strong>in</strong>e gabbros)<br />

and ultramafics (troctolitic lherzolite).<br />

First, PGE data show a three orders of magnitude range<br />

of concentration between the gabbros and the ultramafics.<br />

Without exceptions, the gabbros are extremely depleted <strong>in</strong><br />

PGEs relative to PUM (10-4 to 10-2), whereas the<br />

ultramafics are similar to troctolites recovered from ODP<br />

Hole 735B and show only m<strong>in</strong>or depletion relative to<br />

PUM. The <strong>in</strong>vestigated basalts and diabases show a wide<br />

range of PGE concentrations reflect<strong>in</strong>g ma<strong>in</strong>ly different<br />

degrees of alteration or seafloor weather<strong>in</strong>g. The impact of<br />

alteration is illustrated by the 187Os/188Os isotope ratios<br />

that correlate positively with 1/Os. The troctolite with the<br />

highest osmium concentration shows the lowest<br />

187Os/188Os ratio of 0.1438, whereas the osmium-poor<br />

gabbros and a highly weathered basalt sample have<br />

187Os/188Os ratios between 0.1624 and 0.2288.<br />

Analyses of sulfur, carbon and water concentrations<br />

will help to dist<strong>in</strong>guish between primary mantle-derived<br />

characteristics and secondary alteration signals.<br />

<strong>IODP</strong><br />

The Miocene climatic record of Southwest<br />

Africa: results from a 50-kyr resolutionsilt<br />

gra<strong>in</strong>-size record of DSDP Site 530A (Project:<br />

RCOM TP A5/A6)<br />

B. ROTERS 1 , R. HENRICH 2<br />

1<br />

Research Center Ocean Marg<strong>in</strong>s, Universität Bremen, Postfach<br />

330 440, 28334 Bremen, bastian.roters@uni-bremen.de<br />

2<br />

Fachbereich Geowissenschaften, Universität Bremen, Postfach<br />

330 440, 28334 Bremen, henrich@uni-bremen.de<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

DSDP Site 530A is positioned <strong>in</strong> the Southeast Atlantic<br />

on the northern foot of the Walvis Ridge <strong>in</strong> a distance of<br />

280 km of the Angolan coast. Today it is bathed <strong>in</strong> Deeper<br />

Component Water well below the CCD <strong>in</strong> 4629 m water<br />

depth. Because of low mass accumulation rates (MAR) the<br />

Hole 530A covers sediments from the Holocene down to<br />

the Cretaceous (Shipboard Scientific Party, 1984). The<br />

surveyed section spans from the Burdigalian to the<br />

Tortonian (19 to 9 Myr) and has been sampled <strong>in</strong> 50 kyr<br />

<strong>in</strong>tervals. After the sampl<strong>in</strong>g the sediments were washed<br />

over a 63µm-mesh sieve to remove the sand fraction. The<br />

f<strong>in</strong>e fraction has been separated <strong>in</strong>to clay and silt by us<strong>in</strong>g<br />

the Atterberg method. F<strong>in</strong>ally the gra<strong>in</strong>-size distribution of<br />

the silt fraction was <strong>in</strong>vestigated us<strong>in</strong>g a Micromeritics<br />

Sedigraph. The silt was measured <strong>in</strong> two cycles, after the<br />

first cycle carbonate has been removed from the material<br />

with Hydrochloric Acid. With this method it is possible to<br />

dist<strong>in</strong>guish between the size distributions of the bulk silt,<br />

the terrigeneous silt and the carbonaceous silt. To get more<br />

accurate values of carbonate and organic matter (TOC)<br />

contents of the samples, bulk sediment material was<br />

<strong>in</strong>vestigated with a carbon/sulphur combustion analyser<br />

(LECO CS-200).<br />

The results show very low carbonate contents,<br />

especially <strong>in</strong> the part below 10.5 Myr where <strong>in</strong> some<br />

samples carbonate is totally absent. This is due to the depth<br />

of the site, which is today well below the CCD, as it was<br />

also dur<strong>in</strong>g the Miocene. The low carbonate contents<br />

expla<strong>in</strong> also the low MAR. The TOC values are also low <strong>in</strong><br />

the part below 11.5 Myr. They show a dist<strong>in</strong>ct seesaw<br />

pattern with values rang<strong>in</strong>g between 0.08 and generally 0.3<br />

wt-%. Only <strong>in</strong> some cases TOC contents of more than 0.4<br />

wt-% were found. After 11.5 Myr TOC contents <strong>in</strong> the<br />

sediment rise due to <strong>in</strong>creas<strong>in</strong>g productivity and vary<br />

between 0.2 and 0.8 wt-%. Dur<strong>in</strong>g the productivity rise<br />

also the carbonate contents <strong>in</strong>creased as a result of better<br />

preservation, because of an <strong>in</strong>creased carbonate ra<strong>in</strong> to the<br />

seafloor. The <strong>in</strong>ception of higher productivity <strong>in</strong> surface<br />

waters was due to the onset of coastal upwell<strong>in</strong>g along the<br />

Southwest African marg<strong>in</strong> at around 11 Myr (Diester-<br />

Haass et al., 2002). The <strong>in</strong>fluence of the upwell<strong>in</strong>g and its<br />

filaments is also recognisable <strong>in</strong> the Angolan Bas<strong>in</strong>. The<br />

Sedigraph measurements show, that most of the silt is<br />

concentrated <strong>in</strong> the size fraction between 3 and 6 µm.<br />

Because of the low carbonate contents, only the<br />

terrigeneous silt fraction is mentioned further on. The mean<br />

silt sizes vary between 8 and 12 µm dur<strong>in</strong>g the time<br />

between 19.0 and 13.5 Myr. There is one exception at 16.1<br />

Myr when the mean size is at 18 µm. Possibly here a<br />

turbidite bed has been sampled, because also the clay<br />

contents of this sample are significantly lower than usual.<br />

However, dur<strong>in</strong>g the Middle and Late Miocene the<br />

turbidite activity was generally very low (Stow, 1984)..<br />

The <strong>in</strong>terval between 13.5 and 12.5 Myr has the lowest<br />

mean size values of the whole section, vary<strong>in</strong>g between 6<br />

and 8 µm only. From 11.0 Myr on the mean size <strong>in</strong>crease<br />

and reach a maximum value of about 17 µm.<br />

To adress climatic changes from the gra<strong>in</strong> sizes, the<br />

sources and transport mechanisms for the silt have to be<br />

clarified. Two potential sources may be considered for the<br />

terrigeneous <strong>in</strong>put at the <strong>in</strong>vestigated site. The coastal dry<br />

lands and deserts or a more humid h<strong>in</strong>terland, respectively.<br />

As transport mechanisms three possibilities were taken <strong>in</strong>to<br />

account: w<strong>in</strong>d transport, fluvial supply and sediment

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

transport by bottom currents. Bottom currents as a transport<br />

medium are not taken <strong>in</strong>to account, because the gra<strong>in</strong> size<br />

plot shows cont<strong>in</strong>uous spectra. The rema<strong>in</strong><strong>in</strong>g processes<br />

are w<strong>in</strong>d transport and fluvial supply, which have to be<br />

assigned to specific gra<strong>in</strong> sizes.<br />

From various studies from the Atlantic off Northern<br />

and Southern Africa (Kastanja et al., 2006; Holz et al.,<br />

2004) is known that f<strong>in</strong>er silt is supplied by rivers while<br />

w<strong>in</strong>d is recognized by a coarser size spectrum. Therefore<br />

the gra<strong>in</strong> size distribution is split <strong>in</strong>to a f<strong>in</strong>er (2 to 10 µm)<br />

and a coarser (10 to 63 µm) fraction. The f<strong>in</strong>er fraction is<br />

addressed to fluvial transport and represents humid climate<br />

and the coarser silt represents w<strong>in</strong>d transport and dry<br />

conditions, respectively. The f<strong>in</strong>er silt mean sizes show a<br />

dist<strong>in</strong>ct seesaw pattern between 19.0 and 15.0 Myr. Here,<br />

the peak values clearly display 400 kyr frequency pattern.<br />

From 14.0 Myr to the top of the section the mean sizes<br />

show a decreas<strong>in</strong>g trend. From 11.0 Myr also the f<strong>in</strong>er silt<br />

contents decrease. This po<strong>in</strong>ts to a reduced fluvial supply,<br />

probably giv<strong>in</strong>g evidence to a climatic shift to a dryer<br />

period. The mean sizes for the coarser silt vary <strong>in</strong> a much<br />

broader range. Here the smallest sizes were found between<br />

18.0 and 19.0 Myr. Towards the section top the values are<br />

higher with peaks at 14.5, 13.7 and 9.7 Myr. From 18.0 to<br />

11.0 Myr the values vary between 15 and 18 µm mostly. At<br />

11.0 Myr mean sizes reach values coarser than 18 µm<br />

more often. This may refer to higher seaward w<strong>in</strong>d speeds.<br />

These are aga<strong>in</strong> an <strong>in</strong>dication for a dryer cont<strong>in</strong>ent, because<br />

the transport of humid air masses from the ocean to the<br />

land is prevented. Contemporaneously the seaward w<strong>in</strong>ds<br />

enhance coastal upwell<strong>in</strong>g which started at these times.<br />

References:<br />

Diester-Haass, L., Myers, P. A., Vidal, L. (2002): The late Miocene onset of<br />

high productivity <strong>in</strong> the Benguela Current upwell<strong>in</strong>g system as part of a<br />

global pattern . Mar. Geology, 180(1-4):87-103.<br />

Holz, C, Stuut, J. B.W., Henrich, R. (2004): Terrigenous sedimentation<br />

processes along the cont<strong>in</strong>ental marg<strong>in</strong> off NW Africa: implications<br />

from gra<strong>in</strong>-size analysis of seabed sediments. Sedimentology,<br />

51(5):1145-1154.<br />

Kastanja, M.-M., Diekmann, B., Henrich, R. (2006): Controls on carbonate<br />

and terrigenous deposition <strong>in</strong> the <strong>in</strong>cipient Benguela upwell<strong>in</strong>g system<br />

dur<strong>in</strong>g the middle to the late Miocene (ODP Sites 1085 and 1087).<br />

Paleogeogr.Paleoclimatol.Paleoecol,. 241(3-4):515-530.<br />

Shipboard Scientific Party (1984): Site 530: Southeastern Corner of the<br />

Angola Bas<strong>in</strong>. In: Hay, W. W., Sibuet, J.-C. et al. (eds). Initial Reports.<br />

DSDP, Leg 75. U.S. Government Pr<strong>in</strong>t<strong>in</strong>g Office, Wash<strong>in</strong>gton, pp 29-<br />

285.<br />

Stow, D. A. V. (1984): Turbidite facies, Associations and Sequences <strong>in</strong> the<br />

Southeastern Angola Bas<strong>in</strong>. In: Hay, W. W., Sibuet, J.-C. et al. (eds).<br />

Initial Reports. DSDP, Leg 75. U.S. Government Pr<strong>in</strong>t<strong>in</strong>g Office,<br />

Wash<strong>in</strong>gton, pp 785-799.<br />

<strong>IODP</strong><br />

Cold-water coral mound <strong>in</strong>itiation and early<br />

development – results of benthic<br />

foram<strong>in</strong>iferal assemblages and gra<strong>in</strong>-size<br />

analysis<br />

A. RÜGGEBER 1 , C. DULLO 1 , <strong>IODP</strong> EXP 307 SCIENTIFIC PARTY<br />

1 Leibniz Institut für Meereswissenschaften IFM-GEOMAR,<br />

Wischhofstr. 1-3, 24149 Kiel, arueggeberg@ifm-geomar.de<br />

Cold-water corals reefs and carbonate mound prov<strong>in</strong>ces<br />

<strong>in</strong> the Porcup<strong>in</strong>e Seabight and the Rockall Trough of the<br />

north Atlantic are known s<strong>in</strong>ce their first discovery 10 to<br />

15 years ago (Hovland et al., 1994; Henriet et al., 1998; De<br />

Mol et al., 2002). These cold-water coral ecosystems build<br />

up spectacular, several 100-m high mound structures. The<br />

controll<strong>in</strong>g mechanism of <strong>in</strong>itial mound growth and<br />

111<br />

development are still under debate but recent development<br />

is dependent on sedimentary, oceanographic and climatic<br />

processes (De Mol et al., 2002; Freiwald et al., 2002;<br />

Rüggeberg et al., 2005, 2007; Dorschel et al., 2005).<br />

However, explanations of the orig<strong>in</strong> and evolution of the<br />

Porcup<strong>in</strong>e mounds revolve around two scenarios that may<br />

be expressed as either compet<strong>in</strong>g or complementary<br />

hypotheses:<br />

(1) oceanographic and paleo-environmental conditions<br />

control mound <strong>in</strong>itiation and growth, and<br />

(2) hydrocarbon seepage <strong>in</strong>itiates microbial-<strong>in</strong>duced<br />

carbonate formation and <strong>in</strong>directly fuels coral growth<br />

(endogenous control) (Hovland et al., 1998; Henriet et al.,<br />

2001).<br />

Integrated Ocean Drill<strong>in</strong>g Program (<strong>IODP</strong>) Expedition<br />

307 was proposed to obta<strong>in</strong> evidence for understand<strong>in</strong>g the<br />

orig<strong>in</strong> and evolution of the deepwater carbonate mounds <strong>in</strong><br />

Porcup<strong>in</strong>e Seabight. Challenger Mound, a carbonate<br />

mound structure covered with fossil cold-water coral<br />

rubble, was the focal po<strong>in</strong>t of scientific drill<strong>in</strong>g dur<strong>in</strong>g<br />

Integrated Ocean Drill<strong>in</strong>g Program Expedition 307. Our<br />

study on benthic foram<strong>in</strong>iferal assemblages and gra<strong>in</strong>-size<br />

distribution from the first meters of mound <strong>in</strong>itiation also<br />

<strong>in</strong>dicate an environmental control of their distribution and<br />

variability. No <strong>in</strong>dication of hydrocarbon seepage or<br />

microbial-<strong>in</strong>duced carbonate formation has been found so<br />

far, which supports the first hypothesis that cold-water<br />

coral distribution and growth is controlled by<br />

oceanographic and paleo-environmental conditions. Recent<br />

f<strong>in</strong>d<strong>in</strong>gs of Dullo et al. (<strong>2008</strong>) underl<strong>in</strong>e an environmental<br />

prerequisite of cold-water coral occurrences render<strong>in</strong>g the<br />

second hypothesis unnecessary. Nevertheless, hardground<br />

formation is an essential process from which subsurface<br />

vent<strong>in</strong>g can not be excluded.<br />

References:<br />

De Mol B., Van Rensbergen P., Pillen S., Van Herreweghe K., Van Rooij<br />

D., McDonnell A., Huvenne V., Ivanov M., Swennen R., and Henriet<br />

J.-P. (2002) Large deep-water coral banks <strong>in</strong> the Porcup<strong>in</strong>e Bas<strong>in</strong>,<br />

southwest of Ireland. Mar<strong>in</strong>e Geology 188, 193-231.<br />

Dorschel B., Hebbeln D., Rüggeberg A., Dullo W.-Chr., and Freiwald A.<br />

(2005) Deglacial sweep<strong>in</strong>g of a deep-water carbonate mound. Earth<br />

and Planetary Science Letters 233, 33–44.<br />

Dullo, C., Rüggeberg, A., and Flögel, S. (<strong>2008</strong>) Cold-water coral growth <strong>in</strong><br />

relation to the hydrography of the Celtic and Nordic European<br />

Cont<strong>in</strong>ental Marg<strong>in</strong>. International Journal of Earth Sciences (accepted).<br />

Expedition Scientists, 2005. Modern carbonate mounds: Porcup<strong>in</strong>e drill<strong>in</strong>g.<br />

<strong>IODP</strong> Prel. Rept., 307. doi:10.2204/iodp.pr.307.2005<br />

Freiwald A. (2002) Reef-Form<strong>in</strong>g Cold-Water Corals. In Ocean Marg<strong>in</strong><br />

Systems (ed. G. Wefer, D. Billett, D. Hebbeln, B. B. Jørgensen, M.<br />

Schlüter, and T. v. Weer<strong>in</strong>g), pp. 365-385. Spr<strong>in</strong>ger Verlag.<br />

Henriet J.-P., De Mol B., Pillen S., Vanneste M., Van Rooij D., Versteeg<br />

W., Croker P.F., Shannon P.M., Unnithan V., Bouriak S., and<br />

Chachk<strong>in</strong>e P. (1998) Gas hydrate crystals may help build reefs. Nature<br />

391, 648-649.<br />

Henriet J.-P., De Mol B., Vanneste M., Huvenne V., Van Rooij D., and the<br />

Porcup<strong>in</strong>e-Belgica 97, 98, and 99 Shipboard Parties (2001) Carbonate<br />

mounds and slope failures <strong>in</strong> the Porcup<strong>in</strong>e Bas<strong>in</strong>: a de-velopment<br />

model <strong>in</strong>volv<strong>in</strong>g fluid vent<strong>in</strong>g. In: Shannon, P.M., Haughton, P., and<br />

Corcoran, D. (eds.) Petroleum Exploration of Ireland’s Offshore<br />

Bas<strong>in</strong>s. Geol. Soc. Spec. Publ., 188, 375–383.<br />

Hovland M., Croker P.F., and Mart<strong>in</strong> M. (1994) Fault-associated seabed<br />

mounds (carbonate knolls?) off western Ireland and north-west<br />

Australia. Mar. Pet. Geol., 11, 232–246. doi:10.1016/0264-<br />

8172(94)90099-X<br />

Hovland M., Mortensen P. B., Brattegard T., Strass P., and Rokengen K.<br />

(1998) Ahermatypic coral banks off mid-Norway: evidence for a l<strong>in</strong>k<br />

with seepage of light hydrocarbons. Palaios, 13, 189–200.<br />

Rüggeberg A., Dullo C., Dorschel B., and Hebbeln D. (2007) Environmental<br />

changes and growth history of Propeller Mound, Porcup<strong>in</strong>e Seabight:<br />

Evidence from benthic foram<strong>in</strong>iferal assemblages. International Journal<br />

of Earth Sciences, DOI: 10.1007/s00531-005-0504-1.<br />

Rüggeberg A., Dorschel B., Dullo W.-Chr., and Hebbeln D. (2005)<br />

Sedimentary patterns <strong>in</strong> the vic<strong>in</strong>ity of a carbonate mound <strong>in</strong> the<br />

Hovland Mound prov<strong>in</strong>ce, northern Porcup<strong>in</strong>e Seabight. In: A.

112<br />

Freiwald and J.M. Roberts (eds.) Cold-water Corals and Ecosystems.<br />

Spr<strong>in</strong>ger-Verlag Berl<strong>in</strong> Heidelberg, pp 87-112.<br />

<strong>ICDP</strong><br />

Different records of Late Palaeozoic sea-level<br />

driven cyclothems: one clue for better<br />

understand<strong>in</strong>g controls over cycle<br />

development.<br />

DIETHARD SANDERS 1 , KARL KRAINER 1 , SPENCER LUCAS 2<br />

1 Faculty of Geo- and Atmospheric Sciences, University of<br />

Innsbruck, A-6020 Innsbruck, Austria (EU)<br />

2 New Mexico Museum of Natural History and Science,<br />

Albuquerque, New Mexico NM 87104, USA<br />

Comparative analysis of co-eval Late Palaeozoic cyclic<br />

successions deposited under glacio-eustatic sea-level<br />

changes, but <strong>in</strong> (a) a sett<strong>in</strong>g with active local tectonism<br />

(Austria/Italy), and (b) on a stable epicont<strong>in</strong>ental platform<br />

(New Mexico) has the potential to better discrim<strong>in</strong>ate<br />

controls on cyclothem development than by study with<strong>in</strong> a<br />

s<strong>in</strong>gle area. In the Late Carboniferous to Early Permian<br />

icehouse world, glacio-eustatic sea-level changes caused by<br />

wax<strong>in</strong>g and wan<strong>in</strong>g of the Gondwanan ice shield resulted<br />

<strong>in</strong> deposition of cyclothems of very large geographic<br />

extent. The objectives of research project P20178-N10<br />

(Austrian Research Foundation) are the comparative study<br />

of architecture, composition and orig<strong>in</strong> of (a) Lower<br />

Permian cyclothems <strong>in</strong> the Southern Alps (Europe),<br />

deposited <strong>in</strong> an active tectonic sett<strong>in</strong>g related to rift<strong>in</strong>g,<br />

with (b) Lower Permian cyclothems <strong>in</strong> southwestern New<br />

Mexico (USA), accumulated on a stable epicont<strong>in</strong>ental<br />

shelf. Comparison of cyclothems accumulated <strong>in</strong> these<br />

different tectonic sett<strong>in</strong>gs should allow for a better<br />

recognition of controls over cycle development and<br />

expression of cycle boundaries. In the Southern Alps<br />

(Europe), throughout an Upper Carboniferous to Lower<br />

Permian succession of stacked cyclothems, the architecture<br />

of cyclothems changes markedly up-section, from more-orless<br />

symmetrical (upward-deepen<strong>in</strong>g/upward-shoal<strong>in</strong>g)<br />

cyclothems <strong>in</strong> the lower part to asymmetrical (upwardshoal<strong>in</strong>g)<br />

cyclothems <strong>in</strong> the upper part. Because the Upper<br />

Palaeozoic of the Southern Alps accumulated dur<strong>in</strong>g early<br />

rift<strong>in</strong>g related to the Alp<strong>in</strong>e orogenic cycle, the vertical<br />

change <strong>in</strong> cyclothem style may result from a progressive<br />

<strong>in</strong>fluence of tectonism relative to glacio-eustasy. The<br />

Pedregosa bas<strong>in</strong> of New Mexico (USA) accumulated under<br />

slow, steady subsidence <strong>in</strong> an epicont<strong>in</strong>ental sett<strong>in</strong>g. The<br />

bas<strong>in</strong> conta<strong>in</strong>s a Pennsylvanian to Lower Permian<br />

succession with cyclothems developed <strong>in</strong> the upper part.<br />

Each cyclothem is characterized by an <strong>in</strong>terval of pure,<br />

shallow neritic limestones (rich <strong>in</strong> calcareous algae and<br />

fusul<strong>in</strong>ids) that is sharply capped by a subaerial exposure<br />

surface. The persistent sharp 'capp<strong>in</strong>g' of each of the<br />

cyclothems by a cont<strong>in</strong>uous (on a lateral scale of tens of<br />

kilometers at the least) subaerial exposure surface leads us<br />

to postulate that these cyclothems accumulated under<br />

prevalent <strong>in</strong>fluence of glacio-eustatic sea-level changes,<br />

with tectonism play<strong>in</strong>g only a slightly modulat<strong>in</strong>g<br />

background role relative to glacio-eustasy.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

Pliocene changes <strong>in</strong> terrigenous sediment<br />

<strong>in</strong>put to the eastern tropical and subtropical<br />

Pacific based on ODP sites 1237 and 1239 –<br />

First results from XRF core scann<strong>in</strong>g and<br />

gra<strong>in</strong> size analysis<br />

C. SAUKEL, D. RINCON MARTINEZ, F. LAMY, S. STEPH, A. STURM,<br />

R. TIEDEMANN<br />

Alfred-Wegener-Institut für Polar- und Meeresforschung, Am<br />

Alten Hafen 26, D-27568 Bremerhaven;<br />

Cornelia.Saukel@awi.de<br />

The reconstruction of low-latitude ocean-atmosphere<br />

<strong>in</strong>teractions is one of the major issues of paleoenvironmental<br />

studies. The trade w<strong>in</strong>ds, extend<strong>in</strong>g over 20°<br />

to 30° of latitude <strong>in</strong> both hemispheres, between the<br />

subtropical highs and the <strong>in</strong>tertropical convergence zone<br />

(ITCZ), are dom<strong>in</strong>ant factors of atmospheric circulation<br />

and little is known about their long-term variability on<br />

geological time scales, <strong>in</strong> particular <strong>in</strong> the Pacific sector.<br />

Variations <strong>in</strong> SE trade w<strong>in</strong>d strength and its dust<br />

transport are considered miss<strong>in</strong>g l<strong>in</strong>ks for a comprehensive<br />

understand<strong>in</strong>g of Pliocene changes <strong>in</strong> SE Pacific<br />

oceanography, productivity, El Niño behavior and<br />

associated changes <strong>in</strong> thermocl<strong>in</strong>e depths as well as<br />

upwell<strong>in</strong>g. Our project therefore aims at the reconstruction<br />

of changes <strong>in</strong> South American climate, dust <strong>in</strong>put and SE<br />

trade w<strong>in</strong>d <strong>in</strong>tensities at ODP sites 1237 and 1239 on<br />

millennial and orbital time scales, with a special focus on<br />

periods of pronounced reorganizations <strong>in</strong> global climate<br />

and oceanography, the Pliocene <strong>in</strong>tensification of Northern<br />

Hemisphere Glaciation (NHG) from 3.3-2.4 and the<br />

Pliocene warm period from 5-4 Ma.<br />

Site 1237 is located 140 km off the coast of Peru at<br />

3212 m water depth on the eastern flank of Nazca Ridge.<br />

The area is characterized by high biological productivity,<br />

connected to upwell<strong>in</strong>g, and lies underneath the modern<br />

path of eolian dust transport from the Atacama Desert. Site<br />

1239 was drilled further north, on Carnegie Ridge at 1414<br />

m water depth, 120 km off the coast of Ecuador (Figure 1).<br />

It presumably conta<strong>in</strong>s signals of fluvial sediment<br />

discharge of the Guayas River, the largest river of tropical<br />

South America discharg<strong>in</strong>g <strong>in</strong>to the Pacific.<br />

We use the modern spatial pattern of siliciclastic gra<strong>in</strong><br />

size variability <strong>in</strong> eastern equatorial and subtropical Pacific<br />

(10°N to 25°S) surface sediments as a reference data set for<br />

currently performed down core studies on ODP sites 1237<br />

and 1239. The surface samples were analyzed for gra<strong>in</strong> size<br />

(Beckmann-Coulter laser particle sizer) and clay m<strong>in</strong>eral<br />

(XRD) distributions <strong>in</strong> order to identify sediment dispersal<br />

patterns of terrigenous <strong>in</strong>put, i.e. eolian signals and<br />

possible fluvial overpr<strong>in</strong>ts.<br />

In general, the f<strong>in</strong>e silt fraction dom<strong>in</strong>ates the<br />

siliciclastic component of surface sediments west of the<br />

South American deep-sea trench, with modes rang<strong>in</strong>g from<br />

4.5 to 8µm. First results confirm a decrease <strong>in</strong> gra<strong>in</strong>-size <strong>in</strong><br />

the prevalent w<strong>in</strong>d direction away from the source regions<br />

<strong>in</strong> the Atacama Desert. Dust <strong>in</strong>put thus is a valuable<br />

<strong>in</strong>dicator for changes <strong>in</strong> atmospheric circulation patterns <strong>in</strong><br />

the SE Pacific and for South American cont<strong>in</strong>ental aridity.<br />

Additionally, gra<strong>in</strong>-size distributions <strong>in</strong> the Panama<br />

Bas<strong>in</strong> appear to reflect the pattern of prom<strong>in</strong>ent bottom<br />

water currents.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

As a first analytical method we applied X-ray<br />

fluorescence (XRF) scann<strong>in</strong>g on the ODP cores <strong>in</strong> order to<br />

obta<strong>in</strong> geochemical records <strong>in</strong> millennial-scale resolution.<br />

The measurements of the sections cover<strong>in</strong>g the Pliocene<br />

<strong>in</strong>terval were carried out at the AWI Bremerhaven and the<br />

Marum (Bremen), with second-generation Avaatech XRF<br />

Core Scanners, compris<strong>in</strong>g elements of Al through Ba. We<br />

present semi-quantitative logg<strong>in</strong>g data of ODP sites 1237<br />

and 1239, which reveal relative variations <strong>in</strong> the elemental<br />

composition of the sediments. Changes <strong>in</strong> element<br />

<strong>in</strong>tensities and ratios <strong>in</strong>dicative of dust deposition at site<br />

1237 are of special <strong>in</strong>terest, <strong>in</strong>clud<strong>in</strong>g elements such as K,<br />

Fe, Ti, Al and Si. In order to dist<strong>in</strong>guish between<br />

cont<strong>in</strong>ental aridity and changes <strong>in</strong> w<strong>in</strong>d strength, the data<br />

sets will be compared with gra<strong>in</strong> size data of the<br />

terrigenous sediment <strong>in</strong>put over time.<br />

For site 1237 these elements are considerably lower <strong>in</strong><br />

the warm Pliocene period than <strong>in</strong> the Pleistocene,<br />

<strong>in</strong>tensities start<strong>in</strong>g to <strong>in</strong>crease not until the beg<strong>in</strong>n<strong>in</strong>g of the<br />

NHG at ∼3.3 Ma. Especially the rise <strong>in</strong> the Fe record <strong>in</strong><br />

comb<strong>in</strong>ation with magnetic susceptibility values is<br />

<strong>in</strong>terpreted as an enhancement of dust supply. A parallel<br />

<strong>in</strong>crease of opal concentrations (shipboard measurements)<br />

and relative decrease of Ca concentrations suggest changes<br />

<strong>in</strong> the productivity regime related to changes <strong>in</strong> oceanic<br />

surface circulation.<br />

In contrast, the geochemical records of site 1239 show<br />

a completely different pattern, without the pronounced<br />

<strong>in</strong>crease <strong>in</strong> elements <strong>in</strong>dicat<strong>in</strong>g (eolian) terrigenous <strong>in</strong>put<br />

but a peak <strong>in</strong> Fe <strong>in</strong>tensities around 3.1 Ma. This co<strong>in</strong>cides<br />

with a significant <strong>in</strong>crease <strong>in</strong> opal accumulation rates<br />

start<strong>in</strong>g at 3.6 Ma, which is <strong>in</strong>terpreted as an effect of<br />

enhanced upwell<strong>in</strong>g (Steph et al. <strong>in</strong> review). Shifts <strong>in</strong><br />

orbital cycles can be recognized with<strong>in</strong> the considered<br />

elements. These will be object of further <strong>in</strong>vestigation, as<br />

well as some conspicuous data variations <strong>in</strong> the earlier<br />

Pliocene, which suggest alterations due to diagenetic<br />

processes.<br />

Prelim<strong>in</strong>ary results of gra<strong>in</strong> size analyses po<strong>in</strong>t to<br />

stronger eolian transport to site 1239 than expected.<br />

Figure 1. SEC=South Equatorial Current, NECC=North Equatorial<br />

Countercurrent, EUC=Equatorial Undercurrent, PCC=Peru-Chile<br />

Current, PCCC=Peru-Chile Countercurrent, CC=Coastal Current,<br />

GU=Gunther Undercurrent. Modern mean annual sea-surface<br />

temperatures (<strong>in</strong> °C) after Ocean Climate Laboratory, 1999<br />

(Tiedemann & Mix, 2007). Yellow arrows <strong>in</strong>dicate prevalent w<strong>in</strong>d<br />

direction.<br />

113<br />

<strong>ICDP</strong><br />

Mixed-layered clay m<strong>in</strong>erals and their<br />

geological significance <strong>in</strong> the San Andreas<br />

Fault Observatory at depth drillhole<br />

(SAFOD) <strong>in</strong> Parkfield, California<br />

A.M. SCHLEICHER 1 , L.N. WARR 2 , B.A. VAN DER PLUIJM 3<br />

1<br />

Universität Erlangen-Nuernberg, Geozentrum Nordbayern,<br />

Schlossgarten 5, 91054 Erlangen, Germany<br />

2<br />

Ernst-Moritz-Arndt-Universitaet Greifswald, Institut für<br />

Geographie und Geologie, Friedrich-Ludwig-Jahn-Str. 17,<br />

17487 Greifswald, Germany<br />

3<br />

University of Michigan, Department of Geological Sciences,<br />

1100 University Ave, C.C. Little Build<strong>in</strong>g, Ann Arbor, MI<br />

48109, U.S.A<br />

The m<strong>in</strong>eralization of clays <strong>in</strong> fault zones and their<br />

<strong>in</strong>fluence <strong>in</strong> fluid-rock <strong>in</strong>teraction, rock deformation and<br />

shear strength has been suggested as a possible explanation<br />

for a weak fault behavior. As often reported along the<br />

exhumed segments of the San Andreas Fault, a number of<br />

mechanically weak m<strong>in</strong>eral phases, <strong>in</strong>clud<strong>in</strong>g illite,<br />

chlorite, smectite, as well as kaol<strong>in</strong>ite, serpent<strong>in</strong>e and talc<br />

occur <strong>in</strong> fault zones, and are typically associated with<br />

<strong>in</strong>tense brittle deformation and fluid migration under lowtemperature<br />

conditions (Wu 1974). The San Andreas Fault<br />

Observatory at Depth (SAFOD) ma<strong>in</strong>-hole, drilled <strong>in</strong><br />

Parkfield/California <strong>in</strong> 2004 and 2005 and cored <strong>in</strong> 2007<br />

(Hickman 2004) provides here a unique opportunity to<br />

characterize the natural state and the structure of clay<br />

m<strong>in</strong>erals <strong>in</strong> fault rocks at depth and to study the <strong>in</strong>terplay<br />

between clay formation, fault<strong>in</strong>g and fluid migration <strong>in</strong> an<br />

active member of the fault system (Fig. 1a, b).<br />

Previous studies of rock cutt<strong>in</strong>gs from the SAFOD pilot<br />

hole and the ma<strong>in</strong> borehole revealed diverse clay m<strong>in</strong>eral<br />

phases <strong>in</strong> various segments of the fault zone (Solum et al.<br />

2006, Tourscher et al. submitted, Bradbury et al. 2007).<br />

Several studies suggested that the occurrence of swell<strong>in</strong>g<br />

clays <strong>in</strong> fault rocks, either <strong>in</strong> discrete form or as mixedlayered<br />

clay m<strong>in</strong>erals, <strong>in</strong>fluence the shear strength of fault<br />

zones (e.g. Tempe et al. 2006). One explanation can be the<br />

occurrence of a low layer charged smectitic clay and a<br />

mixed-layered illite-smectite or chlorite-smectite phase that<br />

has been described as th<strong>in</strong>-film coat<strong>in</strong>gs on fault and<br />

fracture surfaces, as well as neo-crystallization with<strong>in</strong><br />

mudrock matrix and ve<strong>in</strong>s at ca. 3 km vertical depth along<br />

the San Andreas Fault (Schleicher et al. 2006). These<br />

m<strong>in</strong>eral phases are known to be mechanically weak due to<br />

their ability to adsorb structured water with<strong>in</strong> their charged<br />

<strong>in</strong>terlayer sites, and thus may control seismogenic vs.<br />

creep<strong>in</strong>g behavior (e.g. Wu 1975).<br />

A recent detailed m<strong>in</strong>eralogical study of f<strong>in</strong>e-gra<strong>in</strong>ed<br />

mudrocks sampled from three spot cores along the SAFOD<br />

drill hole (3066m, 3436m and 3992m measured<br />

depths/MD) reveal authigenic illite, chlorite, smectite,<br />

illite-smectite (I-S) and chlorite-smectite (C-S) mixedlayered<br />

clays, ma<strong>in</strong>ly characteristic of deep diagenetic<br />

conditions (Schleicher et al. submitted, Figure 2). The rock<br />

chips at 3066 m MD derive from a ~30 cm broad, clay rich<br />

shear zone, and appears to lie ~ 300 m above the ma<strong>in</strong><br />

fault. The rock fragments at 3436 m MD are shaly to very<br />

f<strong>in</strong>e gra<strong>in</strong>ed silty rock chips, up to 60 mm <strong>in</strong> average size.

