Ninth international conference on - Marum

9 th International Conference on 

Gas in Marine 

Sediments 

15 – 19 September 2008 

University of Bremen, Germany 

Congress Schedule, 

Information 

& 

ABSTRACTS

9 th International Conference on 

Gas in Marine 

Sediments 

September 15 – 19, 2008 

University of Bremen, Germany 

Congress Schedule, 

Information, and Abstracts 

Hosts 

The <strong>conference</strong> is jointly hosted by Gerhard Bohrmann, Department of Geosciences, 

University of Bremen and Bo Barker Jørgensen, Max Planck Institute for Marine 

Microbiology, Bremen. 

Local organizing committee 

Gerhard Bohrmann 

Heiko Sahling 

Greta Ohling 

Angelika Rinkel 

Thomas Pape 

Bo Barker Jørgensen 

Ulrike Tietjen

Program overview 

Monday 

September 15 

Tuesday 

September 16 

Wednesday 

September 17 

Thursday 

September 18 

Friday 

September 19 

Morning Afternoon Evening 

09:00 – 19:00 Field trip to the Harz Mountains 

09:00 – 11:00 Talks 

11:00 – 11:30 Coffee 

11:30 – 13:00 Talks 

13:00 – 14:00 Lunch 

09:00 – 11:00 Talks 

11:00 – 11:30 Coffee 

11:30 – 13:00 Talks 

13:00 – 14:00 Lunch 

09:00 – 11:00 Talks 

11:00 – 11:30 Coffee 

11:30 – 13:00 Talks 

(HERMES & WND 

project session) 

13:00 – 14:00 Lunch 

14:00 – 16:00 Talks 

16:00 – 16:30 Coffee 

16:30 -18:30 Posters 

16:30 – 18:30 OFOP 

short course 

16:30 – 17:30 IODP 

core repository 

14:00 – 16:00 Talks 

16:00 – 16:30 Coffee 

16:30 -18:00 Talks 

14:00 – 16:00 Talks 

16:00 – 16:30 Coffee 

16:30 -18:30 Posters 

08:30 – 20:00 Field trip to Spiekeroog, 

the Wadden Sea 

19:00 Registration 

Icebreaker/Barbecue 

at MPI 

19:30 

Conference Dinner 

Town hall cellar 

Field Trip to the Harz Mountains guided by Jörn Peckmann 

The field trip starts at 8:30 am at the Betriebshof on the northern side of the Geo building (see map). We will 

use several vans to visit the outcrops. We plan to visit two locations, one north of the Harz Mountains and 

one in the Harz Mountains during a one-day field trip (200 km southeast of Bremen). The first site is the type 

location where Kalkowsky suggested the term "stromatolite" for the first time (1908). The outcrop shows 

wonderful stromatolitic structures in lacustrine sediments of the lower Triassic Buntsandstein. The second 

location is an Early Carboniferous seep site on top of the drowned Devonian Iberg atoll reef. Please bring 

rain gear and field boots. Hard hats will be provided. The costs for food and drinks for the lunch break will be 

between 5 to 10 Euros depending on your appetite. We will be back at least around 19:00 so that we will not 

miss the icebreaker. 

Field Trip to Spiekeroog, Frisian Wadden Sea guided by Christian Winter & Achim 

Wehrmann 

A bus will bring us to Neuharlingersiel from where the ferry boat will start at 11:00. 45 minutes later we will 

arrive on the island. Like other Frisian barrier islands Spiekeroog is separated from the mainland coast by a 

backbarrier or tidal basin, well known as the Wadden Sea, which is completely inundated at high tide and 

largely exposed at low tide. During the field trip we will see major sediment environments represented in this 

highly dynamic tidal system on the island. The walking distance of the field trip is 8-9 km, so hiking boots as 

well as a rain coat would be helpful. For sun protection also sun lotion is needed. The ferry back starts at 

17:00 and the bus transportation from Neuharlingersiel back to Bremen will take until around 20:00. 

Conference Dinner 

The <strong>conference</strong> dinner is planned for Wednesday evening in the historical “Cellar of the town hall" 

(Rathauskeller) which is the "exquisite foundation" of the Gothic building from 1405. Food will be included 

into the <strong>conference</strong> fee (not the drinks).

How to find the Campus and the Geo Building of the University of Bremen 

Arriving in Bremen by train: Exit the main station in direction Centrum. Take tram number 6 direction 

Universität. Disembark from tram at stop Universität – Zentralbereich. After disembarking, cross the tracks 

and go up the stairs found by the bridge. In 50m (opp. Mensa) turn right. The grey building on your right with 

white banister and metal world map is the GEOscience building. 

Arriving by plane at the airport: Take tram number 6 direction Universität. Disembark from tram at stop 

Universität – Zentralbereich. After disembarking, cross the tracks and go up the stairs found by the bridge. In 

50m (opp. Mensa) turn right. The grey building on your right with white banister and metal world map is the 

GEOscience building. 

Overview map of the city of Bremen. 

Campus map of the University of Bremen showing the main locations of the <strong>conference</strong>.

9 th International Conference on Gas in Marine Sediments 

Bremen University, September 15 – 19, 2008 

Monday, Sept 15, 2008 

09:00 – 19:00 Field trip to the Harz Mountains guided by Jörn Peckmann 

19:00 – 21:00 Icebreaker, registration at the Max Planck Institute for marine Microbiology 

Tuesday, Sept 16, 2008 

08:00 Registration starts in front of the lecture room (Geo building) 

09:00 – 09:15 Opening of the <strong>conference</strong> in the lecture hall (Geo building) 

09:15 – 09:45 Leifer I, Kamerling M, Luyendyk B, Wilson D, Stubbs C, Lorensen T (invited talk): 

Large-scale spatial and temporal trends in seep emissions in the Coal Oil 

Point seep field – Using a seep resistance model to understand geologic and 

environmental control 

09:45 – 10:00 Bigalke N, Gust G, Rehder G: Hydrodynamically constrained flux of in-situ 

generated methane hydrate dissolving into undersaturated seawater 

10:00 – 10:15 Stöhr M, Schanze J, Khalili A: Gas-liquid mass transfer of rising bubbles: 

Visualization via PLIF 

10:15 – 10:30 Nikolovska A, Sahling H, Bohrmann G: Underwater acoustics in 

marine seeps research 

10:30 – 10:45 Géli L, Henry P, Zitter TAC, Dupré S, Tryon M, Çağatay MN, Mercier 

de Lépinay B, Le Pichon X, Şengör AMC, Görür N, Natalin B, Uçarkuş G, 

Özeren S, Bourlange S, Volker D, Marnaut Scientific Party: Acoustic detection of 

gas emissions and active tectonics within the submerged section of the North 

Anatolian Fault zone in the Sea of Marmara 

10:45 – 11:00 Greinert J, McGinnis D, Naudts L, Linke P, De Batist M: Spatial methane 

bubble flux quantification from seeps into the atmosphere on the Black Sea 

shelf 

11:00 – 11:30 Coffee break 

11:30 – 11:45 Sahling H, Bohrmann G, Artemov Y, Bahr A, Brüning M, Klapp SA, 

Klaucke I, Kozlova E, Nikolovska A, Pape T, Reitz A, Wallmann K: Gas bubble 

streams at Vodyanitskii mud volcano, Sorokin Trough, Black Sea 

11:45 – 12:00 Pape T, Bahr A, Abegg F, Hohnberg HJ, Klapp SA, Bohrmann G: 

Shallow gas hydrates in an eastern Black Sea high intensity gas seepage area 

– Quantification by autoclave technology

12:00 – 12:15 Stadnitskaia A, Ivanov MK, Poludetkina EN, Kreulen R, van Weering TCE: 

Sources of hydrocarbon gases in mud volcanoes from the Sorokin Trough, NE 

Black Sea, based on molecular and carbon isotopic compositions 

12:15 – 12:30 Ion G, Ion E, Dutu F, Popa A, Radulescu V: Gas presence in the 

sediment pile – Black Sea case 

12:30 – 12:45 Sakvarelidze E, Amanatashvili I, Meskhia V, Glonti L: About relation 

between seismicity and anomalies of thermal field in the eastern part of the 

Black Sea water area 

12:45 – 13:00 Zitter TAC, Henry P, Géli L. Ozeren S, Çağatay MN, Mercier de Lépinay B, 

Tryon M, Bourlange S, Burnard P, Sultan N, Marnaut Scientific Party: Fluid 

seepage and mass wasting processes along the North Anatolian Fault on the 

Sea of Marmara 

13:00 – 14:00 Lunch 

14:00 – 14:30 Rehder G, Boetius A, deBeer D, Häckel M, Inagaki F, Mehrtens C, 

Nakamura K, Ratmeyer V, Schneider J, Yanagawa K (invited talk): Where Mother 

Earth runs lab for us – Investigating carbon storage in the deep sea by 

looking at natural CO2 seepage in the Okinawa Trough hydrothermal system 

14:30 – 14:45 Orange DL, Teas PA, Decker J, Baillie P, Widodo, Hamdani A, Widjanarko, 