114<br />

These samples belong probably to the ma<strong>in</strong> fault area at<br />

3300–3353 m MD, which is marked by an area of <strong>in</strong>tense<br />

fractur<strong>in</strong>g, with cas<strong>in</strong>g deformation at circa 3300 m<br />

(Zoback et al. 2005) and enhanced cataclasis comb<strong>in</strong>ed<br />

with strong alteration (Bradbury et al. 2007). The third rock<br />

chips at 3992 m MD represents the deepest part of the<br />

drillhole outside the ma<strong>in</strong> fault. One important part <strong>in</strong> this<br />

study is to l<strong>in</strong>k the m<strong>in</strong>eral-growth <strong>in</strong> these rocks with the<br />

fault behavior and the circulation of crustal fluids <strong>in</strong><br />

sedimentary rocks, to have thorough knowledge of the<br />

complete diagenetic history of the faulted rocks both <strong>in</strong><br />

space and time.<br />

The electron microscopy images (SEM, HRTEM), Xray<br />

analysis (XRD, XTG) and geo-chemical (ICP-OES)<br />

<strong>in</strong>vestigations of rock fragments and cutt<strong>in</strong>gs from this<br />

drill-site show significant differences <strong>in</strong> their m<strong>in</strong>eral<br />

characteristics, hydration behavior, and as well fabric and<br />

textural relationships. All samples show more or less strong<br />

signs of deformation, with weak flatten<strong>in</strong>g fabrics def<strong>in</strong>ed<br />

by k<strong>in</strong>ked detrital mica gra<strong>in</strong>s. However, the <strong>in</strong>tensity of<br />

fractur<strong>in</strong>g and fold<strong>in</strong>g is highest <strong>in</strong> samples from the core<br />

of the fault (3436 m MD and <strong>in</strong> lesser extent at 3066 m<br />

MD) compared to clay-rich lithologies ly<strong>in</strong>g beneath the<br />

fault (3992 m MD). XTG analyses of mica gra<strong>in</strong>s with<strong>in</strong><br />

<strong>in</strong>tact rock fragments reveal weak compaction fabrics,<br />

whereby the slightly stronger fabrics observed <strong>in</strong> the fault<br />

zones at 3066 and 3436 m MD (2.0 to 2.7 m.r.d)<br />

correspond with the most deformed mica gra<strong>in</strong>s. Such<br />

weak fabrics <strong>in</strong> fault gouge or strongly deformed fault rock<br />

has often been detected, for example <strong>in</strong> the Punchbowl<br />

fault <strong>in</strong> Southern California (Solum et al. 2003), reflect<strong>in</strong>g<br />

the limitation of effectiveness of foliation development and<br />

fluid focus<strong>in</strong>g along the fault. In spite of its deeper depth,<br />

the silty lithology at 3992 m MD appears to have a slightly<br />

weaker fabric which conforms to the less deformed state of<br />

this lithology.<br />

Authigenic clays that precipitate <strong>in</strong> the matrix and<br />

with<strong>in</strong> pores are associated with strongly dissolved quartz<br />

and feldspar gra<strong>in</strong>s (both plagioclase and K-feldspar). XRD<br />

and HR-TEM of illite and I-S m<strong>in</strong>erals show variable types<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1: a) Location map of the SAFOD Pilot Hole <strong>in</strong> Parkfield/California; b) The SAFOD borehole site at Parkfield, show<strong>in</strong>g the three<br />

phases of drill<strong>in</strong>g. Dur<strong>in</strong>g phase 3 <strong>in</strong> 2007, lateral cores were extracted, allow<strong>in</strong>g sampl<strong>in</strong>g of fault rocks from the ma<strong>in</strong> fault at ca. 3 km<br />

depth (http://www.icdp-onl<strong>in</strong>e.de/sites/sanandreas/objectives/objectives.html)<br />

of crystal-chemical features. Randomly ordered (R0,<br />

>R0-R3) I-S m<strong>in</strong>erals with ca. 20 to 25% smectite layers<br />

are the dom<strong>in</strong>ant clay species across the San Andreas fault<br />

zone (sampled at 3066 and 3301 m MD, Fig. 2a-d),<br />

whereas a highly ordered (>R3) I-S with ca. 2-5 % smectite<br />

layers is the dom<strong>in</strong>ant phase beneath the fault zone<br />

(sampled at 3992 m MD, Figure 2e-f). The most smectiterich<br />

assemblages with the highest water content are<br />

reported from the actively deform<strong>in</strong>g creep zone at ca.<br />

3300-3353 m MD, with I-S (75:25) and C-S (50:50). The<br />

clay particles <strong>in</strong> the faulted rocks (at 3066 m and 3435 m<br />

MD) are similar <strong>in</strong> their average size and shape, commonly<br />

around 20-50 nm <strong>in</strong> thickness and more than 100 nm long<br />

(Fig. 2b, d). At 3992 m MD, ma<strong>in</strong>ly illite crystals of around<br />

50-80 nm <strong>in</strong> average thickness have been determ<strong>in</strong>ed,<br />

partly together with chlorite packets of similar thickness<br />

(Fig. 2f). Random XRD powder preparations for polytype<br />

determ<strong>in</strong>ation and TEM imag<strong>in</strong>g confirm the mixture of at<br />

least two different types of illitic m<strong>in</strong>erals <strong>in</strong> all samples.<br />

At 3066 m MD, a 1M polytype occurs <strong>in</strong> the smallest gra<strong>in</strong><br />

size. A broad reflection hump and a raised background<br />

level suggest a high degree of disorder<strong>in</strong>g <strong>in</strong> the f<strong>in</strong>est<br />

gra<strong>in</strong> sizes (1Md polytype). In the larger gra<strong>in</strong> sizes (> 2<br />

μm), a 2M1 polytype occurs, reflect<strong>in</strong>g the micas of detrital<br />

orig<strong>in</strong>. However, mixtures of 2M1 and 1M illite polytypes<br />

have been <strong>in</strong>vestigated <strong>in</strong> all samples. The f<strong>in</strong>e gra<strong>in</strong>ed<br />

m<strong>in</strong>eral phases were likely formed dur<strong>in</strong>g the circulation of<br />

aqueous fluids along permeable fractures and ve<strong>in</strong>s by<br />

dissolution-precipitation reactions, partly at the expense of<br />

the detrital packets.<br />

Adopt<strong>in</strong>g available k<strong>in</strong>etic models for the<br />

crystallization of I-S <strong>in</strong> burial sedimentary environments<br />

with the current m<strong>in</strong>eralogy, borehole depths and thermal<br />

structure, the conditions and tim<strong>in</strong>g of I-S growth can be<br />

evaluated. Assum<strong>in</strong>g a typical K+ concentration of 100 –<br />

200 ppm for sedimentary br<strong>in</strong>es, a present day geothermal<br />

gradient of 35 °C/km and a borehole temperature of ca. 112<br />

°C for the sampled depths, most of the I-S m<strong>in</strong>erals can be<br />

predicted to have formed over the last 4 to 11 Ma, and are<br />

probably still <strong>in</strong> equilibrium with circulat<strong>in</strong>g fluids. The

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

exception to this simple burial pattern is the occurrence of<br />

the mixed layered phases with higher smectite content at<br />

3236 m MD than predicted by the burial model. These<br />

m<strong>in</strong>erals occur <strong>in</strong> the actively creep<strong>in</strong>g section of the fault<br />

and as local th<strong>in</strong> film clay coat<strong>in</strong>g described on polished<br />

brittle slip surfaces. The composition of the latter phases<br />

could be expla<strong>in</strong>ed either by the <strong>in</strong>fluence of cooler fluids<br />

circulat<strong>in</strong>g along this segment of the fault or the flow of Kdepleted<br />

br<strong>in</strong>es, and may be therefore <strong>in</strong>timately l<strong>in</strong>ked to a<br />

weak fault behavior of the San Andreas Fault.<br />

References:<br />

-Bradbury K.K, Barton D.C., Solum J.G., Draper S.D., Evans J.P. (2007)<br />

M<strong>in</strong>eralogic and textural analyses of drill cutt<strong>in</strong>gs from the San<br />

Andreas Fault Observatory at Depth (SAFOD) boreholes: Initial<br />

<strong>in</strong>terpetations of fault zone composition and constra<strong>in</strong>ts on geologic<br />

models, Geosphere, 3, 5, 299-318<br />

-Hickman S., Zoback M., Ellsworth W. (2004) Introduction to special<br />

section: Prepar<strong>in</strong>g for the San Andreas Fault Observatory at Depth,<br />

Geophysical Research Letters, 31, LI2SO<br />

-Schleicher A.M., Warr L.N., van der Pluijm B.A. (subm): Mixed-layered<br />

clay m<strong>in</strong>erals and their geological significance: samples from the San<br />

Andreas Fault at ~ 2.5 - 3 km depth (SAFOD at Parkfield, California),<br />

Contribution to M<strong>in</strong>eralogy and Petrology<br />

115<br />

-Schleicher A.M., van der Pluijm B.A., Solum J.G., Warr L.N. (2006): The<br />

orig<strong>in</strong> and significance of clay-coated fractures <strong>in</strong> mudrock fragments<br />

of the SAFOD borehole (Parkfield, California); Geophysical Research<br />

Letters DOI 10.1029/2006GL026505<br />

-Solum J.G., van der Pluijm B.A., Peacor D.R., Warr L.N. (2003) Influence<br />

of phyllosilicate m<strong>in</strong>eral assemblages, fabrics, and fluids on the<br />

behavior of the Punchbowl fault, southern California, Journal of<br />

Geophysical Research 108, B5:5-1, to 5-12<br />

-Solum J.G., Hickman S., Lockner D., Moore D., van der Pluijm B.,<br />

Schleicher A.M., Evans, J.P. (2006): M<strong>in</strong>eralogical characterization of<br />

protolith and fault rocks from the SAFOD ma<strong>in</strong> hole; Geophysical<br />

Research Letters 34, DOI 10.1029/2006GL027285<br />

-Tempe S.D., Lockner D.A., Solum J.G., Morrow C.A., Wong T.F., Moore<br />

D.E. (2006) Frictional strength of cutt<strong>in</strong>gs and core from SAFOD<br />

drillhole phases 1 and 2, Geophysical Research Letters, 33: L23307,<br />

doi:10.1029/2006GL027626<br />

-Tourscher S., Schleicher A.M., van der Pluijm B.A., Warr L.N. (subm)<br />

Elemental Geochemistry of samples from fault segments of the San<br />

Andreas Fault Observatory at Depth (SAFOD) drill hole; Journal of<br />

Geophysical Research<br />

-Wu F.T., Blatter L., Roberson H. (1975) Clay gouges <strong>in</strong> the San Andreas<br />

fault system and their possible implications, Pure Applied Geophysics,<br />

113: 87-96References:<br />

-Zoback M., Hickman S., Ellsworth W. (2005) Drill<strong>in</strong>g, sampl<strong>in</strong>g, and<br />

measurements <strong>in</strong> the San Andreas Fault at seismogenic depth, EOS 87<br />

(Fall Meet. Suppl.), abstr. T23E-01<br />

Fig. 2: Mixed-layered clays <strong>in</strong> the SAFOD mud-rocks. a,b) illite-smectite at 3066 m MD <strong>in</strong> pores with a relatively high degree of<br />

order<strong>in</strong>g, c, d) smectitic illite-smectite at 3436 m MD <strong>in</strong> ve<strong>in</strong>s and pores with a low degree of order<strong>in</strong>g, e, f) very small amounts of illitesmectite<br />

at 3992 m MD <strong>in</strong> pores with a very high degree of order<strong>in</strong>g

116<br />

<strong>IODP</strong><br />

The Cretaceous-Paleogene (K-Pg) transition<br />

<strong>in</strong> ODP Leg 207, Western Atlantic: From the<br />

Chicxulub impact to the first Paleocene<br />

hyperthermal events<br />

P. SCHULTE 1 , A. DEUTSCH 2 , S. TOBIAS 3 , A. KONTNY 4 , K.G.<br />

MACLEOD 5 , S. KRUMM 1<br />

1<br />

Institut für Geologie - M<strong>in</strong>eralogie, Universität Erlangen, D-<br />

91054 Erlangen, Germany (schulte@geol.uni-erlangen.de)<br />

2<br />

Institut für Planetologie, Universität Münster, D-48149 Münster,<br />

Germany<br />

3<br />

Bruker AXS Microanalysis GmbH, Schwarzschildstr. 12, D-<br />

12489 Berl<strong>in</strong>, Germany<br />

4<br />

Geologisches Institut der Universität Karlsruhe, Strukturgeologie<br />

und Tektonophysik, D-76187 Karlsruhe, Germany<br />

5<br />

Department of Geological Sciences, University of Missouri,<br />

Columbia, Missouri 65211, USA<br />

The ODP Leg 207 from the Demerara Rise, tropical<br />

western North Atlantic, has recovered an expanded and<br />

stratigraphically complete Cretaceous-Paleogene (K-Pg)<br />

sedimentary record <strong>in</strong>clud<strong>in</strong>g latest Maastrichtian and<br />

Danian clayey chalks, separated by the Chicxulub ejectabear<strong>in</strong>g<br />

event deposit at the K-Pg boundary (MacLeod et<br />

al., 2007). Our comb<strong>in</strong>ation of high-resolution<br />

m<strong>in</strong>eralogical and isotope geochemical analysis with<br />

shipboard geophysical data revealed (i) a remarkable<br />

complex Chicxulub ejecta deposit and (ii) severe<br />

paleoceanographic changes follow<strong>in</strong>g the K-Pg boundary<br />

with possible evidence for two early Danian hyperthermal<br />

events.<br />

(i) The graded, 2-3 cm thick Chicxulub ejecta deposit<br />

consists of >0.3-1 mm-sized spherules. They are generally<br />

altered to dioctahedral smectite. Some, however, show<br />

<strong>in</strong>ternal Fe-Mg-enriched globules and microkrystites<br />

<strong>in</strong>dicative of silicate-silicate “liquid immiscibility” and<br />

quench<strong>in</strong>g from a melt, suggest<strong>in</strong>g a primary orig<strong>in</strong>.<br />

Similar Fe-Mg-enrichment has been observed <strong>in</strong> Chicxulub<br />

spherules from Mexico and Texas (Schulte & Kontny,<br />

2005; Schulte et al. 2006). In the upper part of the K-Pg<br />

ejecta deposit, spherule composition becomes enriched <strong>in</strong><br />

Fe-Mg – reflect<strong>in</strong>g a more mafic progenitor– and shocked<br />

quartz and feldspars, as well as abundant calcite and<br />

dolomite clasts are present. The carbonates are texturally<br />

and compositionally divers <strong>in</strong>clud<strong>in</strong>g (i) rounded massive<br />

to porous calcite clasts, <strong>in</strong> part with a dist<strong>in</strong>ct sponge-like<br />

texture, (ii) accretionary carbonate clasts consist<strong>in</strong>g of sub-<br />

µm-sized calcite and dolomite crystallites, (iii) rounded<br />

carbonate clasts with corroded rims enveloped by radiallygrown<br />

Ca-rich clay m<strong>in</strong>eral phases, and (iv) euhedral<br />

dolomite crystals. The association with typical Chicxulub<br />

ejecta spherules and shocked silicic m<strong>in</strong>eral phases and<br />

conf<strong>in</strong>ement to the mm-thick upper part of the ejecta<br />

deposit suggests that these carbonates are mostly derived<br />

from the Yucatan carbonate platform. The sponge-like<br />

porous carbonate clasts are similar to textures observed <strong>in</strong><br />

experimantally shocked carbonates (Agr<strong>in</strong>ier et al., 2001),<br />

though a biogenic orig<strong>in</strong> is currently under scrut<strong>in</strong>y as well.<br />

However, the corroded carbonate, enveloped by silicates<br />

melts provide evidence for <strong>in</strong>tense thermal alteration<br />

dur<strong>in</strong>g the impact event, associated with beg<strong>in</strong>n<strong>in</strong>g<br />

des<strong>in</strong>tegration of carbonate phases.<br />

Generally, the graded nature, the complex composition<br />

of the ejecta, and the, <strong>in</strong> part, good preservation of delicate<br />

spherule textures suggests an orig<strong>in</strong> as primary air-fall<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

deposit. The microstratigraphy of the K-P ejecta deposit at<br />

ODP Leg 207 is unlike other distal K-Pg spherule deposits<br />

recovered <strong>in</strong> the Atlantic or Pacific realm that are mostly<br />

affected by turbidity currents and consist of silicic<br />

spherules. However, it strongly resembles the terrestrial<br />

dual-layer K-Pg deposit <strong>in</strong> the Western Interior, though the<br />

acidic swamp environments <strong>in</strong> the Western Interior may<br />

have precluded preservation of carbonates. Therefore, ODP<br />

Leg 207 provides the first evidence for dispersal of<br />

shocked calcite and dolomite by the Chicxulub impact to a<br />

distal K-Pg site. The occurrence of the Chicxulub-derived<br />

spherule layer at the base of planktic foram<strong>in</strong>ifera Biozone<br />

P0 <strong>in</strong> conjunction with the mass ext<strong>in</strong>ction of planktonic<br />

foram<strong>in</strong>ifera, an Ir anomaly, and a strong negative δ 13 C<br />

anomaly, strengthens the genetic l<strong>in</strong>k between the<br />

Chicxulub impact and the K-Pg boundary clay.<br />

(ii) The K-Pg boundary <strong>in</strong> ODP Leg 207 Site 1259C is<br />

characterized by a sharp –2.5 per mil δ 13 C anomaly,<br />

followed by an immediate positive 1 per mil shift dur<strong>in</strong>g<br />

Zone P0. Concomitantly, calcite contents drops from >80<br />

% to less than 20 % followed by rapid recovery to about 35<br />

%. Dur<strong>in</strong>g Zone Pα, however, δ 13 C values decrease aga<strong>in</strong><br />

(–0.3 per mil). At the onset of Zone P1a, about 200 ky post<br />

K-Pg, two rapid –0.5 per mil δ 13 C shifts occur that both are<br />

associated with a 1 per mille lower<strong>in</strong>g of δ 18 O values and a<br />

50 % reduction of the carbonate content. Rietveld<br />

ref<strong>in</strong>ement of XRD data revealed improved calcite<br />

crystall<strong>in</strong>ity dur<strong>in</strong>g both <strong>in</strong>tervals that may result from the<br />

preferential removal of weakly crystallized carbonate<br />

phases dur<strong>in</strong>g dissolution episodes associated with<br />

shallow<strong>in</strong>g of the lysocl<strong>in</strong>e. The onset of several dm-mthick,<br />

iron oxide and hydroxide-rich red sta<strong>in</strong>ed <strong>in</strong>tervals<br />

about 20-40 cm above the K-Pg <strong>in</strong> all early Danian ODP<br />

Leg 207 cores, is probably related to additional<br />

oceanographic changes <strong>in</strong> the Atlantic (e.g., <strong>in</strong>flux of<br />

oxygen-rich deepwater) dur<strong>in</strong>g the early Danian.<br />

Subsequently, dur<strong>in</strong>g Zone P1b/P1c, the absence of red<br />

sta<strong>in</strong><strong>in</strong>g and the significant <strong>in</strong>crease of pyrite <strong>in</strong>dicates<br />

more reduc<strong>in</strong>g depositional conditions possibly associated<br />

with the warm<strong>in</strong>g of surficial waters as <strong>in</strong>dicated by<br />

generally lighter δ 18 O values dur<strong>in</strong>g this <strong>in</strong>terval. In<br />

conclusion, our results correlate well with stable isotope<br />

data from other South Atlantic DSDP (527, 528) and North<br />

Atlantic ODP (171) Sites (Quillévéré et al., <strong>2008</strong>),<br />

suggest<strong>in</strong>g significant oceanographic changes follow<strong>in</strong>g the<br />

K-Pg boundary as well as the presence of two short periods<br />

of transient greenhouse gas-driven warm<strong>in</strong>g and carbonate<br />

dissolution <strong>in</strong> the early Paleocene (named “Dan-C2 event”)<br />

analogous to the Paleocene-Eocene Thermal Maximum<br />

(PETM).<br />

References:<br />

Agr<strong>in</strong>ier, P., Deutsch, A., Schärer, U., Mart<strong>in</strong>ez, I., 2001, Fast backreactions<br />

of shock-released CO2 from carbonates: An experimental<br />

approach. Geochimica et Cosmochimica Acta, 65(15), 2615-2632.<br />

MacLeod, K.G., Whitney, D.L., Huber, B.T., Koeberl, C., 2007, Impact and<br />

ext<strong>in</strong>ction <strong>in</strong> remarkably complete K/T boundary sections from<br />

Demerara Rise, tropical western North Atlantic. Geological Society of<br />

America Bullet<strong>in</strong>, 119(1), 101-115.<br />

Quillévéré, F., Norris, R.D., Kroon, D., Wilson, P.A., Wilson, P., <strong>2008</strong>,<br />

Transient ocean warm<strong>in</strong>g and shifts <strong>in</strong> carbon reservoirs dur<strong>in</strong>g the<br />

early Danian. Earth and Planetary Science Letters, 265(3-4), 600-615.<br />

Schulte, P., Kontny, A., 2005, Chicxulub ejecta at the Cretaceous-Paleogene<br />

(K-P) boundary <strong>in</strong> Northeastern México. In: Hörz, F., Kenkmann, T.,<br />

Deutsch, A. (Eds.): Large meteorite impacts III. Special Paper, 384,<br />

Geological Society of America, Boulder, Colorado, 191-221.<br />

Schulte, P., Speijer, R.P., Mai, H., Kontny, A., 2006, The Cretaceous-<br />

Paleogene (K-P) boundary at Brazos, Texas: Sequence stratigraphy,<br />

depositional events and the Chicxulub impact. Sedimentary Geology,<br />

184(1-2), 77-109.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Trac<strong>in</strong>g Siberian permafrost history<br />

G. SCHWAMBORN 1<br />

1 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, 14473<br />

Potsdam; Germany<br />

The El´gygytgyn Impact Crater on Chukotka Pen<strong>in</strong>sula<br />

provides the unique opportunity to identify recent to Late<br />

Pleistocene permafrost conditions <strong>in</strong> terrestrial deposits and<br />

to trace back the permafrost history when us<strong>in</strong>g suitable<br />

proxy data with the adjacent lake sediment archive. At<br />

maximum this may retrieve a palaeoenvironment history<br />

conta<strong>in</strong><strong>in</strong>g changes <strong>in</strong> permafrost conditions back to 3.6<br />

Myr BP, the time of the meteor impact. Knowledge about<br />

the Late Quaternary changes as verified <strong>in</strong> the terrestrial<br />

deposits provide an <strong>in</strong>terpretation scheme that can be<br />

applied to more ancient portions of the glacial cycles as<br />

covered by the lake sediment archive.<br />

Currently, the weather<strong>in</strong>g detritus at El´gygtgyn Crater<br />

is created under cont<strong>in</strong>uous permafrost conditions. It passes<br />

through typical mechanisms of periglacial landscape<br />

dynamics (i.e. solifluction, surface wash, thermo erosion,<br />

river erosion) <strong>in</strong>to the lake, which is placed <strong>in</strong> the central<br />

bas<strong>in</strong>. Based on field observation and laboratory analysis of<br />

frozen ground deposits several conclusions are highlighted<br />

describ<strong>in</strong>g periglacial dynamics dur<strong>in</strong>g the Late<br />

Quaternary. (1) Subaerial terrace formation result<strong>in</strong>g from<br />

slope debris deposition was <strong>in</strong>itiated dur<strong>in</strong>g the Late<br />

Pleistocene / Holocene transition. Dur<strong>in</strong>g Late Holocene<br />

the accumulation rate on the slopes decreases. (2) Icewedge<br />

architecture with<strong>in</strong> frozen ground allows identify<strong>in</strong>g<br />

two generations of Holocene ground ice formation. Nearsurface<br />

thermal change occurred at 4000 yr BP creat<strong>in</strong>g<br />

narrow-meshed ice wedge polygons on top of Early<br />

Holocene wide-meshed polygons. (3) Pore ice oxygen<br />

isotope signatures reveal that the regional Holocene<br />

Thermal Maximum happened at about 9000 yr BP. A<br />

relative 18O m<strong>in</strong>imum at about 4000 yr BP po<strong>in</strong>ts to<br />

more arid and cool conditions at this time. (4) The crater<br />

undergoes a pr<strong>in</strong>cipal lake level drop <strong>in</strong> Late Quaternary<br />

time. Age determ<strong>in</strong>ation of pebble bars that surround the<br />

lake reveal a m<strong>in</strong>imum age of 13,000 yr BP for the ancient<br />

shorel<strong>in</strong>es. Dat<strong>in</strong>g is based on the analysis of a permafrost<br />

core that was extracted beh<strong>in</strong>d the raised bars, where slope<br />

deposits have accumulated after the bar formation. (5)<br />

M<strong>in</strong>eralogical ratios (quartz to feldspar) and s<strong>in</strong>gle quartz<br />

gra<strong>in</strong> micromorphology have been tested on Holocene<br />

frozen ground deposits as proxy data reflect<strong>in</strong>g the strength<br />

of cryogenic weather<strong>in</strong>g. The selective cryogenic break-up<br />

of gra<strong>in</strong>s is particularly related to thaw-freeze dynamics <strong>in</strong><br />

the active layer. When applied to the lake sediments the<br />

m<strong>in</strong>eralogical data illustrate the persistence of cryogenic<br />

weather<strong>in</strong>g <strong>in</strong> the catchment at least back to about 300,000<br />

yr BP, the time that is covered by first lake sediment cores.<br />

Future <strong>ICDP</strong> deep drill<strong>in</strong>gs <strong>in</strong>to the permafrost and the<br />

lake will enable to extend knowledge about permafrost<br />

changes back <strong>in</strong>to time. This will cover the<br />

Pliocene/Pleistocene boundary when northern hemispheric<br />

glaciations started to <strong>in</strong>tensify and the onset of permafrost<br />

formation is assumed.<br />

References:<br />

Schwamborn, G., Fedorov, G., Schirrmeister, L., Meyer, H., Hubberten, H. -<br />

W., <strong>2008</strong>. Boreas 37, 55–65.<br />

Schwamborn, G., Meyer, H., Fedorov, G., Schirrmeister, L., Hubberten, H. -<br />

W., 2006. Quaternary Research 66 (2), 259-272..<br />

117<br />

Position of El´gygytgyn Impact Crater <strong>in</strong> Chukotka. Permafrost<br />

studies are based on surface samples, from shallow and from<br />

planned <strong>ICDP</strong> deep drill<strong>in</strong>g <strong>in</strong> <strong>2008</strong>.<br />

<strong>ICDP</strong><br />

Noble gases and phengite 40 Ar/ 39 Ar ages <strong>in</strong><br />

ultra-high-pressure eclogites of the CCSD<br />

core<br />

W.H. SCHWARZ, M. TRIELOFF, R. ALTHERR<br />

Universität Heidelberg, M<strong>in</strong>eralogisches Institut, Im Neuenheimer<br />

Feld 236, D-69120 Heidelberg<br />

Noble gases (He, Ne, Ar, Kr and Xe) can be used as<br />

tracers for the evolution and history of mantle-derived<br />

rocks, and fluid-rock <strong>in</strong>teraction with crustal or<br />

atmosphere-derived fluids. The different isotope signatures<br />

of the mantle, the crust and/or the atmosphere and the<br />

elemental fractionation of these components offer an<br />

enormous sensitivity to dist<strong>in</strong>guish a variety of processes<br />

[1-4]. The aims of this study are to obta<strong>in</strong> noble gas<br />

isotopic data <strong>in</strong> UHP eclogites, and a complete<br />

characterization of UHP rocks from the core of the Ch<strong>in</strong>ese<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g Program (Donghai).<br />

Isotopic compositions will allow to identify possible<br />

mantle (deep/shallow), crustal and atmosphere-derived<br />

components. The history of these components and their<br />

carrier phases and host rocks can be further constra<strong>in</strong>ed by<br />

fractionation processes reflected <strong>in</strong> element ratios.<br />

CCSD Ma<strong>in</strong>-Hole (MH) eclogites are probably of<br />

different orig<strong>in</strong> [5,6]. For example, the eclogites from<br />

depth of down to 530m are probably of cumulate orig<strong>in</strong><br />

similar to Bixil<strong>in</strong>g and Maowu <strong>in</strong> Dabie Shan; the protolith<br />

of the eclogite from unit 2 (530-600m) is a Fe-Ti-rich<br />

gabbroic rock-body, whereas that of the eclogite with<strong>in</strong><br />

ultramafic rocks from unit 3 (600-690m) is of mantle<br />

orig<strong>in</strong>; eclogites from unit 4 (690-1160m) and unit 6 (1600-<br />

2050m) that are <strong>in</strong>terlayered with paragneiss are<br />

metamorphic supracrustal rocks. Geochemical<br />

characteristics of orthogneiss (unit 5, 1160-1600m) and<br />

paragneiss suggest that their protoliths are probably of<br />

granitic and of supracrustal sedimentary orig<strong>in</strong>s,<br />

respectively.

118<br />

Apparent Age [Ga]<br />

0.300<br />

0.280<br />

0.260<br />

0.240<br />

0.220<br />

0.200<br />

0.180<br />

CCSD MH-14<br />

t = 241.5 ± 1.3 Ma<br />

<strong>in</strong>t<br />

0 20 40 60 80 100<br />

Fractional 39 Ar release<br />

Ar-Ar age spectra for the samples CCSD Ma<strong>in</strong>-Hole MH-14 and MH-20<br />

Oxygen isotope analysis show δ18O values rang<strong>in</strong>g<br />

form -10.41 to +9.63‰ [7]. For the first noble gas<br />

<strong>in</strong>vestigations we choose four eclogite samples CCSD MH-<br />

14, 16, 20 and 24 from different depth of 962, 1066, 1690,<br />

1855m (k<strong>in</strong>dly handed by Yil<strong>in</strong> Xiao and Joachim Hoefs) –<br />

MH-14 and 16 with negative δ18O-values (-5.2 and -<br />

4.0‰), MH-20 and 24 with positive values (+6.0 and<br />

+5.7‰) [8]. The composition of MH-14 and 16 eclogite<br />

samples is ma<strong>in</strong>ly garnet, cl<strong>in</strong>opyroxene and epidote, with<br />

high-sal<strong>in</strong>ity fluid <strong>in</strong>clusions <strong>in</strong> the last two m<strong>in</strong>erals. Some<br />

accessory m<strong>in</strong>erals are present, e.g. phengite <strong>in</strong> sample 14.<br />

MH-20 and 24 samples additionally conta<strong>in</strong> quartz with<br />

CO2 rich fluid <strong>in</strong>clusions – a small portion of phengite is<br />

present <strong>in</strong> sample MH-20.<br />

From the samples MH-14 and 20 the phengites were<br />

separated and Ar-Ar <strong>in</strong>cremental heat<strong>in</strong>g age spectra were<br />

measured (see figure below). Sample MH-14 has an age of<br />

241.5 ± 1.3 Ma consistent with U/Pb ages for a UHP event<br />

(e.g. [9]). MH-20 has an age of 1103 ± 6 Ma, which is<br />

consistent with Lu/Hf model ages and the bimodal age<br />

distribution reported by [9]. The δ18O values for MH-14 is<br />

-5.2 and for MH-20 +6.0, <strong>in</strong>dicat<strong>in</strong>g a correlation between<br />

δ18O values and the Ar-Ar age of the phengites. The<br />

eclogites with high sal<strong>in</strong>ity fluid <strong>in</strong>clusions <strong>in</strong> cpx and ep<br />

have negative δ18O values and young Ar-Ar- ages,<br />

reflect<strong>in</strong>g a UHP event with meteoric fluids present. The<br />

positive δ18O value correlates with the high Ar-Ar age.<br />

This correlation should also be reflected <strong>in</strong> noble gas<br />

compositions – the high-sal<strong>in</strong>ity fluids/young samples<br />

should show a more atmospheric noble gas isotopic and<br />

elemental compositon, because the <strong>in</strong>volved meteoric<br />

fluids should conta<strong>in</strong> dissolved atmospheric He, Ne, Ar,<br />

Kr and Xe. The old samples with positive δ18O values<br />

were not or less affected by fluidal overpr<strong>in</strong>t and thus<br />

should have reta<strong>in</strong>ed the orig<strong>in</strong>al MORB or subcont<strong>in</strong>ental<br />

lithospheric mantle (SCLM) noble gas isotopic<br />

composition.<br />

Apparent Age [Ga]<br />

1.40<br />

1.20<br />

1.00<br />

0.80<br />

0.60<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

CCSD MH-20<br />

t = 1103 ± 6 Ma<br />

<strong>in</strong>t<br />

0 20 40 60 80 100<br />

Fractional 39 Ar release<br />

References:<br />

[1] Trieloff M., Kunz J., Clague D.A., Harrison D. and Allègre C.J. (2000)<br />

Science 288, 1036-1038.<br />

[2] Trieloff M., Kunz J. (2005) Phys. Earth Planet. Int. 148, 13-38.<br />

[3] Hopp J., Trieloff M., Altherr R. (2004) Earth Planet. Sci. Lett. 219, 61-<br />

76.<br />

[4] Buik<strong>in</strong> A.I., Trieloff M., Hopp J., Althaus T., Korochantseva E.V.,<br />

Schwarz W.H., Altherr R. (2005) Earth Planet. Sci. Lett. 230, 143-162.<br />

[5] Hoefs J., Xiao Y. Zhang Z., Romer R.L. (2004) AGU abstr.<br />

[6] Zhang Z.M., Xu Z.Q., Liu F.L., You Z.D., Shen K., Yang J.S., Li T.F.,<br />

Chen C.Z. (2004) Acta Petr. S<strong>in</strong>ica 20, 27-42.<br />

[7] Chen R.-X., Zheng Y.-F., Gong B., Zhao Z.-F., Gao T.-S., Chen B., Wu<br />

Y.-B. (2007) Chem. Geol. 242, 51-75.<br />

[8] Xiao Y. Zhang Z., Romer R.L., Hoefs J., van den Kerkhof A. (2005)<br />

Mitt. Östereich. M<strong>in</strong>. Ges. 150.<br />

[9] Chen R.-X., Zheng Y.-F., Gong B., Zhao Z.-F., Tang J., Wu F.-Y. and<br />

Liu X.M. (2007) J. metamorphic Geol. 25, 873-894.<br />

<strong>IODP</strong><br />

Shallow Submar<strong>in</strong>e Hydrothermal Systems<br />

Along the Tonga-Kermadec Island Arc:<br />

First Results from R/V SONNE Cruise<br />

SO192/2<br />

ULRICH SCHWARZ-SCHAMPERA 1 , REINER BOTZ 2 , MARK<br />

HANNINGTON 3 AND SHIPBOARD SCIENTIFIC PARTY<br />

1 BGR <strong>Hannover</strong>, Stilleweg 2, 30655 <strong>Hannover</strong><br />

2 Institut für Geowissenschaften, C.-A.-U. Kiel, Ludewig-Meyn-<br />

Straße 10, 24118 Kiel<br />

3 University of Ottawa, Department of Earth Sciences, 140 Louis<br />

Pasteur, Ottawa, Ontario, K1N 6N5 Canada<br />

The German-Canadian cruise SO-192/2 MANGO<br />

aimed at the exploration of shallow submar<strong>in</strong>e volcanic<br />

centers along the Tonga-Kermadec arc. The Tonga-<br />

Kermadec arc represents a 2500 km-long cha<strong>in</strong> of active<br />

submar<strong>in</strong>e volcanoes <strong>in</strong> the western Pacific and is the<br />

s<strong>in</strong>gle largest cont<strong>in</strong>uous cha<strong>in</strong> of submar<strong>in</strong>e arc volcanoes<br />

<strong>in</strong> the Pacific and one of the most volcanically active.<br />

Cruise SO-192/2 visited volcanic complexes and associated<br />

vent sites at the southern and northernmost Kermadec and<br />

the southern Tonga volcanic arcs, and at the southern Valu<br />

Fa ridge. Key objectives of this program were to study the<br />

fluid and geochemical <strong>in</strong>put and output <strong>in</strong> the Tonga-<br />

Kermadec subduction zone <strong>in</strong> order to exam<strong>in</strong>e the<br />

relationship between tectonic, magmatic, and hydrothermal<br />

processes along this volcanic cha<strong>in</strong>. The cruise studied and<br />

sampled the Calypso vent fields offshore New Zealand, the<br />

Monowai volcanic complex at the northern tip of the<br />

Kermadec arc, the so-called Volcano 19 at the southern<br />

Tonga arc and Volcano 1 offshore Tongatapu. The H<strong>in</strong>e<br />

H<strong>in</strong>a vent field is located at the southern tip of the Valu Fa<br />

ridge <strong>in</strong> the Lau back-arc bas<strong>in</strong> and approaches the Tonga<br />

island arc with<strong>in</strong> only 25 km. All sites represent large

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

caldera systems, eruption craters, fault-controlled rift<br />

systems and large volcanic edifices <strong>in</strong> water depths<br />

between 180 and 1100m.<br />

Hydrothermal activity was known to exist at all the<br />

different sites from SO-135, SO-167, and the 2005 STKAP<br />

research cruises. Hydrothermal activity along the<br />

Kermadec island arc was <strong>in</strong>itially studied dur<strong>in</strong>g SO-135 at<br />

the Calypso vent sites, and at the Clark and Brothers<br />

Seamount. The extensive mapp<strong>in</strong>g and dredge program<br />

dur<strong>in</strong>g SO-167 encountered for the first time<br />

hydrothermally altered basalts, basaltic andesites and<br />

pumiceous rhyolites at four volcanoes along a 650 km<br />

segment of the Tonga island arc. A follow-up survey<br />

dur<strong>in</strong>g the 2005 SITKAP cruise us<strong>in</strong>g the PISCES<br />

submersibles from the Hawaiian Undersea Research Lab<br />

(HURL) discovered extensive hydrothermal activity and<br />

high-temperature vents associated with prom<strong>in</strong>ent caldera<br />

systems at Volcanoes 1 and 19. The vents showed strong<br />

evidence for phase separation processes and related base<br />

and precious metal precipitation. Initial sampl<strong>in</strong>g program<br />

focused on the characterization of the discharg<strong>in</strong>g fluids<br />

and associated precipitates. First spectacular results and<br />

limited sampl<strong>in</strong>g capacities and time dur<strong>in</strong>g the use of the<br />

PISCES submersibles made it necessary to revisit the sites<br />

dur<strong>in</strong>g SO-192/2.<br />

The Calypso site is characterized by the discharge of<br />

hydrothermal fluids at shallow water depths of 190 m at<br />

temperatures up to 200°C. The seafloor shows areas of<br />

bacterial mat, bubble streams and shimmer<strong>in</strong>g water.<br />

M<strong>in</strong>eralization consists of slabs of sulfur-cemented ash rich<br />

<strong>in</strong> hydrocarbons, and massive anhydrite. Weak acidity and<br />

high H2S contents of the fluids <strong>in</strong>dicate a mixture between<br />

seawater and hydrothermal fluids. The vents show strong<br />

evidence for phase separation processes and related base<br />

and precious metal precipitation at depth. The Monowai<br />

volcanic complex has an active volcanic cone, <strong>in</strong>dicated by<br />

audible bump<strong>in</strong>g and visible discoloration and upwell<strong>in</strong>g at<br />

the surface. The new map from SO-192/2 shows that near<br />

summit eruptions over the past three years have completely<br />

<strong>in</strong>filled a former collapse scar and buried the reconstructed<br />

summit cone. The recent summit at 98 mbsl has arisen 40<br />

m s<strong>in</strong>ce the last mapp<strong>in</strong>g <strong>in</strong> 2004. The Monowai caldera<br />

hosts low-temperature (10-42°C) vents at a l<strong>in</strong>ear ridge of<br />

basaltic dikes, flows, and volcaniclastic sediments <strong>in</strong> a<br />

water depth of about 1150 m. The ridge is heavily<br />

encrusted by mussels. Acid sulfate alteration of the<br />

volcanics is accompanied by dissem<strong>in</strong>ated marcasite<br />

m<strong>in</strong>eralization. Volcano 19 at the southern end of the<br />

Tonga arc is the location of high-temperature hydrothermal<br />

activity. Two dist<strong>in</strong>ct fields of vent<strong>in</strong>g exist at the large<br />

stratovolcano. One is associated with a caldera structure<br />

and exhibits numerous Fe-oxide chimneys, Feoxyhydroxide-<br />

and barite crusts, and vent<strong>in</strong>g of<br />

shimmer<strong>in</strong>g water up to 112°C. The high-temperature vents<br />

occur at the summit cone complex at water depths of 385 -<br />

540 mbsl and represent the shallowest high-temperature<br />

hydrothermal field known so far. This area comprises<br />

clusters of large barite and anhydrite chimneys, and is<br />

covered by extensive deposits of Fe-oxyhydroxides and<br />

hydrothermally cemented ash. The sulfate-sulfide<br />

chimneys are characterized by vigorous vent<strong>in</strong>g of clear<br />

fluids with temperatures on the seawater boil<strong>in</strong>g curve up<br />

to 270°C, pH values of 4.6-6.1, and low gas contents. The<br />

occurrence of phase separation is evident and can be seen<br />

119<br />

as flame-like jets of steam discharg<strong>in</strong>g from multiple<br />

chimney orifices. Pyrite, sphalerite-wurtzite, galena and<br />

chalcopyrite l<strong>in</strong>e the <strong>in</strong>teriors of the chimneys whereas the<br />

outer rims are enriched <strong>in</strong> arsenic sulfides. Phase separated<br />

fluids are responsible for the significant enrichment of gold<br />

<strong>in</strong> the precipitates. At Volcano 1, low- to mediumtemperature<br />

vent<strong>in</strong>g is associated with a large scoria cone.<br />

An area of Fe-oxide encrusted ash, a field of sulfur crusts<br />

covered by vent mussels, altered volcaniclastic rocks, and<br />

crusts of massive pyrite are the characteristics of the<br />

hydrothermal process. Vent<strong>in</strong>g at a maximum temperature<br />

of 70°C was found at two locations.<br />

Volcanic arcs represent a potentially extensive source<br />

of shallow hydrothermal vent fields and auriferous sulfide<br />

precipitates. The new f<strong>in</strong>d<strong>in</strong>gs contribute to a number of<br />

epithermal-style and transitional types of m<strong>in</strong>eralization<br />

now be<strong>in</strong>g recognized <strong>in</strong> the Tonga-Kermadec arc system<br />

and <strong>in</strong> other island arcs. Identification and understand<strong>in</strong>g of<br />

these systems have major genetic implications for volcanic<br />

and metallogenic processes <strong>in</strong> the geological past and are a<br />

major contribution <strong>in</strong> the understand<strong>in</strong>g of processes <strong>in</strong><br />

oceanic and cont<strong>in</strong>ental subduction zones.<br />

<strong>IODP</strong><br />

Porosity <strong>in</strong> different alteration types of the<br />

oceanic crust as a control of element<br />

mobilization – determ<strong>in</strong>ation of diffusion<br />

transport by <strong>in</strong>-situ FTIR-spectroscopy<br />

A.V. SIMONYAN 1,2 , S. DULTZ 1 , H. BEHRENS 2 , J. PASTRANA 3 , U.<br />

SCHWARZ-SCHAMPERA 4<br />

1 Institute of Soil Science, Leibniz University of <strong>Hannover</strong>,<br />

Herrenhäuser Str. 2, D-30419 <strong>Hannover</strong><br />

2 Institute of M<strong>in</strong>eralogy<br />

3 Institute of Bioproduction Systems, Biosystems and Horticultural<br />

Eng<strong>in</strong>eer<strong>in</strong>g Section, Leibniz University of <strong>Hannover</strong>,<br />

Herrenhäuser Str.2, D-30419 <strong>Hannover</strong><br />

4 Federal Institute of Geosciences and Natural Resources, Stilleweg<br />

2, D-30655 <strong>Hannover</strong><br />

Introduction<br />

The rate of seawater/rock <strong>in</strong>teraction and alteration of<br />

the oceanic crust depends on the rock permeability and on<br />

the accessible specific surfaces. Diffusion and reaction<br />

processes with<strong>in</strong> pores, most of them located <strong>in</strong>side<br />

unfractured rock fragments, have strong <strong>in</strong>fluence on<br />

mobilization and immobilization of elements <strong>in</strong><br />

hydrothermal fluids. The scope of our project is to<br />

<strong>in</strong>vestigate systematically the role of pores and rock<br />

permeability on element turnover <strong>in</strong> oceanic hydrothermal<br />

systems. Samples from ODP leg 169 at Middle Valley,<br />

Juan de Fuca Ridge and dredged basalts from the East<br />

Pacific Rise are used to capture a wide range of rock types<br />

from strongly altered sediments to nearly unchanged<br />

basement rocks. In order to correlate results of diffusion<br />

transport with material properties of the rocks, various<br />

methods were applied for the characterization of textures<br />

and porosity.<br />

Pore Volume, pore size distribution and connectivity<br />

of the pore system<br />

Pore volume of connected pores and the distribution of<br />

pore sizes were determ<strong>in</strong>ed by mercury <strong>in</strong>trusion<br />

porosimetry (MIP). The pore size distribution was<br />

calculated from the m<strong>in</strong>imum pressure required to fill pores<br />

of a certa<strong>in</strong> radius with Hg by us<strong>in</strong>g the Washburn

120<br />

equation. In a modification of MIP, Hg was replaced by<br />

Wood`s metal (50 % Bi, 25 % Pb, 12.5 % Zn and 12.5 %<br />

Cd), an alloy which solidifies below 78°C. Thus, pore<br />

structures can be visualized <strong>in</strong> polished sections us<strong>in</strong>g<br />

back-scattered electron (BSE) images and enhanced<br />

topographical (ET) images. Details of the method are<br />

described <strong>in</strong> Dultz et al. (2006).<br />

Pore volumes of basalts determ<strong>in</strong>ed by MIP vary from<br />

0.5 vol.% for a dredged basalt to 17.1 vol.% for strongly<br />

altered basalt from ODP drill<strong>in</strong>g hole 856H. Significant<br />

higher porosities from 23.9 to 51.0 vol.% were found <strong>in</strong><br />

sediments of ODP leg 169. In pore size distribution broad<br />

maxima are found <strong>in</strong> the sub-micrometer range. The most<br />

frequent pore sizes are observed <strong>in</strong> the range between 15<br />

and 200 nm. In back-scattered electron images, pores<br />

<strong>in</strong>truded with Wood`s metal are shown <strong>in</strong> white (Fig. 1a,<br />

b). Interconnected porosity is observed with<strong>in</strong> the whole<br />

fragment of porphyritic basalt, which has a porosity of 13.6<br />

vol.%. A marked tortuosity of the pore system is visible at<br />

higher magnification (Fig. 1b).<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

3D pore structure<br />

High-resolution 3D X-ray tomography with short<br />

wavelength light emitted by high-velocity electrons<br />

(synchrotron radiation) was performed on cyl<strong>in</strong>drical<br />

sections 2.1 mm <strong>in</strong> diameter. A series of projection images<br />

(typically 1024 with a pixel size of 0.7 µm) was recorded.<br />

The thickness of each “slice” represents the pixel size. The<br />

voxel size is therefore 0.7 x 0.7 x 0.7 (µm). To image and<br />

quantify the voids, the grey-scale histogram was segmented<br />

by a threshold <strong>in</strong>terval rang<strong>in</strong>g from 0 to 121. The 3D<br />

images were calculated with circular arrays hav<strong>in</strong>g a<br />

diameter of 900 pixels. Three-dimensional images were<br />

created by display<strong>in</strong>g the area pixels of the separated<br />

regions. As only voids with a volume >9.261 µm³ were<br />

visualized, some pores appear unconnected. The<br />

anisotropy of the pore orientation is given by the red l<strong>in</strong>e<br />

<strong>in</strong> Fig. 2b. In the cyl<strong>in</strong>drical arrays with a height of 70 and<br />

a diameter of 700 µm the complex structure of the pore<br />

networks can be detected (Fig. 2a, b).<br />

Fig. 1. (a) Back-scattered electron images show<strong>in</strong>g the homogeneity of pore networks <strong>in</strong> porphyritic basalt (sample ODP8, 0856 H, 065R)<br />

after <strong>in</strong>trusion with Wood`s metal. 200x magnification; (b) The presence of secondary m<strong>in</strong>erals and the tortuosity of the pores is visible at a<br />

magnification of 5000x. White: Wood`s metal.<br />

Fig. 2. Three dimensional image of voids <strong>in</strong> a cyl<strong>in</strong>drical section of (a) diabase, 0856H 055R (ODP5 ) and (b) basalt, 0856H 065R (ODP8).<br />

Red l<strong>in</strong>e shows the anisotropy of pore orientation <strong>in</strong> this sample. The scale is one pixel with a size of 0.7 µm.<br />

b

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Diffusion transport<br />

Diffusion processes of solutions with<strong>in</strong> the porous<br />

network were studied <strong>in</strong> situ, us<strong>in</strong>g a novel experimental<br />

cell attached to a FTIR-microscope. H2O→D 2O exchange<br />

was performed with three typical samples with porosity<br />

rang<strong>in</strong>g from 6.3 to 7.7 vol. % at temperatures from 5 to<br />

50°C at ambient pressure. Two samples from ODP drill<strong>in</strong>g<br />

(ODP5 and ODP8 shown <strong>in</strong> Fig. 1 and 2) are strongly and<br />

partially altered basalts, respectively. The third dredged<br />

basalt (D13) from Juan de Fuca Ridge, sampled from the<br />

core of the rock fragment, represents fresh basalt.<br />

Sample preparation is as follows: A basaltic rock<br />

sample with typical diameter of ~ 5 mm is polished on one<br />

side and fixed with m<strong>in</strong>imum amount of UV-glue <strong>in</strong> the<br />

center of a polished silica glass plate (thickness: 1 mm;<br />

size: 12 x 12 mm). After that, the sample is polished from<br />

the upper side to a thickness of about 0.1-0.15 mm. Then,<br />

the sample is covered with a second th<strong>in</strong> round silica glass<br />

plate (ca. 0.07 mm thick, typical diameter of ~5 mm),<br />

provid<strong>in</strong>g a complete seal<strong>in</strong>g of the sample by the glue and<br />

the glass plates. After that, one side of the sample plate was<br />

carefully re-opened by cutt<strong>in</strong>g the upper glass plate and the<br />

sample plate with a diamond band saw.<br />

The sample assemblage is <strong>in</strong>serted <strong>in</strong>to a brass sample<br />

holder which can be placed <strong>in</strong> a FTIR-microscope to<br />

collect <strong>in</strong>frared absorption spectra. One rubber O-r<strong>in</strong>g with<br />

a diameter of 2 mm is placed on top of the sample-cover<strong>in</strong>g<br />

glass plate, another one with 7 mm diameter was put<br />

around the sample. Both r<strong>in</strong>gs are squeezed by a Plexiglas<br />

plate with same base area as the ground plate. The<br />

Plexiglas plate is equipped with drill<strong>in</strong>gs for the <strong>in</strong>let and<br />

the outlet of the solution, enabl<strong>in</strong>g a circulation of the<br />

solution around the sample. The system is closed with a<br />

brass screw which presses on the Plexiglas plate. The<br />

solution can be cont<strong>in</strong>uously pumped through the sample<br />

holder us<strong>in</strong>g a peristaltic pump. Due to the small free<br />

volume around the sample (typically 7-9 mm 3 ), the solution<br />

with<strong>in</strong> the cell can be completely exchanged by another<br />

one with<strong>in</strong> seconds at the given flow rate (5.2 mm 3 /s).<br />

Constant temperature <strong>in</strong> the cell is adjusted by a flux of<br />

tempered water which passes through the sample holder.<br />

The temperature of the water flux was adjusted <strong>in</strong> the range<br />

from 5 to 50°C us<strong>in</strong>g a thermostat. The temperature <strong>in</strong> the<br />

cell is measured with a K-type thermocouple which is<br />

located on top of the Plexiglas plate, about 2.5 mm away<br />

from the IR spot. Temperature variations dur<strong>in</strong>g our<br />

experiments did not exceed ± 0.5 °C.<br />

Before the experiment, the sample assemblage was<br />

placed <strong>in</strong> a glass conta<strong>in</strong>er and evacuated to < 0.1 mbar to<br />

remove air from the open pores with<strong>in</strong> the m<strong>in</strong>erals. After<br />

hold<strong>in</strong>g it for about 30 m<strong>in</strong> under vacuum, water was<br />

<strong>in</strong>serted <strong>in</strong> the conta<strong>in</strong>er with a syr<strong>in</strong>ge through a rubber<br />

membrane. The samples were completely covered by water<br />

and after open<strong>in</strong>g the conta<strong>in</strong>er, the water was pressed <strong>in</strong>to<br />

the pores by the ambient air pressure.<br />

At a well-def<strong>in</strong>ed distance from the open side (typically<br />

1.5-2.1 mm), IR absorption spectra were cont<strong>in</strong>uously<br />

recorded with a small aperture aligned parallel to the open<br />

side of the sample plate. The distance between<br />

measurement po<strong>in</strong>t and the solution/sample <strong>in</strong>terface was<br />

always shorter (ca. 2-3 times) than the length of the open<br />

side of the sample. The design of the experimental cell<br />

provides simple one-dimensional diffusion conditions at<br />

least <strong>in</strong> the <strong>in</strong>itial stage of the experiment.<br />

121<br />

Total water contents and the local porosity were<br />

measured us<strong>in</strong>g the near-<strong>in</strong>frared comb<strong>in</strong>ation band at 5200<br />

cm -1 . The progress of the exchange reaction was<br />

determ<strong>in</strong>ed <strong>in</strong> situ us<strong>in</strong>g the OD stretch<strong>in</strong>g vibration band<br />

<strong>in</strong> the <strong>in</strong>frared at 2520 cm -1 . Concentrations of D 2O were<br />

calculated from basel<strong>in</strong>e-corrected peak heights by the<br />

Lambert-Beer law. Effective diffusivities of water <strong>in</strong> the<br />

porous medium Deff were derived by fitt<strong>in</strong>g timeabsorbance<br />

curves to the appropriate solution of Fick’s 2 nd<br />

law.<br />

The obta<strong>in</strong>ed diffusion data for samples from the<br />

oceanic basaltic rocks are shown <strong>in</strong> Fig. 3a. The calculated<br />

effective diffusion coefficients Deff are <strong>in</strong> the range from<br />

10-9 to 10-11 m2/s that is one-two orders of magnitude<br />

smaller than the diffusion coefficients Ds for H+ and H2O<br />

<strong>in</strong> liquid water and <strong>in</strong> aqueous solutions (Li und Gregory,<br />

1974; Mills, 1973). The diffusion data were used to<br />

estimate the activation energies (Ea) of the transport<br />

process by the Arrhenius equation Deff = D0⋅exp(-Ea/RT).<br />

The calculated Ea values for ODP5, ODP8 and D13<br />

samples are comparable with the activation energies for H+<br />

and OH- <strong>in</strong> liquid water (13.7 and 19.8 kJ/mol,<br />

respectively). Despite the high error due to the small<br />

temperature <strong>in</strong>terval, the pre-exponential factor for porous<br />

basaltic samples shows significant difference from the D0<br />

of liquid water. The sample with the largest amount of<br />

secondary m<strong>in</strong>erals (ODP5) has low value of Ea. Higher<br />

activation energy is found for the samples with welldeveloped<br />

pore network, conta<strong>in</strong><strong>in</strong>g no or relatively small<br />

amount of secondary phases (D13, ODP8).<br />

An important property of porous media is the<br />

diffusional tortuosity factor X, measur<strong>in</strong>g the <strong>in</strong>fluence of<br />

pore structure on the diffusivity of ion/molecule/particle<br />

flow <strong>in</strong> the porous medium. Diffusional tortuosity factor<br />

is identical <strong>in</strong> form to the ratio of bulk molecular<br />

diffusivity (Ds) to the effective molecular diffusivity (Deff)<br />

measured by steady-state diffusion experiments (Dullien,<br />

1992). In complex natural materials as used <strong>in</strong> this study,<br />

the tortuosity of porous structure can not be directly<br />

measured due to large variations <strong>in</strong> pore size, pore<br />

geometry, pore distribution, and connectivity of pores (see<br />

Fig.1). But comparison of the effective water diffusivity<br />

Deff with diffusion data for liquid water Ds can be used to<br />

constra<strong>in</strong> experimentally these values. At the conditions of<br />

our experiments, the diffusional tortuosity factor X is<br />

determ<strong>in</strong>ed from equation X = Ds/Deff , where the<br />

diffusion coefficients Ds is molecular diffusivity H2O <strong>in</strong><br />

liquid water from Mills (1973).<br />

The measured tortuosity factors for our samples are<br />

plotted <strong>in</strong> Fig.3b as a function of volume porosity ∅<br />

determ<strong>in</strong>ed by MIP. We are aware of the uncerta<strong>in</strong>ty of this<br />

approach because the average porosity of the basalts may<br />

differ from the porosity of the samples measured by MIP.<br />

It is known that the theoretical and empirical X values<br />

show <strong>in</strong> general a negative dependence on ∅ , lead<strong>in</strong>g to<br />

the simple conclusion that the amount of pores def<strong>in</strong>es the<br />

efficiency of diffusion. However, our results <strong>in</strong>dicate that<br />

the morphology and structure of pore network filled with<br />

secondary m<strong>in</strong>erals may have a strong <strong>in</strong>fluence on the<br />

diffusivity of aqueous solutions. For <strong>in</strong>stance, sample<br />

ODP5 with the largest amount of pores has the highest<br />

values of X up to 265. This sample exhibits<br />

<strong>in</strong>homogeneously distributed and disconnected pores with<br />

a large proportion of secondary phases. The presence of<br />

b

122<br />

precipitated m<strong>in</strong>erals <strong>in</strong>side the pore system may affect the<br />

transport ways for water molecules. The lowest tortuosity<br />

factor is found for the sample with well-developed pore<br />

network and relatively small amount of secondary phases<br />

(ODP8). These f<strong>in</strong>d<strong>in</strong>gs have important impact on<br />

understand<strong>in</strong>g of element release dur<strong>in</strong>g alteration of<br />

oceanic rocks.<br />

log Deff (m 2 /s)<br />

Tortuosity factor, X<br />

-9.9<br />

-10.1<br />

-10.3<br />

-10.5<br />

300<br />

250<br />

200<br />

150<br />

100<br />

a<br />

y = -0.07x - 8.16<br />

R 2 = 0.88<br />

ODP5<br />

ODP8<br />

D13<br />

ODP5-2<br />

ODP8-2<br />

D13-2<br />

50<br />

0.06 0.065 0.07 0.075 0.08<br />

Porosity, Φ<br />

y = -0.08x - 7.56<br />

R 2 = 0.87<br />

-10.7<br />

30 31 32 33 34 35 36<br />

10 4 / T (K)<br />

ODP5<br />

ODP8<br />

D13<br />

ODP5-2<br />

ODP8-2<br />

D13-2<br />

Figure 3. (a) Arrhenius-plot for water diffusion <strong>in</strong> porous basaltic<br />

rocks; (b) Tortuosity factor as a function of porosity.<br />

References:<br />

Dullien F.A.L.: Porous media. Fluid transport and Pore Structure, 2nd<br />

edition, Academic Press, San Diego, California, pp.574 (1992).<br />

Dultz S., Behrens H., Simonyan A., Kahr G., Rath T.: Determ<strong>in</strong>ation of<br />

porosity and pore connectivity <strong>in</strong> feldspars from soils of granite and<br />

saprolite.<br />

Soil Science 171, 675-694 (2006).<br />

Li Y.-H., Gregory S.: Diffusion of ions <strong>in</strong> sea water and <strong>in</strong> deep-sea<br />

sediments. Geochim. Cosmochim. Acta 38, 703-714 (1974).<br />

Mills R.: Self-diffusion <strong>in</strong> normal and heavy water <strong>in</strong> the range 1-45°C. J.<br />

Phys. Chem. 77, 685-689 (1973).<br />

<strong>IODP</strong><br />

Late Miocene surface water history <strong>in</strong> the<br />

northern South Ch<strong>in</strong>a Sea: Relationship to<br />

East Asian summer monsoon evolution and<br />

variability<br />

S. STEINKE, J. GROENEVELD, H. JOHNSTONE<br />

DFG - Forschungszentrum Ozeanränder der Universität Bremen,<br />

Leobener Str., D-28359 Bremen<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

The monsoon system represents one of the basic<br />

elements of global atmospheric circulation that controls the<br />

redistribution of latent and sensible heat and its evolution<br />

and variability play a significant role <strong>in</strong> our understand<strong>in</strong>g<br />

of global climate (Webster et al., 1998). We used comb<strong>in</strong>ed<br />

measurements of Mg/Ca and stable oxygen isotopes <strong>in</strong> tests<br />

of the planktonic foram<strong>in</strong>ifera G. quadrilobatus-sacculifer<br />

from Ocean Drill<strong>in</strong>g Program (ODP) Site 1146A<br />

(19°27.40’N; 116°16.37’E; water depth of 2092 m) to<br />

reconstruct the hydrographic and thermal history of the<br />

northern South Ch<strong>in</strong>a Sea (SCS), and hence changes <strong>in</strong><br />

East Asian monsoon climate dur<strong>in</strong>g the Late Miocene. The<br />

study covers the Late Miocene time <strong>in</strong>terval from 10 to 6<br />

Ma, a period of postulated profound shifts <strong>in</strong> the <strong>in</strong>tensity<br />

of the East Asian monsoon (EAM). Located offshore the<br />

Pearl River, or its predecessor, the location of Site 1146A<br />

is considered as provid<strong>in</strong>g a very sensitive record for<br />

changes <strong>in</strong> river<strong>in</strong>e <strong>in</strong>put as result of changes <strong>in</strong> cont<strong>in</strong>ental<br />

humidity/aridity.<br />

G. quadrilobatus-sacculifer Mg/Ca-SST estimates vary<br />

between 25°C and 29°C <strong>in</strong> the <strong>in</strong>vestigated time <strong>in</strong>terval.<br />

The Mg/Ca SST estimates suggest a dist<strong>in</strong>ct cool<strong>in</strong>g trend<br />

from ~10 Ma (~29°C) to 7.5 Ma (~26°C) that is followed<br />

by an abrupt <strong>in</strong>crease <strong>in</strong> SSTs around 7.5 Ma. Lower<br />

temperatures around 26°C are recorded for the time<br />

<strong>in</strong>terval 7 Ma to 6 Ma. Local δ 18 O seawater estimates imply<br />

dist<strong>in</strong>ct lighter values between ~8.5 Ma and 7.5 Ma that we<br />

attribute to an <strong>in</strong>crease <strong>in</strong> precipitation and <strong>in</strong>creased river<br />

run-off from the Pearl River system, or its predecessor, due<br />

to a period of <strong>in</strong>tensified summer EAM. An <strong>in</strong>tensified<br />

East Asian summer monsoon around 8 Ma is consistent<br />

with studies from the southern SCS (Chen et al., 2004;<br />

Wan et al., 2006), but is <strong>in</strong> marked contrast to<br />

m<strong>in</strong>eralogical and sedimentological records at the same site<br />

that imply a profound shift <strong>in</strong> the <strong>in</strong>tensity of the w<strong>in</strong>ter<br />

EAM relative to summer EAM, as well as aridity of the<br />

Asian cont<strong>in</strong>ent around 8 Ma (Wan et al., 2007). We<br />

suggest that the summer monsoon simultaneously<br />

strengthened along with the w<strong>in</strong>ter monsoon <strong>in</strong> the<br />

northern SCS region at 8 Ma as it was also postulated for<br />

the period from about 3.6 to 2.6 Ma (An et al., 2001).<br />

An, Z., Kutzbach, J.E., Prell, W.L., Porter, S.C., 2001. Evolution of Asian<br />

monsoons and phased uplift of the Himalaya-Tibetan plateau s<strong>in</strong>ce the<br />

Late Miocene times. Nature 411, 62-65.<br />

Wan, S., Li, A., Clift, P.D., Jiang, H., 2006. Development of the East Asian<br />

summer monsoon: Evidence from the sediment record <strong>in</strong> the South<br />

Ch<strong>in</strong>a Sea s<strong>in</strong>ce 8.5 Ma. Palaeogeography, Palaeoclimatology,<br />

Palaeoecology 241, 139-159.<br />

Wan, S., Li, A., Clift, P.D., Stuut, J.-B.W., 2007. Development of the East<br />

Asian monsoon: M<strong>in</strong>eralogical and sedimentologic records <strong>in</strong> the<br />

northern South Ch<strong>in</strong>a Sea s<strong>in</strong>ce 20 Ma. Palaeogeography,<br />

Palaeoclimatology, Palaeoecology 254, 561-582.<br />

Webster, P.J., Magana, V.O., Palmer, T.N., Shukla, J., Tomas, R.A., Yanai,<br />

M., Yasunari, T., 1998. Monsoons: Processes predictability, and the<br />

prospects for prediction, <strong>in</strong> the TOGA decade. Journal of Geophysical<br />

Research 103, 14451-14510.<br />

<strong>IODP</strong><br />

Atlantic-Pacific <strong>in</strong>termediate- and deep-water<br />

δ 13 C gradients dur<strong>in</strong>g the late Neogene (Leg<br />

202)<br />

A. STURM 1 , R. TIEDEMANN 1 , S. STEPH 1<br />

1 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, Am<br />

Alten Hafen 26, 27568 Bremerhaven, Germany;<br />

Arne.Sturm@awi.de

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

This study compares <strong>in</strong>termediate and deep-water δ 13 C<br />

records from the Atlantic/Caribbean (sites 704, 925/926,<br />

982, 1000) and the east Pacific (sites 846, 1236, 1237,<br />

1241) for the time <strong>in</strong>terval from 8.8 – 2.0 Ma. The<br />

comparison reflects changes <strong>in</strong> Atlantic-Pacific nutrient<br />

distributions and thus changes <strong>in</strong> thermohal<strong>in</strong>e circulation.<br />

At the <strong>in</strong>termediate water level, Pacific and Atlantic<br />

δ 13 C values were similar prior to 4.2 Ma; the difference<br />

<strong>in</strong>creased after 4.2 Ma s<strong>in</strong>ce upper Atlantic nutrient<br />

concentrations decreased, probably <strong>in</strong> response to the<br />

shoal<strong>in</strong>g of the Central American Seaway; between 3 and<br />

2.3 Ma the δ 13 C difference rema<strong>in</strong>s relatively constant.<br />

The δ 13 C gradient between the deep Atlantic and the<br />

deep Pacific rema<strong>in</strong>ed relatively constant from 7-3 Ma and<br />

decreased after 3 Ma due to reduced formation of NADW<br />

dur<strong>in</strong>g glacials along with <strong>in</strong>tensification of NHG;<br />

<strong>in</strong>creas<strong>in</strong>g δ 13 C values at SE Atlantic CDW Site 704<br />

suggest stronger <strong>in</strong>fluence of NADW after 4.5 Ma.<br />

The δ 13 C values between the shallow Atlantic and the<br />

deep eastern Pacific are very similar prior to 8.5 Ma. After<br />

8.5 Ma, the Atlantic - Pacific difference strongly <strong>in</strong>creased<br />

until 5.9 Ma. The tim<strong>in</strong>g of the observed changes <strong>in</strong><br />

Atlantic-Pacific δ 13 C gradients suggest <strong>in</strong>fluences from<br />

ocean gateway dynamics.<br />

<strong>ICDP</strong><br />

Tephra <strong>in</strong>put <strong>in</strong>to Lake Van<br />

M. SUMITA 1 , H-U. SCHMINCKE 1<br />

1 Research Division 4, Leibniz-Institute of Mar<strong>in</strong>e Science, IFM-<br />

GEOMAR, Wischhofstr.1 24148 Kiel, Germany<br />

The active Nemrut Volcano (Eastern Anatolia) has<br />

supplied Late Quaternary and Holocene tephra layers as<br />

dom<strong>in</strong>antly rhyolitic fallout and pyroclastic flows<br />

(represented as syn-ignimbrite turbidites) <strong>in</strong>to huge<br />

adjacent alkal<strong>in</strong>e Lake Van. Selected tephra layers <strong>in</strong> the<br />

cores drilled dur<strong>in</strong>g the exploratory phase (2004) <strong>in</strong><br />

preparation for a major <strong>ICDP</strong> drill<strong>in</strong>g project planned for<br />

2009 have been analyzed texturally and compositionally.<br />

The 16 tephra layers studied (T1 ~ T16) fall <strong>in</strong>to two<br />

compositionally dist<strong>in</strong>ct groups (EMP analysis): alkal<strong>in</strong>e to<br />

per-alkal<strong>in</strong>e (comenditic) (PA-type) and sub-alkal<strong>in</strong>e<br />

rhyolites (SA-type). The comenditic rhyolites differ from<br />

sub-alkal<strong>in</strong>e rhyolites by significantly higher Fe, Ti, total<br />

alkalis and halogens (F, Cl) and lower-Al, Mg, Ca, K.<br />

Among the mafic phenocrysts, green hedenbergitic cpx<br />

characterizes the comendites, bi and lesser amph subalkal<strong>in</strong>e<br />

tephra layers. Both types of rhyolites are clearly<br />

separated <strong>in</strong> time reflect<strong>in</strong>g secular changes <strong>in</strong> source<br />

magma compositions. We tentatively <strong>in</strong>terpret all tephra<br />

layers studied to have been sourced <strong>in</strong> Nemrut volcano.<br />

Comenditic rhyolites are also represented by the major<br />

Subrecent hydroclastic tephra (surge and fallout deposits)<br />

blanket<strong>in</strong>g the caldera rim and <strong>in</strong>terpreted as result<strong>in</strong>g from<br />

a subpl<strong>in</strong>ian eruption through the caldera lake. All<br />

Holocene tephra layers are comenditic rhyolites (PA-type)<br />

while tightly grouped late Pleistocene rhyolite tephras are<br />

sub-alkal<strong>in</strong>e (SA-type). The oldest tephra cored (T16),<br />

however, is compositionally identical to the Holocene<br />

comendites. This twofold clear change <strong>in</strong> composition<br />

greatly facilitates correlation between cores.<br />

Apart from six tephra layers (T1, T6, T7, T11, T12 and<br />

T13) of mixed lithology <strong>in</strong>terpreted as represent<strong>in</strong>g<br />

123<br />

rework<strong>in</strong>g follow<strong>in</strong>g an eruption, primary tephra layers<br />

represent both fallout and turbidites. The latter show clear<br />

gra<strong>in</strong> size contrast between the coarse-gra<strong>in</strong>ed basal and<br />

f<strong>in</strong>e-gra<strong>in</strong>ed top layers. Because of the abundance of f<strong>in</strong>e<br />

ash <strong>in</strong> the strongly graded layers, turbidites are <strong>in</strong>terpreted<br />

to reflect entry of pyroclastic/hydroclastic density currents<br />

<strong>in</strong>to Lake Van.<br />

Contrary to our expectation, all Holocene tephra glass<br />

shards are extremely fresh. Zeolites <strong>in</strong>side shards occur <strong>in</strong><br />

tephra layers older than T13 although glass <strong>in</strong> comenditic<br />

T16 is fresh. Whether or not glass alteration is correlated<br />

with a drastic <strong>in</strong>crease <strong>in</strong> alkal<strong>in</strong>ity of pore waters<br />

downward is unclear.<br />

The abundance of angular and non- or only slightly<br />

vesicular vitric shards <strong>in</strong> most tephra layers – and their<br />

dom<strong>in</strong>ance <strong>in</strong> some – <strong>in</strong>dicates that hydroclastic<br />

fragmentation by thermal shock result<strong>in</strong>g from magmawater<br />

<strong>in</strong>teraction was common. The textural resemblance<br />

of glass shards to those of the sub-recent base surge tephra<br />

mantl<strong>in</strong>g the caldera rim suggests that the younger tephra<br />

layers may reflect eruption of rhyolite magma through<br />

Nemrut caldera lake that may therefore have existed for<br />

some time. Magma-groundwater <strong>in</strong>teraction and/or<br />

subaqueous eruptions cannot be excluded, however.<br />

Occurrence of highly vesicular pumice <strong>in</strong> most tephra<br />

layers – and their dom<strong>in</strong>ance <strong>in</strong> a few - <strong>in</strong>dicates<br />

pl<strong>in</strong>ian/sub-pl<strong>in</strong>ian pyroclastic/hydroclastic eruption.<br />

The tephra layers represent slightly more than one<br />

major explosive eruption/1ka. As is common <strong>in</strong> volcanic<br />

systems, however, explosive eruptions were not evenly<br />

spaced <strong>in</strong> time. The last historic eruption of Nemrut (1440<br />

AD) was m<strong>in</strong>or (lava flow). Further large explosive<br />

eruptions could be expected <strong>in</strong> the foreseeable future.<br />

Future eruptions could produce fallout or pyroclastic flows<br />

or both, mak<strong>in</strong>g the town of Tatvan at the shore of Lake<br />

Van highly vulnerable. Monitor<strong>in</strong>g of Nemrut should be<br />

implemented.<br />

<strong>IODP</strong><br />

Cold-Water Coral Mound Growth –<br />

implications from Challenger Mound<br />

(<strong>IODP</strong> Exp. 307 – Modern carbonate<br />

mounds: Porcup<strong>in</strong>e Drill<strong>in</strong>g)<br />

J. TITSCHACK 1 , M. THIERENS 2 , B. DORSCHEL 2 , C. SCHULBERT 1 , A.<br />

FREIWALD 1 , A. KANO 3 , C. TAKASHIMA 3 , N. KAWAGOE 3 , X. LI 4 AND<br />

THE <strong>IODP</strong> EXPEDITION 307 SCIENTIFIC PARTY<br />

1<br />

GeoZentrum Nordbayern, Universität Erlangen-Nürnberg,<br />

Germany<br />

2<br />

Department of Geology, University College Cork, Ireland<br />

3<br />

Department of Earth and Planetary Systems Science, Hiroshima<br />

University, Japan<br />

4<br />

Earth Sciences Department, Nanj<strong>in</strong>g University, Ch<strong>in</strong>a<br />

Cold-water coral mounds, associated with Lophelia<br />

pertusa and Madrepora oculata, widely occur <strong>in</strong> the modern<br />

oceans and came <strong>in</strong>to focus of geobiological and<br />

oceanographic research dur<strong>in</strong>g the last decades. The<br />

Porcup<strong>in</strong>e Seabight, be<strong>in</strong>g the target area of more than 20<br />

scientific cruises dur<strong>in</strong>g the last few years, represents one<br />

of the most <strong>in</strong>tensely studied cold-water coral areas with<br />

over thousand mounds so far. Extensive data, e.g. highresolution<br />

seismics, multibeam, side-scan sonar and surface<br />

samples, made the Porcup<strong>in</strong>e Seabight a prime target for<br />

the <strong>IODP</strong> drill<strong>in</strong>g.

124<br />

<strong>IODP</strong> Expedition 307 ‘Modern carbonate mounds:<br />

Porcup<strong>in</strong>e Drill<strong>in</strong>g’ was designed to (1) close the data gap<br />

between large-scale seismic and detailed ecological and<br />

sedimentological studies, (2) shed light on the nucleation<br />

and growth of cold-water coral mounds, (3) constra<strong>in</strong> a<br />

stratigraphic framework for the slope/mound system, (4)<br />

identify and correlate regional erosional surfaces identified<br />

<strong>in</strong> seismics, and (5) <strong>in</strong>vestigate the hypothesized presence<br />

of hydrocarbons as the energy source for mound nucleation<br />

and susta<strong>in</strong>ed mound growth. A downslope suite of three<br />

sites centred around Challenger Mound on the east slope of<br />

the Porcup<strong>in</strong>e Seabight was drilled to address these key<br />

questions (Fig. 1).<br />

This study concentrates on the growth as well as on the<br />

carbonate budget of Challenger Mound <strong>in</strong> respect to the<br />

adjacent slope deposits through time. So far only little is<br />

known about mound <strong>in</strong>itiation, mound growth and its<br />

carbonate budget. All exist<strong>in</strong>g models are based on the<br />

analysis of short gravity cores which cover only the Late<br />

Pleistocene and Holocene time <strong>in</strong>terval. The cores of<br />

Challenger Mound provide the unique possibility to study<br />

this fasc<strong>in</strong>at<strong>in</strong>g environment back to the Late Pliocene (<<br />

~2.7 Ma) and especially to evaluate its growth and<br />

carbonate budget through time. Therefore, the coral and<br />

total carbonate content of the coral-bear<strong>in</strong>g deposits was<br />

analysed by evaluat<strong>in</strong>g the macroscopic coral content with<br />

digital core section image analysis (resolution: 10 cm)<br />

comb<strong>in</strong>ed with XRD analysis (resolution: ~75 cm) of the<br />

matrix sediement, based on the method described by<br />

Dorschel et al. (2007). In total, 1499 images and 195 XRD<br />

samples were quantified. Estimations of sedimentation<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

rates were based on the chronostratigraphic model from<br />

Kano et al. (2007).<br />

Challenger Mound is positioned <strong>in</strong> the Belgica Mound<br />

Prov<strong>in</strong>ce (BMP), which comprises 64 mounds with heights<br />

of up to 190 m of which 17 are buried mounds. They<br />

developed <strong>in</strong> two ridges <strong>in</strong> a depth range between 700 –<br />

Fig. 1. A: Location Map show<strong>in</strong>g the position of the Belgica Mound Prov<strong>in</strong>ce (red square) <strong>in</strong> the Porcup<strong>in</strong>e Seabight (PS). B: Location<br />

map of the site transect drilled dur<strong>in</strong>g <strong>IODP</strong> Expedition 307. C: 3D-visualisation of the Belgica Mound Prov<strong>in</strong>ce. Red dots <strong>in</strong>dicate<br />

<strong>IODP</strong> 307 site positions.<br />

1000 mbsl (meters below sea level). Challenger Mound<br />

itself is an asymmetrically-semiburied mound <strong>in</strong> the BMP<br />

with an elevation of about 50 m (780 – 830 mbsl) above<br />

the adjacent seafloor. Shallow seismic profiles <strong>in</strong>dicate that<br />

Challenger Mound is, as many other mounds <strong>in</strong> the<br />

Porcup<strong>in</strong>e Seabight, seated on the regional erosional C10<br />

unconformity (Fig. 2). Accord<strong>in</strong>g to the stratigraphic model<br />

of Kano et al. (2007), two major growth stages can be<br />

differentiated <strong>in</strong> Challenger Mound, unit M1 and M2<br />

(Fig.2), separated by a major hiatus.<br />

Mound sediments recovered from site U1317 were<br />

characterised by dom<strong>in</strong>antly unlithified light greyish to<br />

dark greenish coral float- to rudstones with a wacke- to<br />

packstone matrix rarely <strong>in</strong>terbedded by th<strong>in</strong> wacke- to<br />

packstone layers. The carbonate content varied between<br />

21.2 and 82.4 wt.% (mean: 58.2 wt.% <strong>in</strong> unit M1 and 61.9<br />

wt.% <strong>in</strong> unit M2) and exhibited cyclic patterns <strong>in</strong> unit M1.<br />

In unit M2 no clear cyclic variations were identified. These<br />

observations were supported by colour data from the onmound<br />

site U1317 (Fig. 3). Dropstones, only reach<strong>in</strong>g the<br />

site as ice rafted detritus dur<strong>in</strong>g glacials, generally occurred<br />

<strong>in</strong> <strong>in</strong>tervals with low carbonate contents, thus <strong>in</strong>dicat<strong>in</strong>g<br />

<strong>in</strong>creased siliciclastic import and reduced carbonate<br />

production dur<strong>in</strong>g glacial <strong>in</strong>tervals. Unconformities<br />

occurred ma<strong>in</strong>ly where the carbonate content was<br />

decreas<strong>in</strong>g or low, which suggest their formation dur<strong>in</strong>g the

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

start up-phase of glacials or dur<strong>in</strong>g full glacials (Fig. 3).<br />

The coral-bear<strong>in</strong>g deposits overlaid a glauconitic and partly<br />

sandy siltstone (P1 <strong>in</strong> Fig. 2) of Miocene age. The top of<br />

this underly<strong>in</strong>g unit was developed as firmground.<br />

Kano et al. (2007) computed mean sedimentation rates<br />

of about 15 cm/ka for the lower unit M1 (Figs. 2, 3; 155.22<br />

mbsf – 22.98 mbsf) and 5 cm/ka <strong>in</strong> the upper unit M2<br />

(22.98 mbsf – 0 mbsf). Hence, mean bulk sediment<br />

accumulation rates were 30.1 g/(cm 2 ×ka) <strong>in</strong> unit M1 and<br />

9.5 g/(cm 2 ×ka) <strong>in</strong> unit M2, and mean total carbonate<br />

accumulation rates were 17.7 and 5.9 g/(cm 2 ×ka). The<br />

carbonate accumulation rate could be further subdivided<br />

<strong>in</strong>to a mean coral accumulation rate with 7.2 and 1.9<br />

g/(cm 2 ×ka) and a matrix calcite accumulation rate with<br />

13.3 and 5.1 g/(cm 2 ×ka), for units M1 and M2,<br />

respectively. Hereby it was important to note that the given<br />

matrix calcite accumulation rates were relative to the<br />

siliciclastic sediment fraction (coral-derived carbonate is<br />

removed). This was <strong>in</strong>terpreted as the carbonate content of<br />

the plankton-derived sediment fraction <strong>in</strong> Challenger<br />

Mound.<br />

The adjacent drift deposits (P3 <strong>in</strong> Fig. 2), targeted at<br />

site U1318 and U1316, consisted of greyish brown silty<br />

clays, which were frequently <strong>in</strong>terbedded by f<strong>in</strong><strong>in</strong>g upward<br />

sand beds <strong>in</strong> the lower part. Dropstones occured <strong>in</strong> dist<strong>in</strong>ct<br />

<strong>in</strong>tervals. Unit P3 showed a mean carbonate content of 16.6<br />

wt.% and 17.3 wt.% <strong>in</strong> U 1318 ands U1316, respectively.<br />

Mean sedimentation rates were <strong>in</strong> the range of 7.1 to 7.7<br />

cm/ka. Consequently, mean bulk sediment accumulation<br />

rates were 14.2 – 14.9 g/(cm 2 ×ka) and mean total carbonate<br />

accumulation rates varied between 2.4 and 2.6 g/(cm 2 ×ka).<br />

Comparisons of Challenger Mound unit M2 with the<br />

time-equivalent off-mound drift deposits of unit P3 (Fig. 2)<br />

show that the sedimentation rate and bulk sediment<br />

accumulation rate of unit M2 are lower by a factor of about<br />

0.5 - 0.7 relative to the time-equivalent unit P3 at site<br />

U1316 and U1318. This clearly <strong>in</strong>dicates the ongo<strong>in</strong>g<br />

burial of Challenger Mound by the adjacent drift deposits<br />

s<strong>in</strong>ce ~1.24 Ma ago (Fig. 2). In contrast, the total carbonate<br />

accumulation rates is enhanced <strong>in</strong> unit M2 by a factor of<br />

about 2.4 relative to the drift deposits. This is due to the<br />

enhanced content of total carbonate <strong>in</strong> the mound (~45<br />

wt.%). The result<strong>in</strong>g carbonate accumulation rates for unit<br />

M1 are <strong>in</strong> the range of the fast grow<strong>in</strong>g cold-water coral<br />

mounds of Norwegian shelf (L<strong>in</strong>dberg and Mienert, 2005),<br />

and for unit M2 of the slow grow<strong>in</strong>g Propeller Mound,<br />

Hovland Mound Prov<strong>in</strong>ce, Porcup<strong>in</strong>e Seabight (Dorschel et<br />

al., 2007).<br />

The chronostratigraphic transect across Challenger<br />

Mound (Fig. 2) clearly shows that this mound <strong>in</strong>itiated<br />

while <strong>in</strong> the entire region erosive conditions prevailed. The<br />

ma<strong>in</strong> mound growth phase M1 of about 130 m (from<br />

155.22 mbsf, ~2.7 Ma, to 22.98 mbsf, ~1.6 Ma) happened<br />

prior to the onset of drift deposition <strong>in</strong> the Porcup<strong>in</strong>e<br />

Seabight (~1.24 Ma ago). Hence, dur<strong>in</strong>g <strong>in</strong>terval M1<br />

growth conditions must have been very favourable<br />

result<strong>in</strong>g <strong>in</strong> high accumulation rates. Unconformities have<br />

been sparse. However, the number of unconformities<br />

<strong>in</strong>creases towards the base and top of unit M1 suggest<strong>in</strong>g<br />

reoccur<strong>in</strong>g periods unfavourable for mound growth even<br />

before the major unconformity between the units M1 and<br />

M2.<br />

A dramaticall change <strong>in</strong> mound evolution occurred at<br />

about 1.64 Ma marked by the onset of the major erosional<br />

125<br />

event (unconformity at 22.98 mbsf). This ‘mound crisis’,<br />

lasted until about 0.84 Ma. After the ‘mound crisis’<br />

Challenger Mound never recovered completely. In unit M2,<br />

above the major hiatus, mound growth rates were reduced<br />

compared to unit M1 and the number of unconformities<br />

enhanced suggest<strong>in</strong>g frequently unfavourable conditions<br />

for mound growth. The onset of the deposition of drift<br />

sediments adjacent to Challenger Mound with<br />

sedimentation rates exceed<strong>in</strong>g these of Challenger Mound<br />

unit M2 clearly shows the ongo<strong>in</strong>g burial of Challenger<br />

Mound s<strong>in</strong>ce 1.24 Ma ago.<br />

References:<br />

De Mol, B., Van Rensbergen, P., Pillen, S., Van Herreweghe, K., Van Rooji,<br />

D., McDonnell, A., Huvenne, V., Ivanov, M., Swennen, R., and<br />

Henriet, J.P., 2002, Large deep-water coral banks <strong>in</strong> the Porcup<strong>in</strong>e<br />

Bas<strong>in</strong>, southwest of Ireland: Mar<strong>in</strong>e Geology, v. 188, p. 193-231.<br />

Dorschel, B., Hebbeln, D., Rüggeberg, A., and Dullo, C., 2007, Carbonate<br />

budget of a cold-water coral carbonate mound: Propeller Mound,<br />

Porcup<strong>in</strong>e Seabight: International Journal of Earth Science, v. 96, p.<br />

73-83.<br />

Kano, A., Ferdelman, T.G., Williams, T., Henriet, J.-P., Ishikawa, T.,<br />

Kawagoe, N., Takashima, C., Kakizaki, Y., Abe, K., Sakai, S.,<br />

Brown<strong>in</strong>g, E.L., Li, X., Andres, M.S., Bjerager, M., Cragg, B.A., De<br />

Mol, B., Dorschel, B., Foubert, A., Frank, T.D., Fuwa, Y., Gaillot, P.,<br />

Gharib, J., Gregg, J.M., Huvenne, V.A.I., Léonide, P., Mangelsdorf,<br />

K., Monteys, X., Novosel, I., O'Donnell, R., Rüggeberg, A., Samark<strong>in</strong>,<br />

V., Sasaki, K., Spivack, A.J., Tanaka, A., Titschack, J., van Rooij, D.,<br />

and Wheeler, A.J., 2007, Age constra<strong>in</strong>s on the orig<strong>in</strong> and growth<br />

history of a deep-water coral mound <strong>in</strong> the northeast Atlantic drilled<br />

dur<strong>in</strong>g Integrated Ocean Drill<strong>in</strong>g Program Expedition 307: Geology, v.<br />

35, p. 1051-1054.<br />

L<strong>in</strong>dberg, B., and Mienert, J., 2005, Postglacial carbonate production by<br />

cold-water corals on the Norwegian shelf and their role <strong>in</strong> the global<br />

carbonate budget: Geology, v. 33, p. 537-540.