Bernard BB, Brooks JM, Levey M, AOA Geophysics Shipsboard Reps: Mapping 

and sampling seafloor seeps to prove hydrocarbon prospectivity in 

Indonesia’s frontier basins 

14:45 – 15:00 Mau S, Heintz M. Valentine DL: Methane budget of the down-current 

plume from Coal Oil Point seep field, Santa Barbara Channel, California 

15:00 – 15:15 Naudts L, Greinert J, Poort J, Belza J, Vangampelaere E, Boone D, 

Linke P, Henriet JP, De Batist M: Submeter mapping of methane seeps by 

ROV observations and measurements at the Hikurangi Margin, 

New Zealand 

15:15 – 15:30 Schwalenberg K, Pecher I, Poort J, Coffin R, Wood W, Jegen M: Evidence 

of submarine gas hydrate deposits in context with methane seepage and 

active venting on the Hikurangi margin, NZ, from marine controlled 

source electromagnetics 

15:30 – 15:45 Bussmann I, Schloemer S, Wessels M, Schlüter M, Spickenboom K: 

Pockmark-like structures in Lake Constance 

15:45 – 16:00 Spiess V, Fekete N, Ding F, Caparachin C, Foucher JP and the M76/3 shipboard 

scientific parties: Shallow gas accumulation and seepage in deep water on the 

SW African continental margin – seismic and acoustic signatures 


16:30 – 18:30 Poster session

Wednesday, Sept 17, 2008 

09:00 – 09:30 Pimenov N, Ulyanova M, Kanapasky T, Veslopolova E, Sivkov V (invited talk): 

Microbial activity in the south-eastern Baltic Sea (Russian sector) with 

special reference to the methane and sulfur cycling 

09:30 – 09:45 Raggi L, Schubotz F, Hinrich KU, Sahling H, Dublier N: Bacterial symbionts 

related to hydrocarbon degraders in mussels from the asphalt cold seep 

Chapopote, Gulf of Mexico 

09:45 – 10:00 Knab NJ, Dale AW, Jørgensen BB: Thermodynamic and kinetic control on 

anaerobic oxidation of methane and sulfate reduction 

10:00 – 10:15 Schellig F, Schmale O, Niemann H, Rehder G: Dispersion of biomarker in the 

AOM dominated upper sediment of Quepos slide offshore Costa Rica 

10:15 – 10:30 Zemskaya TI, Shubenkova OV, Chernitsina SM, Egorov AV, Kalmychkov GV, 

Pogadaeva TP, Khlystov OM, Buryukhaev S, Namsaraev BB: Microbial 

communities in sediments of Lake Baikal mud volcanoes 

10:30 – 10:45 Deusner C, Ferdelmann TG, Widdel F: High-pressure continuous-incubation 

studies of sediments containing highly active communities of anaerobic 

methanotrophs 

10:45 – 11:00 Formolo MJ, Lyons TW: Carbon and sulfur cycling at cold seeps in the 

Gulf of Mexico and new perspectives on old seeps 


11:30 – 11:45 Felden J, Niemann H, Lichtschlag A, de Beer D, Wenzhöfer F, Boetius A: 

Budgets of oxygen, sulfate and methane fluxes at an active mud volcano 

11:45 – 12:00 Matveeva T, Mazurenko L, Prasolov E, Kulikova M, Beketov E, Poort J, 

Shoji H, Jin YK, Obzhirov A, Logvina E, Krylov A, Minami H, Hachikubo A: 

Gas hydrates on the Sakhalin slope (the Sea of Okhotsk): Origin, formation 

control, and gas resources 

12:00 – 12:15 Lorenson TD: Methane seepage from the Arctic Shelf – Origin from 

permafrost, gas hydrate, or river-borne organic matter? 

12:15 – 12:30 Logvina E, Krylov A, Matveeva T, Stadtnitskaia A, von Weering TCE, 

Ivanov M, Blinova V: The authigenic chimney formation in the Gibraltar 

Diapiric Ridge (NE Atlantic) 

12:30 – 12:45 Somoza L and MVSEIS 08 Team: New discovery of mud volcanoes related to 

active strike-slip faults and thrusting ridges in the Moroccan margin (Gulf of 

Cadiz, Eastern Central Atlantic) 

12:45 – 13:00 Piñero E, Cruz Larrasoaña, Martínez Ruiz F, Gràcia E: Magnetic iron- 

sulphides as methane proxies in southern Hydrate Ridge sediments (ODP Leg 

204): Preliminary results 

13:00 – 14:00 Lunch

14:00 – 14:30 Kastner M, Torres M, Solomon E, Spivack A (invited talk): Marine pore fluid 

profiles of dissolved sulfate; Do they reflect in situ methane fluxes? 

14:30 – 14:45 Riedinger N, Jørgensen BB: Methane fluxes in diffusion-controlled marine 

sediments: Consequences for the global methane cycle 

14:45 – 15:00 Tizzard L, Judd A, Upstill-Goddard R, Uher G: The contribution to atmospheric 

methane from sub-seabed sources on the UK continental shelf 

15:00 – 15:15 Solomon EA, Kastner M, MacDonald I: Considerable methane fluxes to the 

atmosphere from perennial deepwater hydrocarbon plumes in the Gulf of 

Mexico 

15:15 – 15:30 Valyaev BM: Gas hydate reservoir of carbon in the global system of 

subsurfacial carbon reservoirs 

15:30 – 15:45 Bourry C, Charlou JL, Donval JP, Ruffine L, Foucher JP, Chazallon B, 

Moreau M, Brunelli M: Bubble and gas hydrate characterization in marine 

sediments from contrasted geological environment 

15:45 – 16:00 Schlüter M, Gentz T, Bussmann I, Wessels M, Schlömmer S: Application 

of Membrane Inlet Mass Spectrometry for online analysis of seafloor 

emissions to the water column and the atmosphere at pockmarks in Lake 

Constance 


16:00 – 16:15 Clark JF, Washburn L: Variability of gas composition and flux intensity in 

natural marine hydrocarbon seeps 

16:15 – 16:30 García Gil S, Muñoz Sobrino C, Iglesias J, Judd A, Diez B: A relationship 

between Holocene sea-level change and shallow gas generation 

16:30 – 16:45 Natalicchio M, Dela Pierre F, Martire L, Petrea C, Clari P, Cavagna S: 

Methane-derived carbonate concretions as proxies of an ancient gas hydrate 

stability zone: Evidences from Upper Miocene sediments of the Tertiary 

Piedmont Basin (NW Italy) 

16:45 – 17:00 Petrea C, Martire L, Natalicchio M, Dela Pierre F, Cavagna S, Clari P: 

Direct petrographic evidence of the past occurrence of gas hydrates in 

Oligo-Miocene sediments of the Tertiary Pierdmont Basis (NW Italy) 

17:00 – 17:15 Iglesias J, García Gil S, Judd A, Ercilla G: When a pockmark is not a pockmark: 

Large pockmark-like features on the Landes Plateau (Bay of Biscay) 

17:15 – 17:30 Monteys X, Garcia X, Szpak M, García Gil S, Kelleher B, O’Keeffe E: Multi- 

disciplinary approach to the study and environmental implications of two 

large pockmarks on the Malin Shelf, Ireland 

17:30 – 17:45 Ding F, Spiess V, Fekete N, Brüning M, Bohrmann G: The role of near-surface 

structures in hydrocarbon accumulation and seepage, case studies in 

Campeche Knolls, Gulf of Mexico and the frontal Makran Prism 

19:30 Conference Dinner (Town hall cellar)

Thursday, Sept 18, 2008 

09:00 – 09:30 Ivanov M, Blinova V, Malyshev N, Pevzner R, Volkonskaya A, Bouriak S (invited 

talk) Mapping and main characteristics of multiple BSR reflectors in the 

Tuapse Trough (Black Sea) 

09:30 – 09:45 Maignien L, Parkes J, Cragg B, Boon N, R/V James Cook JC10 Shipboard 

scientific party: Environmental constrains on anaerobic methane oxidation and 

microbial community structure in marine sediments: The case of Cadiz mud 

volcanoes 

09:45 – 10:00 Dondurur D, Coşkun S, Gürçay S, Okay S, Özer P, Çifçi G, Ergün M: 

Acoustic observations of shallow gas accumulations, gas seeps and 

active pockmarks in the Gulf of Izmir, Aegean Sea 

10:00 – 10:15 Chevalier N, Bouloubassi I, Stadtnitskaia A, Pierre C, Hopmans E, 

Damste JS, Saliot A: Archaeal and bacterial lipids at cold seeps on the 

Norwegian margin 

10:15 – 10:30 Wenzhöfer F, Felden J, Lichtschlag A, de Beer D, Feseker T, Foucher JP, 

Bohrmann G, Inagaki F, Boetius A: Methane emission and associated 

biogeochemical consumption rates: How important are cold seep geo- 

structures on a local and global scale 

10:30 – 10:45 Lichtschlag A, Felden J, Wenzhöfer F, Boetius A, de Beer D: Thiotrophic 

mats and their association with methane seeps – Comparison of different cold 

seep sites 

10:45 – 11:00 Pierre C, Bayon G, Blanc Vallerion MM, Rouchy JM, Mascle J, Dupré S, 

Bouloubassi I, Sarrazin J, Foucher JP, Medeco scientific team: Authigenic 

carbonate crusts from active cold seep sites in the Eastern Mediterranean: 

New results from MEDECO cruise 


11:30 – 11:45 Foucher JP, Feseker T, Dupré S, Fabri MC, Harmegnies F, Normand A, 

Satra C, Boetius A: How unstable with time are submarine mud volcanoes: 

Examples from the European seas 

11:45 – 12:00 Dupré S, Brosolo L, Mascle J, Pierre C, Harmegnies F, Mastalerz V, Bayon G, 