126<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 2. General<br />

sedimentary facies<br />

of a <strong>IODP</strong> 307 site<br />

transect plotted on a<br />

seismic cross<br />

section (modified<br />

after De Mol et al.,<br />

2002). Key<br />

unconformities are<br />

shown <strong>in</strong> red with<br />

the duration (based<br />

on 87Sr/86Sr-dates<br />

of Kano et al.,<br />

2007). For all sites<br />

the total carbonate<br />

contents are plotted.<br />

Mean carbonate<br />

contents for each<br />

unit are plotted<br />

beside the columns.<br />

Fig. 3. Log of the on-mound hole U1317E show<strong>in</strong>g<br />

a core pictures stuck, 87 Sr/ 86 Sr-dates of Kano et al.<br />

(2007) with calculated sedimentation rates, the<br />

coral quantity based on the surface picture<br />

quantification, bulk sediment composition (surface<br />

picture quantification comb<strong>in</strong>ed with matrix<br />

sediment XRD analysis) and calculated<br />

accumulation rates for the bulk sediment, total<br />

carbonate. Unconformities are <strong>in</strong>dicated by red<br />

s<strong>in</strong>uous l<strong>in</strong>es. SR: Sedimentation rate.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

Cyclostratigraphy and Time Series Analysis<br />

From Borehole KAP/107 (Amynteon Bas<strong>in</strong>,<br />

northwestern Greece)<br />

N. TOUGIANNIDIS 1 , T. SEIDLER 1 , C. ROLF 2 , M. WEBER 1 , P.<br />

ANTONIADIS 3 AND W. RICKEN 1<br />

1 Institute of Geology and M<strong>in</strong>eralogy, University of Cologne,<br />

Zülpicher Str. 49a, 50674 Köln, Germany<br />

2 Leibnitz Institute for Applied Geosciences, <strong>Hannover</strong>, Germany<br />

3 Department of M<strong>in</strong><strong>in</strong>g and Mettalurgy - National Technical<br />

University of Athens, Heroon Polytechniou Str. 9, 15780<br />

Zografou-Athens, Greece<br />

We <strong>in</strong>itiated a project to study rhythmic bedd<strong>in</strong>g of<br />

Pliocene strata <strong>in</strong> the Ptolemais Bas<strong>in</strong>, northern Greece.<br />

Sediments show alteration of carbonates and lignites,<br />

reflect<strong>in</strong>g orbital-controlled humidity and temperature<br />

changes. Targeted sites <strong>in</strong>clude five outcrops and several,<br />

up to 400-m deep drill<strong>in</strong>gs. This presentation concentrates<br />

on core KAP/107, a 220-m long drill site retrieved by the<br />

Greek Public Power Cooperation <strong>in</strong> the Amynteon Sub-<br />

Bas<strong>in</strong>. Our <strong>in</strong>itial goal is to develop a robust<br />

chronostratigraphic model for the Miocene to Pleistocene<br />

for the eastern Mediterranean. For this purpose, we<br />

conducted paleomagnetic measurements on site KAP/107<br />

and correlated the result<strong>in</strong>g magnetic pattern to the<br />

Ptolemais stack of Steenbr<strong>in</strong>k et al. (2003), which, <strong>in</strong> turn,<br />

is correlated to the GTPS (Cande and Kent, 1995).<br />

As a prelim<strong>in</strong>ary result, Amynteon core KAP/107<br />

covers a time period between 6.7 and 2.8 Ma. Then we<br />

conducted photospectrometric measurements of<br />

a*,b*,L*ΔE* <strong>in</strong> order to obta<strong>in</strong> high-resolution (1-cm<br />

<strong>in</strong>crement) paleoclimate proxy data (e.g., lightness<br />

provides a very robust proxy for carbonate and lignite<br />

alterations, and the red-green component <strong>in</strong>dicates redox<br />

changes). The result<strong>in</strong>g time series were then studied us<strong>in</strong>g<br />

spectral analysis. We were able to document all orbital<br />

frequencies at 413-ka, 123-ka, 41-ka, 19/23-ka (Berger et<br />

al. 1989).<br />

Future work will <strong>in</strong>clude evolutionary spectral analyses<br />

(ESA) to study the relative importance and the temporal<br />

development of orbital and suborbital frequencies through<br />

time. These studies will also show whether or nor there<br />

were significant changes <strong>in</strong> sedimentation rate, which, <strong>in</strong><br />

turn, should <strong>in</strong>dicate major environmental changes. We<br />

will extend our studies to other sites from the Ptolemais<br />

Bas<strong>in</strong> <strong>in</strong> order to first, evaluate whether there were<br />

significant geographical differences, second, create a<br />

composite record that covers the entire time from the Late<br />

Miocene to the present day, and third, to <strong>in</strong>vestigate<br />

millennial-scale climate change <strong>in</strong> high-sedimentation<br />

sites.<br />

References:<br />

Berger, A.L., Loutre, M.-F., Dehant, V. (1989). Pre Quartenary<br />

Milankovitch Frequencies, Nature, 342, 123-133.<br />

Cande, S.C., and Kent, D.V. (1995). Revised calibration of the geomagnetic<br />

polarity time scale for the Late Cretaceous and Cenozoic, Journal of<br />

Geophysical Research, 100, 6093-6095.<br />

Steenbr<strong>in</strong>k, J., Kloosterboer-van Hoeve, M.L., Hilgen, F.J. (2003).<br />

Millennial-scale climate variations recorded <strong>in</strong> Early Pliocene colour<br />

reflectance time series from the lacustr<strong>in</strong>e Ptolemais Bas<strong>in</strong> (NW<br />

Greece), Global and Planetary Change, 36, 47-75.<br />

127<br />

<strong>IODP</strong><br />

High resolution seismic <strong>in</strong>vestigations of<br />

Anholt Loch, Kattegat: Reconstruction of the<br />

Quaternary depositional history<br />

A. F. TRAMPE 1 , S. KRASTEL 1 , V. SPIESS 1 , T. ANDRÈN 2 , J.HARFF 3<br />

1<br />

Department of Geosciences, University of Bremen, Klagenfurter<br />

Str., 28359 Bremen, Germany<br />

2<br />

Mar<strong>in</strong>e Geology Section, Baltic Sea Research Institute, Seestraße<br />

15, Warnemuende 18119 Roststock, Germany<br />

3<br />

Department of Geology and Geochemestry, Stockholm<br />

University, SE-106 91 Stockholm, Sweden<br />

The Baltic Sea Bas<strong>in</strong> (BSB) is one of the world’s<br />

largest <strong>in</strong>tra-cont<strong>in</strong>ental bas<strong>in</strong>s. BSB has served as<br />

depositional s<strong>in</strong>k throughout its geological history and<br />

accumulated sediments comprise a unique high-resolution<br />

paleoenvironmental archive where the history of the<br />

dra<strong>in</strong>age area and the bas<strong>in</strong> itself is preserved. Present<br />

knowledge of the development of BSB is based on results<br />

from short cores (up to 20 m long), but seismic data and<br />

onshore drill<strong>in</strong>gs <strong>in</strong>dicate much thicker apparently<br />

undisturbed sediment sequences (Eiriksson, 2005; Jensen,<br />

2002; Lykke-Andersen, 1993; Kristensen, 2005).<br />

In 2004 the <strong>IODP</strong> Pre-Proposal “Paleoenvironmental<br />

evolution of the Baltic Sea Bas<strong>in</strong> trough the last glacial<br />

cycle” was submitted by Andrèn et al. (Andrèn, 2004). The<br />

general aim of the proposal is to reconstruct the climatic<br />

response of Northern Europe to the forc<strong>in</strong>g of the Northern<br />

Atlantic atmospheric and oceanic circulation system dur<strong>in</strong>g<br />

the last glacial cycle (Holocene, Weichselian and Eemian)<br />

by us<strong>in</strong>g the sedimentary record of the BSB. Dur<strong>in</strong>g a<br />

seismic pre-site survey <strong>in</strong> February 2006 with the RV<br />

He<strong>in</strong>cke, high-resolution seismic data and sediment echo<br />

sounder data were collected <strong>in</strong> the south-western Baltic<br />

Sea. This pre-site survey was an important step for<br />

submitt<strong>in</strong>g a Full-Proposal <strong>in</strong> October 2007 (Andrèn,<br />

2007). In total 11 sites are proposed based on our and other<br />

seismic data (Fig. 1). Data with the Bremen high-resolution<br />

seismic system were collected around Sites BSB 1 and 2<br />

(Anholt Loch) and BSB 5 to 8 (Hanö Bay and Bornholm<br />

Bas<strong>in</strong>). This work focuses on the Anholt Loch sites. Ma<strong>in</strong><br />

objective of our <strong>in</strong>vestigations is to analyze whether Anholt<br />

Loch conta<strong>in</strong>s sediments of the complete last glacial cycle.<br />

The study area ‘Anholt Loch’ is situated <strong>in</strong> the southern<br />

Kattegat, south-easterly of the Danish island Anholt. The<br />

most important tectonically structure <strong>in</strong> the Anholt Loch<br />

area is the NW-SE trend<strong>in</strong>g Sorgenfrey-Tornquist-zone.<br />

This structure is active s<strong>in</strong>ce Early Paleozoic time (Jensen,<br />

2002). The island Anholt is located <strong>in</strong> the crestal zone of a<br />

southeast-northwest trend<strong>in</strong>g anticl<strong>in</strong>e. The anticl<strong>in</strong>e was<br />

formed dur<strong>in</strong>g the late Cretaceous/Paleogene <strong>in</strong>version<br />

episodes and was later deeply truncated by erosion. The<br />

results of a bor<strong>in</strong>g on the island of Anholt and seismic<br />

<strong>in</strong>vestigations by Lykke-Andersen et al. (1993) suggest that<br />

the Pre-Quaternary sediments below and <strong>in</strong> the vic<strong>in</strong>ity of<br />

Anholt were deposited <strong>in</strong> the Middle and Lower Jurassic.<br />

The Quaternary sediments were <strong>in</strong>terpreted as Holocene to<br />

Saalian <strong>in</strong> age by Lykke-Andersen et al. (1993), while<br />

Jensen at al. (2002) postulated Holocene to Weichselian<br />

sediments. Our new seismic data are used to dist<strong>in</strong>guish<br />

between these two contradict<strong>in</strong>g <strong>in</strong>terpretations, which is<br />

essential for assess<strong>in</strong>g the potential of Anholt Loch for<br />

drill<strong>in</strong>g.

128<br />

Two different streamer systems were used<br />

simultaneously dur<strong>in</strong>g data acquisition: a 300 m long 48<br />

channel streamer and a 50 m long 48 channel shallow<br />

water streamer. The long streamer was ma<strong>in</strong>ly used for<br />

velocity analysis, which is crucial for dist<strong>in</strong>guish<strong>in</strong>g<br />

between Quaternary and older sediments. The higher<br />

resolution data of the shallow water streamer were used for<br />

a structural and seismic attribute analysis.<br />

The valley ‘Anholt Loch’ trends NW-SE, which is the<br />

same direction as the Sorgenfrey-Tornquist zone. It has an<br />

average width of 3 km and was surveyed over a length of<br />

14.5 km. The valley is <strong>in</strong>cised <strong>in</strong> the lowermost facies A,<br />

characterized by tilted reflectors (Fig. 2) and a sharp<br />

<strong>in</strong>crease <strong>in</strong> seismic velocity. Facies A is <strong>in</strong>terpreted as Pre-<br />

Quaternary sediments. A Bor<strong>in</strong>g on the island of Anholt<br />

shows that the Pre-Quaternary sediments are Jurassic <strong>in</strong><br />

age (Lykke-Andersen, 1993). The erosional valley is filled<br />

with a more than 250 m thick sedimentary succession, <strong>in</strong><br />

which five different facies (B-F) could be identified (Fig.<br />

2).<br />

Facies B to F were <strong>in</strong>terpreted as Quaternary<br />

sediments, which were deposited dur<strong>in</strong>g Holocene to<br />

Saalian times. Facies B (Fig. 2) shows a hummocky<br />

reflection pattern and was most likely deposited under<br />

glacial conditions, probably Saalian till. We assume that<br />

facies B also conta<strong>in</strong>s Eemian sediments, which were<br />

altered dur<strong>in</strong>g the Weichsel-Glacial. This <strong>in</strong>terpretation is<br />

supported by a bor<strong>in</strong>g on Anholt, where a 8 m-thick unit of<br />

late Saalian and Eemian age was found <strong>in</strong> 76 m sub bottom<br />

depth (Lykke-Andersen, 1993). The chaotic reflection<br />

pattern of facies C (Fig. 2) refers to glacial till and is<br />

<strong>in</strong>terpreted as Weichselian sediments. Facies D and E (Fig.<br />

2) were most likely deposited under glaciomar<strong>in</strong>e condition<br />

dur<strong>in</strong>g the Weichsel-Glacial and <strong>in</strong> late Weichselian times.<br />

The youngest facies F (Fig. 2) was deposited <strong>in</strong> the<br />

Holocene.<br />

The morphology of the valley ‘Anholt Loch’ is typical<br />

for a subglacial melt water valley. In most cases melt water<br />

valleys trends <strong>in</strong> the same direction as the glacier advances.<br />

There is, however, no glacier known, which trends <strong>in</strong> the<br />

same direction as the valley dur<strong>in</strong>g the last glacial periods<br />

(Elsterian, Saalian and Weichselian). The strike direction<br />

of the valley might be expla<strong>in</strong>ed by the Sorgenfrey-<br />

Tornquist-zone, which trends <strong>in</strong> the same direction and<br />

represents a zone of weakness. Another explanation could<br />

be the distribution of the Pre-Quaternary sediments. The<br />

Jurassic sediments are exposed <strong>in</strong> a wedge-shaped NW-SE<br />

trend<strong>in</strong>g zone below Anholt. These sediments are more<br />

easily erodable than the surround<strong>in</strong>g Cretaceous white<br />

Chalk, and might therefore control the strike direction of<br />

the valley (Lykke-Andersen, 1993).<br />

To sum up, our new seismic data and the occurrence of<br />

Eemian sediments <strong>in</strong> a bor<strong>in</strong>g on Anholt strongly support<br />

that sediments of the complete last glacial cycle exist <strong>in</strong><br />

Anholt Loch, though f<strong>in</strong>al proof can only achieved by<br />

drill<strong>in</strong>g.<br />

References<br />

ANDRÈN T., BITINAS A., BJÖRK S., EMELYANOV E., HARFF J.,<br />

JAKOBSON M., JENSEN J. B., KNUDSEN K. L., KOTILAINEN A.,<br />

LEMKE W., USCINOWICZ S., VESKI S., and ZELCHS V. (2004)<br />

Paleoenvironmental evolution of the Baltic sea bas<strong>in</strong> through the Last<br />

Glacial Cycle (Pre-Proposal).<br />

ANDRÈN T., BJÖRCK S., JÖRGENSEN B. B., KNUDSEN K. L., HARFF<br />

J., BITINAS A., EMELYANOV E., JAKOBSON M., JENSEN J. B.,<br />

KOTILAINEN A., SPIEß V., USCINOWICZ S., VESKI S., and<br />

ZELCHS V. (2007) Paleoenvironmental evolution of the Baltic sea<br />

bas<strong>in</strong> through the Last Glacial Cycle (Full-Proposal).<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

EIRIKSSON J., KRISTENSEN P.-H., LYKKE-ANDERSEN H., BROOKS<br />

K., MURRAY A., KNUDSEN K. L., and GLAISTER C. (2005) A<br />

Sedimentary record from a deep Quarternary valley <strong>in</strong> the southern<br />

Lillebaelt area, Denmark: Eemian and Early Weiselian lithology and<br />

chronology at Mommark. Boreas 35, 320-331.<br />

JENSEN J. B., PETERSEN K. S., KONRADI P., KUIJPERS A., BENNIKE<br />

O., LEMKE W., and ENDLER R. (2002) Neotectonics, sea-level<br />

changes and biological evolution <strong>in</strong> the Fennoscandian Border Zone of<br />

the southern Kattegat Sea. Boreas 31, 133-150.<br />

KRISTENSEN P.-H. and KNUDSEN K. L. (2005) Palaeoenvironments of a<br />

complete Eemian sequence at Mommark, South Denmark:<br />

foram<strong>in</strong>ifera, ostracods and stable Isotopes. Boreas 35, 349-366.<br />

LYKKE-ANDERSEN H., SEIDENKRANTZ M.-S., and KNUDSEN K. L.<br />

(1993) Quarternary sequences and their relation to the pre-Quarternary<br />

<strong>in</strong> the vic<strong>in</strong>ity of Anholt, Kattegat, Skand<strong>in</strong>avia. Boreas 22, 291-298.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1: Bathymetric map of the Baltic Sea Bas<strong>in</strong> with the proposed drill sites BSB-1 to BSB-11. BSB-1 and BSB-2 are located <strong>in</strong><br />

the so called Anholt Loch <strong>in</strong> the Kattegat. The Study area of ‘Anholt Loch’ is marked as a rectangle. (modified after: Andrèn,<br />

2007).<br />

129

130<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 2: Migrated Profile GeoB06-003 (I) and Interpretation (II). Box <strong>in</strong> the bottom right corner of the seismic data (I) shows<br />

sediment echo sounder data of the area marked as black box <strong>in</strong> the seismic data. The location of the profile is shown <strong>in</strong> red <strong>in</strong> the<br />

<strong>in</strong>set map. A: Jurassic, B: Saalian and Eemian C: Weichselian till, D: Weichselian, glacio-mar<strong>in</strong>e sediments, E: late Weichselian, F:<br />

Holocene. For location of the study area see Fehler! Verweisquelle konnte nicht gefunden werden..

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

ANDRILL – Drill<strong>in</strong>g for Geology <strong>in</strong><br />

Antarctica: Aims, Concept, Results and<br />

Future Perspectives of a Successful Program<br />

VIERECK-GOETTE, LOTHAR 1 , NIESSEN, FRANK 2, 3 , KUHN, GERD 3<br />

AND THE D-ANDRILL MEMBERS<br />

(1) Chair D-ANDRILL (Work<strong>in</strong>g Group of LA-SCAR)<br />

(2) Natl. Representative ANDRILL Science Committee (ASC)<br />

(3) Natl. Representative McMurdo - Andrill Science<br />

Implementation Committee (M-ASIC)<br />

ANDRILL (ANtarctic geological DRILL<strong>in</strong>g) is a<br />

multi-national collaboration comprised of scientists,<br />

educators, students, technicians, drillers and support staff<br />

from Germany, Italy, New Zealand, and the United States.<br />

ANDRILL’s goal is to reveal the response of the Antarctic<br />

ice cover to past periods of global warm<strong>in</strong>g and cool<strong>in</strong>g<br />

and forecast its probable future. The specific concept is<br />

drill<strong>in</strong>g a series of proximal sites on the cont<strong>in</strong>ental marg<strong>in</strong><br />

by drill<strong>in</strong>g and recover<strong>in</strong>g sediment core samples from<br />

below the seafloor beneath the Antarctic ice shelf and seaice.<br />

New ANDRILL results will be <strong>in</strong>corporated <strong>in</strong>to ice<br />

sheet and climate computer generated models to better<br />

understand the history and unknown future of our dynamic<br />

planet.<br />

Fund<strong>in</strong>g support for ANDRILL comes from the U.S<br />

National Science Foundation, New Zealand Foundation of<br />

Research, Science, and Technology, Royal Society of New<br />

Zealand Marsden Fund, Antarctica New Zealand, the<br />

Italian National Program for Research <strong>in</strong> Antarctica, the<br />

German Science Foundation and the Alfred Wegener<br />

Institute for Polar and Mar<strong>in</strong>e Research Science. It has<br />

supported the development of a new dedicated drill<strong>in</strong>g<br />

system and drill<strong>in</strong>g camp for float<strong>in</strong>g-ice-based operations<br />

that utilize the ice shelf and sea-ice as drill<strong>in</strong>g platforms.<br />

The two <strong>in</strong>augural ANDRILL projects of the McMurdo<br />

Sound Portfolio <strong>in</strong> the Ross Sea, the McMurdo Ice Shelf<br />

Project (MIS) and the Southern McMurdo Sound Project<br />

(SMS), were drilled <strong>in</strong> late 2006 and late 2007,<br />

respectively. The uniform core recovery was 98%,<br />

cover<strong>in</strong>g alternat<strong>in</strong>g successions of glaciomar<strong>in</strong>e,<br />

terrigenous, volcanic and biogenic sediments of Plio-<br />

Plesitocene to Miocene age as far back as 19 Ma, with 50%<br />

of the stratigraphic time be<strong>in</strong>g preserved <strong>in</strong> the sedimentary<br />

profiles. Analysis of samples and <strong>in</strong>terpretation of the<br />

results will cont<strong>in</strong>ue throughout the International Polar<br />

Year (IPY, 2007-2009).<br />

With<strong>in</strong> the near future (< year 2012) a follow up<br />

portfolio is <strong>in</strong> preparation - and has already past an <strong>IODP</strong><br />

review process – <strong>in</strong> order to drill the Oligocene/Eocene<br />

overly<strong>in</strong>g the West Antarctic Erosional Surface (WARS) at<br />

the Coulman High with<strong>in</strong> the Ross Sea Rift. Targets aimed<br />

for drill<strong>in</strong>g sedimentary sections cover<strong>in</strong>g even older<br />

Paleogen as well as Upper Cretaceous sedimentary records<br />

with<strong>in</strong> Antarctica were proposed, the latest by the German<br />

D-ANDRILL, work<strong>in</strong>g group of the LA SCAR, be<strong>in</strong>g the<br />

extraord<strong>in</strong>ary section of Seymour Island at the eastern<br />

coast of the northern Antarctic Pen<strong>in</strong>sula (Graham Land,<br />

East of James Ross Island). We present these <strong>in</strong>formation<br />

<strong>in</strong> order to arise the <strong>in</strong>terest of geoscientists with<strong>in</strong> the<br />

German drill<strong>in</strong>g community specialized <strong>in</strong> the stratigraphic<br />

<strong>in</strong>tervalls of future ANDRILL targets.<br />

131<br />

<strong>IODP</strong><br />

Climate Cycles and Events <strong>in</strong> the Plio-<br />

/Pleistocene of the Yermak Plateau, Arctic<br />

Ocean: Causes and Consequences based on<br />

X-ray Fluorescence Scanner Data of ODP<br />

Sites 910 and 911<br />

CHRISTOPH VOGT 1 , JENS MATTHIESSEN 2 , HANS-J. BRUMSACK 3 ,<br />

REINHARD X. FISCHER 1<br />

1 Crystallography, Geosciences, University of Bremen,<br />

Klagenfurter Str. 2, 28359 Bremen, cvogt@uni-bremen.de<br />

2 Geosciences, Alfred Wegener Institute for Polar and Mar<strong>in</strong>e<br />

Research, Am Handelshafen 26, 27568 Bremerhaven<br />

3 Geochemistry, Institute for Chemistry and Biology of the Mar<strong>in</strong>e<br />

Environment (ICBM), Carl-von-Ossietzky-University, PO<br />

Box 2503, 26111 Oldenburg<br />

Prilim<strong>in</strong>ary results of ODP Sites 910 and 911 will be<br />

presented. New XRF Scann<strong>in</strong>g data and XRF discrete<br />

sample data are comb<strong>in</strong>ed with exist<strong>in</strong>g and new data on<br />

gra<strong>in</strong>-size, carbonate and organic carbon content and<br />

m<strong>in</strong>eral assemblages of the bulk and the clay fraction.<br />

Validation of XRF scann<strong>in</strong>g data is highly emphasized.<br />

Long-term climate changes on Earth and <strong>in</strong> particular<br />

the Northern Hemisphere glaciations are related to<br />

Milankovich cycles. Up to now, these cycles were studied<br />

at a high resolution <strong>in</strong> Arctic Ocean sediments only <strong>in</strong> the<br />

last 300,000 years due to low biogenic carbonate contents<br />

and restricted age control <strong>in</strong> older sediments. Additionally,<br />

the sedimentary record yields a rather high complexity due<br />

to multiple meltwater events related sedimentation<br />

changes. The Fram Strait/ Yermak Plateau gateway is a<br />

comparatively well-suited region for a study of middle to<br />

upper Pleistocene sediments because a well-constra<strong>in</strong>ed<br />

chronostratigraphy allows unequivocal recognition of<br />

glacial-<strong>in</strong>terglacial cycles (Spielhagen et al., 2004; Knies et<br />

al., 2007). The isotope record of Hole 910A <strong>in</strong> particular<br />

shows, apart from glacial-<strong>in</strong>terglacial cycles, a<br />

considerable millenial-scale variability of environmental<br />

conditions s<strong>in</strong>ce the Brunhes/ Matuyama boundary, caused<br />

partly by frequent supply of freshwater to the Arctic Ocean<br />

(Knies et al., 2007, Matthiessen et al. <strong>in</strong> prep.). This<br />

suggests a pronounced <strong>in</strong>stability of the Arctic climate<br />

system, with major consequences for the environment.<br />

This project applies a presum<strong>in</strong>gly non-destructive<br />

analytical method, the X-ray fluorescence (XRF) scanner,<br />

on a high-resolution <strong>in</strong>vestigation of ODP sites 910 and<br />

911 (Yermak Plateau, Arctic Ocean) to resolve Late<br />

Pliocene to Middle Pleistocene paleoenvironmental and<br />

paleoclimate variability. To fully understand and <strong>in</strong>terpret<br />

the XRF Scanner data a large number of discrete samples is<br />

analysed with various m<strong>in</strong>eralogical and <strong>in</strong>organic<br />

geochemical methods to calibrate the XRF scanner<br />

measurements. These data will be related to exist<strong>in</strong>g and<br />

newly collected data on gra<strong>in</strong>-size, carbonate and organic<br />

carbon content, and the m<strong>in</strong>eralogical composition of the<br />

bulk and clay fraction. The backbone of the study is a large<br />

set of exist<strong>in</strong>g data on surface sediments of the Arctic<br />

Ocean (see www.pangaea.de for all data sets). Some new<br />

surface sediment data has been analyzed dur<strong>in</strong>g the first<br />

month of this project. Our f<strong>in</strong>al goal is to better understand<br />

the sedimentary and paleoenvironmental conditions <strong>in</strong><br />

relation to climate changes on the Northern Hemisphere at<br />

Milankovich time-scales through the last 3-4 million years.

132<br />

Prelim<strong>in</strong>ary results of the first 5 project months are: 1)<br />

Archive and to a lesser extent work halves of the ODP910<br />

and 911 holes are well enough preserved to perform<br />

cont<strong>in</strong>uous scann<strong>in</strong>g. 2) Based on shipboard physical<br />

property data and supported by correlation of the new XRF<br />

scanner data a correlation of ODP holes 910A, B and D<br />

was performed for the first time. This is important as we<br />

can fill cor<strong>in</strong>g gaps and gaps due to previous massive<br />

sampl<strong>in</strong>g of ODP910A, the primary <strong>in</strong>vestigation hole for<br />

the <strong>in</strong>itial high resolution stratigraphy (Knies et al., 2007).<br />

3) The correlation of XRF scann<strong>in</strong>g data of discrete<br />

powdered samples and the full elemental XRF analysis<br />

bears good results and the semiquantitative XRF scanner<br />

data can be validated well. 4) Most dom<strong>in</strong>ant lithological<br />

and sedimentological changes are well represented <strong>in</strong> the<br />

K/Ca-ratio of the sediments <strong>in</strong> particular for the times of<br />

ice-sheet built up and deglaciation times. 5) The Si/Al-ratio<br />

is strongly related <strong>in</strong>creased quartz and ice-rafted debris<br />

contents as well as to gra<strong>in</strong> size and to bottom current<br />

changes. 6) Diagenetic overpr<strong>in</strong>t is well constra<strong>in</strong>ed by the<br />

Mn-record of the sediments.<br />

References:<br />

Knies J, Matthiessen J, Mackensen A, Ste<strong>in</strong> R, Vogt C, Frederichs T, Nam<br />

S-I (2007) Effects of Arctic freshwater forc<strong>in</strong>g on thermohal<strong>in</strong>e<br />

circulation dur<strong>in</strong>g the Pleistocene. Geology 35, 1075-1078.<br />

Matthiessen J, Knies J, Nam S, Vogt C, Frederichs T, Ste<strong>in</strong> R, Mackensen A<br />

(<strong>in</strong> prep.) Pleistocene stable isotope stratigraphy of ODP Hole 910A<br />

from the Yermak Plateau, Eastern Arctic Ocean revisited: Implications<br />

for paleoenvironmental <strong>in</strong>terpretations. Mar<strong>in</strong>e Geology <strong>in</strong> prep.<br />

Spielhagen, R.F. et al., 2004. Arctic Ocean deep-sea record of northern<br />

Eurasian ice sheet history. Quaternary Science Reviews, 23(11-13<br />

(Special Issue: Quaternary Environments of the Eurasian North<br />

(QUEEN))): 1455-1483.<br />

<strong>ICDP</strong><br />

Evolution of the Methane Cycle <strong>in</strong> the<br />

Siberian Arctic: Insights from<br />

Microbiological and Biogeochemical Studies<br />

D. WAGNER 1 , K. MANGELSDORF 2<br />

1 Alfred Wegener Institute, Research Unit Potsdam, Telegrafenberg<br />

A45, 14473 Potsdam, Germany<br />

2 GeoForschungsZentrum Potsdam, Telegrafenberg, 14473<br />

Potsdam, Germany<br />

Permafrost, which underlays around 24% of the<br />

exposed land area (Zhang et al., 1999), relates to<br />

permanently frozen ground with a shallow surface layer of<br />

several centimeters (active layer) that thaws only dur<strong>in</strong>g<br />

the short summer period. About one third of the global soil<br />

carbon is preserved <strong>in</strong> permafrost environments (Gorham,<br />

1991). Currently most strongly discussed with reference to<br />

permafrost is therefore the question: “What will happen to<br />

the carbon stored <strong>in</strong> permafrost, <strong>in</strong> the event of a climate<br />

change?” The relevance of the Arctic carbon reservoir is<br />

highlighted by currently observed climate changes <strong>in</strong> the<br />

Arctic (IPCC, 2007) and by climate models that predict<br />

significant changes <strong>in</strong> temperature and precipitation <strong>in</strong> the<br />

northern hemisphere (Smith et al., 2002). Global warm<strong>in</strong>g<br />

could result <strong>in</strong> a degradation of permafrost area up to 25%<br />

until 2100 (Anisimov et al. 1999). Thaw<strong>in</strong>g of permafrost<br />

and the associated release of climate relevant trace gases,<br />

as a consequence of an <strong>in</strong>tensified microbial turnover of<br />

organic carbon and from ancient methane reservoirs,<br />

represent a potential risk with respect to future global<br />

warm<strong>in</strong>g. For the prediction of the future development of<br />

the permafrost environment and its contribution to the<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

global atmospheric carbon budget, it is important to<br />

understand how the system reacted to environmental<br />

changes <strong>in</strong> the past.<br />

Carbon cycl<strong>in</strong>g under anoxic conditions with<strong>in</strong> the<br />

predom<strong>in</strong>antly wet permafrost environments is ma<strong>in</strong>ly<br />

performed via methane production (methanogenesis),<br />

which is the f<strong>in</strong>al process <strong>in</strong> a sequence of hydrolysis and<br />

fermentation (Sch<strong>in</strong>k and Stams, 2006). Methanogenesis is<br />

solely driven by a small group of strictly anaerobic<br />

organisms called methanogenic archaea (Garcia et al,<br />

2000).<br />

First studies on a Holocene permafrost core from the<br />

Lena Delta (Siberia) <strong>in</strong>dicated <strong>in</strong> situ activity of<br />

methanogenic archaea <strong>in</strong> the perennially frozen sediments<br />

(Wagner et al., 2007). The core showed a dist<strong>in</strong>ct<br />

temperature profile, reach<strong>in</strong>g from +10 °C near the surface<br />

to -11.5 °C at 800 cm depth. Methane was detected <strong>in</strong> all<br />

samples of the permafrost core with the highest<br />

concentrations <strong>in</strong> the upper 450 cm sediment depth. The<br />

archaeal biomarker (phospholipid ether lipids, PLEL)<br />

analyses showed highest concentration <strong>in</strong> the zones with<br />

high CH4 concentrations, while no PLELs were<br />

determ<strong>in</strong>ed <strong>in</strong> the bottom part of the core characterized by<br />

traces of methane. The study show that the evaluation of<br />

microbiological data and their correlation with climatic and<br />

geochemical results represents the basis for the<br />

understand<strong>in</strong>g of the role of permafrost <strong>in</strong> the global<br />

system, <strong>in</strong> particular feedback mechanisms related to<br />

material fluxes and greenhouse gas emissions <strong>in</strong> the scope<br />

of a warm<strong>in</strong>g Earth.<br />

In the scope of the planned project the evolution of the<br />

methane cycle <strong>in</strong> permafrost environments of Northeast<br />

Siberia will be <strong>in</strong>vestigated. Of particular <strong>in</strong>terest is the<br />

understand<strong>in</strong>g of microbial processes and the identification<br />

of the ma<strong>in</strong> microbial players <strong>in</strong>volved <strong>in</strong> the carbon<br />

decomposition under chang<strong>in</strong>g climatic conditions <strong>in</strong> the<br />

present and past. For this purpose a comb<strong>in</strong>ed highresolution<br />

stratigraphic analyses of microbial lipid markers<br />

and ribosomal RNA (quantitative and qualitative microbial<br />

biomarkers) will be applied on permafrost deposits with an<br />

age of up to 300,000 years. The permafrost core will be<br />

recovered from the El’gygytgyn Lake region <strong>in</strong> the scope<br />

of the <strong>ICDP</strong> project “Scientific Drill<strong>in</strong>g at El’gygytgyn<br />

Crater Lake” <strong>in</strong> <strong>2008</strong>. The El’gygytgyn Lake represents an<br />

ideal case study because the region was unglaciated s<strong>in</strong>ce<br />

the time of the meteorite impact. Thus, permafrost <strong>in</strong> this<br />

region went through several climatic stages dur<strong>in</strong>g its<br />

development and it is expected that climatically <strong>in</strong>duced<br />

chemical and physical changes <strong>in</strong> the sedimentary<br />

sequences results <strong>in</strong> variations of the microbial<br />

communities concomitantly affect<strong>in</strong>g the methane gas<br />

fluxes <strong>in</strong> the past. The acquired data will fill fundamental<br />

gaps <strong>in</strong> our knowledge on the paleo carbon dynamics, the<br />

development of microbial communities under chang<strong>in</strong>g<br />

environmental conditions, and will be further used for the<br />

understand<strong>in</strong>g and prediction of the future development of<br />

the methane cycle <strong>in</strong> permafrost environments.<br />

References:<br />

Anisomov OA, Nelson FE, and Pavlov AV (1999) Predictive scenarios of<br />

permafrost development under conditions of global climate change <strong>in</strong><br />

the XXI century. Earth Cryology, 3: 15-25.<br />

Garcia JL, Patel BKC and Olliver B (2000) Taxonomic, phylogenetic and<br />

ecological diversity of methanogenic archaea. Anaerobe 6:205-226<br />

Gorham, E. (1991) Northern peatlands role <strong>in</strong> the carbon cycle and probable<br />

responses to climatic warm<strong>in</strong>g. Ecological Applications 1: 182-195.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

IPCC (2007) Climate Change 2001: The Fourth Assessment Report of the<br />

Intergovernmental Panel on Climate Change. Cambridge: Cambridge<br />

University Press.<br />

Sch<strong>in</strong>k B, Stams AJM (2006) Syntrophism among Prokaryotes. In: Dwork<strong>in</strong><br />