Ducassou E, de Lange G, Foucher JP, Victor ROV Team and Medeco Leg 2 

scientific party: The Menes mud volcano caldera complex: An exceptional site 

of brine seepage in the deep waters off north-western Egypt 

12:00 – 12:15 Praeg D, Mascle J, Geletti R, Uniithan V, Loncke L, Harmegnies F: Evidence 

of gas hydrates on the central Nile deep sea fan 

12:15 – 12:30 Brückmann W, Bialas J, Brown K, Feseker T, Hensen C, Hölz S, Jegen M, 

Linke P, Nuzzo M, Reitz A, Scholz F: The West Nile Delta mud volcano project 

12:30 – 12:45 Feseker T, Nuzzo M, Scholz F, Brown K and P362/2 scientific party: 

Exceptionally high levels of mud volcano activity on the western Nile deep 

sea fan – First results from the P362/2 cruise of R/V POSEIDON

12:45 – 13:00 Nuzzo M, Scholz F, Reitz A, Hensen C, Elvert M, Hinrichs KU, Liebetrau V 

and R/V POSEIDON P362/2 scientific party: The origin of hydrocarbons and 

fluids at North Alex and Giza mud volcanoes, West Nile Delta (Egyptian 

margin) 

13:00 – 14:00 Lunch 

14:00 – 14:30 Dando PR, Canet C, Prol-Ledesma RM (invited talk): Massive carbon dioxide 

venting along the Wagner Fault, Gulf of California, Mexico and the 

associated fauna 

14:30 – 14:45 Hauschildt J, Unnithan V, Vogt J: Gas hydrate induced fluid flow alteration 

14:45 – 15:00 Kaul N, Villinger H: Is heat flow probing a direct measure for gas hydrate 

stability boundary conditions? 

15:00 – 15:15 Kulikova M, Matveeva T, Poort J, Jin Y, Shoji H: 3D modelling of a gas hydrate 

accumulation based on thermal, acoustic and coring data 

15:15 – 15:30 Lavrenova E, Senin B, Kruglyakova M, Gorbunov A: Good opening of oil- andgas-content 

of Azov Sea are result of 3D modeling 

15:30 – 15:45 Egorov AV, Kalmychkov GV, Zemskaya TI, Khlystov OM: Methane distribution in 

the deep water sediments of the Lake Baikal 

15:45 – 16:00 Bohrmann G, Bahr A, Brüning M, Gassner A, Kasten S, Klapp SA, Nasir M, Pape T, 

Spieß V, Rethemeyer J, Rossel P, Sahling H, Thomanek K, 

Yoshinaga M, Zonneveld K: Highly variable seep systems along the Makran 

subduction zone – Influence from the accretionary wedge structure and the 

oxygen minimum zone 


16:30 – 18:30 Poster session 

Friday, Sept 19, 2008 

08:30 – 20:00 Field trip to Spiekeroog, the Wadden Sea 

guided by Christian Winter and Achim Wehrmann

Abstracts of oral presentations 

(alphabetic order)

Abstracts of oral presentations 13 

Hydrodynamically constrained flux of in-situ generated methane hydrate 

dissolving into undersaturated seawater 

N. Bigalke 1 , G. Gust 2 , G. Rehder 3 

1 Leibniz Institute of Marine Sciences, Wischhofstr. 1-3, 24148 Kiel, Germany 

2 Technical University Hamburg-Harburg, Schwarzenbergstr. 95, 21073 Hamburg, Germany 

3 Baltic Sea Research Institute Warnemuende, Seestr. 15, 18119 Rostock, Germany 

Clathrate hydrates of natural gases (“gas hydrates“ in the following) are widely distributed within sediments 

along active and passive continental margins. Gas hydrates and gas hydrate stability specifically have become an 

important field of study in the past decades. The stability of methane hydrate depends on the physicochemical 

equilibrium between all coexisting phases. In terms of P and T, the stability of methane hydrate is well 

constrained. Dissolution due to an undersaturation of dissolved methane (hydrate) in a coexisting liquid phase 

has, however, not been given sufficient attention. Specifically, the flux of methane dissolving into undersaturated 

seawater has yet to be quantified. This is especially true for hydrates that are exposed to flow whether they are 

buried in the marine sediment or whether they are exposed at the immediate sea-floor surface. Assessment of the 

stability of gas hydrates in these environments requires the test if incorporation of hydrodynamic as well as 

thermodynamic variables into numerical models is required to quantify the flux of methane into the ocean. To 

the best of our knowledge, the role of flow on the dissolution of gas hydrates has not yet been determined for 

lack of concise hydrodynamic data, though qualitatively, a response of hydrate dissolution on current velocity 

has been described from an open field experiment (Rehder et al., 2004) Here we report on mass transfer rates of 

CH4 from decomposing in-situ generated flat methane hydrate surfaces exposed to precisely adjusted, spatially 

homogeneous wall shearing stresses at selected P-/T-conditions within the hydrate stability field (30 MPa, 4°C). 

The data reveal that hydrate decomposition is an entirely diffusion-controlled process under the conditions 

investigated. The experiments were carried out in an autoclaved interfacial flux chamber with calibrated, 

spatially homogeneous wall shearing stress characterized as ‘microcosm’ in Tengberg et al. (2004). 

References 

Rehder, G.; Kirby S. H.; Durham, W. B.; Stern, L. A.; Peltzer, E. T.; Pinkston, J.; Brewer, P. G. Dissolution rates 

of pure methane hydrate and carbon-dioxide hydrate in undersaturated seawater at 1000-m depth. Geochim. 

Cosmochim. Acta 2004, 68, 285-292. 

Tengberg, A.; Stahl, H.; Gust, G.; Müller, V.; Arning, U.; Andersson, H.; Hall, P. O. J. Intercalibration of 

benthic flux chambers I. Accuracy of flux measurements and influence of chamber hydrodynamics. Prog. 

Oceanogr. 2004, 60, 1-28. 

Highly variable seep systems along the Makran subduction zone – influence from the 

accretionary wedge structure and the oxygen minimum zone 

G. Bohrmann 1 , A. Bahr 1 , M. Brüning 1 , A. Gassner 1 , S. Kasten 2 , S. Klapp 1 , M. Nasir 3 , T. Pape 1 , V. Spiess 1 , 

J. Rethemeyer 2 , P. Rossel 1 , H. Sahling 1 , K. Thomanek 1 , M. Yoshinaga 1 , K. Zonnefeld 4 

1 Research Center Ocean Margins, University Bremen, Germany 

2 Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, Germany 

3 National Institute of Oceanography, Karachi, Pakistan 

4 Department of Geosciences at University of Bremen, Germany 

Up to 7 km sediments from the oceanic part of the Arabic Plate are folded, sheared and repeatedly thrust within 

the accretionary wedge of the Makran subduction zone. Although these sediments form a huge reservoir for fluid 

and gas seepage just minor amounts of cold seeps have been reported up to recent from this collision zone. We 

therefore conducted a research cruise (R/V METEOR M74/3; 30 October – 28 November, 2007) to the area in 

order to explore the margin for further sea floor seep structures. Indications for potential sites of seepage came 

from TOBI backscatter sea floor mapping and from acoustic plume imaging measured by the onboard 

PARASOUND echosounder during Cruise M74/2. Fifteen acoustic plumes distributed over the entire Makran 

slope showed gas emission sites from the sea floor. We could investigate 9 sites between 500 m and 3000 m 

water depth during 18 dives using ROV QUEST4000. Gas seeps between 575 m and 1020 m water depth are 

highly variable and the occurrence of chemosynthetic fauna shows clear relationship with the oxygen 

concentration within the oxygen minimum zone. Four seeps between 1460 m and 1820 m are characterised by 

large communities of bivalves (Mytilidae, Vesicomyidae), tube worms (Vestimentifera) and authigenic 

carbonates which cover hundreds of square meters of the sea floor. I all cases free gas bubbles have been 

observed to be released at the sea floor. Seeps deeper as 2000 m water depth do not show the carbonate 

pavement and seem to represent recently developed cold seeps. In one case fluid outflow could be observed and 

documented, where no chemosynthetic fauna was found. The distribution of various seep systems from the 

Makran margin will be presented during the talk.

14 


Subduction-induced genesis of fossil cold-seep carbonates from the 

Outer Carpathians 

M. J. Bojanowski 1 

1 Institute of Geochemistry, Mineralogy and Petrology, Faculty of Geology, University of Warsaw, Poland 

The Outer Carpathians is a Miocene thrust-and-fold orogenic belt. The youngest deposits is the Krosno 

Formation, which is represented by flysch siliciclastics: alternating turbidite sandstones and mudstones. They are 

interbeded with numerous slump deposits and are frequently accompanied with soft-sediment deformations, 

clastic dykes, slump bedding, which indicate widespread fluidization and slope destabilization. Sedimentation of 

the Krosno Fm. in the southern part of the Silesian basin occurred in proximity and in close relation to the 

emerging accretionary prism, which was prograding from the south. This work describes cold-seep carbonates 

from this formation, and focuses on their genesis in relation to the orogenic processes. 

The seep carbonates comprise calcite concretions, a laminated limestone bed and a carbonate build-up composed 

of intraformational carbonate breccia. All these rocks are strongly depleted in 13 C and attain δ 13 CPDB values lower 

than -30‰, which unequivocally indicate that the carbonate precipitated due to hydrocarbon oxidation 

(Bojanowski 2007). The fluid inclusions examined in the concretions contain gaseous carbon dioxide and/or 

methane, which is a direct evidence of methane in the porewaters. The laminated limestone bed is 20-cm thick 

and exhibits a clear trend in stable C and O isotopic composition: δ 13 CPDB and δ 18 OPDB values change gradually 

from the base to the top of the bed from -37‰ to -19‰ and from -0,7‰ to -4,8‰ respectively. This trend 

probably reflects isotopic gradient which existed in the porewaters: the proportion of HCO3 - produced by 

methane oxidation to HCO3 - produced by sulfate reduction decreased upwards. Such a gradient could have 

existed in the zone of anaerobic oxidation of methane and it is suggested that the limestone bed precipitated 

within this zone due to a diffuse, although pervasive methane seepage. 

The limestone bed becomes thicker and fractured in the vicinity of the carbonate buildup. The degree of 

fragmentation increases so that the fractured limestone changes gradually to a monomictic intraformational 

breccia on the flanks of the build-up. Towards the center the monomictic breccia is gradually replaced by a 

polymictic breccia. The clasts in the polymictic breccia often include fragments of the monomictic breccia. 

Precipitation of these methane-derived carbonates was mediated by microbial activity, which is suggested by the 

presence of calcified biofilms covering carbonate clasts and calcified filaments of a large sulfur bacteria 

(Bojanowski 2007). The conduit zones, which appear in the center of the build-up, contain also clasts of the 

underlying shales. In contrast to the limestone bed and the concretions, the build-up grew as a result of a more 

focused flow of methane-bearing fluids, probably along a tectonic discontinuity of the arising accretionary 

prism. This fluid rise caused carbonate precipitation and hydraulic brecciation, which happened repeatedly and 

interchangeably with each other. 

Characteristic dark druses occasionally appear in the breccia. The walls of the druses are lined with fringes of 

pure calcite (Fig. 1), which clearly precipitated in cavities. Some druses are even still hollow in the center. 

Fig. 1. Photomicrograph (plane polarized light) of the druses from the polymictic breccia – inferred 

pseudomorphoses after gas hydrates. The width of the image corresponds to 22 mm.


However, the clast-like appearance of the druses suggests that these spaces had originally been particles 

composed of a solid substance, probably gas hydrate aggregates. Such a hypothetic presence of gas hydrate in 

the Silesian basin has been supported by theoretical evaluation of gas hydrate stability in that basin (Bojanowski 

2007). The relative sea-level significantly dropped in the Silesian basin at the final stages of deposition due to 

orogenic movements of the prograding accretionary prism. This could have also triggered extensive gas hydrate 

dissociation, which in turn could have directly caused the large-scale submarine slumping and the widespread 

fluidization of the Krosno Fm. 

Reference 

Bojanowski MJ (2007) Oligocene cold-seep carbonates from the Carpathians and their inferred relation to gas 

hydrates. Facies 53:347-360 

Bubble and gas hydrate characterization in marine sediments from contrasted geological 

environments 

C. Bourry 1 , J. L. Charlou 1 , J. P. Donval 1 , L. Ruffine 1 , J. P. Foucher 1 , B. Chazallon 2 , M. Moreau 3 , M. Brunelli 4 

1 Département Géosciences Marines, IFREMER Centre de Brest, 29 800 PLOUZANE, France 

2 Laboratoire de Spectroscopie Infra-Rouge et Raman (LASIR), Université Lille 1, UNMR CNRS 8516, 59655 

Villeneuve d’Ascq, France 

3 Laboratoire de Physique des Lasers, Atomes et Molécules (CERLA), Université Lille 1, UMR CNRS 8523, 

59655 Villeneuve d’Ascq, France 

4 European Synchrotron Radiation Facility (ESRF), BP 220 – 38043 Grenoble cedex, France 

Sediments on continental margins hold enormous quantities of low molecular weight hydrocarbons as dissolved 

gas, free gas or gas hydrates which crystallize where the necessary pressure and temperature conditions are met 

and where the abundance of methane is sufficient to exceed the local solubility. Gas hydrates and free gas 

bubbles were collected from the West African margin (the Congo-Angola basin, ZAINGO cruise; the Nigerian 

margin, NERIS cruise), Hakon Mosby Mud Volcano on the Norwegian margin (Vicking cruise, HERMES 

Program) and the Marmara Sea (MARNAUT cruise). Physical properties of gas hydrates were measured by Xray 

synchrotron diffraction (European Synchrotron Radiation Facility) and Raman spectroscopy. Gas hydrates 

from Norwegian and African margins crystallize in a type I structure whereas hydrates from the Marmara Sea 

exhibit a type II structure. These first data are in accordance with the stable carbon and hydrogen isotope 

compositions of hydrate-bound gases which indicate that hydrates from the Norwegian and African margins 

have a biogenic origin, in contrast with hydrates from the Marmara Sea which have a thermogenic isotopic 

signature. Chemical and isotopic compositions of gas bubbles collected by the PEGAZ, a new efficient tool 

manipulated by submersibles and/or ROVs, were also compared with those of associated hydrates collected on 

Hakon Moby and in the Marmara Sea. Gas bubbles have the same isotopic signature as hydrates but slight 

differences in chemical composition are observed between bubbles and hydrates, especially for samples from the 

Marmara Sea. Thermodynamical modelling experiments successfully predicted the structure I and II for gas 

hydrates from Hakon Mosby and the Marmara Sea respectively and confirm the link between the gas bubbles 

and hydrates compositions. A notable difference between gas bubbles and hydrates compositions from the 

Marmara Sea confirms clearly that a preferential enclathration in the structure II is CH4 < C2H6 < C3H8 < i- 

C4H10. These results are discussed in terms of the origin of gases, the mechanisms involved in gas hydrate 

formation and the evolution of free gas and hydrates in the marine sediments. 

The West Nile Delta mud volcano project 

W. Brückmann 1 , J. Bialas 1 , K. Brown 1 , T. Feseker 1 , C. Hensen 1 , S. Hölz 1 , M. Jegen 1 , 

P. Linke 1 , M. Nuzzo 1 , A. Reitz 1 , F. Scholz 1 

1 IFM-GEOMAR, Institute for Marine Sciences, Kiel, Germany 

Submarine mud volcanoes have been discovered in large numbers in many different continental margin settings, 

often associated with hydrocarbon provinces. They are characterized by fluid formation and fluidization 

processes occurring at depths of several kilometers below the sea floor which are driving a complex system of 

interacting geochemical, geological and microbial processes. As mud volcanoes (MV) act as natural leakages for 

oil and gas reservoirs, near-surface phenomena can be used for monitoring processes occurring at great depth. In

16 


the West Nile Delta two large mud volcanoes, Giza and North Alex MV, apparently rooted at depths of several 

kilometers have been discovered. Focussing on these mud volcanoes the West Nile Delta (WND) project is using 

existing and newly developed tools and techniques to better understand and quantify the internal dynamics and 

long-term variability of these unique sea floor features and their relation to gas reservoirs. Supported by the 

companies developing gas fields in the wider West Nile Delta area, RWE-Dea and BP Egypt work within the 

WND project is subdivided into four major subtasks: 

* the primary objectives of WND Subproject I are to investigate the origin of fluids, hydrocarbon gases and 

sediments expelled at the North Alex and Giza MV and to constrain in situ rates of fluid expulsion at both sites. 

For this purpose, pore water, gas, sediment and clast samples were retrieved by means of gravity coring and 

multicoring during the first research cruise to the West Nile Delta, R/V POSEIDON P362/2 in February 2008. 

Strong degassing of the sediment samples upon recovery on board was the immediate indicator of present MV 

activity at both sites. Preliminary results from pore water organic and inorganic geochemistry analyses show that 

the fluids seeping at Giza and North Alex have a deep sedimentary origin, with maximum formation 

temperatures of ~150ºC (see presentations by Nuzzo et al. and Reitz et al.). 

* within WND Subproject II new techniques of geophysical imaging of mud volcanoes are developed. As such 

structures tend to be comparatively small, it is difficult to apply large-scale acquisition systems. Here, small and 

flexible systems provide a more cost-effective, high-quality solution that can be operated from small research 

vessels. Therefore, one of the primary aims of this subproject is building a SwathSeis 3D seismic acquisition 

system consisting of up to 24 short parallely towed streamers. Its output , complemented with cross correlations 

from Controlled-Source-Electromagnetic (CSEM) data taken in parallel, is greatly enhancing the quality of 

internal imaging of such structures. 

* the objective of WND Subproject III is the quantification of variability of dewatering and degassing through 

long-term in situ observations of temperature, pressure and fluid flow. It has been long known that the activity of 

mud volcanoes varies significantly over periods of months and weeks. This subproject investigates seepage and 

mud expulsion at both mud volcanoes in the study area to provide detailed information about the variability of 

seepage in space and time. During cruise P362/2 sediment temperature and heat flow measurements conducted at 

both MVs confirmed that both mud volcanoes are currently in an active phase and helped identifying the most 

active parts. Near-surface temperatures of several tenths of °C at both North Alex and Giza MV suggest high 

levels of fluid seepage, potentially associated with very recent mud expulsion. (see presentation by Feseker et 

al.). 

* Finally, biostratigraphic analysis of sediments to determine the eruption history of mud volcanoes and the 

present day distribution patterns of benthic foraminifera are studied as part of WND Subproject IV. 