M, Falkow S, Rosenberg E, Schleifer K-H, Stackebrandt E (eds.)<br />

Prokaryotes, vol 2, Spr<strong>in</strong>ger, New York, pp 309-335<br />

Smith J, Stone R and Fahrenkamp-Uppenbr<strong>in</strong>k J (2002) Trouble <strong>in</strong> polar<br />

paradise: Polar science (Introduction). Science 297: 1489.<br />

Wagner, D., Gatt<strong>in</strong>ger, A., Embacher, A., Pfeiffer, E.-M., Schloter, M., and<br />

Lipski, A. (2007) Methanogenic activity and biomass <strong>in</strong> Holocene<br />

permafrost deposits of the Lena Delta, Siberian Arctic and its<br />

implication for the global methane budget. Global Change Biology 13:<br />

1089-1099.<br />

Zhang, T., Barry, R.G., Knowles, K., Hegnibottom, J.A., and Brown, J.<br />

(1999) Statistics and characteristics of permafrost and ground-ice<br />

distribution <strong>in</strong> the Northern Hemisphere. Polar Geography 2: 132-154.<br />

<strong>IODP</strong><br />

Holocene millennial scale variability <strong>in</strong><br />

surface and deepwater records <strong>in</strong> the North<br />

Atlantic (ODP Site 980, Feni Drift)<br />

T. WAGNER 1 , K.-H. BAUMANN 2 , J. HOLTVOETH 3 , H. MEGGERS 2 , J.-<br />

B. STUUT 1 , C. VOGT 1 , T.I. EGLINTON 4<br />

1)University of Newcastle upon Tyne, United K<strong>in</strong>gdom<br />

2)DFG Research Center Ocean Marg<strong>in</strong>s, University of Bremen,<br />

Germany<br />

3)University of Liverpool, United K<strong>in</strong>gdom<br />

4)Woods Hole Oceanographic Institution, USA<br />

High quality climate records from Greenland ice cores<br />

and North Atlantic sediments reveal that Holocene climate<br />

was far less stable than previously thought. Millennialscale<br />

rapid climate oscillations that characterized the last<br />

glacial <strong>in</strong>terval cont<strong>in</strong>ued at lower amplitude <strong>in</strong>to the<br />

Holocene. Oppo et al. (2003, Nature, 422) have shown<br />

major reductions <strong>in</strong> NADW production around 9,300,<br />

8,000, 5,000, and 2,800 years before present.<br />

In this presentation we focus on a selection of new<br />

results from a multi proxy approach comb<strong>in</strong><strong>in</strong>g gra<strong>in</strong> size,<br />

clay m<strong>in</strong>eralogical, micropaleontologic and geochemical<br />

analyses applied to deglacial-Holocene Feni Drift<br />

sediments from ODP Site 980. The position of this site is<br />

characterized by a high accumulation rates that translate<br />

<strong>in</strong>to excellent time resolution. The nature of the drift<br />

sediments implies that they are <strong>in</strong>fluenced by lateral<br />

transport of re-suspended material potentially provid<strong>in</strong>g<br />

important <strong>in</strong>formation on changes <strong>in</strong> bottom water currents<br />

and pathways of particulate matter transport. To further<br />

explore deep ocean currents <strong>in</strong> relation to climate<br />

variations we explore deglacial-Holocene millennial-scale<br />

proxy records of gra<strong>in</strong> size and clay m<strong>in</strong>eral association<br />

and comb<strong>in</strong>e those with new 14C-dat<strong>in</strong>gs from different<br />

gra<strong>in</strong> fractions and carbon sources.<br />

High resolution gra<strong>in</strong>-size records from ODP Site 980<br />

show dist<strong>in</strong>ct trends <strong>in</strong> the relationship between the clay<br />

and the silt fraction with highest clay contents <strong>in</strong> the early<br />

Holocene section (Figure 1).<br />

Superimposed we observe a series of high frequency<br />

variations <strong>in</strong> both the silt gra<strong>in</strong> sizes and clay m<strong>in</strong>eralogy.<br />

These records are <strong>in</strong>terpreted to document the effects of<br />

variations <strong>in</strong> lateral advection on Holocene drift<br />

sedimentation with supply of terrestrial matter from<br />

different source areas. The approach taken here considers<br />

smectite as an <strong>in</strong>dicator for the orig<strong>in</strong> from the north<br />

(Island/Faroer) whereas illite and chlorite serve as an<br />

<strong>in</strong>dicator for the orig<strong>in</strong> from the east (England/Ireland).<br />

Follow<strong>in</strong>g this concept the records clearly dist<strong>in</strong>guish<br />

several phases of the climate history: The Holocene, the<br />

133<br />

Böll<strong>in</strong>g-Alleröd period and the pre-He<strong>in</strong>rich 1 phase are<br />

characterized by <strong>in</strong>creas<strong>in</strong>g clay <strong>in</strong>put from the east<br />

(British Islands/Ireland), while dur<strong>in</strong>g the He<strong>in</strong>rich 1 event<br />

and dur<strong>in</strong>g the Younger Dryas the clay was imported from<br />

Island. Dur<strong>in</strong>g the Holocene we also recognize high<br />

frequency changes with<strong>in</strong> an overall decreas<strong>in</strong>g trend <strong>in</strong> the<br />

smectite/illite-ratio support<strong>in</strong>g previously not recognized<br />

short term <strong>in</strong>terruptions <strong>in</strong> the deep ocean circulation. At<br />

this po<strong>in</strong>t we can only speculate on their trigger<br />

mechanisms and feedbacks, however, these fluctuations <strong>in</strong><br />

deep water circulation may have had a direct <strong>in</strong>fluence on<br />

surface waters (or vice versa) as suggested by cyclic high<br />

frequency changes <strong>in</strong> the coccolithophorid assemblages<br />

(not shown here). Notably our new records are not <strong>in</strong> phase<br />

with the “Oppo-Events”, but we can not exclude that they<br />

are somehow related.<br />

To obta<strong>in</strong> more <strong>in</strong>formation on the age distribution <strong>in</strong><br />

the different size fractions that translate to different<br />

hydrodynamic regimes of the deep ocean currents we next<br />

explore a set of 14C dat<strong>in</strong>gs (figure 2).<br />

14 C-dat<strong>in</strong>gs of the coarse fraction (planktonic<br />

foram<strong>in</strong>ifera) and the carbonate-free clay fraction (organic<br />

material) are almost equal, because both fractions are not<br />

transported by bottom water currents. The silt fraction<br />

(organic material) <strong>in</strong>stead is significantly older and<br />

herewith potentially transported (figure 2). This effect is<br />

especially documented with<strong>in</strong> the phase between 14,500<br />

and 10,500 years before present, where 14 C dat<strong>in</strong>g of the<br />

different fractions <strong>in</strong>dicates maximum differences. With<strong>in</strong><br />

the Holocene the 14 C age off-set between the different<br />

fractions is significantly smaller, most possible due to a<br />

glacial dilution of older organic components to fresh<br />

material from enhanced primary production.

134<br />

Age (kyrs)<br />

0<br />

2<br />

4<br />

6<br />

8<br />

10<br />

12<br />

14<br />

16<br />

18<br />

20<br />

22<br />

E<br />

Orig<strong>in</strong> from<br />

N<br />

0.4 0.6 0.8 1 1.2 1.4<br />

Smectite/Illite-ratio<br />

(N/E-"orig<strong>in</strong>"<br />

(Island/GB + Ireland-ratio))<br />

0<br />

2<br />

4<br />

6<br />

8<br />

10<br />

12<br />

14<br />

16<br />

18<br />

20<br />

22<br />

Relative abundance<br />

of clay (%)<br />

Illite and Clay<br />

(%)<br />

20 30 40 50 60<br />

32 36 40 44 48<br />

Illite (%)<br />

(Indicator for "orig<strong>in</strong>"<br />

from the East (GB, Irlande))<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

0<br />

2<br />

4<br />

6<br />

8<br />

10<br />

12<br />

14<br />

16<br />

18<br />

20<br />

22<br />

Relative abundance<br />

of clay (%)<br />

Smectite and Clay<br />

(%)<br />

20 40 60<br />

20 30 40 50 60<br />

Smectite (%)<br />

(Indicator for "orig<strong>in</strong>"<br />

from the North (Island))<br />

Figure 1: Relative abundances of clay <strong>in</strong> comparison to the relative abundances of specific clay m<strong>in</strong>erals - smectite as an <strong>in</strong>dicator for a<br />

transport from the north (Island) (upper panel) and illite as an <strong>in</strong>dicator for a transport from the east (Great Brita<strong>in</strong> and Ireland) (middle panel).<br />

In the lower panel the smectite/illite ratio is shown. The shad<strong>in</strong>g is <strong>in</strong>dicat<strong>in</strong>g specific phases <strong>in</strong> the paleoceanographic evolution of the research<br />

area.<br />

Depth (mbsf)<br />

0<br />

1<br />

22<br />

2<br />

3<br />

4<br />

14 C Ages of the organic fraction (silt (triangles), clay(circles))<br />

14 C Ages of the planktonic foram<strong>in</strong>ifera fraction<br />

14 C Ages of the bulk organic fractio (crosses)<br />

10580<br />

10880<br />

years<br />

14030<br />

14490 years<br />

3500 years<br />

5<br />

Age (kyrs)<br />

4000 8000 12000 16000 20000<br />

Figure 2: 14 C-ages of different fractions <strong>in</strong> ODP Site 980. Maximum offsets of up to 3500 years are evident from 10,000 years and 14,500<br />

years between carbonate-free clay and silt.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>IODP</strong><br />

New <strong>IODP</strong> data access: scientific earth<br />

drill<strong>in</strong>g <strong>in</strong>formation service (SEDIS)<br />

H.-J. WALLRABE-ADAMS 1 , M. DIEPENBROEK 1 , R. HUBER 1 , U.<br />

SCHINDLER 1 , , H. GROBE 2 J. COLLIER 3<br />

1 MARUM - Center for Mar<strong>in</strong>e Environmental Sciences, Univ. of<br />

Bremen, Germany<br />

2 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research,<br />

Bremerhaven, Germany<br />

3 <strong>IODP</strong>-MI, Sapporo, Japan<br />

S<strong>in</strong>ce the beg<strong>in</strong>n<strong>in</strong>g of the <strong>IODP</strong> program a great afford<br />

has been done to implement an <strong>in</strong>formation system<br />

benefitt<strong>in</strong>g all <strong>in</strong>volved partners <strong>in</strong> <strong>IODP</strong> (USIO, CDEX;<br />

ECORD).<br />

The Integrated Ocean Drill<strong>in</strong>g Program (<strong>IODP</strong>) is<br />

develop<strong>in</strong>g a web based <strong>in</strong>formation service (Scientific<br />

Earth Drill<strong>in</strong>g Information Service, SEDIS) - to facilitate<br />

access to all data and <strong>in</strong>formation related to scientific ocean<br />

drill<strong>in</strong>g, regardless of orig<strong>in</strong> or location of data. SEDIS will<br />

be designed to <strong>in</strong>tegrate distributed scientific drill<strong>in</strong>g data<br />

via metadata.<br />

The three ma<strong>in</strong> data contributors to SEDIS currently<br />

are the <strong>IODP</strong> implement<strong>in</strong>g organizations (IOs) from the<br />

United States (USIO), Japan (CDEX) and Europe with<br />

Canada (ESO). Each IO uses its own drill<strong>in</strong>g platform and<br />

data management system. Currently SEDIS <strong>in</strong>tegrates the<br />

data search of the IO databases by harvest<strong>in</strong>g distributed<br />

metadata without the necessity to centralize the data<br />

storage. SEDIS will be expanded at a later stage to <strong>in</strong>clude<br />

other scientific drill<strong>in</strong>g data from cont<strong>in</strong>ental or lake<br />

drill<strong>in</strong>g. SEDIS will also <strong>in</strong>clude a publication search<br />

eng<strong>in</strong>e and advanced data search, visualization and<br />

mapp<strong>in</strong>g tools.<br />

SEDIS will be developed <strong>in</strong> three phases:<br />

Phase I [f<strong>in</strong>ished]: Metadata portal for data discovery<br />

and harvest<strong>in</strong>g. Metadata will be provided by the IOs<br />

(http://sedis.iodp.com)<br />

Phase II [<strong>in</strong> progress]: Search database for publications,<br />

reports, m<strong>in</strong>utes, citations and possibly post expedition<br />

research<br />

Phase III: Advanced data search, conversion,<br />

visualization and mapp<strong>in</strong>g tools<br />

The uses <strong>in</strong>ternational standards for metadata and data<br />

exchange and transfer and uses open source components.<br />

<strong>IODP</strong><br />

New tools to determ<strong>in</strong>e paleoceanographic<br />

proxies at ultrahigh (sub-mm) resolution:<br />

gray-scale generation and lam<strong>in</strong>ae count<strong>in</strong>g<br />

<strong>in</strong> sediments from the Antarctic Cont<strong>in</strong>ental<br />

Marg<strong>in</strong><br />

M.E. WEBER 1 , W. RICKEN 1 , G. KUHN 2 , L. REICHELT 1 , M.<br />

PFEIFFER 1 , AND R. GERSONDE 2<br />

1 Institute of Geology and M<strong>in</strong>eralogy, Zuelpicher Str. 49a, 50935<br />

Cologne, Germany (michael.weber@uni-koeln.de)<br />

2 Alfred-Wegener-Institute for Polar and Mar<strong>in</strong>e Research,<br />

Columbusstr., 27568 Bremerhaven, Germany<br />

As a German contribution to the International Mar<strong>in</strong>e<br />

Global Change Study (IMAGES Southern Ocean<br />

Initiative), we study cores retrieved <strong>in</strong> the 90s with RV<br />

Polarstern from the southeastern Weddell Sea, and cores<br />

135<br />

retrieved <strong>in</strong> 2007 with RV Marion Dufresne <strong>in</strong> the Scotia<br />

Sea dur<strong>in</strong>g cruise MD160 with<strong>in</strong> the DFG project<br />

SUBCLIMATE. Some of the sites from the Antarctic<br />

cont<strong>in</strong>ental marg<strong>in</strong> conta<strong>in</strong> f<strong>in</strong>e-gra<strong>in</strong>ed terrigenous<br />

sediment, represent<strong>in</strong>g the last glacial maximum (LGM).<br />

Sediments accumulated on contourite ridges at extremely<br />

high glacial sedimentation rates (up to 4 m/ka!). The most<br />

<strong>in</strong>trigu<strong>in</strong>g characteristic is the abundant mm-scale<br />

lam<strong>in</strong>ation, compris<strong>in</strong>g relatively coarse (silty) and f<strong>in</strong>e<br />

(muddy) layers of detrital composition.<br />

Naturally, we were <strong>in</strong>terested <strong>in</strong> whether the lam<strong>in</strong>ation<br />

represents <strong>in</strong>terannual stratification and could hence be<br />

used as a high-resolution chronology. Therefore, we<br />

developed two tools. First, we extracted gray values at<br />

pixel resolution (i.e., 12 measurements/mm) from scans of<br />

x-radiographs by implement<strong>in</strong>g the so-called BMPix tool.<br />

Then, we used the PEAK tool for semi-automated layer<br />

count<strong>in</strong>g from the gray curves. In 14-m long core PS1789,<br />

for <strong>in</strong>stance, we counted 2430 peaks over 2690 AMS-dated<br />

years (i.e., over 10 m core length), which adds up to 90 %<br />

of the expected years. Accord<strong>in</strong>gly, there is strong<br />

evidence that the lam<strong>in</strong>ation represents <strong>in</strong>terannual<br />

variability and therefore, the sites from the contourite<br />

ridges conta<strong>in</strong> an extremely valuable climate archive for<br />

ultrahigh-resolution studies of glacial climate variability <strong>in</strong><br />

high southern latitudes.<br />

The fact that PEAK counts less layers <strong>in</strong> all sites than<br />

should be present accord<strong>in</strong>g to atomic mass spectrometry<br />

(AMS) dat<strong>in</strong>g, is most likely due to a comb<strong>in</strong>ation of three<br />

facts: (i) m<strong>in</strong>or <strong>in</strong>tercalation of bioturbated sediment (e.g.,<br />

site PS1599 conta<strong>in</strong>s thicker bioturbated <strong>in</strong>tervals than site<br />

PS1789 and thus only 70-50 % of the expected layers), (ii)<br />

missed sediment parts at the top and bottom of each Xradiograph<br />

slice (consider<strong>in</strong>g that from a 14-m long core<br />

almost 60 X-radiograph slices are taken), and (iii)<br />

<strong>in</strong>adequate program sett<strong>in</strong>gs <strong>in</strong> PEAK so that some layers<br />

are not counted.<br />

Future work will <strong>in</strong>clude additional test<strong>in</strong>g and<br />

optimiz<strong>in</strong>g of the tools. Furthermore, we will concentrate<br />

on cores that are entirely lam<strong>in</strong>ated (i.e., show virtually no<br />

<strong>in</strong>tercalation of bioturbated sections) and that will have to<br />

be dated with AMS (e.g., PS1791). Also, we will apply<br />

spectral analysis techniques to evaluate whether there are<br />

decadal to centennial-scale frequency patterns and how<br />

they correlate to low-latitude climate records.<br />

<strong>IODP</strong><br />

Late Miocene Mega Slump<strong>in</strong>g along the<br />

southwest African Coast<br />

E. WEIGELT 1 , G. UENZELMANN-NEBEN 1<br />

1 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, PO<br />

120161, 27515 Bremerhaven, Germany<br />

Large Neogene slumps affected the sedimentary<br />

sequence on the southwest African marg<strong>in</strong>. Based on an<br />

<strong>in</strong>tegrated study of borehole and seismic data we aim to<br />

generate a spatial and chronological classification of slump<br />

scarp traces to ga<strong>in</strong> an understand<strong>in</strong>g of the orig<strong>in</strong> of these<br />

mass-movements. In our contribution, we focus on an<br />

extended slump scarp zone identifiable on all seismic l<strong>in</strong>es<br />

available to us along the eastern Cape Bas<strong>in</strong>. This large<br />

slump<strong>in</strong>g feature is located at the upper slope region of the

136<br />

cont<strong>in</strong>ental marg<strong>in</strong> and dated to orig<strong>in</strong>ate <strong>in</strong> the<br />

Middle/Late Miocene (15-10 Ma ).<br />

In the northern Cape Bas<strong>in</strong>, we def<strong>in</strong>ed a lower age of<br />

about 10 Ma for this slump<strong>in</strong>g scarp zone which is also<br />

acossiated with a sudden change <strong>in</strong> reflection pattern of<br />

seismic units above and below. In contrast, only weak<br />

traces of slump scarps can be dist<strong>in</strong>guished <strong>in</strong> the Middle<br />

Cape Bas<strong>in</strong>. Probably they are masked by a reflection free<br />

zone <strong>in</strong>dicat<strong>in</strong>g the presence of gas and hydrocarbons.<br />

Aga<strong>in</strong>, <strong>in</strong> the southern Cape Bas<strong>in</strong> we have observed<br />

slump<strong>in</strong>g scarps throughout the upper seismic units s<strong>in</strong>ce<br />

the Late Miocene.<br />

As possible preconditions for laterally extended mass<br />

movement we suggest (1) either a high <strong>in</strong>stability of<br />

deposited material result<strong>in</strong>g of an <strong>in</strong>creased sedimentation<br />

<strong>in</strong> response to enhanced upwell<strong>in</strong>g s<strong>in</strong>ce the Middle<br />

Miocene or (2) <strong>in</strong>stabilities due to gas hydrates. A strong<br />

Middle/Late Miocene sea level regression later probably<br />

triggered contemporaneously slump<strong>in</strong>g and slid<strong>in</strong>g.<br />

<strong>IODP</strong><br />

Organic-carbon sources, anoxia, and seasurface<br />

temperature <strong>in</strong> the Paleocene central<br />

Arctic Ocean (<strong>IODP</strong> Expedition 302):<br />

Evidence from biomarkers<br />

P. WELLER 1 , R. STEIN 1<br />

1 Alfred Wegener Institute for Polar and Mar<strong>in</strong>e Research, D-<br />

27568 Bremerhaven, Germany<br />

Dur<strong>in</strong>g <strong>IODP</strong> Expedition 302 (Arctic Cor<strong>in</strong>g<br />

Expedition – ACEX), a more than 200 m thick sequence of<br />

Paleogene organic-carbon (OC) -rich (black shale-type)<br />

sediments has been drilled on Lomonosov Ridge, central<br />

Arctic Ocean (Fig.1; Backman, Moran. McInroy et al.,<br />

2006). Here, we present new biomarker data from this OCrich<br />

Paleogene <strong>in</strong>terval. This biomarker approach allows (i)<br />

a more precise identification of OC sources, (ii) the<br />

characterization of the depositional environment, and (iii)<br />

estimates of paleotemperatures based on alkenones (Weller<br />

and Ste<strong>in</strong>, <strong>2008</strong>). Based on the biomarker data, the<br />

terrestrial OC supply was significantly enriched dur<strong>in</strong>g the<br />

late Paleocene and part of the earliest Eocene, whereas<br />

dur<strong>in</strong>g the PETM and Elmo events as well as the middle<br />

Eocene aquatic OC contributions were <strong>in</strong>creased.<br />

Isorenieratene derivatives are present <strong>in</strong> samples from the<br />

PETM event <strong>in</strong>dicat<strong>in</strong>g eux<strong>in</strong>ic conditions reach<strong>in</strong>g <strong>in</strong>to the<br />

photic zone of the water column (as already described by<br />

Sluijs et al., 2006). These biomarkers, however, could not<br />

be detected <strong>in</strong> samples from the Elmo Event. Thus, eux<strong>in</strong>ic<br />

conditions – although present <strong>in</strong> deeper water mass - did<br />

not extend <strong>in</strong>to the photic zone at that time. In the<br />

underly<strong>in</strong>g “Pre-Elmo” event, on the other hand, the<br />

presence of isorenieratane and related isorenieratene<br />

derivatives po<strong>in</strong>t to similar conditions than those of the<br />

PETM Event. Samples from the early Eocene and the<br />

middle Eocene (<strong>in</strong>clud<strong>in</strong>g the Azolla Freshwater Event) are<br />

characterized by the occurrence of high proportions of<br />

lycopane and high ratios (>0.6) of (n-C35+lycopane)/n-<br />

C31, <strong>in</strong>terpreted as <strong>in</strong>creased freshwater <strong>in</strong>put (Weller and<br />

Ste<strong>in</strong>, <strong>2008</strong>). Source-specific long-cha<strong>in</strong> C37:3-and C37:2-<br />

alkenones were absent <strong>in</strong> the late Paleocene/early Eocene<br />

(Unit 3), but first occurred <strong>in</strong> the biosilicous oozes of Unit<br />

2 at about 300 mcd, i.e., towards the end of the Azolla<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Freshwater Event (Fig.2). The occurrence of the alkenones<br />

are <strong>in</strong>terpreted as <strong>in</strong>creas<strong>in</strong>g mar<strong>in</strong>e <strong>in</strong>fluence dur<strong>in</strong>g the<br />

upper Azolla Freshwater Event, support<strong>in</strong>g Br<strong>in</strong>khuis et al.<br />

(2006).<br />

Fig. 1: Paleogeography and proposed surface-water circulation at<br />

about 50 Ma, and location of <strong>IODP</strong> Expedition 302 cor<strong>in</strong>g site<br />

(Backman, Moran. McInroy et al., 2006).<br />

Mostly, long-cha<strong>in</strong> alkenones, found <strong>in</strong> samples as old<br />

as Cretaceous (e.g., Brassell et al., 2004) and widespread <strong>in</strong><br />

all oceans, are synthesized by mar<strong>in</strong>e phytoplankton<br />

(Volkman et al., 1980; Conte et al., 1992). However, they<br />

were also recorded <strong>in</strong> freshwater environments (e.g., Li et<br />

al., 1995). For the <strong>in</strong>terpretation of the ACEX alkenone<br />

data and – especially - the use of U K´ 37 <strong>in</strong>dex for estimat<strong>in</strong>g<br />

Arctic Ocean sea-surface temperatures (SST), the mar<strong>in</strong>e<br />

orig<strong>in</strong> of the alkenones has to be proven. The distribution<br />

pattern of C37- and C 38 alkenones is an important feature<br />

for dist<strong>in</strong>guish<strong>in</strong>g between mar<strong>in</strong>e and lacustr<strong>in</strong>e alkenoneproducers.<br />

Additionally a relative high abundance of tetraunsaturated<br />

compounds is a characteristic of long cha<strong>in</strong><br />

alkenones <strong>in</strong> limnic systems. The C37:C 38 alkenone ratios of<br />

the ACEX sequence show a mean value of 1.15 still with<strong>in</strong><br />

the range of those found for E. Huxleyi (Weller and Ste<strong>in</strong>,<br />

<strong>2008</strong>). Furthermore, the ACEX sediments are generally<br />

characterized by greatest abundance of di- and triunsaturated<br />

alkenones, whereas the tetraunsaturated<br />

compounds was not found <strong>in</strong> the ACEX sediments. This<br />

suggests that the biosynthesis of alkenones and temperature<br />

dependent ratio of C37-alkenones <strong>in</strong> the middle Eocene<br />

Arctic Ocean might be comparable to modern mar<strong>in</strong>e<br />

systems. Thus, we are confident that the alkenones<br />

represent a mar<strong>in</strong>e signal and can be used for SST<br />

calculation. Us<strong>in</strong>g the U K´ 37 <strong>in</strong>dex, sea-surface temperatures<br />

(SST) have been calculated for a selected set of samples<br />

from the middle Eocene time <strong>in</strong>terval and a first<br />

prelim<strong>in</strong>ary low-resolution record (Fig. 2).

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 2: Long-cha<strong>in</strong> C37:3- and C37:2 -alkenones (µg/g TOC) and SST (°C) reconstruction based on the UK´37 <strong>in</strong>dex <strong>in</strong> sediments from<br />

the ACEX sequence between 195 and 300 mcd (Weller and Ste<strong>in</strong>, <strong>2008</strong>). In addition, TEX86’-derived SST (°C) (based on Br<strong>in</strong>khuis et<br />

al., 2006; Sluijs et al., 2006, <strong>2008</strong>), trend of global benthic δ18O stack (based on Zachos et al., 2001); and IRD data (based on St. John<br />

(<strong>2008</strong>) are shown.<br />

With<strong>in</strong> this time <strong>in</strong>terval, i.e., between about 49 and<br />

44.5 Ma, the SST record shows a dist<strong>in</strong>ct long-term<br />

decrease of about 15°C (Weller and Ste<strong>in</strong>, <strong>2008</strong>). This<br />

general temperature decrease follows very well the global<br />

cool<strong>in</strong>g trend at the end of the Early Eocene Climate<br />

Optimum as deduced from the global benthic isotope stack<br />

(Fig. 2; e.g., Zachos et al., 2001). This general cool<strong>in</strong>g<br />

trend correlates also very well with the amount and flux of<br />

ice-rafted debris (IRD) (St. John, <strong>2008</strong>). At about 46.3 Ma,<br />

IRD first appeared, contemporaneously with a drop <strong>in</strong> SST<br />

to about less than 15°C (Fig. 2). Near 44.8 Ma, co<strong>in</strong>cident<br />

with a further <strong>in</strong>crease <strong>in</strong> IRD, SST of about 10°C was<br />

reached. Based on isotopic equilibrium between terrestrial<br />

carbonate and environmental water, Jahren & Sternberg<br />

(2003) suggest a mean annual temperature of 13°C for the<br />

middle Eocene Arctic (80°N; ~ 45 Ma), which agrees very<br />

well with our estimates. Above the hiatus at about 198<br />

mbsf (Zebra Unit I/5; Miocene), SST values between 11<br />

and 15°C were calculated (Fig. 2).<br />

Our absolute values of the U K´ 37 -based SST rang<strong>in</strong>g<br />

between about 25°C and 10°C, are significantly higher than<br />

those predicted from climate models (Shellito et al., 2003).<br />

They are also dist<strong>in</strong>ctly higher than those calculated us<strong>in</strong>g<br />

the TEX86’ <strong>in</strong>dex (Fig. 2), a new SST proxy based on the<br />

temperature-dependent proportion of different isomers of<br />

glycerol dibiphytanyl glycerol tetra ethers (GDGTs),<br />

specific biomarkers produced by mar<strong>in</strong>e crenarchaeota<br />

(Schouten et al. 2002). For the early Eocene time <strong>in</strong>terval<br />

where TEX86 temperatures of about 10 to 20°C were<br />

determ<strong>in</strong>ed (Sluijs et al., <strong>2008</strong>), unfortunately no alkenone<br />

SSTs could be determ<strong>in</strong>ed due to the absence of alkenones.<br />

For the Azolla phase, the U K´ 37 -based SST vary between<br />

about 20°C and 25°C, whereas the TEX86’-derived SST<br />

137<br />

vary between 8°C and 13°C (Br<strong>in</strong>khuis et al., 2006)<br />

(Fig. 2). The maximum U K´ 37 -based SST values between<br />

49 and 47 Ma represent<strong>in</strong>g the f<strong>in</strong>al stage of the Early<br />

Eocene Climate Optimum, are <strong>in</strong> the same range as those<br />

determ<strong>in</strong>ed for the PETM us<strong>in</strong>g the TEX86’ approach<br />

(Sluijs et al., 2006).<br />

Assum<strong>in</strong>g that both SST records are correct, how these<br />

differences can be expla<strong>in</strong>ed? While U K´ 37-based SST<br />

reflects the SST <strong>in</strong> the shallower euphotic zone (upper 10<br />

m) where the temperature is highly variable, Crenarchaeota<br />

live deeper down (~ 100 m), where temperature<br />

fluctuations are less pronounced. In addition, planktonic<br />

crenarchaeota typically have their ma<strong>in</strong> phase of growth<br />

dur<strong>in</strong>g the annual cycle outside the ma<strong>in</strong> period of<br />

phytoplankton blooms (Schouten et al., 2002). Thus,<br />

UK´37 -based SST probably reflects summer SST <strong>in</strong> the<br />

central Arctic Ocean (cf., Axelrod et al., 1984) whereas the<br />

TEX86’-derived values may represent more the (annual<br />

mean) w<strong>in</strong>ter SST, i.e., the difference between both data<br />

sets may represent the seasonal temperature variability.<br />

This <strong>in</strong>terpretation is <strong>in</strong> agreement with reconstructions of<br />

a strong High Northern Latitudes seasonal temperature<br />

variability of >10°C dur<strong>in</strong>g the early-middle Eocene, as<br />

estimated from morphological features of plant fossils<br />

(e.g., Greenwood and W<strong>in</strong>g, 1995).<br />

Our alkenone SSTs of 10-17°C determ<strong>in</strong>ed for the time<br />

<strong>in</strong>terval 46.3-44.8 Ma characterized by the first occurrence<br />

of IRD (Fig. 2), seems to be not unrealistic. If they<br />

represent rather the summer SST and due to the strong<br />

seasonal variability of >10°C, favourable conditions for<br />

sea-ice formation may have occurred dur<strong>in</strong>g w<strong>in</strong>ter time.<br />

This could have been a situation similar to that observed <strong>in</strong>

138<br />

the modern Baltic Sea where summer temperatures of<br />

>15°C and w<strong>in</strong>ter temperatures

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Machlus, M., Hemm<strong>in</strong>g, S.R., Olsen, P.E., and Christie-Blick, N., 2004,<br />

Eocene calibration of geomagnetic polarity time scale reevaluated:<br />

Evidence from the Green River Formation of Wyom<strong>in</strong>g: Geology, v.<br />

32, p. 137-140.<br />

Ogg, J.G., and Smith, A.G., 2004, The geomagnetic polarity time scale, <strong>in</strong><br />

Gradste<strong>in</strong>, F., Ogg, J., and Smith, A., eds., A Geological Timescale<br />

2004, Cambridge University Press, p. 63-86.<br />

Smith, M.E., Carroll, A.R., and S<strong>in</strong>ger, B.S., <strong>2008</strong>, Synoptic reconstruction<br />

of a major ancient lake system: Eocene Green River Formation,<br />

western United States: Geological Society of America Bullet<strong>in</strong>, v.<br />

120(1): p. 54-84.<br />

<strong>IODP</strong><br />

Mo- and U-isotope variations <strong>in</strong> black shales:<br />

Potential tracers for the quantification of<br />

oceanic anoxia<br />

S. WEYER 1 , C. MONTOYA-PINO 1 , J. PROSS AND W. OSCHMANN 1<br />

1 Universität Frankfurt, Institut für Geowissenschaften, Altenhöfer<br />

Allee 1, D-60431 Frankfurt<br />

The atmosphere and the oceans have kept relatively<br />

oxic throughout the Phanerozoic. Nevertheless, remarkable<br />

variations of atmospheric oxygen (by a factor of 3-5) have<br />

been modeled for this time period by us<strong>in</strong>g different<br />

geochemical and isotopic proxies (e.g. Berner, 2006; Algeo<br />

et al., 2007). These variations appear to go along with<br />

major oceanic anoxic events (OAEs), e.g. dur<strong>in</strong>g the lower<br />

Jurassic and Mid-Cretaceous. These OAEs are<br />

characterized by significant black shale formation, partially<br />

on a global scale. Duration and causes for enhanced<br />

oceanic anoxia are variable, but they appear to be l<strong>in</strong>ked to<br />

environmental changes, such as CO2-levels, climate, ocean<br />

ventilation and primary production. Currently we have<br />

little possibilities to quantify the spatial extent of anoxic<br />

conditions <strong>in</strong> the oceans. As anoxic environment are a<br />

major s<strong>in</strong>k for redox sensitive trace metals, such as Mo and<br />

U, these metals are suitable and have been widely used to<br />

study redox conditions of oceanic environments.<br />

Burial of trace metals <strong>in</strong>to their oceanic s<strong>in</strong>ks is<br />

frequently associated with isotope fractionation. Anbar,<br />

Siebert and co-workers have shown that Mo-isotopes<br />

display significant fractionation between oxic and anoxic<br />

environments (up to 3 ‰ <strong>in</strong> δ 98 Mo/ 95 Mo). Thus, a change<br />

<strong>in</strong> the relative portion of oxic versus anoxic s<strong>in</strong>ks should be<br />

associated with a significant change of the oceanic Moisotope<br />

mass balance. Arnold et al. (2004) have used this<br />

isotope systematics to show that deep oceans have been<br />

widely eux<strong>in</strong>ic dur<strong>in</strong>g most of the proterozoic. More<br />

recently, Weyer et al. (<strong>2008</strong>) showed that the 238 U/ 235 U<br />

isotope ratio can also be significantly fractionated (on a ‰level)<br />

between oxic and anoxic environments. Both isotope<br />

systems together may thus be suitable to quantify anoxic<br />

s<strong>in</strong>ks of Mo and U and with that the expansion of oceanic<br />

environments through geological time.<br />

We have been <strong>in</strong>vestigat<strong>in</strong>g the isotopic compositions<br />

of Mo and U of black shales from mayor oceanic anoxic<br />

events, such as OAE-2 and the Toarcian OAE, which may<br />

have lasted over a period of ≈ 0.5 and ≈ 1 Ma, respectively<br />

(Erbacher et al., 2005; Suan et al., <strong>2008</strong>). Prelim<strong>in</strong>ary<br />

results <strong>in</strong>dicate that black shales from these periods <strong>in</strong>deed<br />

display isotope systematics, which are different from those<br />

displayed by modern black shales. Although <strong>in</strong>terpretation<br />

of the limited dataset is not straight forward at the current<br />

state, the observed Mo and U isotope signals may be<br />

l<strong>in</strong>ked, at least partially, to an enhanced anoxic s<strong>in</strong>k for<br />

redox sensitive trace metals dur<strong>in</strong>g these periods.<br />

139<br />

References<br />

Algeo, T.J. and Ingall, E. (2007 <strong>in</strong> press) Sedimentary Corg:P ratios,<br />

paleocean ventilation, and Phanerozoic atmospheric pO2.<br />

Palaeogeography, Palaeoclimatology, Palaeoecology.<br />

Arnold G. L., Anbar A. D., Barl<strong>in</strong>g J., and Lyons T. W. (2004)<br />

Molybdenum isotope evidence for widespread anoxia <strong>in</strong> Mid-<br />

Proterozoic oceans. Science 304, 87-90.<br />

Barl<strong>in</strong>g J., Arnold G. L., and Anbar A. D. (2001) Natural mass dependent<br />

variations <strong>in</strong> the isotope compositions of molybdenum. Earth and<br />

Planetary Science Letters 193, 447-457.<br />

Berner, R.A. (2006) GEOCARBSULF: A comb<strong>in</strong>ed model for Phanerozoic<br />

atmospheric O2 and CO2. Geochimica et Cosmochimica Acta 70,<br />

5653-5664.<br />

Erbacher J., Friedrich O., Wilson P. A., Birch H., and Mutterlose J. (2005)<br />

Stable organic carbon isotope stratigraphy across oceanic anoxic event<br />

2 of Dmerara Rise, western tropical Atlantic. Geochemistry<br />

Geophysics Geosystems 6, 2004GC000850.<br />

Siebert C., Nägler T. F., von Blanckenburg F., and Kramers J. D. (2003)<br />

Molybdenum isotope records as a potential new proxy for<br />

paleooceanography. Earth and Planetary Science Letters 211, 159-171.<br />

Suan, G., Pittet, B., Bour, I, Mattioli, E, Duarte L.V., Mailliot S. (<strong>2008</strong> <strong>in</strong><br />

press): Duration of the Early Toarcian carbon isotope excursion<br />

deduced from spectral analysis: consequence for its possible causes.<br />

Earth and Planetary Science Letters.<br />

Weyer S., Anbar A. D., Gerdes A., Gordon G., Algeo T. J., and Boyle E. A.<br />

238 235<br />

(<strong>2008</strong>) Natural fractionation of U/ U. Geochimica et<br />

Cosmochimica Acta 72, 345-359.<br />

<strong>ICDP</strong><br />

Characterization of gas from seismogenic<br />

depths of the San Andreas Fault at SAFOD<br />

T. WIERSBERG 1 AND J. ERZINGER 1<br />

1<br />

GeoForschungsZentrum Potsdam, Telegrafenberg, 14473<br />

Potsdam<br />

The on-l<strong>in</strong>e analysis of the molecular composition of<br />

gas, extracted from return<strong>in</strong>g drill-mud, followed by<br />

isotopic studies on gas samples has been proven bee<strong>in</strong>g a<br />

powerful tool to reveal <strong>in</strong>formation on the geochemistry of<br />

fluids and gases at seismogenic depths of the SAFOD (San<br />

Andreas Fault Observatory at Depth) wells (Erz<strong>in</strong>ger et al.<br />

2004, Wiersberg and Erz<strong>in</strong>ger, 2007, <strong>2008</strong>). These studies<br />

imply separation of two <strong>in</strong>dividual hydrological systems by<br />

a low-permeable fault core at SAFOD. From the pr<strong>in</strong>cipal<br />

formation gases (hydrocarbons, CO2 and H 2), the latter<br />

might be of mechanochemical orig<strong>in</strong>, wheras CO 2 and<br />

hydrocarbons clearly derive from organic sources. The<br />

contribution of mantle-derived fluids to the total fluid<br />

<strong>in</strong>ventory is only small.<br />

However, drill-mud gas analysis hardly provides<br />

<strong>in</strong>formation on absolute gas concentration of the drilled<br />

formation with high spatial resolution. In addition to drillmud<br />

gas analysis, we have therefore extracted and analysed<br />

gas from drill core samples dur<strong>in</strong>g the drill<strong>in</strong>g operations at<br />