Pockmark-like structures in Lake Constance 

I. Bussmann 1,2 , S. Schloemer 3 , M. Wessels 4 , M. Schlüter 2 , K. Spickenboom 3 

1 University of Konstanz 

2 Alfred-Wegener Institute 

3 Federal Institute for Geosciences and Natural Resources, Germany 

4 Institute for Lake Research, Langenargen 

The role of lakes in the global methane budget seems to be higher than previously thought. Numerous 

pockmarks have been described for the marine environment, but at freshwater fluid seeps the geological, 

chemical and biological processes operating are largely unknown. 

Based on different observations of intense gas flow through the water column at Lake Constance two joint 

research cruises were conducted in winter 2005/06 to systematically search and study these structures. Several 

large fields of pockmark like structures were found in the eastern part of the lake (side scan sonar, echo sounder). 

Water and gas was selectively sampled and based on these preliminary data a joint DFG-funded research project 

was arranged. 

The objectives are to (1) locate, describe and map pockmark areas at Lake Constance, (2) identify the pockmark 

formation mechanism, (3) quantify the methane flux and the temporal variability and (4) identify the source of 

methane. 

So far more than 450 pockmarks larger > 2 m have been identified by side-scan sonar. The pockmarks vary 

largely in size (dm-range to maximum diameters of 15m) and spatial distribution. At some places, they are 

irregular spaced, but now and then smaller decimetre sized pockmarks are evenly spaced along small lineaments. 

Often, large pockmarks are located at morphological highs, such as channel rims or little hills at the lake floor. 

There is no morphological evidence for a catastrophic gas release (solid discharge at the rim, or irregular 

sediment patterns near the pockmarks). The observed structures point to a constant gas release from a deeper 

reservoir.


Two representative locations (water depth 12m and 85m) close to the former Rhine estuary have been selected 

for further geochemical examinations. After deploying a digital horizontal sonar system at the lake floor to allow 

for exact positioning, water and sediment samples were taken within the pockmark with niskin bottles from a 

rosette and multicorer. In addition, sediment samples and gas samples were taken by divers across the shallow 

pockmark. Gas concentration and isotope ratios of dissolved gas in water were measured using standard GC-FID 

and GC-irMS techniques. Methane concentration in sediment samples was measured directly after coring by 

means of by a diffusion-based methane sensor. 

Preliminary results of the isotope analysis of methane (δ 13 C, δD) and CO2 (δ 13 C) as well as the absence of 

higher molecular weight alkanes strongly indicate a bacterial formation of the gases rather than a thermogenic 

origin of the methane. The results of the analysis of free gas of the sediments indicate the methyl formation as 

dominant pathway. However, up to now available data suggest a certain difference in the gases located at the 

deep pockmark, the corresponding reference site and gas sampled at the shallow pockmark. 

In the sediments of the deep pockmark high methane concentrations were recorded, however with no significant 

differences between the pockmark and control cores. At the shallow pockmark sediment cores could be 

positioned more precisely. Here methane concentrations vary within meters in order of magnitude. 

Several autonomous devices for gas flow measurements using different approaches were deployed in March 

2008 at selected gas emanating pockmarks. Data are not yet available but will hopefully presented 

. 

Fig 1: Sonar image of a large pockmark (diameter 16m) at Lake Constance. Note the gas bubbles ascending 

from the structure 

δ 13 C-methane (‰) 

-110 

-90 

-70 

-50 

-30 

artificial 

methane 

fermentation 

mix 

-10 

-400 -300 -200 -100 

mix 

CO 2 reduction 

thermal 

δD-methane (‰) 

MUC 1 inside deep pockmark 

MUC 2 reference site deep pockmark 

stab tubes shallow pockmark 

TT(m) 

TT(h) 

atmosphere 

Fig. 2: Carbon and deuterium isotopical composition of selected samples in a diagnostic diagram

18 


Archaeal and bacterial lipids at cold seeps on the Norwegian margin 

N. Chevalier 1 , I. Bouloubassi 1 , A. Stadnitskaia 2 , C. Pierre 1 , E. Hopmans 2 , J. Sinninghe Damste 2 and A. Saliot 1 

1 Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques (LOCEAN/IPSL), 

Université Pierre et Marie Curie, Paris, France 

2 Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, Texel, The Netherlands 

In the framework of the HERMES project, the VICKING cruise (2006) focussed on the exploration and 

multidisciplinary study of fluid escape features (pockmarks and mud volcanoes) on the Norwegian margin. 

Detailed observations and multidisciplinary sub-sampling was carried out with the ROV Victor 6000 and a set of 

specific tools in two sites: the northern flank of the Storegga Slide characterized by the occurrence of gas 

hydrates in the slope sediments, large slides and numerous fluid escape structures, mainly pockmarks (Nyegga) 

and the active mud expulsions at the Hakon Mosby Mud Volcano. 

We investigated specific, diagnostic lipids in carbonates crusts and sediments aiming to gain insight into 

microbial assemblages and processes in these methane-rich settings and compare them with previously studied 

cold seeps on European margins. Carbonate crusts generally contained abundant 13 C-depleted lipids from 

methanotrophic archaea along with lipids derived from unspecified sulphate reducing bacteria, confirming their 

formation through anaerobic oxidation of methane (AOM). Similarly, the lipid composition of two sediment 

push-cores taken in an area colonised by gastropods and pogonophorans (16 cm) and bacterial mat (5 cm) at the 

Nyegga pockmark showed high amounts of AOM-derived archaeal and bacterial lipids. Their vertical 

distribution profiles reflect maximum AOM-related microbial biomass at ca. 8-10 cm below the sea floor for 

sediment in the gastropods/pogonophorans area and 1-2 cm for sediment in the bacterial mat site. Compared to 

available biomarker data from cold seep settings, the occurrence, relative abundance and distribution of specific 

13 C-depleted archaeal lipids among crocetane, unsaturated PMI’s, archaeol, sn2-hydroxyarchaeol and glycerol 

tetraethers pointed to the prevalent presence of ANME-2 and ANME-1 archaeal groups. Characteristic 

fingerprints for AOM-related sulphate reducers comprised specific fatty acids and non-isoprenoidal glycerol 

diethers and monoethers. Their patterns reflect the presence of SRB typically found in association with the 

ANME archaea. Discrepancies in archaeal and bacterial lipid fingerprints compared to previously investigated 

seep settings, including the Hakon Mosby Mud Volcano on the Norwegian margin, may indicate the presence of 

multiple ANME/SRB assemblages or contributions from methane-depended microbial species not yet 

characterised. 

Variability of gas composition and flux intensity in natural marine hydrocarbon 

seeps 

F. J. Clark 1 and L. Washburn 2 

1 Dept. of Earth Science, University of California, Santa Barbara, CA 93106, USA 

2 Dept. of Geography, University of California, Santa Barbara, CA 93106, USA 

The relationship between surface bubble composition and gas flux to the atmosphere was examined at Coal Oil 

Point seep field, which is located about 3 km offshore of Santa Barbara County, CA in the Santa Barbara 

Channel. The field research was conducted using a spar buoy designed to simultaneously measure the surface 

gas flux, the buoy’s position with differential GPS, and collect gas samples. Bubbling gas flux was objectively 

mapped with a spatial resolution of about 2 m. Results show that the gas composition varies by 10-20% at subseeps 

within large seep areas. The total flux of gas from these areas exceed 3,000 m 3 /day. The nitrogen mole 

fraction correlated directly with oxygen mole fraction (R 2 = 0.94) and inversely with methane mole fraction (R 2 = 

0.97). These data demonstrate that the bubble composition is modified by gas exchange during ascent from the 

seafloor: dissolved air enters and hydrocarbon gases leave the bubbles. While compositional differences were 

observed at sub-seeps, there was no relationship between flux and composition. Factors other than seep intensity 

controls the amount of gas transfer between the ocean water and bubbles. Therefore, when calculating the 

atmospheric source function of specific gases such as methane from marine seeps, it is best to use mean 

compositional values determined for bubbles collected near the sea surface.


Massive carbon dioxide venting along the Wagner Fault, 

Gulf of California, Mexico, and the associated fauna 

P. R. Dando 1 , C. Canet 2 , R. M. Prol-Ledesma 2 

1 Marine Biological Association of the United Kingdom, Citadel Hill. Plymouth PL1 2PB, UK 

2 Departemento de Recursos Naturales, Instituto de Geofisica, UNAM, Mexico 

The northern Gulf of California is an extensional basin that has been nearly filled with sediments from the 

Colorado River system and volcanic and marine deposits. The northernmost basins today are the 200 m deep 

Wagner and Consag Basins that overly 5 Km of sedimentary deposits. Extensional stresses have caused heavy 

faulting of these sediments, especially along the Wagner Fault that runs along the NE boundary of these basins. 

Large-scale CO2 release occurs along this faults gave rise to gas-saturated sediment, gas chimneys, pockmarks 

and sorted sediments, hard grounds due to cemented sediments, mud-volcanism and massive gas plumes that 

reach the sea surface and acidify the entire water-column. These features were mapped using a TOPAS subbottom 

profiler and echosounders. Preliminary sampling indicated that the fauna of the venting area has a higher 

diversity than that of the surrounding sediments where polychaete-dominated the fauna, comprising 97 % of all 

specimens. 

One of an estimated 15000 gas plumes in the northern Gulf of California. 