SAFOD <strong>in</strong> 2007 by us<strong>in</strong>g a technique modified from Arai<br />

et al. (2001). After drill core recovery, core pieces (chunks<br />

from core preparation, from the core catcher, and subcore<br />

samples) were immediately placed <strong>in</strong> a gas bag, which was<br />

sealed and placed <strong>in</strong> a desiccator. For six hours, the<br />

desiccator was evacuated to few mbar, caus<strong>in</strong>g<br />

accumulation of gas extracted from the rock sample <strong>in</strong> the<br />

gas bag. Thereafter, the liberated gas was spiked with 20cc<br />

Kr and admitted to a gas chromatograph and a gas mass<br />

spectrometer for analysis.<br />

The SAFOD wells traverse 768m of Tertiary and<br />

Quaternary sediments on the Pacific Plate, underla<strong>in</strong> by<br />

Mesozoic granites. The straight SAFOD Pilot Hole was<br />

drilled down to 2168m hole depth, whereas the ma<strong>in</strong> hole<br />

(MH), drilled <strong>in</strong> two phases, was deviated northeastward to<br />

<strong>in</strong>tersect the SAF between approx. 3100–3450m bore hole<br />

depth and penetrates the North American Plate at ~3km

140<br />

vertical depth. Below approx. 1900m hole depth, the MH<br />

drilled only sedimentary strata. In a third phase (SAFOD-<br />

III) <strong>in</strong> 2007, three side tracks were drilled to obta<strong>in</strong> drill<br />

core samples from the active mov<strong>in</strong>g part of the SAF at<br />

seismogenic depths.<br />

On-l<strong>in</strong>e drill-mud gas data shows good agreement<br />

between the SAFOD-MH and the sidetracks <strong>in</strong> the<br />

distribution of hydrocarbons versus depth and their<br />

molecular composition. The absolute gas concentrations<br />

differ, as drill-mud flow rate, rate of penetration, and drillmud<br />

composition are dist<strong>in</strong>ct for each hole. The depth<br />

distribution of CH4 as well as C1/(C2+C3) values correlate<br />

well between drill-mud gas analysis and core-gas<br />

extraction, mostly even on small spatial scale. Up to<br />

64mg/g CH4 could be extracted from drill core, which is<br />

not unusual for sedimentary strata. Aquil<strong>in</strong>a et al. (1998)<br />

found maximal CH 4 concentration of approx. 1000ppmv <strong>in</strong><br />

drill-mud when drill<strong>in</strong>g sediments (Balazuc borehole,<br />

France) and ~60mg/g CH4 by leach<strong>in</strong>g of drill core samples<br />

from correspond<strong>in</strong>g depths. CH 4 concentrations from<br />

SAFOD drill-core samples are <strong>in</strong> the same range, whereas<br />

CH4 <strong>in</strong> correspond<strong>in</strong>g drill-mud gas is higher (more than<br />

3000ppmv). This discrepancy is probably caused by<br />

dist<strong>in</strong>ct bore hole parameters (see above) and different<br />

efficiency of gas extraction. Isotope studies (δ 13 C, H/D) on<br />

hydrocarbons, extracted from drill core and drill-mud, are<br />

ongo<strong>in</strong>g to obta<strong>in</strong> more detailed <strong>in</strong>formation on their<br />

genesis and orig<strong>in</strong>.<br />

References:<br />

Aquil<strong>in</strong>a L., Baubron J.-C., Defoix D., Dégranges P., Disnar J.-R., Marty B.,<br />

and Robé M.-C., 1998. Characterization of gases <strong>in</strong> sedimentary<br />

formation through monitor<strong>in</strong>g dur<strong>in</strong>g drill<strong>in</strong>g and core leach<strong>in</strong>g<br />

(Balazuc borehole, Deep Geology of France Programme), Applied<br />

Geochemistry 13 (6), 673-686.<br />

Arai T., Okusawa T. and Tsukahara H., 2001. Behaviour of gases <strong>in</strong> the<br />

Noijma Fault Zone revealed from chemical composition and carbon<br />

isotope ratio of gases extracted from DPRI 1800 m drill core, The<br />

Island Arc 10, 430-438.<br />

Erz<strong>in</strong>ger J., Wiersberg T. and Dahms E. (2004) Real-time mud gas logg<strong>in</strong>g<br />

dur<strong>in</strong>g drill<strong>in</strong>g of the SAFOD Pilot Hole <strong>in</strong> Parkfield, CA, Geophys.<br />

Res. Lett. 31, L15S18, doi:10.1029/2003GL019395<br />

Wiersberg T. and Erz<strong>in</strong>ger J. (2007) A helium isotope cross-section study<br />

through the San Andreas Fault at seismogenic depths, G-cubed 8, No.1,<br />

doi: 10.1029/2006GC001388<br />

Wiersberg T. and Erz<strong>in</strong>ger J. (<strong>2008</strong>) On the orig<strong>in</strong> and spatial distribution of<br />

gas at seismogenic depths of the San Andreas Fault from drill mud gas<br />

analysis, Applied Geochemistry (<strong>in</strong> review).<br />

<strong>ICDP</strong><br />

Molecular clock approaches: bridg<strong>in</strong>g the<br />

gap between cont<strong>in</strong>ental deep drill<strong>in</strong>g and<br />

evolutionary biology <strong>in</strong> ancient Lake Ohrid<br />

T. WILKE 1 , C. ALBRECHT 1 , B. WAGNER 2 , S. KRASTEL 3 , K.<br />

REICHERTER 4 , G. DAUT 5 , M. WESSELS 6<br />

1 Tierökologie und Spezielle Zoologie, Justus-Liebig-Universität<br />

Giessen, tom.wilke@allzool.bio.uni-giessen.de<br />

2 Institut für Geologie und M<strong>in</strong>eralogie, Universität zu Köln<br />

3 Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Kiel<br />

4 Neotektonik und Georisiken, RWTH Aachen<br />

5 Institut für Geographie der Friedrich Schiller Universität Jena<br />

6 Institut für Seenforschung; Langenargen<br />

The Balkan Lake Ohrid is worldwide the ancient lake<br />

with the highest degree of endemism tak<strong>in</strong>g lake size <strong>in</strong>to<br />

account. Whereas its hydrology is fairly well studied, the<br />

geological history of Lake Ohrid is largely unknown. Age<br />

estimates vary, for example, from 1-10 My. Most<br />

hypotheses for the orig<strong>in</strong> of extant Lake Ohrid were<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

established almost 100 years ago and none of these<br />

hypotheses has been tested with<strong>in</strong> a modern scientific<br />

framework. Moreover, there is controversy about whether<br />

the outstand<strong>in</strong>g degree of endemism <strong>in</strong> Lake Ohrid is the<br />

result of presumed long-term environmental stability or<br />

rapid breaks of the lake’s environment due to major<br />

geological, hydrological or climatic changes.<br />

Field campaigns carried out from 2003 to 2007 aimed<br />

at study<strong>in</strong>g the biodiversity and faunal evolution of Lake<br />

Ohrid endemic taxa <strong>in</strong> space and time. Based on genetic,<br />

morphological, ecological, and biogeographical data, the<br />

follow<strong>in</strong>g questions are be<strong>in</strong>g <strong>in</strong>vestigated:<br />

(1) orig<strong>in</strong> of different <strong>in</strong>vertebrate groups <strong>in</strong> Lake<br />

Ohrid; i.e., whether Lake Ohrid acted as evolutionary<br />

reservoir or whether extant species evolved through <strong>in</strong>tralacustr<strong>in</strong>e<br />

speciation,<br />

(2) age of evolutionary l<strong>in</strong>eages,<br />

(3) orig<strong>in</strong> of extant Lake Ohrid, i.e., whether Lake<br />

Ohrid constitutes a derivate a) of the Mesohellenic trough,<br />

b) of today’s Adriatic Sea, c) of Lake Pannon, or d)<br />

whether the lake formed de novo <strong>in</strong> dry “poljes” (karstic<br />

fields) from exist<strong>in</strong>g spr<strong>in</strong>gs and/or rivers, and<br />

(4) environmental factors that drive <strong>in</strong>tra-lacustr<strong>in</strong>e<br />

diversification, i.e., whether long-term stability or rapid<br />

changes of the lake’s environment are responsible for the<br />

high biodiversity seen today.<br />

Our prelim<strong>in</strong>ary evolutionary data already suggest<br />

concurrent patterns of radiation and speciation among<br />

diverse endemic taxa <strong>in</strong> Lake Ohrid. The data also support<br />

the de novo hypothesis of lake orig<strong>in</strong> probably dur<strong>in</strong>g the<br />

Pliocene and a cont<strong>in</strong>uous existence ever s<strong>in</strong>ce. Moreover,<br />

concurrent genetic brakes <strong>in</strong> several <strong>in</strong>vertebrate groups<br />

<strong>in</strong>dicate that major geological and/or environmental events<br />

must have shaped the evolutionary history of endemic<br />

faunal elements <strong>in</strong> Lake Ohrid. Most significantly, the<br />

average age of endemic species radiations of 2 My and the<br />

average age of the split to their respective sister groups<br />

outside the lake of 3 My not only def<strong>in</strong>e the evolutionary<br />

effective age of the lake (i.e., the time s<strong>in</strong>ce when faunas<br />

have cont<strong>in</strong>uously existed) but also provide an <strong>in</strong>dication<br />

for the geological age of extant Lake Ohrid. Our results,<br />

however, can only be verified by a deep drill<strong>in</strong>g campaign.<br />

Data from a deep drill<strong>in</strong>g project <strong>in</strong> Lake Ohrid would<br />

allow for:<br />

(1) test<strong>in</strong>g the de novo hypothesis of lake orig<strong>in</strong>,<br />

(2) <strong>in</strong>vestigat<strong>in</strong>g the l<strong>in</strong>kage between major<br />

geological/environmental events and major evolutionary<br />

events,<br />

(3) a better understand<strong>in</strong>g of the controll<strong>in</strong>g forces of<br />

evolution and ext<strong>in</strong>ction of species, and<br />

(4) f<strong>in</strong>e-tun<strong>in</strong>g local molecular clocks <strong>in</strong> several groups<br />

of benthic <strong>in</strong>vertebrates.<br />

Evolutionary aspects <strong>in</strong> general and molecular clock<br />

analyses <strong>in</strong> particular will, <strong>in</strong> turn, also enrich the planned<br />

deep drill<strong>in</strong>g campaign <strong>in</strong> Lake Ohrid: endemic<br />

biodiversity and unique evolutionary patterns provide a<br />

prime motivation for a deep drill<strong>in</strong>g project <strong>in</strong> Lake Ohrid,<br />

evolutionary patterns provide the framework for a<br />

hypothesis-driven deep drill<strong>in</strong>g, andevolutionary data<br />

might help <strong>in</strong>terpret<strong>in</strong>g geological and hydrological<br />

<strong>in</strong>formation obta<strong>in</strong>ed by deep drill<strong>in</strong>g.<br />

We strongly believe that a comb<strong>in</strong>ation of molecularbased<br />

evolutionary biology and deep drill<strong>in</strong>g may not only<br />

be of great benefit for the proposed <strong>ICDP</strong> project <strong>in</strong> Lake

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Ohrid, it may also be of <strong>in</strong>terest for other <strong>IODP</strong>/<strong>ICDP</strong><br />

campaigns <strong>in</strong> the years to come, and certa<strong>in</strong>ly will help to<br />

better understand the triggers of species conservation and<br />

evolution as a matter of global significance.<br />

<strong>ICDP</strong><br />

Aerial extent of palaeoenvironmental<br />

reconstructions <strong>in</strong> southern Patagonia<br />

MICHAEL WILLE<br />

Sem<strong>in</strong>ar for Geography and Education, University of Cologne,<br />

Gronewaldstr. 2, D-50931 Cologne, Germany<br />

Dur<strong>in</strong>g the past years the multi proxy <strong>in</strong>vestigation of<br />

several sediment cores from Laguna Potrok Aike (52°S,<br />

70°W; 113 m a.s.l.) led to a paleoenvironmental and<br />

climate reconstruction for the South Patagonian ma<strong>in</strong>land<br />

cover<strong>in</strong>g the last 56 ka (Haberzettl et al. 2007, Haberzettl et<br />

al. <strong>2008</strong>, Wille et al. 2007). Lake <strong>in</strong>ternal proxies were<br />

used to reconstruct lake level fluctuations which were<br />

translated to humid and dry <strong>in</strong>tervals caused by an<br />

<strong>in</strong>teraction of precipitation, w<strong>in</strong>d speed and w<strong>in</strong>d direction<br />

as the most important factors of the recent climate.<br />

The mechanism that was suggested can be described as<br />

follows: Lake level of Laguna Potrok Aike and<br />

precipitation decrease dur<strong>in</strong>g periods of persistently high<br />

w<strong>in</strong>ds from westerly directions whereas dur<strong>in</strong>g periods of<br />

enhanced easterly w<strong>in</strong>ds lake level and precipitation<br />

<strong>in</strong>crease (Mayr et al. 2007). However, although this<br />

mechanism of easterly w<strong>in</strong>ds br<strong>in</strong>g<strong>in</strong>g ra<strong>in</strong> to Laguna<br />

Potrok Aike and the eastern parts of the steppe area was<br />

suggested, it was unclear and relatively unlikely whether<br />

this mechanism also applies for the eastern foot of the<br />

Andes and the area west of Laguna Potrok Aike.<br />

A comparison of pollen <strong>in</strong>flux and sedimentation rate<br />

from Laguna Potrok Aike and a new sediment record from<br />

Brazo Sur of Lago Argent<strong>in</strong>o (BRS 1/06, 50°34'54''S,<br />

72°54'52''W, 198 m a.s.l.) shows that between 10,200 and<br />

7300 cal BP the profiles have a parallel trend. This strongly<br />

suggests that the strong dry phase found <strong>in</strong> Laguna Potrok<br />

Aike between ca. 8600 and 7300 cal BP also occurred at<br />

the foot of the Andes and that the above described<br />

mechanism that controls humidity and drought must also<br />

be tested for sites at the foot of the Andes. Therefore,<br />

future <strong>in</strong>vestigation of sites <strong>in</strong> the vic<strong>in</strong>ity of Laguna<br />

Potrok Aike are needed to evaluate to which aerial extent<br />

paleoenvironmental and climate reconstructions can be<br />

expanded <strong>in</strong> southern Patagonia.<br />

References:<br />

Haberzettl, T. et al. (2007) Lateglacial and Holocene wet-dry cycles <strong>in</strong><br />

southern Patagonia: chronology, sedimentology and geochemistry of a<br />

lacustr<strong>in</strong>e record from Laguna Potrok Aike, Argent<strong>in</strong>a. The Holocene,<br />

17: 297-310.<br />

Haberzettl, T. et al. (<strong>2008</strong>) Hydrological variability and explosive volcanic<br />

activity <strong>in</strong> southeastern Patagonia dur<strong>in</strong>g Oxygen Isotope Stage 3 and<br />

the Holocene <strong>in</strong>ferred from lake sediments of Laguna Potrok Aike,<br />

Argent<strong>in</strong>a. Palaeogeography, Palaeoclimatology, Palaeoecology: <strong>in</strong><br />

press.<br />

Mayr, C. et al. (2007) Holocene variability of the Southern Hemisphere<br />

westerlies <strong>in</strong> Argent<strong>in</strong>ean Patagonia (52°S). Quaternary Science<br />

Reviews, 26: 579-584.<br />

Wille, M. et al. (2007) Vegetation and climate dynamics <strong>in</strong> southern South<br />

America: The microfossil record of Laguna Potrok Aike, Santa Cruz,<br />

Argent<strong>in</strong>a. Review of Palaeobotany and Palynology, 146, 234–246<br />

141<br />

<strong>ICDP</strong><br />

Petrology of melt bear<strong>in</strong>g lithologies <strong>in</strong> drill<br />

core Eyreville-B, Chesapeake Bay impact<br />

structure<br />

A. WITTMANN 1,2 , L. HECHT 2 , W. U. REIMOLD 2 , R. T. SCHMITT 2 ,<br />

T.KENKMANN 2 , B.HANSEN 2 ,V. A. FERNANDES 3<br />

1 Lunar and Planetary Institute, Houston TX 77058-1113, USA;<br />

axel.wittmann@yahoo.com<br />

2 Museum of Natural History, M<strong>in</strong>eralogy, Humboldt-University<br />

Berl<strong>in</strong>, 10115 Berl<strong>in</strong>, Germany<br />

3 Berkeley Geochronology Center, Berkeley, CA 94709, USA<br />

The Chesapeake Bay impact structure formed on the<br />

cont<strong>in</strong>ental marg<strong>in</strong> of Virg<strong>in</strong>ia, USA. The impact affected a<br />

target with a water column of 0 to 340 m on top of 400–<br />

1500 m unconsolidated siliciclastic sediments that overlaid<br />

a Neoproterozoic crystall<strong>in</strong>e basement. The result<strong>in</strong>g<br />

structure has a diameter of 80–95 km with a ~38 km<br />

diameter central crater [1]. The USGS-<strong>ICDP</strong> Eyreville<br />

drill<strong>in</strong>g is placed about 9 km NNE’ off the presumed center<br />

of the structure <strong>in</strong> the central crater’s annular moat [2]. The<br />

drill<strong>in</strong>g reached a depth of 1776.2 m and recovered ~950 m<br />

of resurge deposits that overlie a section of suevite-like<br />

impactites beween 1397 and ~1550 m. Prelim<strong>in</strong>ary<br />

petrography and geochemistry of these rocks are presented<br />

with implications for their petrogenesis.<br />

Some 50 core samples were available for study along<br />

with cont<strong>in</strong>uous core box photographs (courtesy of D.S.<br />

Powars, USGS). Except for two subunits of impact melt<br />

rocks, a particulate matrix (particle sizes below ~0.5 mm)<br />

is present throughout the sequence <strong>in</strong> variable modal<br />

proportions between 24–75 vol.%. Cataclased lithic blocks<br />

and clasts larger than ~50 cm <strong>in</strong> size are conf<strong>in</strong>ed to the<br />

basal part of the section from 1468 to ~1550 m. With one<br />

exception, clasts <strong>in</strong> the section above (1397–1468 m) are<br />

80 wt.% and around 63–64<br />

wt.% can be dist<strong>in</strong>guished. Two dist<strong>in</strong>ct shapes occur<br />

among such melt particles. Ameboid shaped, ubiquituously<br />

occurr<strong>in</strong>g melt particles with variable contents of deformed<br />

vesicles that <strong>in</strong>dicate deposition above the glass transition<br />

temperature. And, more scarcely, shard-shaped melt<br />

particles with broken vesicle rims that likely <strong>in</strong>dicate<br />

airborne transport.. Such shard-shaped melt particles occur<br />

especially <strong>in</strong> graded <strong>in</strong>tercalations, towards the top of the<br />

sequence, and <strong>in</strong> the upper part of the overly<strong>in</strong>g resurge<br />

deposit.

142<br />

Larger pods of clast-rich, unbrecciated impact melt<br />

rock occur at 1401.84–1409.37 m as holocrystall<strong>in</strong>e and at<br />

1450.2–1451.51 m as hypocrystall<strong>in</strong>e varieties. However,<br />

core box images <strong>in</strong>dicate the presence of many more<br />

impact melt pods up to 21 cm thick that are concentrated<br />

between 1397 and 1430 m. The hypocrystall<strong>in</strong>e impact<br />

melt rock reta<strong>in</strong>ed rare glassy melt of a rhyolitic<br />

composition with ~5 wt.% volatiles. Both melt rocks are<br />

currently used for radiometric dat<strong>in</strong>g of the impact event by<br />

the 40Ar/39Ar method. Until now, the event is constra<strong>in</strong>ed<br />

by analyses of ejecta material and biostratiraphy to a late<br />

Eocene age [1]. Whole rock chemical compositions of the<br />

impact melt rocks are similar to average values of the<br />

associated suevites.A prelim<strong>in</strong>ary petrologic evaluation of<br />

the section suggests that a basal part (~1468 to ~1550 m) is<br />

characterized by melt poor suevites and lithic impact<br />

breccias <strong>in</strong>tercalated with block-size clasts. Together with<br />

frequent flow-textures <strong>in</strong> the matrix and alignments of<br />

components, this could represent groundsurge deposits of<br />

the earliest excavation stage. Above this depth, a mixture<br />

of fallback and ground-surge material appears present<br />

because rapidly quenched, likely orig<strong>in</strong>ally airborne melt<br />

particles and graded sections occur. Towards the top,<br />

fallback material appears to be dom<strong>in</strong>ant with more<br />

prom<strong>in</strong>ent airborne components such as shard-like melt<br />

particles, scarce mantled particles, and dist<strong>in</strong>ct size sort<strong>in</strong>g<br />

of components.<br />

The temporal duration of the deposition of the<br />

complete suevite-like section is constra<strong>in</strong>ed by numerical<br />

models to ~6 m<strong>in</strong>utes after the impact because resurg<strong>in</strong>g<br />

water-sediment suspension <strong>in</strong>vaded the central impact<br />

structure then [3,4]. This resurge deposited ~950 m of<br />

sediments, <strong>in</strong>clud<strong>in</strong>g up to 270 m thick blocks, and<br />

reworked ejecta. Lithostatic load<strong>in</strong>g from these deposits<br />

asserted a pressure of ~20–25 MPa on the suevite-like<br />

section, which likely led to flatten<strong>in</strong>g and consolidation of<br />

the suevite-like sequence. The clast-rich impact melt rocks<br />

<strong>in</strong>dicate <strong>in</strong>-situ cool<strong>in</strong>g of melt that was emplaced <strong>in</strong> a<br />

viscous state under dry conditions because no hyaloclastitelike<br />

fragmentation occurred. The different types of melt<br />

particles were rapidly cooled below the glass transition<br />

temperature of 600–775 °C for rhyolitic melts [5] from<br />

<strong>in</strong>itial temperatures above ~1800 °C that are <strong>in</strong>dicated by<br />

the presence of clasts of decomposed zircon [6]. Although<br />

these melt particles are pervasively altered, some <strong>in</strong>dicate<br />

compositional differences that suggest retention of<br />

characteristics of precursor rocks, and thus, <strong>in</strong>complete<br />

chemical homogenization. In contrast, the unbrecciated<br />

impact melt rocks appear geochemically fairly<br />

homogeneous. This may have implications for the effect<br />

and the distribution of volatiles dur<strong>in</strong>g an oceanic impact<br />

event.<br />

Acknowledgments: K. Wünnemann, D. Stöffler, P.<br />

Czaja, H.-R. Knöfler, C. Crasselt (MfN Berl<strong>in</strong>); H.<br />

Povenmire (IT Melbourne, FL), K. Ross, T. Teague<br />

(Berkeley GC); S. Mayr (TU Berl<strong>in</strong>); G. Coll<strong>in</strong>s (IC<br />

London); G. Gohn (USGS Reston); K. Bartosova (U<br />

Vienna); R. Gibson (U Witwatersrand).<br />

References:<br />

[1] Horton J. W. jr. et al. (2005) USGS Prof. Paper # 1688, pp. 464.<br />

[2] Gohn G. S. et al. (2006) Scientific Drill<strong>in</strong>g 3, 34-37.<br />

[3] Coll<strong>in</strong>s G. S. & Wünnemann K. (2005) Geology 33, 925-928.<br />

[4] Kenkmann T. et al. (2007) GSA annual Meet<strong>in</strong>g, Abstract # 199-4.<br />

[5] Giordano D. et al (2005) J. Vol. & Geoterm. Res. 142, 105-118.<br />

[6] Wittmann A. et al. (2006) Meteor. & Planet. Sci. 41, 433-454.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

<strong>ICDP</strong><br />

TEM of eclogite from the Ch<strong>in</strong>ese<br />

Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g project at<br />

Donghai<br />

Z.Q. XU 1 , W.F. MÜLLER 2 , F.E. BRENKER 3<br />

1<br />

Institute of Geology, Ch<strong>in</strong>ese Academy of Geological Science,<br />

Bej<strong>in</strong>g 100037<br />

2<br />

Geomaterialwissenschaft, Fachbereich 11, Technische Universität<br />

Darmstadt, Schnittspahnstr. 9, 64287 Darmstadt, Germany;<br />

wmueller@geo.tu-darmstadt.de<br />

3Geozentrum der Goethe-Universität Frankfurt, Altenhöferallee 1,<br />

60438 Frankfurt am Ma<strong>in</strong>, Germany<br />

The locality of the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific Deep<br />

Drill<strong>in</strong>g Project (CCSD) is at Donghai <strong>in</strong> the Sulu segment<br />

of the Dabie-Sulu ultrahigh pressure metamorphic belt (cf.<br />

Xu et al. 2005). We have studied the m<strong>in</strong>erals of six<br />

eclogite samples from the ma<strong>in</strong> hole by methods of<br />

transmission electron microscopy (TEM) <strong>in</strong> order to<br />

characterise their microstructures. The goal is to contribute<br />

to the knowledge of the formation and exhumation of<br />

ultrahigh pressure eclogites, with special attention to<br />

deformation features. The samples <strong>in</strong>vestigated stem from<br />

223, 318, 331, 397, 452 and 584 m depths of the drill<strong>in</strong>g<br />

hole. The first four samples belong to the lithologic unit 1<br />

of Zhang et al. (2006), the last to unit 2. In our TEM-study<br />

we found omphacite, amphibole, garnet, Na-rich<br />

plagioclase, quartz, K-feldspar, and phengite.<br />

Omphacite: The chemical composition of omphacites is<br />

variable which is <strong>in</strong> agreement with Zhang et al. (2005).<br />

Omphacites with <strong>in</strong>termediate compositions between the<br />

end-members jadeite and diopside have electron diffraction<br />

patterns with sharp and <strong>in</strong>tense superstructure reflections of<br />

the type h + k odd. TEM-images, especially <strong>in</strong> dark field,<br />

show large antiphase doma<strong>in</strong>s (APDs) on the order of 1<br />

µm. Their displacement vector is R = 1/2[110] (Champness<br />

1973; Phakey & Ghose 1973). The APDs are a<br />

consequence of the convergent order<strong>in</strong>g of Al (Fe3+) and<br />

Mg (Fe2+) which leads to the diffusion-controlled<br />

transition of the disordered omphacite with space group<br />

C2/c to ordered omphacite with space group P2/n, which<br />

takes place below about 800 °C (depend<strong>in</strong>g on<br />

composition). The presence of APDs shows that the<br />

omphacites crystallised first <strong>in</strong> the disordered structure<br />

with the C2/c-lattice and the crystallisation of most, if not<br />

all omphacites took place with<strong>in</strong> the phase regime of the Pphase<br />

accord<strong>in</strong>g to the estimated peak metamorphic<br />

temperatures (e.g. Zhang et al. 2006). Omphacites rich <strong>in</strong><br />

the jadeite component or <strong>in</strong> the diopside component display<br />

small APDs on the order of about 20 to 50 nm. The<br />

temperature history was about the same for the omphacite<br />

with the large and that with the small APDs, because they<br />

occurred <strong>in</strong> the same TEM-specimen. Therefore, the reason<br />

for the different doma<strong>in</strong> size is the different chemical<br />

composition.<br />

Indications of plastic deformation of the omphacites of<br />

our samples are not common. Dislocations are only<br />

occasionally observed. Interaction with the antiphase<br />

doma<strong>in</strong> boundaries (APBs) were observed. Deformation<br />

tw<strong>in</strong> lamellae on (100) and small-angle gra<strong>in</strong> boundaries<br />

(SAGBs) due to recovery effects were not seen, <strong>in</strong> contrast<br />

to the omphacites from the Eclogite Zone of the Tauern<br />

W<strong>in</strong>dow (Müller & Franz <strong>2008</strong>). Only one fault parallel to<br />

(010) was found. Such faults are frequent <strong>in</strong> omphacites

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

from the Lower Schist Cover and the Eclogite Zone of the<br />

Tauern W<strong>in</strong>dow (Müller et al. 2004, Müller & Franz <strong>2008</strong>).<br />

Amphibole gra<strong>in</strong>s show occasionally CMFs parallel to<br />

(010) and rarely free dislocations and SAGBs. Noteworthy<br />

is a semi-coherent <strong>in</strong>terface between an amphibole and an<br />

omphacite, which is made up by dislocations.<br />

Garnet is ma<strong>in</strong>ly free of dislocations. However, there is<br />

one case of a SAGB formed by two sets of dislocations.<br />

Quartz and K-feldspar: Quartz associated with Kfeldspar<br />

was observed <strong>in</strong> the samples from 223 m and from<br />

318 m. No coesite was seen. The quartz typically conta<strong>in</strong>s<br />

free dislocations or dislocations organised <strong>in</strong>to SAGBs.<br />

Na-rich plagioclase of a composition with<strong>in</strong> the<br />

peristerite gap (≈ An12) was observed <strong>in</strong> the sample from<br />

331 m. It shows modulated structures with a preferential<br />

orientation about 5° tilted aga<strong>in</strong>st (010). The wavelengths<br />

are around 20 to 25 nm. A fa<strong>in</strong>t tweed structure is visible <strong>in</strong><br />

some areas of the gra<strong>in</strong>.<br />

Conclusions: The general observation is that<br />

microstructures due to deformation are not frequent <strong>in</strong> the<br />

CCSD samples studied compared to the eclogites from the<br />

Tauern W<strong>in</strong>dow. This is especially evident for omphacite<br />

which usually carries the deformation of eclogites and<br />

shows a wealth of deformation-<strong>in</strong>duced crystal defects <strong>in</strong><br />

the eclogites from the Tauern W<strong>in</strong>dow (Müller et al., 2004;<br />

Müller & Franz <strong>2008</strong>). The omphacites from the ultrahigh<br />

pressure metamorphic unit of Lago di Cignana,<br />

Valtournenche, Western Alps, also did not show<br />

deformation tw<strong>in</strong>n<strong>in</strong>g, and CMFs are very rare, but they<br />

often conta<strong>in</strong>ed SAGBs as <strong>in</strong>dication of recovery of<br />

deformed omphacites (Müller & Compagnoni 2007). We<br />

see that nature and concentration of deformation-<strong>in</strong>duced<br />

microstructures <strong>in</strong> samples recovered from geologic units<br />

with complex formation, subduction and exhumation<br />

histories may be quite different.<br />

Fund<strong>in</strong>g by the Deutsche Forschungsgeme<strong>in</strong>schaft is<br />

gratefully acknowledged.<br />

1-4 References:<br />

Champness PE (1973) Speculation on an order-disorder transformation <strong>in</strong><br />

omphacite. Am. M<strong>in</strong>eral. 58, 540-542<br />

Müller WF, Compagnoni R (2007) TEM of eclogite from the ultrahigh<br />

pressure metamorphic unit at Lago di Cignana, Western Alps.<br />

International Eclogite Field Symposium. Skye and Lochalsh, Scotland,<br />

p. 40-41<br />

Müller WF, Franz G (<strong>2008</strong>) TEM-microstructures <strong>in</strong> omphacite and other<br />

m<strong>in</strong>erals from eclogite near to thrust zone; the Eclogite Zone –<br />

Venediger nappe area, Tauern W<strong>in</strong>dow, Austria. N. Jahrb. M<strong>in</strong>eral.<br />

Abh. (<strong>in</strong> press)<br />

Müller WF, Brenker FE, Barnert EB, Franz G. (2004) Cha<strong>in</strong> multiplicity<br />

faults <strong>in</strong> deformed omphacite from eclogite. Eur. J. M<strong>in</strong>eral. 16, 37-48<br />

Phakey PP, Ghose S (1973) Direct observation of anti-phase doma<strong>in</strong><br />

structure <strong>in</strong> omphacite. Contr. M<strong>in</strong>eral. Petrol. 39, 239-245<br />

Xu ZQ, Yang J, Rob<strong>in</strong>son PT (2005) Deep drill<strong>in</strong>g <strong>in</strong> the Dabie-Sulu<br />

ultrahigh pressure metamorphic belt, Ch<strong>in</strong>a. EOS 86 (8), 77-78<br />

Zhang Z, Xiao Y, Hoefs J, Liou JG, Simon K (2006) Ultrahigh pressure<br />

metamorphic rocks from the Ch<strong>in</strong>ese Cont<strong>in</strong>ental Scientific Drill<strong>in</strong>g<br />

project: I. Petrology and geochemistry of the ma<strong>in</strong> hole (0-2,050 m).<br />

Contr. M<strong>in</strong>eral. Petrol. 152, 4258<br />

143<br />

<strong>IODP</strong><br />

Cultivation of Sulfate-Reduc<strong>in</strong>g Bacteria<br />

from Deep Sediment Layers<br />

that are Influenced by Crustal Fluids (<strong>IODP</strong><br />

Leg 301)<br />

K. ZIEGELMÜLLER 1 , M. KÖNNEKE 1 , H. CYPIONKA 1 , B. ENGELEN 1<br />

1 Institut für Chemie und Biologie des Meeres, Universität<br />

Oldenburg, Carl-von-Ossietzky Straße 9-11, D-26129<br />

Oldenburg, Germany<br />

Crustal fluids may fuel the deep biosphere<br />

Microbiological studies on sediment cores collected<br />

dur<strong>in</strong>g DSDP and ODP have consistently demonstrated the<br />

presence of a mar<strong>in</strong>e ‘deep biosphere’ (e.g. D'Hondt et al.,<br />

2004). Microbial communities were found to be present <strong>in</strong><br />

sediments down to several hundreds of meters below the<br />

seafloor (Parkes et al., 2000). Furthermore, recent<br />

<strong>in</strong>vestigations <strong>in</strong>dicated that the deep biosphere extends<br />

<strong>in</strong>to the upper basaltic layers of the oceanic crust (Cowen<br />

et al., 2003; Huber et al., 2006, Nakagawa et al., 2006).<br />

These porous volcanic layers are characterized by the<br />

circulation of seawater, form<strong>in</strong>g the largest aquifer on<br />

Earth. Due to their geochemical composition, the<br />

circulat<strong>in</strong>g fluids are supposed to fuel the deep biosphere<br />

by <strong>in</strong>trusion of oxidized compounds <strong>in</strong>to overlay<strong>in</strong>g<br />

sediments (DeLong, 2004).<br />

<strong>IODP</strong> Expedition 301 offered an excellent opportunity<br />

to test this hypothesis. Drill<strong>in</strong>g was conducted at the Juan<br />

de Fuca Ridge, <strong>in</strong> the northeast Pacific Ocean. This<br />

location is one of the most <strong>in</strong>tensively studied areas <strong>in</strong><br />

terms of fluid flow hydrology and impact on<br />

sedimentological sett<strong>in</strong>gs (Fisher et al. 2005). At <strong>IODP</strong> Site<br />

U1301 (water depth: 2650 m, sediment thickness: 265 m)<br />

sulfate diffuses <strong>in</strong>to the sediment column from two sites,<br />

from bottom-seawater and the crustal aquifer, result<strong>in</strong>g <strong>in</strong><br />

two sulfate-methane <strong>in</strong>terfaces, and <strong>in</strong> an upper and a lower<br />

potential sulfate reduction zone (Fig.1a). For<br />

microbiological analyses high quality, non-contam<strong>in</strong>ated<br />

sediment samples were obta<strong>in</strong>ed by advanced piston<br />

cor<strong>in</strong>g, as <strong>in</strong>dicated by perfluorocarbon tracer (PFT)<br />

measurements (Lever et al., 2006).<br />

Sulfate diffusion from below keeps microbes alive<br />

With<strong>in</strong> the first phase of our <strong>in</strong>vestigations, we have<br />

quantified the abundance of microorganisms with various<br />

methods and determ<strong>in</strong>ed microbial activities like sulfate<br />

reduction, anaerobic oxidation of methane, and exoenzyme<br />

activity at nearby <strong>in</strong> situ temperatures throughout the<br />

sediment column (Engelen & Ziegelmüller et al., <strong>2008</strong>). In<br />

short, microbial cell densities decreased with sediment<br />

depth. Cell counts showed local peaks follow<strong>in</strong>g geological<br />

sett<strong>in</strong>gs and were enhanced <strong>in</strong> basement-near layers (data<br />

not shown). Potential metabolic rates (Fig. 1b) were<br />

elevated around the lower sulfate-methane transition zone<br />

(SMTZ). Us<strong>in</strong>g the semi-quantitative most probable<br />

number (MPN) technique, a significant fraction of the<br />

microbial community could be stimulated to grow ex situ<br />

from the lower sulfate-conta<strong>in</strong><strong>in</strong>g zone. Our f<strong>in</strong>d<strong>in</strong>gs<br />

clearly <strong>in</strong>dicated that <strong>in</strong>digenous microbial populations are<br />

present, alive and metabolically active <strong>in</strong> deeply buried<br />

layers.