High-pressure continuous-incubation studies of sediments containing highly active communities 

of anaerobic methanotrophs 

C. Deusner 1 , T. G. Ferdelman 1 , F. Widdel 1 

1 Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany 

The anaerobic oxidation of methane (AOM) coupled to sulfate reduction in marine sediments is an important 

sink in the global methane budget. However, the biochemistry of methane oxidation and assimilation by 

anaerobic methanotrophs (ANMEs) is not yet fully understood and knowledge about the regulating factors is 

very limited. 

For the study of mechanism and regulation of AOM as well as to enrich the catalyzing organisms from 

environmental samples we have established a unique multiple-phase continuous-incubation system that is 

designed to simulate conditions of high concentrations of aqueous gases (e.g. gas seeps, hydrate systems). The 

system is designed to be operated in a wide range of pressure (up to 45 MPa) and temperature (up to 230°C). 

In long-term continuous-incubation studies at 15 MPa with approximately 60 mM of aqueous methane using 

dilute biomass prepared from microbial mats from the Black Sea and a hydraulic retention time of 35 h, AOM

20 


rates reached 6 mMol⋅gDW -1 ⋅d -1 . It was shown that the process was insensitive towards changing substrate 

concentrations and the accumulation of dissolved sulfide of up to 18 mM. Furthermore, the biomass could 

survive prolonged periods of starvation. After eight weeks of incubation without supplying substrate, analysis of 

total biomass indicated than no significant degradation of biomass took place. Cell integrity was confirmed by 

FISH (Fluorescent In Situ Hybridization) analysis. AOM activity was re-established after supplying methane 

without measurable lag phase. 

Unexpectedly, in experiments where we varied biomass density, AOM rates at high methane partial pressure 

were not dependent on biomass concentration. FISH analysis with specific probes revealed the enrichment of 

sulfate-reducing bacteria (SRB) as compared to ANME. This is in contrast to batch incubation at near 

atmospheric pressure where usually ANMEs are enriched compared to sulfate reducing bacteria. This 

observation combined with the apparent process stability towards changing incubation conditions and the high 

methane turnover rates suggest that both ANME and SRB are active in the catalysis of methane oxidation and 

that the biochemical system and the physiological coupling of the organisms must allow a high degree of both 

flexibility and efficiency towards changing availabilities of C1 compounds. 

Possible BSR reflections on high resolution multichannel seismic reflection profiles from western 

Black Sea continental slope 

D. Dondurur 1 , S. Coşkun 1 , S. Gürçay 1 , S. Okay 1 , P. Özer 1 , G. Çifçi 1 , M. Ergün 1 

1 Dokuz Eylül University, Institute of Marine Sciences and Technology, Inciraltı, Izmir, Turkey 

Black Sea is an interesting semi-isolated basin with occurrences of several gas-related processes. Abundant 

organic matter supply and rapid sediment deposition cause high amounts of shallow gas accumulations as well as 

gas hydrate formations in deeper basin, and pockmarks, gas seeps and mud volcanoes are common all around the 

basin. 

Approximately 360 km of high resolution multi-channel seismic reflection data were collected together with 

high resolution 3.5 kHz Chirp profiles from the western Black sea continental slope using a 96 channel seismic 

recorder and 45+45 inch 3 GI gun in order to map possible shallow gas accumulations as well as gas hydrate 

formations appears as Bottom Simulating Reflections (BSR) on the seismic lines. On the processed lines, some 

very high amplitude reflections which mimic the seabed were observed (Fig. 1). They lie approximately 200 ms 

below the sea floor and appear just below the channel banks, and therefore they are interpreted as BSR 

reflections associated with the channel-levee systems. 

We also computed complex trace attributes of these anomaly reflections and obtained reflection strength 

(envelope), apparent polarity and instantaneous frequency sections. BSR reflections which were observed have 

very large amplitude with negative polarity with respect to the seabed reflection as usual case. 

Fig. 1: Multichannel seismic reflection data from western Black Sea slope showing a BSR reflection.


Acoustic observations of shallow gas accumulations, gas seeps and active pockmarks 

in the Gulf of İzmir, Aegean Sea 

D. Dondurur 1 , S. Coşkun 1 , S. Gürçay 1 , S. Okay 1 , P. Özer 1 , G. Çifçi 1 , M. Ergün 1 

1 Dokuz Eylül University, Institute of Marine Sciences and Technology, Inciraltı, Izmir, Turkey 

The Gulf of İzmir is a semi-enclosed basin which extends E-W direction to the East and N-S direction to the 

West. Water depth changes from 20 m in the inner gulf to about 70 m in the outer parts. It is affected by Western 

Anatolian extensional tectonic regime in N-S direction together with an E-W compressional tectonics, which 

both in-turn produce several strike-slip faults with significant vertical movements both inside of the gulf and on 

land. 

The Gulf could be separated into 7 physic-geographical sub-provinces from inner gulf to outer parts and 

performed high resolution Chirp sub-bottom profiler, multiyear bathymetry and deep-towed combined side scan 

sonar and Chirp sub-bottom profiler systems. The main purpose of the study was to map the active faults of the 

gulf together with possible shallow gas accumulations and gas flares. We have found that southern and 

southwestern boundary of the gulf is strongly affected by active strike-slip faulting with normal component 

which, in place to place, affects the seabed. It has also been observed that there are several other normal faults 

producing small-scale graben structures in the central part of the outer gulf. Especially in areas very close to the 

fault planes, there are several gas flares seen as gas plumes on the Chirp profiles which usually reach to the sea 

surface (Fig. 1). Small-scale collapse structures were also observed on the seabed where the flares occur, which 

indicate pockmark formations. 

In addition to the flares, large scale shallow gas accumulations were also observed on the Chirp profiles as 

acoustically transparent zones with very sharp vertical lateral boundaries located in the southern area of outer 

gulf. This area is the ancient delta of Gediz River and mainly consists of very well bedded terrigenous sediments 

which produce possibly biogenic gas in shallow sediments. 

Fig. 1. Chirp sub-bottom profiler record from outer gulf showing a gas flare. 

The Menes mud volcano caldera complex: 

An exceptional site of brine seepage in the deep waters off north-western Egypt 

S. Dupré 1,2,3 , L. Brosolo 2 , J. Mascle 2 , C. Pierre 1 , F. Harmegnies 3 , V. Mastalerz 4 , G. Bayon 3 , E. Ducassou 5 , G. de 

Lange 4 , J.-P. Foucher 3 , the Victor ROV Team 6 and the Medeco Leg 2 Scientific Party 

1 UPMC, LOCEAN, Paris, France 

2 Géosciences Azur, Villefranche sur Mer, France 

3 Département Géosciences Marines, Ifremer, Plouzané, France 

4 Geosciences Department, Utrecht Universiteit, The Netherlands 

5 Université de Bordeaux I, Talence, France 

6 Genavir, La Seyne/Mer, France 

The Nile Deep Sea Fan hosts numerous active fluid escape structures (Loncke et al., 2004) including several 

large gas emitting mud volcanoes, carbonate mounds and pockmarks, and briny mud volcanoes. During the near 

bottom geophysical surveys of the 2007 Medeco2 expedition (HERMES program), the Victor ROV (Remotely

22 


Operated Vehicle) was equipped with 1) a multibeam Reson 7125 operated at 400 kHz for microbathymetry and 

backscatter seafloor imagery, and 2) a camera OTUS for long range optical black and white imaging. For the 

first time, the detail of the morphology of one of the major fluid releasing complex, previously discovered on the 

foot of the northwestern Egyptian continental slope (Huguen et al., 2007), were revealed. Extending by 3000 

metres water depths and with a diameter of ~8 km, the Menes caldera contains several mud volcanoes, 

associated with brines for the most active of them, Chefren and Cheops (Fig. 1). 

Fig. 1. Shaded morphology map of the Menes mud volcano caldera complex located in the western Nile Deep 

Sea Fan Province. 

Chefren mud volcano is a twin craters structure of 250 to 300 m in diameter each. The northern crater is filled up 

with muddy brine sediments. Within this brine lake, salinity reaches high values (120 to 145 psu). Gas analysis 

in the water column revealed high methane concentrations, 0.4 to 5.6 mmol/l. The temperatures within the lake 

indicate uniform values with depth, reaching ~60°C. In contrast, the southern crater is relatively cold with 

thermal gradients similar to background values. This crater 10 to 20 metres deep corresponds to a former brine 

lake that is at present inactive in terms of brine seepage. Running outflows emitted from the northern brine lake 

are visible all around the mud volcano with its most recent activity located at the northern side. The seepage 

activity there corresponds to highly unstable seafloor environment. The fauna is mostly restricted within the 

close periphery of the brine lake. The small and narrow subcircular plateaus that composed the upper part of the 

crater attract many crabs and polychaete tubeworms. Within the brine lake, the less unstable areas appear to be 

characterized by dense accumulation of white filaments that correspond to sulfur associated with arcobater, 

sulphide oxidizing bacteria (Boetius et al.). 

Cheops mud volcano, similarly to Chefren, exhibits high salinity values and methane concentrations 

(respectively 210 to 240 psu and 2.4 to 3.7 mmol/l). Cheops mud volcano, with an average diameter of ~250m, 

is composed of a brine lake surrounded by an almost continuous depression ring, covered in some places with 

recent outflows. This latter probably corresponds to a former edge of the lake. As previously suspected by 

Huguen et al. (2007), the inner domain of this mud volcano correlates with an almost flat top where numerous 

muddy brine pools, decimetre to metre in scale and covered by whitish filaments, were observed at the surface of 

the lake. An average temperature of ~43°C was recorded from the surface of the lake down to 440m through a 

very unconsolidated material. The uniformity of the temperature profile with depth clearly supports the 

occurrence of first order active convection within a mud/brine/fluid conduit. 