144<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig.1 Depth profiles of (a) geochemical parameters and (b) metabolic activities. The phylogenetic affiliation of enriched sulfatereduc<strong>in</strong>g<br />

bacteria from surface- and basement-near layers is <strong>in</strong>dicated. SR, sulfate reduction, AOM, anaerobic oxidation of methane,<br />

SMTZ, sulfate-methane transition zone.<br />

Fig.2 DGGE-f<strong>in</strong>gerpr<strong>in</strong>ts of different subcultures. DNA bands were assigned to the closest related bacteria. A) Anoxically <strong>in</strong>cubated<br />

enrichment cultures and test for facultative growth under oxic conditions. A1+2) Anoxic subcultures, still conta<strong>in</strong><strong>in</strong>g different<br />

species. A3) Subculture of only one strict anaerobic stra<strong>in</strong>. B) DGGE profiles of subcultures that exhibited vibrio-shaped cells.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Molecular tools to monitor microbial enrichment<br />

cultures and subsequent isolations<br />

Our <strong>in</strong>vestigations now focus on the analysis of<br />

cultivated members of the deep biosphere. Initial<br />

enrichments were performed <strong>in</strong> liquid dilution series and<br />

substrate gradient tubes. These cultures were started<br />

onboard the JOIDES Resolution immediately after core<br />

recovery. In order to stimulate growth of anaerobes,<br />

especially of sulfate-reduc<strong>in</strong>g bacteria, artificial seawater<br />

conta<strong>in</strong><strong>in</strong>g sulfate as term<strong>in</strong>al electron acceptor was<br />

amended with a def<strong>in</strong>ed substrate mixture <strong>in</strong> micromolar<br />

concentrations. Enrichment cultures were <strong>in</strong>cubated at<br />

20°C <strong>in</strong> the dark and at atmospheric pressure. Molecular<br />

screen<strong>in</strong>g was used to overview the diversity of cultivated<br />

microorganisms and to guide further isolation procedures<br />

via deep agar cultures and liquid dilution series.<br />

For molecular screen<strong>in</strong>g, DNA was extracted from a)<br />

enrichment cultures that showed microbial growth<br />

determ<strong>in</strong>ed by microscopic analysis or b) transferred<br />

colonies. 16S ribosomal RNA gene fragments were<br />

amplified by PCR and separated via denatur<strong>in</strong>g gradient<br />

gel electrophoresis (DGGE). Dist<strong>in</strong>ct bands were excised,<br />

reamplified and sequenced. 16S rDNA sequences were<br />

phylogenetically identified us<strong>in</strong>g the BLASTn tool for the<br />

affiliation to their next relatives.<br />

Due to low DNA-extraction yields, nested PCR was<br />

necessary. Inspite of that a high diversity of grow<strong>in</strong>g<br />

bacteria was reflected <strong>in</strong> complex DGGE band<strong>in</strong>g patterns.<br />

The screen<strong>in</strong>g revealed 22 operational taxonomic units<br />

(OTU) from seven eubacterial phyla, commonly found <strong>in</strong><br />

natural environments: Firmicutes, Act<strong>in</strong>obacteria, Beta-,<br />

Gamma-, Delta- and Epsilonbacteria, Cytophaga-<br />

Flavobacterium-Bacteroides. Furthermore, DNA-signatures<br />

related to previously described sulfate-reduc<strong>in</strong>g bacteria<br />

(SRB) were detected <strong>in</strong> enrichments from 1.3, 31, 75 and<br />

even 260 mbsf.<br />

Two different sulfate-reduc<strong>in</strong>g communities enriched<br />

from the sediment column<br />

So far, the cont<strong>in</strong>ous use of microscopy, molecular<br />

screen<strong>in</strong>g of subcultures (Fig.2) and H2S measurements led<br />

to a culture collection that is dom<strong>in</strong>ated by different sulfate<br />

reducers orig<strong>in</strong>at<strong>in</strong>g from top and bottom sediments<br />

(Fig. 1). Desulfosporos<strong>in</strong>us- and Desulfotomaculumrelated<br />

Firmicutes were repeatedly enriched from the upper<br />

sulfate-reduction zone (1.3, 9 and 31 mbsf). These sporeform<strong>in</strong>g<br />

SRB are widespread and previously isolated from<br />

both, oceanic and terrestrial habitats (eg. Moser et al.,<br />

2005, Detmers et al., 2004). From fluid-<strong>in</strong>fluenced<br />

sediments two different sulfate-reduc<strong>in</strong>g<br />

Deltaproteobacteria were isolated. The stra<strong>in</strong>s affiliated<br />

with Desulfotignum balticum (260 mbsf) and<br />

Desulfovibrio <strong>in</strong>donensis (239, 252 and 260 mbsf),<br />

respectively. While Desulfovibrio species are commonly<br />

found <strong>in</strong> the deep biosphere (e.g. Bale et al., 1997, Sass and<br />

Cypionka, 2004) the recently described genus<br />

Desulfotignum comprizes four species, only. Two of them<br />

have been isolated from mar<strong>in</strong>e habitats (Kuever et al.,<br />

2001, Sch<strong>in</strong>k et al., 2002).<br />

More sulfate-reduc<strong>in</strong>g Deltaproteobacteria were<br />

enriched from both, seawater-<strong>in</strong>fluenced (1.3 mbsf) and<br />

crustal-fluids <strong>in</strong>fluenced sediment layers (239 and 260<br />

mbsf). DGGE-band analysis resulted <strong>in</strong> an affiliation to<br />

Desulfovibrio aespoeensis (Fig.2B), a newly described<br />

sulfate reducer, supposed to be <strong>in</strong>dicative for deep granitic<br />

145<br />

rock aquifers (Motamedi and Pedersen, 1998). Currently<br />

we are work<strong>in</strong>g on the isolation of these stra<strong>in</strong>s <strong>in</strong>to pure<br />

cultures to f<strong>in</strong>ally get access to their physiological<br />

properties.<br />

Physiological experiments with sulfate-reduc<strong>in</strong>g<br />

isolates to unravel adaptions and lifestyles<br />

In general, subsequent physiological characterization<br />

will elucidate the role of our isolates <strong>in</strong> biogeochemical<br />

cycles and their adaptations to this nutrient-limited habitat.<br />

We are especially <strong>in</strong>terested <strong>in</strong> the substrate spectrum of<br />

the sulfate-reduc<strong>in</strong>g Deltaproteobacteria thriv<strong>in</strong>g <strong>in</strong> the<br />

deepest sediment layers. These stra<strong>in</strong>s are also tested for<br />

chemolithoautotrophy, i.e. growth on H2/CO2, s<strong>in</strong>ce<br />

hydrogen may act as the key electron donor <strong>in</strong> basaltic<br />

environments (Stevens and McK<strong>in</strong>ley, 1995). The use of<br />

alternative electron acceptors like manganese(IV), iron(III),<br />

nitrate or sulfur-compounds is exam<strong>in</strong>ed as well.<br />

Furthermore, the maximum growth temperature of our<br />

Desulfovibrio stra<strong>in</strong>s was 45°C at ambient pressure.<br />

However, some of these isolates were obta<strong>in</strong>ed from<br />

basement-near layers with an <strong>in</strong> situ temperature of ~60°C<br />

(Fig.1). We suppose, that <strong>in</strong>cubation experiments under <strong>in</strong><br />

situ pressure (~300 bar) would lead to higher growth<br />

temperatures.<br />

Conclusions<br />

The enrichment of non-spore form<strong>in</strong>g sulfate reducers<br />

from the crust-near layers <strong>in</strong>dicates the presence of a viable<br />

and active deep biosphere and emphasizes the impact of<br />

crustal fluids on overly<strong>in</strong>g sediments. Regard<strong>in</strong>g the<br />

worldwide expansion of the crustal fluid aquifer, we<br />

assume that this impact is an important driv<strong>in</strong>g force for<br />

deep subsurface populations on a global scale.<br />

References:<br />

Bale, S.J., Goodman, K., Rochelle, P.A., Marchesi, J.R., Fry, J.C.,<br />

Weightman, A.J., and Parkes, R.J., 1997. Desulfovibrio profundus sp.<br />

nov., a novel barophilic sulfate-reduc<strong>in</strong>g bacterium from deep sediment<br />

layers <strong>in</strong> the Japan Sea. Int. J. Syst. Bacteriol., 47:515-521.<br />

Cowen, J.P., Giovannoni, S.J., Kenig, F., Johnson, H.P., Butterfield, D.,<br />

Rappé, M.S., Hutnak, M., and Lam, P., 2003. Fluids from ag<strong>in</strong>g ocean<br />

crust that support microbial life. Science 299:120-123.<br />

DeLong, E., 2004. Microbial life breathes deep. Science 306:2198-2200.<br />

Detmers, J., Strauss, H., Schulte, U., Bergmann, A., Knittel, K., Kuever, J.,<br />

2004. FISH shows that Desulfotomaculum spp. are the dom<strong>in</strong>at<strong>in</strong>g<br />

sulfate-reduc<strong>in</strong>g bacteria <strong>in</strong> a prist<strong>in</strong>e aquifer. Microbial Ecology,<br />

47:236-242.<br />

D'Hondt, S., Jørgensen, B.B., Miller, D.J., Batzke, A., Blake, R., Cragg,<br />

B.A., Cypionka, H., Dickens, G.R., Ferdelman, T., H<strong>in</strong>richs, K.-U.,<br />

Holm, N.G., Mitterer, R., Spivack, A., Wang, G., Bek<strong>in</strong>s, B., Engelen,<br />

B., Ford, K., Gettemy, G., Rutherford, S.D., Sass, H., Skilbeck, C.G.,<br />

Aiello, I.W., Guèr<strong>in</strong>, G., House, C.H., Inagaki, F., Meister, P., Naehr,<br />

T., Niitsuma, S., Parkes, R.J., Schippers, A., Smith, D.C., Teske, A.,<br />

Wiegel, J., Naranjo Padilla, C., Solis Acosta, J.L., 2004. Distributions<br />

of microbial activities <strong>in</strong> deep subseafloor sediments. Science<br />

306:2216-2221.<br />

Engelen, B., Ziegelmüller, K., Wolf, L., Köpke, B., Gittel, A., Treude, T.,<br />

Nakagawa, S., Inagaki, F., Lever, M.A., Ste<strong>in</strong>sbu, B.O., and Cypionka,<br />

H., <strong>2008</strong>. Fluids from the oceanic crust support microbial activities<br />

with<strong>in</strong> the deep biosphere. Geomicrobiol. J (<strong>in</strong> press)<br />

Fisher, A.T., Urabe, T., Klaus, A., and the <strong>IODP</strong> Expedition 301 Scientists,<br />

2005. <strong>IODP</strong> Expedition 301 <strong>in</strong>stalls three borehole crustal<br />

observatories, prepares for three-dimensional, cross-hole experiments<br />

<strong>in</strong> the northeastern Pacific Ocean. Sci. Drill. 1:6–11.<br />

Huber, J.A., Johnson, H.P., Butterfield, D.A., and Baross, J.A., 2006.<br />

Microbial life <strong>in</strong> ridge flank crustal fluids. Environ. Microbiol., 8:88-<br />

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Kuever, J., Könneke, M., Galushko, A., and Drzyzga, O., 2001.<br />

Reclassification of Desulfobacterium phenolicum as Desulfobacula<br />

phenolica comb. nov. and description of stra<strong>in</strong> SaxT as Desulfotignum<br />

balticum gen. nov., sp. nov.. Int. J. Syst. Evol. Microbiol., 51:171-177.<br />

Lever, M.A., Alper<strong>in</strong>, M., Engelen, B., Inagaki, F., Nakagawa, S., Ste<strong>in</strong>sbu,<br />

B.O., and Teske, A., and <strong>IODP</strong> Expedition 301 Scientists, 2006. Trends<br />

<strong>in</strong> basalt and sediment core contam<strong>in</strong>ation dur<strong>in</strong>g <strong>IODP</strong> Expedition<br />

301. Geomicrobiol. J. 23:517-530.<br />

Moser, D.P., Gihr<strong>in</strong>g, T.M., Brockman, F.J., Fredrickson, J.K., Balkwill,<br />

D.L., Dollhopf, M.E., Sherwood Lollar, B., Pratt, L.M., Boice, E.,<br />

Southam, G., Wanger, G., and Baker, B.J., 2005. Desulfotomaculum

146<br />

and Methanobacterium spp. dom<strong>in</strong>ate a 4- to 5-kilometer-deep fault.<br />

Appl. Environ. Microbiol. 71:8773–8783.<br />

Motamedi, M., and Pedersen, K, 1998. Desulfovibrio aespoeensis sp. nov., a<br />

mesophilic sulfate-reduc<strong>in</strong>g bacterium from deep groundwater at Äspö<br />

hard rock laboratory, Sweden. Int. J. Sys. Bacteriol., 48:311-315.<br />

Nakagawa, S., Inagaki, F., Suzuki, Y., Ste<strong>in</strong>sbu, B.O., Lever, M.A., Takai,<br />

K., Engelen, B., Sako, Y., Wheat, C.G., Horikoshi, K., and Integrated<br />

Ocean Drill<strong>in</strong>g Program Expedition 301 Scientists, 2006. Microbial<br />

community <strong>in</strong> black rust exposed to hot ridge-flank crustal fluids. Appl.<br />

Environ. Microbiol.<br />

72:6789-6799.<br />

Parkes, R.J., Cragg, B.A., and Wellsbury, P., 2000. Recent studies on<br />

bacterial populations and processes <strong>in</strong> subseafloor sediments: A review.<br />

Hydrogeol J<br />

8:11-28.<br />

Sass, H., and Cypionka, H. 2004. Isolation of sulfate-reduc<strong>in</strong>g bacteria from<br />

the terrestrial deep subsurface and description of Desulfovibrio<br />

cavernae sp. nov.. Sys. App. Microbiol. 27:541-548.<br />

Sch<strong>in</strong>k, B., Thiemann, V., Laue, H., and Friedrich, M.W., 2002.<br />

Desulfotignum phosphitoxidans sp. nov., a new mar<strong>in</strong>e sulfate reducer<br />

that oxidizes phosphite to phosphate. Arch. Microbiol., 177:381-91.<br />

Stevens, T.O., and McK<strong>in</strong>ley, J.P., 1995. Lithoautotrophic microbial<br />

ecosystems <strong>in</strong> deep basalt aquifers. Science, 270:450-455.<br />

<strong>IODP</strong><br />

Physical Properties of Mar<strong>in</strong>e Sediments<br />

Undergo<strong>in</strong>g Subduction – Results from<br />

Heated Shear Experiments at the Nankai<br />

Covergent Marg<strong>in</strong><br />

K. ZIMMERMANN 1 , A. HÜPERS 1 , A. KOPF 1<br />

1 DFG-Research Center Ocean Marg<strong>in</strong>s, University of Bremen,<br />

P.O. Box 330440, 28334 Bremen, Germany. E-mail:<br />

kattiz@uni-bremen.de, Fax: +4942121865810<br />

Subduction zones produce frequently earthquakes of<br />

magnitude M8 or larger. These events occur along the<br />

subduction plate boundary thrust with<strong>in</strong> a temperature<br />

range of 100-150°C to 350-450°C, known as the<br />

seismogenic zone. The reason for the onset of coseimic<br />

behaviour of the sediments is still unknown. Diagenetic<br />

and consolidation processes are supposed to alter the<br />

mechanical properties of the <strong>in</strong>itially weak sediments,<br />

which may lead to the onset of unstable slid<strong>in</strong>g behaviour.<br />

However, effects of PT conditions equivalent to the updip<br />

limit on mechanical properties of mar<strong>in</strong>e sediments are still<br />

poorly understood. S<strong>in</strong>ce natural samples from these depths<br />

are not available, we conducted isothermal compaction test<br />

equivalent to the updip limit to overcome this shortcom<strong>in</strong>g.<br />

For this, we focused on end-member lithologies from<br />

underthrust section of the <strong>in</strong>com<strong>in</strong>g plate at the Nankai<br />

marg<strong>in</strong> (Japan), where the Phillipp<strong>in</strong>e Plate subducts under<br />

the Eurasian Plate with a velocity of ~4cm/yr.<br />

Three samples of mar<strong>in</strong>e sediments with different gra<strong>in</strong><br />

sizes (clay - silt) were compacted up to 70 Mpa at different<br />

temperatures (20°C, 100°C, 150°C) <strong>in</strong> an hydrothermal<br />

oedometer apparatus to simulate subduction down the slab.<br />

Afterwards these compacted samples were sheared <strong>in</strong> a<br />

direct shear box at a normal load of 3.8 MPa, room<br />

temperature conditions up to a displacement of 8 mm with<br />

a velocity of 3 x 10-3mm/s. Furthermore, remoulded<br />

aliquots of the same samples of compacted clay- (smectite<br />

and illite) and quartz-rich sediments were sheared at up to<br />

16 MPa normal stress to high displacement rate us<strong>in</strong>g a<br />

r<strong>in</strong>g shear device. Those tests were carried out at four shear<br />

velocities and both at room temperature under seawater<br />

saturated conditions, and were then subsequently heated to<br />

>80°C seawater saturated under dra<strong>in</strong>ed conditions.<br />

As a ma<strong>in</strong> result from the direct shear experiments, the<br />

clay-rich sediments show the most pronounced stra<strong>in</strong><br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

soften<strong>in</strong>g with high peak strength and very low residual<br />

coefficient of friction. In contrast, the silty samples show<br />

little stra<strong>in</strong> soften<strong>in</strong>g. Additionally, the discrepancy<br />

between µpeak and µresidual is largest for the smectiteclay<br />

compared to the silty specimens. This <strong>in</strong>crease <strong>in</strong> peak<br />

relative to residual strength may be expla<strong>in</strong>ed by the higher<br />

effective surface area <strong>in</strong> the samples poor <strong>in</strong> quartz content.<br />

With<strong>in</strong> all tests conducted so far, the samples compacted at<br />

20°C seem slightly stronger than those which got thermally<br />

altered. At high displacements dur<strong>in</strong>g the r<strong>in</strong>g shear<br />

experiments, the friction coefficient of clay m<strong>in</strong>erals<br />

(σn≈2 MPa) show similar values and are much smaller<br />

than the quartz rich sample (ca. µresidual of 0.13-0.23). At<br />

higher normal stresses (up to ≈16 MPa) and room<br />

temperature, the friction coefficients almost double. When<br />

the same samples are heated to >80°C, more pore water as<br />

well as clay m<strong>in</strong>eral-bound water is released so that the<br />

specimens show a stra<strong>in</strong> harden<strong>in</strong>g behaviour and approach<br />

friction coefficients of µ>0.4. The data correlate well with<br />

friction values estimated for plat boundary faults with<br />

<strong>in</strong>creas<strong>in</strong>g depth.<br />

<strong>ICDP</strong><br />

Climate and environmental variability dur<strong>in</strong>g<br />

the past 56 ka atLaguna Potrok Aike<br />

(southern Patagonia, Argent<strong>in</strong>a), the site of<br />

the <strong>ICDP</strong> lake drill<strong>in</strong>g project “PASADO”<br />

B. ZOLITSCHKA 1 , F.S. ANSELMETTI 2 , D. ARIZTEGUI 3 , H.<br />

CORBELLA 4 , T. HABERZETTL 5 , A. LÜCKE 6 , C. MAYR 7 , C.<br />

OHLENDORF 1 , F. SCHÄBITZ 8 , M. WILLE 8<br />

1 University of Bremen, Institute of Geography (Geopolar), 28359<br />

Bremen, Germany (zoli@uni-bremen.de)<br />

2 Swiss Federal Institute of Aquatic Science & Technology<br />

(Eawag), 8600 Dübendorf, Switzerland<br />

3 University of Geneva, Section of Earth Sciences, 1205 Geneva,<br />

Switzerland<br />

4 Argent<strong>in</strong>e Museum of Natural History, 1007 Buenos Aires,<br />

Argent<strong>in</strong>a<br />

5 Sedimentology and Environmental Geology, Geoscience Center,<br />

University of Gött<strong>in</strong>gen, 37077 Gött<strong>in</strong>gen, Germany<br />

6 Institute for Chemistry and Dynamics of the Geosphere (ICG) V:<br />

Sedimentary Systems, Research Center Jülich, 52425 Jülich,<br />

Germany<br />

7 GeoBio-Center LMU and Dept. of Earth & Environmental<br />

Sciences, University of Munich, 80333 Munich, Germany<br />

8 Sem<strong>in</strong>ar for Geography and Education, University of Cologne,<br />

50931 Cologne, Germany<br />

For mid to high southern latitudes climate<br />

reconstructions extend<strong>in</strong>g well beyond the Holocene and<br />

the Late-Glacial are mostly restricted to either mar<strong>in</strong>e<br />

sediments or to Antarctic ice cores. Until now, records<br />

from the cont<strong>in</strong>ental realm are rare or not existent. Here we<br />

start to close this gap for southern South America by<br />

<strong>in</strong>vestigat<strong>in</strong>g sediment records from Laguna Potrok Aike, a<br />

ca. 770 ka maar lake <strong>in</strong> the dry steppe of southern<br />

Argent<strong>in</strong>a (52°S, 70°W). This term<strong>in</strong>al lake from<br />

southernmost Patagonia is highly sensitive to hydrological<br />

changes and its lacustr<strong>in</strong>e record provides unique<br />

cont<strong>in</strong>ental data of variations <strong>in</strong> climate, hydrology and<br />

related dust deposition (Haberzettl et al., 2007; Mayr et al.,<br />

2007). Furthermore, it eventually may act as a cornerstone<br />

for paleodata-model comparison of the Southern<br />

Hemisphere. With<strong>in</strong> the <strong>ICDP</strong>-funded “Potrok Aike maar<br />

lake sediment archive drill<strong>in</strong>g project” (PASADO), more<br />

than 400 m of sediment are scheduled to be <strong>in</strong>vestigated <strong>in</strong>

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

an <strong>in</strong>ternational and <strong>in</strong>terdiscipl<strong>in</strong>ary approach possibly<br />

extend<strong>in</strong>g this terrestrial record to the Matuyama/Brunhes<br />

geomagnetic polarity reversal. This would be the transition<br />

from the lower to the middle Pleistocene co<strong>in</strong>cid<strong>in</strong>g with<br />

the mar<strong>in</strong>e oxygen isotope stage boundary 20/19. Not only<br />

for the older part of the record we therefore expect a high<br />

potential for paleomagnetic dat<strong>in</strong>g <strong>in</strong> addition to<br />

tephrochronology. This will not only <strong>in</strong>crease the<br />

comparability to Antarctic ice cores considerably but also<br />

improve the correlation with mar<strong>in</strong>e sediment records.<br />

Here we present a piston core transect from the<br />

submerged lake level terrace at 30 m water depth across a<br />

cor<strong>in</strong>g site on the relatively steep northern slope of the<br />

lacustr<strong>in</strong>e bas<strong>in</strong> at 47 m water depth down to the 100 m<br />

deep and flat central bas<strong>in</strong> of Laguna Potrok Aike.<br />

Correlation of such different records from quite diverse<br />

depositional environments was only possible through l<strong>in</strong>ks<br />

via volcanic ash layers. Additional time control of the<br />

multi-proxy sediment <strong>in</strong>vestigations was achieved by<br />

radiocarbon (AMS 14C) and optically stimulated<br />

lum<strong>in</strong>escence (OSL) dat<strong>in</strong>g. F<strong>in</strong>ally, the obta<strong>in</strong>ed<br />

chronology reaches back <strong>in</strong> time to ca. 56 ka BP. To<br />

improve our understand<strong>in</strong>g of the underly<strong>in</strong>g synoptic<br />

climate forc<strong>in</strong>g, reconstructions are merged with modern<br />

process studies.<br />

Lake level high and low stands are documented by<br />

detailed levell<strong>in</strong>g of subaerial terraces <strong>in</strong> the catchment<br />

area with a differential global position<strong>in</strong>g system and by<br />

survey<strong>in</strong>g of subaquatic terraces <strong>in</strong> the lake bas<strong>in</strong> with a 3.5<br />

kHz seismic system. One low stand (ca. 8600 to 7300 cal.<br />

yrs BP) and one certa<strong>in</strong> high stand (ca. AD 1480 to 1930)<br />

as well as an assumed lake level high stand dur<strong>in</strong>g the<br />

Late-Glacial or the last glacial (probably before ca. 13,200<br />

cal. yrs BP) have been confirmed. Process studies<br />

demonstrate that these changes <strong>in</strong> water volume <strong>in</strong>fluence<br />

the formation of endogenic calcite precipitation which is<br />

preserved <strong>in</strong> the sedimentary record. An understand<strong>in</strong>g of<br />

the underly<strong>in</strong>g climatic forc<strong>in</strong>g is achieved by a<br />

comparison of modelled lake level variations with<br />

<strong>in</strong>strumental meteorological data <strong>in</strong>dicat<strong>in</strong>g that the lake<br />

level is ma<strong>in</strong>ly driven by precipitation, related w<strong>in</strong>d<br />

strength and w<strong>in</strong>d direction. Lake levels and precipitation<br />

decrease dur<strong>in</strong>g periods of persistently high w<strong>in</strong>ds from<br />

westerly directions, whereas lake levels and precipitation<br />

<strong>in</strong>crease dur<strong>in</strong>g periods of enhanced easterly w<strong>in</strong>ds. Such a<br />

relation is expla<strong>in</strong>ed by strengthen<strong>in</strong>g of the Southern<br />

Hemispheric Westerlies and block<strong>in</strong>g of ra<strong>in</strong>-br<strong>in</strong>g<strong>in</strong>g<br />

cyclones from the east (less ra<strong>in</strong>) or more frequent<br />

occurrences of cyclones from the South Atlantic (more<br />

ra<strong>in</strong>). S<strong>in</strong>ce lake volume controls the autochthonous<br />

lacustr<strong>in</strong>e carbonate precipitation, the amount of<br />

sedimentary calcite content as well as its isotopic<br />

composition archives these recurrence patterns of weather<br />

conditions.<br />

Reconstructions for the last 1500 years document a<br />

lake level high-stand preceeded by pronounced cyclicities<br />

of calcite precipitation which are also mirrored by the<br />

oxygen isotope (δ18O) record. This high stand of 8.8 m<br />

above the present day lake level ocurred between AD 1480<br />

and 1930 – a tim<strong>in</strong>g that co<strong>in</strong>cides with the northern<br />

hemispheric Little Ice Age (Haberzettl et al., 2005). The<br />

dist<strong>in</strong>ct Holocene drought between ca. 8600 and 7300 cal.<br />

yrs BP is highlighted by a seismically and lithologically<br />

detected unconformity at around 33 m below the present<br />

147<br />

lake level at the site of a submerged lake level terrace<br />

(Haberzettl et al., <strong>2008</strong>) and <strong>in</strong>creased values for <strong>in</strong>organic<br />

carbon, higher sedimentation rates and a dist<strong>in</strong>ctly different<br />

isotopic composition of organic matter at the deep central<br />

bas<strong>in</strong> of the lake (Haberzettl et al., 2007). This po<strong>in</strong>ts to a<br />

lower lake level with <strong>in</strong>creased <strong>in</strong>wash of soil material<br />

from the former lake shore which has fallen dry dur<strong>in</strong>g this<br />

period. Before 13,200 cal. yrs BP carbonates disappear<br />

completely and we assume that this is the time of highest<br />

lake levels which is furthermore related to the formation of<br />

an outflow at ca. 21 m above the present day lake level.<br />

References:<br />

Haberzettl, T. et al. (2005) Climatically <strong>in</strong>duced lake level changes dur<strong>in</strong>g<br />

the last two millennia as reflected <strong>in</strong> sediments of Laguna Potrok Aike,<br />

southern Patagonia (Santa Cruz, Argent<strong>in</strong>a). Journal of Paleolimnology<br />

33: 283-302.<br />

Haberzettl, T. et al. (2007) Lateglacial and Holocene wet-dry cycles <strong>in</strong><br />

southern Patagonia: chronology, sedimentology and geochemistry of a<br />

lacustr<strong>in</strong>e record from Laguna Potrok Aike, Argent<strong>in</strong>a. The Holocene,<br />

17: 297-310.<br />

Haberzettl, T. et al. (<strong>2008</strong>) Hydrological variability and explosive volcanic<br />

activity <strong>in</strong> southeastern Patagonia dur<strong>in</strong>g Oxygen Isotope Stage 3 and<br />

the Holocene <strong>in</strong>ferred from lake sediments of Laguna Potrok Aike,<br />

Argent<strong>in</strong>a. Palaeogeography, Palaeoclimatology, Palaeoecology: <strong>in</strong><br />

press.<br />

Mayr, C. et al. (2007) Holocene variability of the Southern Hemisphere<br />

westerlies <strong>in</strong> Argent<strong>in</strong>ean Patagonia (52°S). Quaternary Science<br />

Reviews, 26: 579-584.<br />

<strong>IODP</strong><br />

Rock magnetic identification and<br />

geochemical process models of greigite<br />

formation <strong>in</strong> Quaternary mar<strong>in</strong>e sediments<br />

from the Gulf of Mexico (<strong>IODP</strong> Hole<br />

U1319A)<br />

Y. FU 1,2 , T. VON DOBENECK 1 , CH. FRANKE 1,3 , DAVID HESLOP 1 ,<br />

SABINE KASTEN 1,4<br />

1 Fachbereich Geowissenschaften, Universität Bremen,<br />

Klagenfurter Strasse, 28359 Bremen, Germany<br />

2 School of Eng<strong>in</strong>eer<strong>in</strong>g and Sciences, Jacobs University Bremen,<br />

Campus R<strong>in</strong>g 1, 28759 Bremen, Germany<br />

3 Laboratoire des Sciences du Climat et de l’Environnement CEA-<br />

CNRS-UVSQ, Campus du CNRS, Bât. 12, Avenue de la<br />

Terrasse, 91198 Gif-sur-Yvette Cedex, France<br />

4 Alfred Wegener Institut für Polar- and Meeresforschung, Mar<strong>in</strong>e<br />

Geochemie, Am Handelshafen 12, 27570 Bremerhaven,<br />

A 160 m long hemipelagic, ma<strong>in</strong>ly turbiditic Late<br />

Pleistocene sediment sequence from the Brazos-Tr<strong>in</strong>ity<br />

<strong>in</strong>traslope bas<strong>in</strong> IV off Texas (<strong>IODP</strong> Hole U1319A) was<br />

<strong>in</strong>vestigated with paleo- and rock magnetic methods.<br />

Numerous layers depleted <strong>in</strong> iron oxides and enriched by<br />

the ferrimagnetic iron sulfide m<strong>in</strong>eral greigite (Fe3S 4) were<br />

detected by diagnostic magnetic properties. From the<br />

distribution of these layers, their stratigraphic context and<br />

the present geochemical zonation, we developed two<br />

conceptual reaction models of greigite formation <strong>in</strong> nonsteady<br />

depositional environments. The “sulfidization<br />

model” predicts s<strong>in</strong>gle or tw<strong>in</strong> greigite layers by<br />

<strong>in</strong>complete transformation of iron monosulfides with<br />

polysulfides around the sulfate methane transition (SMT).<br />

The “oxidation model” expla<strong>in</strong>s greigite formation by<br />

partial oxidation of iron monosulfides near the iron redox<br />

boundary dur<strong>in</strong>g periods of downward shift<strong>in</strong>g oxidation<br />

fronts.<br />

The stratigraphic record provides evidence that both<br />

these greigite formation processes act here at typical depths<br />

of about 12 mbsf and 3 mbsf. Numerous “fossil” greigite

148<br />

layers most likely preserved by rapid upward shifts of the<br />

redox zonation denote past SMT and respective sea floor<br />

positions characterized by stagnant hemipelagic<br />

sedimentation conditions. Six diagenetic stages from a<br />

prist<strong>in</strong>e magnetite-dom<strong>in</strong>ated to a fully greigite-dom<strong>in</strong>ated<br />

magnetic m<strong>in</strong>eralogy were differentiated by comb<strong>in</strong>ation of<br />

hysteresis and remanence parameters.<br />

The more structured upper part (0-40 mbsf) of the<br />

record bears well-preserved greigite layers grouped around<br />

present and past, now abandoned geochemical boundaries.<br />

The lower part of the record (40-156 mbsf) shows an<br />

advanced degree of magnetite depletion and many spurious<br />

greigite and pyrite layers, but the signatures are poorly<br />

developed or conserved and cannot be easily identified<br />

with our models at this stage. Rock magnetic signatures of<br />

temporarily static and rapidly shift<strong>in</strong>g SMT positions give<br />

h<strong>in</strong>ts at the rhythm of sediment spills and their external<br />

control by sea-level change.<br />

Conceptual models of greigite layer formation and<br />

preservation <strong>in</strong> non-steady state sedimentary systems. Black<br />

curves mark hypothetical oxygen, nitrate, sulfate, methane and<br />

hydrogen sulfide profiles, arrows <strong>in</strong>dicate shifts of iron redox<br />

boundary and sulfate-methane transition by alternate<br />

hemipelagic and turbiditic sedimentation. The “sulfidization<br />

model” (a-d) predicts s<strong>in</strong>gle or tw<strong>in</strong> greigite layers by<br />

<strong>in</strong>complete sulfidization of iron monosulfide with polysulfide<br />

around the SMT. The “oxidation model” (e-h) expla<strong>in</strong>s<br />

greigite formation by partial oxidation of iron monosulfides<br />

with nitrate at the iron redox boundary dur<strong>in</strong>g periods of<br />

downward shift<strong>in</strong>g oxidation fronts. Although both greigite<br />

formation pathways may proceed simultaneously, the<br />

alternative direct pyrite formation is assumed <strong>in</strong> the lower<br />

diagrams.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Us<strong>in</strong>g a determ<strong>in</strong>istic multivariate group<strong>in</strong>g approach<br />

based on concentration-<strong>in</strong>dependent magnetic hysteresis<br />

characteristics (doma<strong>in</strong> state and coercivity) we track the<br />

iron oxide alteration pathway from a primary magnetic<br />

m<strong>in</strong>eral assemblage rich <strong>in</strong> f<strong>in</strong>e magnetite over an<br />

<strong>in</strong>creas<strong>in</strong>gly depleted relict stage consist<strong>in</strong>g predom<strong>in</strong>antly<br />

of coarser and Ti-rich particles. Dur<strong>in</strong>g further<br />

sulfidization, the secondary magnetic m<strong>in</strong>eral greigite<br />

grows from an ultra-f<strong>in</strong>e (< 50 nm), magnetically <strong>in</strong>stable<br />

SP phase to a more mature and magnetically dom<strong>in</strong>ant SD<br />

(> 50 nm) phase with magnetic carrier potential.<br />

Reaction k<strong>in</strong>etics and diffusion times are certa<strong>in</strong>ly<br />

essential, but have not been regarded <strong>in</strong> this primarily rock<br />

magnetic and stratigraphic approach. We yet lack evidence<br />

to decide, to what extent microorganisms are <strong>in</strong>volved <strong>in</strong> or<br />

responsible for the observed greigite formation, but<br />

consider this a very likely possibility.<br />

<strong>IODP</strong><br />

Geotechnical behaviour and magnetic fabrics<br />

of rapidly deposited Quaternary sediments,<br />

Ursa Bas<strong>in</strong>, Gulf of Mexico – first results<br />

S. MEISSL 1 , J.H. BEHRMANN 1<br />

1 IFM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel, Germany,<br />

smeissl@ifm-geomar.de<br />

Integrated Ocean Drill<strong>in</strong>g Program (<strong>IODP</strong>) Expedition<br />

308 (Expedition 308 Scientists, 2005; Flem<strong>in</strong>gs et al, 2006,<br />

Behrmann et al., 2006) was the first part of a twocomponent<br />

program dedicated to the study of overpressure<br />

and fluid flow on the Gulf of Mexico cont<strong>in</strong>ental slope.<br />

The scientific programme exam<strong>in</strong>ed how sedimentation,<br />

overpressure, fluid flow, and deformation are coupled a<br />

passive marg<strong>in</strong> sett<strong>in</strong>g. One of the two drill<strong>in</strong>g targets was<br />

the Ursa Bas<strong>in</strong>, situated about 150 km due south of New<br />

Orleans, Louisiana (USA) <strong>in</strong> about 1000 m of water. The<br />

region is of economic <strong>in</strong>terest because of its prolific<br />

oilfields that lie at depths >4000 meters below seafloor<br />

(mbsf). Mahaffie (1994) described the geological character<br />

of the Mars oilfield, and the more recently explored Ursa<br />

field is <strong>in</strong> Mississippi Canyon Blocks 855, 897, and 899. In<br />

the Ursa Bas<strong>in</strong>, Late Quaternary sedimentation is among<br />

the most rapid on Earth (grand average: 10 mm/year). The<br />

sections of mud are underconsolidated throughout, and<br />

severe overpressure conditions were documented at all<br />

three sites drilled (U1322, U1323, U1324). In addition,<br />

sedimentation <strong>in</strong> the form of mass transport deposits<br />

(MTD) plays a major role.<br />

In the course of this project, we were so far <strong>in</strong>terested<br />

<strong>in</strong> <strong>in</strong>vestigat<strong>in</strong>g the relative strengths and mechanical<br />

behaviour of underconsolidated Late Pleistocene<br />

mudstones, and identify differences between normally<br />

sedimented material and sections affected by submar<strong>in</strong>e<br />

slump<strong>in</strong>g <strong>in</strong> the form of MTD. Furthermore we analysed<br />

magnetic fabrics <strong>in</strong> sediments from the most <strong>in</strong>tensely<br />

slumped site (Site U 1322), to identify fabric-build<strong>in</strong>g<br />

factors such as sedimentary, compactive and mass transport<br />

processes.<br />

Triaxial tests were performed at University of Freiburg.<br />

Setup and use of the apparatus are documented <strong>in</strong> Roeser<br />

(2007). To date, a total of 15 tests (13 successful, 2 failed)<br />

were performed as CU-tests (consolidated and undra<strong>in</strong>ed)<br />

to approximately simulate <strong>in</strong> situ conditions. Tests were

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

carried out <strong>in</strong> constant stra<strong>in</strong> rate mode to large (ca. 20%)<br />

axial shorten<strong>in</strong>g <strong>in</strong> order to elucidate the post-yield<br />

behaviour. Material properties, like cohesion, coefficient of<br />

friction and <strong>in</strong>ternal angles of friction were def<strong>in</strong>ed with<br />

these tests. Additionally, water content and gra<strong>in</strong> density<br />

were determ<strong>in</strong>ed with rout<strong>in</strong>es accord<strong>in</strong>g to the German<br />

Industry Norm (DIN). Fracture angles were measured on<br />

the samples after test<strong>in</strong>g, to provide an additional means of<br />

estimat<strong>in</strong>g angles of static friction. Consolidation of the<br />

samples after saturation was used to determ<strong>in</strong>e hydraulic<br />

conductivity and permeability <strong>in</strong> a rout<strong>in</strong>e ak<strong>in</strong> to<br />

oedometer test<strong>in</strong>g (see Roeser, 2007, for description). A<br />

s<strong>in</strong>gle test required about two weeks <strong>in</strong>clud<strong>in</strong>g<br />

supplementary measurements, saturation, consolidation<br />

compression, and post-test data analysis. Two or preferably<br />

three tests were perfomed at conf<strong>in</strong><strong>in</strong>g pressures rang<strong>in</strong>g<br />

from 0.5 to 1.8 MPa on a whole-round sample at different<br />

conf<strong>in</strong><strong>in</strong>g pressures. This was achieved by divid<strong>in</strong>g the<br />

whole round <strong>in</strong>to two or three aliquots. R<strong>in</strong>g shear tests<br />

were performed at the RCOM Institute, University of<br />

Bremen, us<strong>in</strong>g a Bromhead RS r<strong>in</strong>g shear apparatus (see<br />

Roeser, 2007, for description of equipment and analytical<br />

procedures). To simulate high-stra<strong>in</strong> deformation dur<strong>in</strong>g<br />

large movements on slump surfaces, water-saturated<br />

remoulded sediments were sheared to high stra<strong>in</strong>s.<br />

Measurements were performed with axial loads rang<strong>in</strong>g<br />

from 1 MPa to approximately 16 MPa at four different<br />

rates of shear (steps of 0.005, 0.014, 0.18 and 1.8 mm/m<strong>in</strong>).<br />

Because of the very high clay contents, the samples<br />

required very long consolidation periods, result<strong>in</strong>g <strong>in</strong> about<br />

ten days duration for a s<strong>in</strong>gle test s<strong>in</strong>gle. Measurements of<br />

Anisotropy of Magnetic Susceptibilty (AMS) were<br />

performed at Mar<strong>in</strong>e Geophysics, Bremen University. We<br />

used a Geofyzika Brno KLY-2 Kappa Bridge for<br />

measurements, and the ANISOFT 20 software package for<br />

data analysis (Hrouda, 1990). The directions and pr<strong>in</strong>cipal<br />

axis lengths of the AMS ellipsoid Kmax ≥ K<strong>in</strong>t ≥ Km<strong>in</strong><br />

were determ<strong>in</strong>ed from 15 directional magnetic<br />

susceptibility measurements, sufficient to constra<strong>in</strong> the<br />

AMS tensor (e.g Kopf & Behrmann, 1997). We determ<strong>in</strong>ed<br />

AMS ellipsoids <strong>in</strong> 250 samples taken from Site U1322<br />

cores. The samples come from eleven mass transport<br />

deposits and from the <strong>in</strong>terven<strong>in</strong>g layers produced by<br />

normal fallout sedimentation. The objective was to<br />

compare the magnetic fabrics from both sediment types.<br />

Reorientation of AMS pr<strong>in</strong>cipal axes was undertaken us<strong>in</strong>g<br />

the available tensor tool orientation data for the hydraulic<br />

piston cores taken at Site U1322. Our prelim<strong>in</strong>ary results<br />

are as follows.<br />

Triaxial tests: So far, four samples were analyzed from<br />

Site U1324. Sedimentological description (Flem<strong>in</strong>gs et al.,<br />

2006) <strong>in</strong>dicated slightly different sett<strong>in</strong>gs: normally<br />

deposited hemipelagic sediments, levee turbidites and<br />

distal turbidites. The samples were taken from depths<br />

between 353 and 409 meters below sea floor (mbsf). We<br />

have tried to determ<strong>in</strong>e peak deviatoric stresses, Young’s<br />

moduli, and changes <strong>in</strong> pore pressure. Stress paths were<br />

recorded to derive friction coefficients, angles of friction<br />

and cohesion. Supplementary measurements provided<br />

water content and gra<strong>in</strong> density. All measured peak<br />

deviatoric stresses are very small, and lie between 45,3 kPa<br />

and 140 kPa. Range of E modules is between about two<br />

and six kPa <strong>in</strong> the samples com<strong>in</strong>g from less than 407<br />

mbsf. The distal turbidite from 409 mbsf has a dist<strong>in</strong>ctly<br />

149<br />

higher E module (range: 13.6 to 17.4 kPa). Permeabilities<br />

are <strong>in</strong> the range of 10-16 to 10-17 m2, and hydraulic<br />

conductivities are around 10-9 to 10-10 ms-1. Gra<strong>in</strong><br />

densities of the tested samples are slightly above 2.7, and<br />

water contents range from 18.3% to 27.6%. One sample<br />

com<strong>in</strong>g from a mass transport deposit (MTD) at Site<br />

U1322 was analyzed so far.<br />

Here tests showed that the material is weaker than the<br />

normally sedimented material: peak daviatoric stresses<br />

range from about 27 kPa to 42 kPa, but E modules are<br />

similar to the weak normally sedimented samples (5.7 - 7.6<br />

kPa). Stress paths from all samples <strong>in</strong>dicate that the<br />

material is somewhat overconsolidated, but this effect is<br />

least notable <strong>in</strong> those samples that were sheared at around<br />