References 

Huguen, C., Foucher, J.-P., Mascle, J., Ondréas, H., Thouement, M., Gontharet, S., Stadnitskaia, A., Pierre, C., 

Bayon, G., Loncke, L., Boetius, A., Bouloubassi, I., De Lange, G., Fouquet, Y., Woodside J., M., and the 

NAUTINIL Scientific Party, The Western Nile Margin Fluid seepage features: “in situ” observations of the 

Menes caldera (NAUTINIL Expedition, 2003). In review, Marine Geology, Special ESF Issue. 

Loncke, L., Mascle, J., and Fanil Scientific Parties, 2004, Mud volcanoes, gas chimneys, pockmarks and mounds 

in the Nile deep-sea fan (eastern Mediterranean); geophysical evidences: Marine and Petroleum Geology, 

21, 669-689.


Methane distribution in the deep-water sediments of the Lake Baikal 

A. V. Egorov 1 , G. V. Kalmychkov 2 , T. I. Zemskaya 3 , O. M. Khlystov 3 

1 P.P.Shirshov Institute of Oceanology RAS, 36, Nakhimovsky Avenue, Moscow 117218 

2 Institute of Geochemistry SB RAS, 1a, Favorsky, Irkutsk 664033, Russia; 

3 Limnological Institute SB RAS, 3, Ulan-Batorskaya, Irkutsk 664033, Russia; 

The Lake Baikal is the deepest lake in the World (1640 m). The lake’s water is fresh and cold. Below the 300 

meters depth the water temperature is practically constant and equals 3.3÷3.5 0 С. As a result, the bottom 

thermobaric conditions are favorable for the gas hydrate (GH) stability starting from ~350 m. It marks out the 

Lake Baikal among the other lakes and approaches it to the World Ocean, where favorable conditions for GH 

stability exist at the 90 % of the bottom. As well as for the Ocean, only a lack of methane limits the GH 

formation in the Baikal deep-water sediments. From this point of view the investigations of the methane 

distribution in the bottom sediments can help to estimate the possibilities and magnitudes of methane 

accumulation in the form of GH. 

In spite of that GH in the Baikal sediments were first found in 1997, the regular studies of the methane 

distribution in the sediments started only in 2003. Some results of these studies for the period 2003-2007 are 

presented here. The field studies were conducted both at the background stations, and in the areas of prospective 

underwater gases discharge. In some of these areas the GH samples were lifted. The methane concentrations 

were measured in the sediments sampled with ordinary nonhermetic gravity cores, so in a case of extremely high 

concentration the part of gas should be lost. Methane content was determined with the traditional Head Space 

Technique and gas chromatograph with flame ionization detector [Bol'shakov Egorov 1987]. The probes were 

analyzed during a day after sampling. The data received for the Lake Baikal was compatible with the data from 

the different regions of the Ocean received with the same technique during the expedition in the last 20 years. 

There were obtained the main features of the Lake Baikal deep-water sediments methane vertical distribution. 

The methane concentration in the surface sediments varies over a wide range, reaching up to four orders of 

magnitude (from 1 μl/l up to 20 ml/l). As a rule, the methane content linearly increased with the depth. However 

in some profiles it was possible to distinguish the concavities that are typical for the methane distribution in the 

marine sediments. 

We propose a model for the estimating of the possible GH accumulation depth in the sediments, based on the 

rate of the growth of methane concentration with depth. The possible GH presence depth was estimated for the 

background areas as 100-130 meters, which coincided with the data on a BSR depth position and the results of 

the GH detection in the frames of the BDP-97 program. The calculated model depths of the GH occurrences are 

in accordance with the observed depths in four investigated GH bearing Baikal areas. 

The upward diffusion methane flux in sediments is characterized by values from 100 up to 5000 m 3 /km 2 year. 

The first value corresponded to the background areas, while the second characterized the zones of the located 

methane discharge. 

The total value of upward methane flux (about 2*10 6 m 3 /year) allows us to estimate the minimal value of the 

annual methane turnover in the Baikal Lake. The obtained estimates of the upward methane fluxes were used for 

an estimation of the potential resources methane in the GH form. Taking into account the geological age of the 

Lake Baikal, the density of the methane resources in the GH form can reach 5,35*10 8 m 3 /km 2 . Therefore, the 

potential resources of GH in the Lake Baikal sediments ( ~1*10 13 m 3 ) can be comparable with the largest in the 

World Ocean GH congestion at Blake Ridge. 

Budgets of oxygen, sulfate and methane fluxes at an active mud volcano 

J. Felden 1 , H. Niemann 1 , A. Lichtschlag 1 , D. deBeer 1 , F. Wenzhöfer 1 , A. Boetius 1,2 

1 Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany 

2 Jacobs University Bremen, 28759 Bremen, Germany 

The Håkon Mosby Mud Volcano (HMMV) is an active mud volcano which has been studied in high resolution 

during several ROV-equipped cruises within the last few years in the framework of the EU project HERMES. 

Based on first biogeochemical measurements and visual observations, the HMMV has been subdivided into three 

main habitats 1) the flat center dominated by aerobic oxidation of methane, 2) large thiotrophic bacterial mats 

covering an area dominated by anaerobic oxidation of methane coupled to sulfate reduction (AOM), and 3) fields 

of siboglinid tubeworms extending with their roots into a subsurface AOM zone (1). In this study, variations in 

microbial activities within and between the identified habitats were analyzed by situ biogeochemical 

measurements from 4 different expeditions. Budgets of methane and oxygen for the entire HMMV were 

established using total fluxes of dissolved methane and oxygen between seafloor and water column measured in 

selected habitats and estimates of areal distribution of habitats.

24 


For our investigations we used a combination of different in situ devices (Microprofiler, Benthic chamber) and 

ex situ techniques to quantify the dominant biogeochemical processes. Total oxygen consumption and methane 

emission rates were measured using a ROV operated benthic chamber module incubating a sediment area of 

approximately 280 cm 2 with overlaying bottom water. Sediment cores were incubated with radiolabeled tracer 

( 14 CH4 and 35 SO4 2- ) to determine ex situ methane oxidation and sulfate reduction rates. 

The data indicate that Beggiatoa mats from different areas of the HMMV have on average similar and high 

turnover rates of methane (10 mmol m -2 d -1 ) and sulfate (14 mmol m -2 d -1 ). On a smaller scale within one 

Beggiatoa mat small heterogeneities are measurable, reflected also in the bacterial coverage of the sediment 

surface. Additionally, aerobic oxidation of methane within the mat may be an important sink for oxygen, as 

biomarker analyses indicate the presence of bacterial methantrophs (2). The total oxygen consumption rates from 

Beggiatoa mats are significantly higher than the previously reported diffusive uptake rates, and may be explained 

by high abundances of meiobenthos (mainly nematodes (3)). 

Compared to other seep systems (4) our methane emission rates reveal a much higher export of dissolved 

methane to the hydrosphere. Our data indicated that 4 times more dissolved methane is emitted (215 mol d -1 ) to 

the water column than via gas bubble flow (5) and in total nearly 40 % of the methane is consumed within the 

sediment of the HMMV. The research was carried out in the framework of the BMBF-DFG Geotechnologies 

program “MUMM” as well as of the EU 6th FP HERMES. 

References 

H. Niemann et al., Nature 443, 854 (Oct 19, 2006). 

M. Elvert, H. Niemann, Organic Geochemistry 39, 167 (2008). 

S. van Gaever et al., (in prep. .). 

A. Boetius, E. Suess, Chemical Geology 205, 291 (MAY 14, 2004). 

E. J. Sauter et al., Earth and Planetary Science Letters 243, 354 (Mar 30, 2006). 

Exceptionally high levels of mud volcano activity on the western Nile deep sea fan – 

First results from the P362/2 cruise of R/V Poseidon 

T. Feseker 1 , M. Nuzzo 1 , F. Scholz 1 , K. Brown 1 and the P362/2 scientific party 

1 IFM GEOMAR, Leibniz Institute of Marine Sciences at Kiel University, Germany 

Mud volcanoes act as natural leakages for oil and gas reservoirs and provide insights into fluid formation and 

fluidization processes that occur at depths of several kilometers below the seafloor. Giza mud volcano (Giza 

MV) and North Alex mud volcano (North Alex MV) are located in the vicinity of designated gas production 

wells on the upper slope of the western Nile deep-sea fan. The dynamics of these unique seafloor features that 

are apparently rooted at depths of more than 5 km and their relation to gas reservoirs is investigated within the 

framework of the West Nile Delta Project at IFM-GEOMAR. 

Both mud volcanoes were studied in detail during the research cruise P362/2 of the German R/V Poseidon in 

February 2008. Sediment samples were obtained using a multicorer and a gravity corer. The geochemical 

porewater composition and the gas content of the samples were determined in order to characterize the source of 

the fluids and to quantify the seepage rates. Sedimentological and micropaleontological analyses of the samples 

were conducted to provided information about the origin of the mud matrix and the clasts. In addition, a large 

number of in-situ sediment temperature and heat flow measurements yielded detailed maps of temperature 

anomalies associated with the ascent of fluids and mud. 