1.7 MPa conf<strong>in</strong><strong>in</strong>g pressure. This is an <strong>in</strong>dication that the<br />

<strong>in</strong> situ effective stress <strong>in</strong> the depth range <strong>in</strong>vestigated at<br />

Site U1324 may be close to this value. Inferences to be<br />

made about static coefficients of friction from stress paths<br />

are at a very prelim<strong>in</strong>ary stage, but show surpris<strong>in</strong>gly high<br />

values (0.8 or more) for the normally sedimented samples<br />

at the range of mean effective stresses considered (20 –100<br />

kPa). For the MTD sample the friction coefficient estimate<br />

is def<strong>in</strong>itely lower (0.44 at a mean effective stress range of<br />

20 – 40 kPa). Inferred cohesions are <strong>in</strong> the range of 10 – 20<br />

kPa, underl<strong>in</strong><strong>in</strong>g the very weak nature of the Ursa Bas<strong>in</strong><br />

sediments.<br />

R<strong>in</strong>g shear tests: Four samples, two each from Site<br />

U1322 and from Site U1324 were analyzed so far. As<br />

experiments were under dra<strong>in</strong>ed conditions, comparison<br />

with the results to those from the undra<strong>in</strong>ed triaxial tests is<br />

not straightforward, but some similarities are evident.<br />

Shear strengths recorded at about 1 MPa normal stress (8<br />

kg axial load) are very low at 100 – 300 kPa, ris<strong>in</strong>g more or<br />

less l<strong>in</strong>early to values between 3 MPa and 4.5 MPa at 15<br />

MPa normal stress (128 kg axial load).<br />

Friction coefficients from all samples are <strong>in</strong> the range<br />

of 0.13 to 0.31, with <strong>in</strong>ternal angles of friction of<br />

approximately 7.4° to 17.2°. These are values not unusual<br />

for smectite-rich clays and muds. There is no obvious<br />

difference between the frictional behaviour of the three<br />

samples from normally sedimented sections and the one<br />

from a MTD, except for the fact that the MTD material<br />

(Sample U1322B-26H) is the weakest, and shows the least<br />

sensitivity of frictional coefficients to changes <strong>in</strong> shear<strong>in</strong>g<br />

rate and axial load. As samples subjected to r<strong>in</strong>g shear<strong>in</strong>g<br />

are remoulded, with no rema<strong>in</strong><strong>in</strong>g primary microfabric, this<br />

could be related to composition and/or the mode of clay<br />

flocculation and charg<strong>in</strong>g effects. Further <strong>in</strong>vestigations<br />

will show whether this is a phenomenon <strong>in</strong>herently related<br />

to mass transport deposits. More analyses of samples from<br />

both groups of sediments are needed, however, to further<br />

explore this question.<br />

Anisotropy of Magnetic susceptibility (AMS): Down to<br />

235 mbsf at Site U1322, eleven mass transport deposits<br />

(MTD 1 – MTD 11) were sampled, and results were<br />

compared with results of samples <strong>in</strong> the overly<strong>in</strong>g and<br />

underly<strong>in</strong>g normally sedimented sections (COMP 1 –<br />

COMP 11). In the MTD samples AMS ellipsoids are<br />

mostly triaxial, with a large spread, but with a larger<br />

proportion of prolate shapes, except for the uppermost<br />

MTD 1. AMS ellipsoid shapes <strong>in</strong> the <strong>in</strong> the subjacent<br />

normally sedimented samples are dist<strong>in</strong>ctly more oblate.<br />

Our prelim<strong>in</strong>ary <strong>in</strong>terpretation is that this difference<br />

reflects a compactive history <strong>in</strong> the normally sedimented

150<br />

sections, and a comb<strong>in</strong>ation of compaction and shear<strong>in</strong>g <strong>in</strong><br />

the MTDs. Below 174 mbsf (MTD 6 – MTD 11), this<br />

dist<strong>in</strong>ction is present as well, but the support<strong>in</strong>g database is<br />

generally smaller. A common feature of almost all MTDs<br />

is the larger P-factor if compared with the subjacent<br />

normally deposited sediments. In the straightforward<br />

<strong>in</strong>terpretative approach this h<strong>in</strong>ts to more <strong>in</strong>tense<br />

deformation; a feature that was probably impr<strong>in</strong>ted onto the<br />

Ursa Bas<strong>in</strong> muds and clays dur<strong>in</strong>g downslope movement.<br />

Orientations of the pr<strong>in</strong>cipal axes of the AMS ellipsoid<br />

are different between normally sedimented muds and those<br />

com<strong>in</strong>g from MTDs. In several cases the MTD data show<br />

E-W to to ESE-WNW Kmax, orientations, and a remarkable<br />

deviation of K m<strong>in</strong> from the vertical axis, which is the<br />

orientation of Km<strong>in</strong> <strong>in</strong> the overly<strong>in</strong>g normally sedimented<br />

units. There, a dom<strong>in</strong>antly E-W oriented K max is thought to<br />

reflect the sediment transport direction over the channel<br />

levee, eastward from the Southwest Pass and Ursa Canyons<br />

to the west. Vertical Km<strong>in</strong> is <strong>in</strong>terpreted to relate to fabric<br />

build<strong>in</strong>g by uniaxial compaction. In the MTD, the<br />

orientation of Kmax is equally <strong>in</strong>terpreted to reflect the<br />

transport signal. However, the observed average 30° tilt<strong>in</strong>g<br />

from the vertical of K m<strong>in</strong> to a steep southerly dip most<br />

likely related to additional shear<strong>in</strong>g and compaction<br />

imposed by slump<strong>in</strong>g events. Complete analysis of the<br />

AMS data is hoped to reveal details <strong>in</strong> the modes of<br />

sedimentation, transport and slump<strong>in</strong>g.<br />

References:<br />

Behrmann, J.H., Flem<strong>in</strong>gs, P.B., John, C.M., and the Expedition 308<br />

Scientists, 2006. Rapid sedimentation, overpressure and focused fluid<br />

flow, Gulf of Mexico cont<strong>in</strong>ental marg<strong>in</strong>. Scientific Drill<strong>in</strong>g, 3, 12-17.<br />

doi:10.2204/iodp.sd.3.03.2006<br />

Expedition 308 Scientists, 2005. Overpressure and fluid flow processes <strong>in</strong><br />

the deepwater Gulf of Mexico: slope stability, seeps, and shallow-water<br />

flow. <strong>IODP</strong> Prel. Rept., 308. doi:10:2204/iodp.pr.308.2005<br />

Flem<strong>in</strong>gs, P.B., Behrmann, J.H., John, C.M., and the Expedition 308<br />

Scientists, 2006. Proc. <strong>IODP</strong>, 308: College Station TX (Integrated<br />

Ocean Drill<strong>in</strong>g Program Management International,<br />

Inc.).doi:10.2204/iodp.proc.308.101.2006.http://iodp.tamu.edu/publicat<br />

ions/exp308/308title.htm<br />

Hrouda, F., et al., 1990. A package of programs for statistical evaluation of<br />

magnetic data us<strong>in</strong>g IBM-PC computers. EOS, Trans. Amer. Geophys.<br />

Union, Fall Meet<strong>in</strong>g, San Francisco, p. 1289.<br />

Kopf, A. & Behrmann, J.H., 1997. Fabric evolution and mechanisms of<br />

diagenesis <strong>in</strong> f<strong>in</strong>e gra<strong>in</strong>ed sediments from the Kita-Yamato trough,<br />

Japan Sea. J. Sedimentary Research, 67, 604-614.<br />

Mahaffie, M.J., 1994. Reservoir classification for turbidite <strong>in</strong>tervals at the<br />

Mars discovery, Mississippi Canyon Block 807, Gulf of Mexico. In<br />

Bouma, A.H., and Perk<strong>in</strong>s, B.G. (Eds.), Submar<strong>in</strong>e Fans and Turbidite<br />

Roeser, G., 2007. Petrography, physical properties, and geotechnical<br />

behavior of modern sediments, Southern Chile Trench. Doctoral<br />

Thesis, Univ. Freiburg, 129 pp.<br />

<strong>IODP</strong><br />

A new view of the Neogene to Quaternary<br />

evolution of the Maldives carbonate platform<br />

(Indian Ocean)<br />

C. BETZLER 1 , C. HÜBSCHER 2 , T. LÜDMANN 3 , J. REIJMER 4 , A.<br />

DROXLER 5 , S. LINDHORST 1 , M 74/4 SHIPBOARD SCIENTIFIC PARTY<br />

1<br />

Geological and Palaeontological Institute, Hamburg University<br />

2<br />

Institute of Geophysics, Hamburg University<br />

3<br />

Institute of Biogeochemistry and mar<strong>in</strong>e Chemistry, Hamburg<br />

University<br />

4<br />

Dept. of Sedimentology and Mar<strong>in</strong>e Geology, University<br />

Amsterdam<br />

5<br />

Dept. of Earth Science MS-126, Rice University Houston<br />

The Maldives carbonate platform <strong>in</strong> the Indian Ocean<br />

is the second largest isolated carbonate platform <strong>in</strong> the<br />

world oceans. It has been the subject of several studies<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

highlight<strong>in</strong>g the role of global sea-level changes for its<br />

evolution dur<strong>in</strong>g the last 60 Mio years. New geophysical<br />

and geological data recorded dur<strong>in</strong>g the Meteor cruise M<br />

74/4 (project “NEOMA”) <strong>in</strong> December 2007 <strong>in</strong>troduce new<br />

aspects which challenge this model. The data complement<br />

an exist<strong>in</strong>g data set for <strong>IODP</strong> Proposal 514 Full 6, and new<br />

site survey data will allow to expand, to sharpen, and to<br />

revise the concepts forwarded <strong>in</strong> this proposal.<br />

The Maldives consist of two N-S oriented rows of<br />

atolls enclos<strong>in</strong>g the up to 500 m deep Inner Sea. Seismic<br />

and hydroacoustic data measured <strong>in</strong> the Inner Sea reveal<br />

that the atolls are l<strong>in</strong>ed by active giant drift bodies<br />

separated from the atolls by a current moat and covered by<br />

migrat<strong>in</strong>g submar<strong>in</strong>e dunes. Dune and moat facies can be<br />

traced back <strong>in</strong>to time, thus allow<strong>in</strong>g reconstruct<strong>in</strong>g the<br />

signatures of bottom currents <strong>in</strong> the sediments back for the<br />

last 5 or possibly even 8 Mio years. Therefore, these strong<br />

currents were a major controll<strong>in</strong>g factor of platform slope<br />

sedimentation and of platform evolution. It is proposed that<br />

currents not only shape the carbonate platform slopes, but<br />

that they are also responsible for the so-called empty<br />

bucket geometry of the atolls, because shallow water<br />

carbonate produced <strong>in</strong> the <strong>in</strong>ner platform was cont<strong>in</strong>uously<br />

exported out of the atolls and re-distributed <strong>in</strong> the drift<br />

bodies. Ultimately this implies that the Maldives are a<br />

current-controlled carbonate platform and that its peculiar<br />

geometry is directly l<strong>in</strong>ked to its oceanographic sett<strong>in</strong>g.<br />

The new data show that the Maldives carbonate platform is<br />

dissected by a series of deeply rooted faults. The most<br />

spectacular expression of these faults on the seafloor are<br />

str<strong>in</strong>gs and clusters of giant pockmarks with diameters of<br />

up to 1500 m and depths of up to 180 m. Pockmarks<br />

correlate vertically with faults and partly with p<strong>in</strong>nacles<br />

previously <strong>in</strong>terpreted as more than 25 Mio years old patch<br />

reefs. To our knowledge this is the first record of giant<br />

pockmarks <strong>in</strong> isolated carbonate platforms far away from<br />

any cont<strong>in</strong>ental marg<strong>in</strong>. Hydroacoustic surveys of the<br />

pockmarks and sediment sampl<strong>in</strong>g (box cores and piston<br />

cores) <strong>in</strong>dicate that they are possibly not active and that at<br />

least some of them serve as sediment s<strong>in</strong>ks which conta<strong>in</strong><br />

the record of past events. In one of the pockmarks, for<br />

example, the tsunamite layer generated by the 2004 Indian<br />

Ocean tsunami was recovered.<br />

<strong>ICDP</strong><br />

FAR-DEEP: Successful completion of the<br />

first phase<br />

H. STRAUSS 1 , M. REUSCHEL 1 , V. MELEZHIK 2,3<br />

1 Geologisch-Paläontologisches Institut, Westfälische Wilhelms-<br />

Universität Münster, Corrensstr. 24, 48149 Münster, Germany<br />

2 Geological Survey of Norway, Leiv Eirikssons vei 39, 7491<br />

Trondheim, Norway<br />

3 Centre for Geobiology, Bergen University, P.O.BOX 7803, N-<br />

5020 Bergen, Norway<br />

The Archaean-Palaeoproterozoic transition (2500-2000<br />

Ma) represents one of the most critical transitions <strong>in</strong><br />

Earth’s history as it reflects the emergence of an aerobic<br />

Earth System. Essential to understand<strong>in</strong>g this <strong>in</strong>terval are<br />

studies that <strong>in</strong>tegrate the various proxy datasets which<br />

document the different processes operat<strong>in</strong>g at this time.<br />

The FAR-DEEP drill<strong>in</strong>g project addresses this 500 million<br />

year <strong>in</strong>terval def<strong>in</strong><strong>in</strong>g the Archaean – Palaeoproterozoic<br />

transition that is characterised by a series of unprecedented

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

environmental upheavals out of which the nascent aerobic<br />

Earth System emerged.<br />

Three overarch<strong>in</strong>g scientific objectives will be<br />

addressed by the FAR-DEEP project: (i) to establish a well<br />

characterised, well dated, well archived section for the<br />

period 2500-2000 Ma; (ii) to document the changes <strong>in</strong> the<br />

biosphere and the geosphere associated with the rise <strong>in</strong><br />

atmospheric oxygen; and (iii) to develop a self-consistent<br />

model to expla<strong>in</strong> the genesis and tim<strong>in</strong>g of the<br />

establishment of aerobic Earth Systems.<br />

Drill<strong>in</strong>g started on May 22 th , 2007 near Shunga Village<br />

<strong>in</strong> Karelia, Russia and f<strong>in</strong>ished on October 29 th , 2007,<br />

aga<strong>in</strong> <strong>in</strong> Karelia. Locations <strong>in</strong>between <strong>in</strong>cluded several<br />

sites on the Kola Pen<strong>in</strong>sula and <strong>in</strong> northern Russia.<br />

Throughout the entire summer and early fall, a total of<br />

fifteen drillholes, totall<strong>in</strong>g 3,560 m of excellent core<br />

material was recovered and is now available at the<br />

Geological Survey of Norway for the archiv<strong>in</strong>g and<br />

follow<strong>in</strong>g research by an <strong>in</strong>ternational group of scientists<br />

from 14 countries.<br />

<strong>IODP</strong><br />

Biogeochemistry of acetate <strong>in</strong> the deep<br />

mar<strong>in</strong>e biosphere – new <strong>in</strong>sights from stable<br />

carbon isotopic <strong>in</strong>vestigations<br />

V. HEUER 1 , J. POHLMAN 2 , M. TORRES 3 , M. ELVERT 1 , AND K.-U.<br />

HINRICHS 1<br />

1 Fachbereich Geowissenschaften, Universität Bremen, 28359<br />

Bremen, Germany<br />

2 U.S. Geological Survey, Woods Hole, USA<br />

3 College of Oceanic and Atmospheric Sciences, Oregon State<br />

University, USA<br />

The Deep Biosphere and the Subseafloor Ocean is one<br />

of three major research themes of the Integrated Ocean<br />

Drill<strong>in</strong>g Program (<strong>IODP</strong>) and with<strong>in</strong> this theme, gas<br />

hydrate studies are a high priority <strong>in</strong>itiative <strong>in</strong> the <strong>in</strong>itial<br />

science plan (IPSC, 2001). A large fraction of methane <strong>in</strong><br />

mar<strong>in</strong>e gas hydrates results from biogenic sources, but the<br />

processes that generate methane <strong>in</strong> deeply buried sediments<br />

and the carbon flow <strong>in</strong> the deep biosphere rema<strong>in</strong> to be<br />

elucidated. <strong>IODP</strong> Expedition 311 drilled a transect across<br />

the Cascadia Marg<strong>in</strong>, NE Pacific, to study the distribution<br />

and evolution of gas hydrates <strong>in</strong> an active cont<strong>in</strong>ental<br />

marg<strong>in</strong>. In our post-cruise research we study<br />

biogeochemical processes <strong>in</strong> the deep subsurface by<br />

decipher<strong>in</strong>g the <strong>in</strong>formation encoded <strong>in</strong> structural and<br />

isotopic properties of sedimentary organic molecules. This<br />

paper reports our f<strong>in</strong>d<strong>in</strong>gs from compound-specific isotopic<br />

analysis of low-molecular-weight organic compounds such<br />

as acetate.<br />

Acetate is a key metabolite <strong>in</strong> anaerobic metabolism<br />

and highly relevant for the cycl<strong>in</strong>g of carbon <strong>in</strong> mar<strong>in</strong>e<br />

sediments. The water-soluble C2-compound is produced<br />

either by fermentation of organic matter or by CO2<br />

reduction (autotrophic acetogenesis) and it serves as an<br />

important substrate for a variety of microorganisms<br />

<strong>in</strong>clud<strong>in</strong>g sulfate reduc<strong>in</strong>g bacteria and methanogens.<br />

Rapid turnover typically ma<strong>in</strong>ta<strong>in</strong>s acetate concentrations<br />

at low levels around 10 µM <strong>in</strong> the pore-waters of nearsurface<br />

sediments (e.g., Wellsbury and Parkes, 1995; Wu et<br />

al., 1997). However, <strong>in</strong> deeply-buried sediments acetate<br />

concentrations can be three orders of magnitude higher<br />

151<br />

(Egeberg and Barth, 1998), which is suggestive of a<br />

globally important, but poorly understood, acetate source<br />

that may be essentical for the the presence of a deep<br />

subseafloor biosphere (e.g., Wellsbury et al., 1997; Parkes<br />

et al., 2007).<br />

Stable isotopes provide a means to constra<strong>in</strong> details of<br />

carbon cycl<strong>in</strong>g. The relative abundance of both isotopes<br />

(δ 13 C) <strong>in</strong> a compound can provide <strong>in</strong>formation about its<br />

sources, s<strong>in</strong>ks, and participation <strong>in</strong> biogeochemical<br />

processes. This concept has been broadly applied <strong>in</strong><br />

isotope paleontology as well as <strong>in</strong> biogeochemical studies.<br />

A prom<strong>in</strong>ent example is the use of stable isotopes <strong>in</strong> the<br />

identification of methane sources and s<strong>in</strong>ks (e.g., Whiticar<br />

et al., 1986; Whiticar, 1999). Similarly, the stable carbon<br />

isotope composition of acetate has been proposed to be a<br />

sensitive <strong>in</strong>dicator of early diagenetic processes and their<br />

relative rates <strong>in</strong> sediments (Blair et al., 1987; Blair and<br />

Carter, 1992). However, due to severe analytical obstacles,<br />

δ 13 C values of acetate have only seldom been reported for<br />

<strong>in</strong> situ pore-waters of natural soils and sediments (e.g.,<br />

Blair et al., 1987; Blair and Carter, 1992; Krüger et al.,<br />

2002; Mohammadzadeh et al., 2005; Heuer et al., 2006).<br />

Just with the recent development of onl<strong>in</strong>e isotope-ratiomonitor<strong>in</strong>g<br />

liquid chromatography/mass spectrometry (irm-<br />

LC/MS) (Krummen et al., 2004), rout<strong>in</strong>e carbon isotope<br />

analysis of water soluble metabolites has started to evolve<br />

<strong>in</strong>to a realistic task (e.g., Heuer et al., 2006; Penn<strong>in</strong>g et al.,<br />

2006; Penn<strong>in</strong>g and Conrad, 2006; Conrad et al., 2007).<br />

This study has yielded the first pore-water profiles for<br />

the carbon isotope compositions of acetate and lactate <strong>in</strong><br />

the context of isotopic <strong>in</strong>formation on other carbon-bear<strong>in</strong>g<br />

compounds <strong>in</strong> deep subseafloor sediments. Isotopic<br />

relationships between acetate and both dissolved organic<br />

carbon (DOC) and dissolved <strong>in</strong>organic carbon (DIC)<br />

provide previously <strong>in</strong>accessible <strong>in</strong>formation on the carbon<br />

flow and the presence and activity of specific functional<br />

prokaryotic communities <strong>in</strong> dist<strong>in</strong>ct horizons of the<br />

sediment with characteristic modes of acetate turnover.<br />

We suggest that this zonation is l<strong>in</strong>ked to sedimentary<br />

redox conditions where under highly reduc<strong>in</strong>g conditions a<br />

large fraction of acetate is produced by autotrophic<br />

reduction of CO2, while under more oxidiz<strong>in</strong>g (suboxic)<br />

conditions acetate is closely track<strong>in</strong>g isotopic compositions<br />

of its fermented precursors. An example is illustrated <strong>in</strong><br />

Figure 1. Site U1329 represents the eastward limit of gas<br />

hydrate occurrence on the northern Cascadia marg<strong>in</strong> where<br />

pore-waters are methane saturated but gas hydrates are not<br />

abundant (Riedel et al., 2006). Acetate and lactate were the<br />

two major volatile fatty acids with concentrations reach<strong>in</strong>g<br />

up to 89 µM and 25 µM, respectively. The depth profile<br />

for the carbon isotopic composition of pore-water acetate at<br />

<strong>IODP</strong> Site 1329 exemplifies that the modes of acetate<br />

production and consumption vary dist<strong>in</strong>ctly with depth.<br />

We consider δ 13 C values of acetate close to those of total<br />

organic matter (~-20‰) as characteristic for production of<br />

acetate from sedimentary organic matter comb<strong>in</strong>ed with a<br />

s<strong>in</strong>k that leads to little or no isotopic fractionation <strong>in</strong> the<br />

residual acetate pool (zone I and IV <strong>in</strong> Fig. 1). Acetoclastic<br />

methanogenesis is associated with a strong isotopic<br />

fractionation creat<strong>in</strong>g 13 C-depleted CH 4 and a 13 C-enriched<br />

pore-water acetate pool (zone III <strong>in</strong> Fig. 1). In contrast,<br />

production of acetate from H2 and CO 2 results <strong>in</strong> acetate<br />

that is dist<strong>in</strong>ctly 13 C-depleted relative to DIC and usually

152<br />

also relative to dissolved organic carbon DOC (zone II <strong>in</strong><br />

Fig. 1).<br />

Isotopic relationships between acetate and other carbon<br />

pools provide novel <strong>in</strong>sights <strong>in</strong>to the patterns of carbon<br />

flow. They reveal clear trends that correspond to sediment<br />

depth and show specific differences between <strong>in</strong>dividual<br />

sites:<br />

Isotopic compositions of acetate and lactate differ<br />

dist<strong>in</strong>ctly. δ 13 C-value Isotopic compositions of acetate and<br />

lactate differ dist<strong>in</strong>ctly. δ 13 C-values of acetate range from<br />

-46.0 to -11.0‰ while δ 13 C-values of lactate scatter around<br />

-20.9 ± 1.8‰.<br />

Carbon isotopic compositions of lactate generally track<br />

those of DOC which tend to be slightly enriched <strong>in</strong> 13C<br />

relative to TOC. This relationship is consistent with both<br />

lactate and DOC be<strong>in</strong>g generated from related pools of<br />

dissolved organic compounds.<br />

Most sensitive to variations <strong>in</strong> s<strong>in</strong>ks and sources of<br />

acetate is its isotopic relationship with DOC and lactate;<br />

e.g., δ13C-values of acetate relative to DOC range from<br />

23.7‰ lower to 9.3‰ higher. Broadly, 13C-depletions<br />

<strong>in</strong>dicate some flux of acetate from CO2 reduction <strong>in</strong>to the<br />

acetate pool (e.g, Gelwicks et al. 1989) while 13Cenrichments<br />

po<strong>in</strong>t to flux of acetate <strong>in</strong>to acetoclastic<br />

methanogenesis (e.g., Krzycki et al. 1987; Gelwicks et al.<br />

1994).<br />

Isotopic evidence <strong>in</strong>dicates a simultaneous reduction of<br />

CO2 to both acetate and methane. This f<strong>in</strong>d<strong>in</strong>g is <strong>in</strong><br />

conflict with thermodynamic constra<strong>in</strong>ts but the likely<br />

compartmentalization of the sediment <strong>in</strong>to heterogenic<br />

microenvironments provides a plausible explanation.<br />

CO2 reduction to acetate appears most important <strong>in</strong><br />

close proximity to the sulfate methane <strong>in</strong>terface (SMI).<br />

Below the SMI, the relative importance of this acetate<br />

source decreases with depth. We suggest this trend reflects<br />

the progressive alteration of substrates for fermentation<br />

with relatively hydrogen-rich compounds be<strong>in</strong>g more<br />

abundant <strong>in</strong> fresher organic matter and thus releas<strong>in</strong>g more<br />

hydrogen <strong>in</strong> shallower sediments than <strong>in</strong> deeply buried<br />

recalcitrant organic matter.<br />

The presence of acetogenic CO2-reduction po<strong>in</strong>ts to<br />

microbial loops that cycle carbon with<strong>in</strong> the sediment prior<br />

to its term<strong>in</strong>al release <strong>in</strong> the form of CO2 and methane.<br />

While thermodynamics <strong>in</strong>dicate that acetoclastic<br />

methanogenesis is equally favorable throughout the<br />

methanogenic zone, carbon isotope biogeochemistry<br />

suggests that the relative fraction of acetate which flows to<br />

acetoclastic methanogenesis <strong>in</strong>creases with depth.<br />

Our contribution highlights the potential of isotopic<br />

compositions of water-soluble metabolites as sensitive<br />

monitors of reactive networks of microbial carbon turnover<br />

<strong>in</strong> subsurface environments. Our observations also raise<br />

new questions regard<strong>in</strong>g the factors controll<strong>in</strong>g the<br />

expression of dist<strong>in</strong>ct modes of acetate turnover <strong>in</strong> certa<strong>in</strong><br />

layers of the sediments.<br />

References:<br />

Blair N. E., Martens C. S., and Des Marais D. J., 1987. Natural abundance<br />

of carbon isotopes <strong>in</strong> acetate from a coastal mar<strong>in</strong>e sediment. Science<br />

236, 66 - 68.<br />

Blair N. E. and Carter J., W. D., 1992. The carbon isotope biogeochemistry<br />

of acetate from a methanogenic mar<strong>in</strong>e sediment. Geochimica et<br />

Cosmochimica Acta 56(3), 1247-1258.<br />

Conrad R., Chan O. C., Claus P., and Casper P., 2007. Characterization of<br />

methanogenic Archaea and stable isotope fractionation dur<strong>in</strong>g methane<br />

production <strong>in</strong> the profundal sediment of an oligotrophic lake (Lake<br />

Stechl<strong>in</strong>, Germany). Limnology and Oceanography 52(4), 1393-1406.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Egeberg, P. K., and T. Barth. 1998. Contribution of dissolved organic<br />

species to the carbon and energy budgets of hydrate bear<strong>in</strong>g deep sea<br />

sediments (Ocean Drill<strong>in</strong>g Program Site 997 Blake Ridge). Chemical<br />

Geology 149: 25-35.<br />

Gelwicks J. T., Risatti J. B., and Hayes J. M. 1989. Carbon isotope effects<br />

associated with autotrophic acetogenesis. Organic Geochemistry 14(4),<br />

441 - 446.<br />

Gelwicks J. T., Risatti J. B., and Hayes J. M. 1994. Carbon-Isotope Effects<br />

Associated with Aceticlastic Methanogenesis. Applied and<br />

Environmental Microbiology 60(2), 467-472.<br />

Heuer, V., M. Elvert, S. Tille, X. Prieto Mollar, L. Hmelo, M. Krummen,<br />

and Kai-Uwe H<strong>in</strong>richs. 2006. Onl<strong>in</strong>e δ13C analysis of volatile fatty<br />

acids <strong>in</strong> sediment/porewater systems by liquid chromatography-isotope<br />

ratio-mass spectrometry. Limnology and Oceanography: Methods. 4:<br />

346-357.<br />

Heuer, V., Pohlman, J., Torres, M., Elvert, M., H<strong>in</strong>richs, K.-U. The stable<br />

carbon isotope biogeochemistry of volatile fatty acids <strong>in</strong> deep<br />

subsurface sediments at the Cascadia Marg<strong>in</strong>. <strong>in</strong> preparation.<br />

IPSC (2001): Integrated Ocean Drill<strong>in</strong>g Program Initial Science Plan, 2003-<br />

2031. available onl<strong>in</strong>e:<br />

http://www.iodp.org/pdf/<strong>IODP</strong>_Init_Sci_Plan.f<strong>in</strong>al.pdf.<br />

Krüger M., Eller G., Conrad R., and Frenzel P. 2002. Seasonal variation <strong>in</strong><br />

pathways of CH4 production and <strong>in</strong> CH4 oxidation <strong>in</strong> rice fields<br />

determ<strong>in</strong>ed by stable carbon isotopes and specific <strong>in</strong>hibitors. Global<br />

Change Biology 8(3), 265-280.<br />

Krummen M., Hilkert A. W., Juchelka D., Duhr A., Schluter H. J., and<br />

Pesch R. 2004. A new concept for isotope ratio monitor<strong>in</strong>g liquid<br />

chromatography/mass spectrometry. Rapid Communications <strong>in</strong> Mass<br />

Spectrometry 18(19), 2260-2266.<br />

Krzycki J. A., Kenealy W. R., DeNiro M. J., and Zeikus J. G. 1987. Stable<br />

carbon isotope fractionation by Methanosarc<strong>in</strong>a barkeri dur<strong>in</strong>g<br />

methanogenesis from acetate, methanol, or carbon dioxide-hydrogen.<br />

Applied and Environmental Microbiology 53(10), 2597-2599.<br />

Mohammadzadeh H., Clark I., Marschner M., and St-Jean G. 2005.<br />

Compound specific isotopic analysis (CSIA) of landfill leachate DOC<br />

components. Chemical Geology 218(1-2), 3-13.<br />

Parkes R. J., Wellsbury P., Mather I. D., Cobb S. J., Cragg B. A.,<br />

Hornibrook E. R. C., and Horsfield B. 2007. Temperature activation of<br />

organic matter and m<strong>in</strong>erals dur<strong>in</strong>g burial has the potential to susta<strong>in</strong><br />

the deep biosphere over geological timescales. Organic Geochemistry<br />

38(6), 845-852.<br />

Penn<strong>in</strong>g H., Claus P., Casper P., and Conrad R. 2006. Carbon isotope<br />

fractionation dur<strong>in</strong>g acetoclastic methanogenesis by Methanosaeta<br />

concilii <strong>in</strong> culture and a lake sediment. Applied and Environmental<br />

Microbiology 72(8), 5648-5652.<br />

Penn<strong>in</strong>g H. and Conrad R. 2006. Carbon isotope effects associated with<br />

mixed-acid fermentation of saccharides by Clostridium papyrosolvens.<br />

Geochimica et Cosmochimica Acta 70(9), 2283-2297.<br />

Riedel, M., Collett, T.S., Malone, M.J., and the Expedition 311 Scientists.<br />

2006. Proc. <strong>IODP</strong>, 311: Wash<strong>in</strong>gton, DC (Integrated Ocean Drill<strong>in</strong>g<br />

Program Management International, Inc.).<br />

doi:10.2204/iodp.proc.311.2006<br />

Wellsbury, P., K. Goodman, T. Barth, B. A. Cragg, S. P. Barnes, and R. J.<br />

Parkes. 1997. Deep mar<strong>in</strong>e biosphere fuelled by <strong>in</strong>creas<strong>in</strong>g organic<br />

matter availability dur<strong>in</strong>g burial and heat<strong>in</strong>g. Nature 388: 573-576.<br />

Wellsbury P. and Parkes R. J. 1995. Acetate Bioavailability and Turnover <strong>in</strong><br />

an Estuar<strong>in</strong>e Sediment. FEMS Microbiology Ecology 17(2), 85-94.<br />

Whiticar M. J., Faber E., and Schoell M. 1986. Biogenic methane formation<br />

<strong>in</strong> mar<strong>in</strong>e and freshwater environments: CO2 reduction vs. acetate<br />

fermentation--Isotope evidence. Geochimica et Cosmochimica Acta<br />

50(5), 693-709.<br />

Whiticar M. J. 1999. Carbon and hydrogen isotope systematics of bacterial<br />

formation and oxidation of methane. Chemical Geology 161(1-3), 291-<br />

314.<br />

Wu H. G., Green M., and Scranton M. I. 1997. Acetate cycl<strong>in</strong>g <strong>in</strong> the water<br />

column and surface sediment of Long Island Sound follow<strong>in</strong>g a bloom.<br />

Limnology and Oceanography 42(4), 705-713.

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong><br />

Fig. 1: Depth profiles for the carbon isotope composition of water-soluble metabolites <strong>in</strong> the northern Cascadia Marg<strong>in</strong> (<strong>IODP</strong> Exp. 311, Site<br />

U1329), <strong>in</strong>clud<strong>in</strong>g acetate, lactate, and DOC <strong>in</strong> pore-water samples, CH4 and CO2 <strong>in</strong> void gas samples. Grey l<strong>in</strong>e <strong>in</strong>dicate average δ 13 C of TOC <strong>in</strong><br />

the solid phase (J.-H. Kim, personal communication). Isotopic relationships suggest the presence of four dist<strong>in</strong>ct geochemical zones at Site<br />

U1329: Zone I, 0-7 mbsf, where the carbon isotopic composition of acetate closely resembles δ 13 C-values of DOC and lactate; Zone II, 7-65 mbsf,<br />

where acetate is dist<strong>in</strong>ctly depleted <strong>in</strong> 13 C compared to lactate, DOC, and CO2; Zone III, 65-135 mbsf, where acetate is enriched <strong>in</strong> 13 C relative to<br />

lactate and DOC, and Zone IV, >134 mbsf, which co<strong>in</strong>cides with the zone of free gas below the BSR where δ 13 C of acetate tracks that of lactate<br />

and DOC. (Heuer et al., <strong>in</strong> prep.)<br />

<strong>IODP</strong><br />

Evolutionary history of selected<br />

coccolithophore species <strong>in</strong> the North Atlantic<br />

dur<strong>in</strong>g the Pliocene to Pleistocene<br />

B. BOECKEL 1 , K.-H. BAUMANN 1 , M. GEISEN 2<br />

1<br />

FB5 Geowissenschaften, Universität Bremen, Klagenfurterstr.,<br />

28359 Bremen<br />

2<br />

Alfred Wegner Institut, Am Handlesdhafen 12, 27570<br />

Bremerhaven<br />

Coccolithophorids, as one of the ma<strong>in</strong> open ocean<br />

primary producers, play key roles <strong>in</strong> the global carbon and<br />

carbonate cycles. Their coccoliths are the s<strong>in</strong>gle most<br />

important component of deep-sea oozes and chalks and<br />

provide key floral, isotopic, and biomarker signals for<br />

<strong>in</strong>terpret<strong>in</strong>g global change <strong>in</strong> the geological record. Their<br />

exceptional fossil record makes them an outstand<strong>in</strong>g<br />

biostratigraphic group and gives them unusual potential for<br />

test<strong>in</strong>g evolutionary hypotheses.<br />

153<br />

Selected keystone coccolith taxa, which are<br />

characterized by a global distribution and a cont<strong>in</strong>uous<br />

geological record, were quantified and morphologically<br />

analyzed. By means of Plio- to Holocene Atlantic time<br />

series the range of their morphological variability is<br />

assessed to elucidate their evolutionary development.<br />

Geologic <strong>in</strong>vestigations on species level diversity allow<br />

tentative concepts on speciation to be tested, evaluated and<br />

to track long-term patterns, <strong>in</strong> order to identify periods of<br />

niche differentiation. Special attention is directed to<br />

<strong>in</strong>teractions with biotic and abiotic factors.<br />

Selected coccolithophorid species from three DSDP /<br />

ODP sites <strong>in</strong> the North Atlantic cover<strong>in</strong>g the last 5 Ma<br />

were biometrically characterized and the spatial<br />

distribution patterns of dist<strong>in</strong>ct morphotypes from the<br />

tropical to northern NE-Atlantic Ocean were reconstructed.<br />

Moreover, speciation and species evolution were evaluated<br />

with respect to the decl<strong>in</strong>e and ext<strong>in</strong>ction events of other<br />

floral elements.<br />

The chosen time-<strong>in</strong>terval, encompass<strong>in</strong>g the Pliocene to<br />

Quaternary is characterised by significant geologic and<br />

climate relevant events: changes <strong>in</strong> oceanic and<br />

atmospheric circulation l<strong>in</strong>ked to the clos<strong>in</strong>g of the Isthmus<br />

of Panama (4.6 Mio years BP); the build<strong>in</strong>g up of the<br />

northern hemisphere ice shields 3.1 Mio years ago; the<br />

onset of enhanced ice growth between 3.1 and 2.6 Mio

154<br />

years BP and f<strong>in</strong>ally the development of the Quaternary<br />

glacial-/<strong>in</strong>terglacial-cyclicity.<br />

The evolution and structure of the Pliocene and<br />

Quaternary floral assemblages was strongly <strong>in</strong>fluenced by<br />

these events. Hence, dur<strong>in</strong>g this time <strong>in</strong>terval several<br />

dramatic changes <strong>in</strong> floral composition occurred, such as<br />

the extreme decl<strong>in</strong>e of the reticulofenestrids up to the<br />

ext<strong>in</strong>ction of some morpho-structures, e.g. the discoasterids<br />

and sphenoliths.<br />

A total of five species complexes was quantitatively<br />

and morphologically analysed <strong>in</strong>clud<strong>in</strong>g Calcidiscus<br />

leptoporus, Florisphaera profunda, Syracosphaera pulchra,<br />

Umbilicosphaera sibogae, and Coccolithus pelagicus.<br />

The biometric results obta<strong>in</strong>ed for the last 2Ma years<br />

display that Umbilicosphaera spp. form their own, stable<br />

morphospace. Surpris<strong>in</strong>gly the comparison of the mean of<br />

simple size measurements on the three different species<br />

showed only a low variation <strong>in</strong> time. The same applies for<br />

the shape of the s<strong>in</strong>gle coccoliths. Only U. sibogae shows a<br />

clear variation <strong>in</strong> the rim width which is due to the species<br />

U. rotula appear<strong>in</strong>g <strong>in</strong> the 4 Ma samples. This is reflected<br />

by a strong bimodal distribution that can be tracked down<br />

<strong>in</strong> the geological record for at least 2 Ma. This <strong>in</strong>dicates<br />

that the last common ancestor might be older than<br />

estimated until now.<br />

The Calcidiscus leptoporus species complex shows<br />

strong variation through space and time. Besides the three<br />

well established recent “morphotypes” and Calcidiscus<br />

mac<strong>in</strong>tyrei, a species that became ext<strong>in</strong>ct <strong>in</strong> the uppermost<br />

Pliocene, there are several <strong>in</strong>tegrades appear<strong>in</strong>g. Although<br />

coccoliths of the modern species complex are round, <strong>in</strong><br />

certa<strong>in</strong> <strong>in</strong>tervals oval forms appeared. These might prove as<br />

valuable for biostratigraphic purposes.<br />

<strong>IODP</strong>/<strong>ICDP</strong> <strong>Kolloquium</strong> <strong>Hannover</strong>, 12.-14.03.<strong>2008</strong>

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