Giza MV is a 2-km-wide circular feature approximately 25 nautical miles off the Egyptian coast at a water depth 

of 700 m that was studied for the first time during this cruise. Both geochemical porewater analyses and in-situ 

sediment temperature measurements indicate that the activity is focussed at the highest point of the mud volcano, 

slightly southeast of the geometrical center. Sediment temperatures of around 40 °C at 5 mbsf, high gas 

concentrations and a rapid decrease of porewater chlorinity with depth suggest on-going seepage of gas-rich, 

chloride-depleted porewater. Away from the center, the temperature gradients decrease rapidly and the 

geochemical transition zone between the bottom water and the mud volcano fluid becomes wider. 

North Alex MV is located approximately 25 nautical miles north-east of Giza MV at a water depth of 500 m. 

Circular in shape, the main mud volcano is less than 1.5 km wide, while the surrounding moat reaches up to 3 

km in diameter. Previous investigations of this mud volcano in 2003 and 2004 within the framework of the 

Euromargins/Mediflux project had shown evidence for gas ebullition at the center and moderate levels of fluid 

seepage. During the cruise P362/2, in contrast, sediment temperatures of more than 70 °C at 5 mbsf and a very 

sharp geochemical porewater boundary between seawater and mud volcano fluids at the center of the mud 

volcano pointed to extremely high seepage rates and very recent mud expulsion. Numerous authigenic


precipitates such as carbonate chimneys and pyrite cristals that were found in the sediment samples suggest a 

long history of methane seepage at North Alex MV. 

Based on the results of this cruise, further investigations in November 2008 will focus on the subsurface 

structure of the two mud volcanoes. Uncabled seafloor observatories will be installed to study the dynamics of 

their activity over a period of several years. 

Carbon and sulfur cycling at cold seeps in the Gulf of Mexico and new perspectives on 

old seeps 

M. J. Formolo 1* and T. W. Lyons 2 

1 Department of Geological Sciences, University of Missouri, Columbia, Missouri, 65211 

(*) present address: Max-Planck-Institute for Marine Microbiology, Bremen, Germany 

2 Department of Earth Sciences, University of California, Riverside, 92521 

The Green Canyon region in the northern Gulf of Mexico is characterized by abundant cold seeps. It provides an 

ideal natural laboratory to study biogeochemical cycling of sulfur, carbon, and oxygen in clathrate- and 

hydrocarbon-rich deep marine settings. Of particular interest are diagnostic sulfur isotope compositions 

associated with bacterial sulfate reduction (BSR) coupled to the anaerobic oxidation of methane and the 

oxidation of other non-methane hydrocarbons. Whereas most of the published literature regarding sulfur 

isotopes in cold-seep systems pertain to pore-water species, our comprehensive study integrates both dissolved 

and solid sulfur species and their sulfur isotope properties, including: acid-volatile sulfides (AVS), pyrite, 

elemental sulfur (S°), and dissolved sulfate and sulfide. 35 SO4 2- reduction rate measurements and δ 13 C and δ 18 O 

data for authigenic carbonates are also integrated into this sulfur biogeochemical framework to address sulfate 

reduction rates driven by the variability in both the fluxes and composition of hydrocarbon seepage throughout 

the region. 

Our results indicate extreme variability, in the concentrations of dissolved sulfur species and 35 SO4 2- reduction 

rates, over small spatial scales and brief temporal intervals within short distances (meters) from active seeps. 

Such small-scale variability must reflect the structure and temporal dynamics of hydrocarbon migration in the 

presence of low amounts of background organic matter. Our previous work demonstrated that electron donors 

other than methane drive significant levels of microbial activity at these seeps. Furthermore, we showed that the 

δ 18 O and δ 13 C signatures of the authigenic carbonates document active destabilization of hydrates, while 

recording the microbial oxidation of mixed pools of methane and non-methane hydrocarbons. These variations in 

hydrocarbon input are related to the observed variability in the dissolved-sulfur species. 

Solid-phase sulfur species and authigenic carbonate concentrations also exhibit extreme heterogeneity 

throughout the Green Canyon. Elevated pyrite and diagenetic carbonate contents, and the depleted δ 13 C values 

of associated carbonates, relative to background sediments are diagnostic of active seepage; however, δ 34 S 

compositions indicate more complex histories. The concentrations and δ 34 S values of the transient, 

‘instantaneous’ products of sulfur cycling - AVS and S° - record evolution of the sulfur reservoir as elevated 

δ 34 S values that increase with depth. Most of the pyrite appears to form very early, presumably as a consequence 

of limitations in reactive Fe. 

In cold-seep environments the sulfur isotope composition of the solid-phase pool is controlled by a balance 

between the rates of sulfate reduction driven by external fluxes of hydrocarbons, the recycling of sulfur species, 

and the available reactive iron pool. These variations lead to an observed decoupling between the instantaneous 

products of sulfur cycling and the final pyrite δ 34 S signatures preserved in the sediments. When sulfate reduction 

rates are elevated due to enhanced hydrocarbon seepage, the pyrite δ 34 S signature does not adequately record the 

evolution of the sulfur reservoir but instead represents an early formed pyrite recording the initial stages of 

sulfate depletion. In modern cold seep settings the generation of instantaneous products continues to record the 

evolution of the sulfur reservoir. As such, δ 34 S values for pyrite can show consistently light sulfur isotope values 

that fail to record (integrate) the full extent of BSR and sulfur recycling, and thus the intensity of the seep 

system. Since pyrite can misrepresent the magnitude of BSR, and the instantaneous products are transient in 

nature, we suggest that sulfate trapped within the diagenetic carbonate (carbonate-associated sulfate) may 

provide another isotopic window into the recognition and characterization of cold seeps, particularly when 

supplies of reactive Fe are limited.

26 


How unstable with time are submarine mud volcanoes: Examples from the European seas 

(ARK XIX/3, MEDIFLUX and HERMES Projects). 

J.-P. Foucher 1 , T. Feseker 1,3 , S. Dupré 1,2 , M.-C. Fabri 1 , F. Harmegnies 1 , A. Normand 1 , C. Satra 1 , A. Boetius 4 

1 Ifremer, Brest, France, 

2 Géosciences Azur, Villefranche sur Mer, France, 

3 IFM-GEOMAR, Kiel, Germany, 

4 Max-Planck-Institute for Marine Microbiology, Bremen, Germany 

Several onshore mud volcanoes are known to experience major mud and fluid eruptions with periodicities of 

decades or less. In contrast, little remains known about temporal changes in the activity of submarine mud 

volcanoes. This is mainly because of a lack of observations. We report on geothermal and seafloor mapping data 

that bring observational evidence for temporal changes of the morphology and fluid discharge activity of 

submarine mud volcanoes. We use observations made as part of cooperative projects allowing for repeated 

measurements at selected sites of monitoring in the European seas over the recent years (ARK XIX/3, 

MEDIFLUX and HERMES Projects). 

Håkon Mosby Mud Volcano (HMMV) is an exemplary site of extremely active methane-rich fluid seepage off 

northern Norway. Dive and acoustic gas flare observations point to large variations both in time and space of 

free gas emissions. Free gas bubbling sites observed in 2006 were at seafloor locations distinct from those of 

bubbling sites observed in 2003. Furthermore, a comparison of bathymetric maps produced in 2003 and 2006 

show considerable changes in the morphology of the southern part of the mud volcano. A spectacular change in 

the mud temperature profile in the central part of the volcano occurred during the winter 2005-2006, thus 

attesting to a profound change in the fluid flow system. 

The Nile deep sea fan (NDSF) is another HERMES-targeted area characterized by hydrocarbon-rich water and 

brine seepage. As part of the MEDIFLUX and HERMES projects, high-resolution seafloor mapping surveys and 

dive observations were conducted at several mud volcanoes of the NDSF. Brine-filled craters characterize the 

Cheops and Chefren mud volcanoes in the so-called Menes Caldera that was investigated with L’Atalante 

(2003), the Meteor (2006) and the Pourquoi pas? (2007). Video surveys suggest changes in the brine flow 

activity. At the Isis mud volcano, geothermal and chemical data suggest periods when fluid was flowing into the 

seafloor sediment instead of flowing out of it into the bottom sea water. 

How temporal changes in the fluid flow system impact on the biota remains little observed. A deep-sea 

observatory to monitor chemical flux changes and responses of the benthic communities to these changes has 

been planned at the HMMV (ESONET/LOOME project, MPI Bremen coordinator). 

Diversity of mud volcanoes in the Transylvanian Basin (Romania) 

A. Gál 1 , Z. Unger 2 

1 Babeş-Bolyai University, Department of Physical Geography, Cluj-Napoca, Romania 

2 Hungarian Geological Institute, Budapest, Hungary 

Mud volcanoes are common in many sedimentary basins, where fine-grained, plastic, buoyant sediments ascend 

through the sedimentary succession. The Transylvanian Basin, known as one of Europe's best delimitated and 

highly purified hydrocarbon basins (99% methane), represents a suitable location for the occurrence of mud 

volcanoes. The average thickness of the sediment sequence is 4-5 km, its actual architecture being complicated 

by the migration of salt and lateral tensions related to the uplift of the Carpathians. 

In comparison with the Azerbaijani mud volcanoes which are several hundreds of meters high and more than 1 

km large, the mud volcanoes of Transylvania are miniature features, having a maximum of 6 meters in height 

and 20 meters in diameter and are characterized by quiescent activity. 

The mud volcanoes are spread all over the basin, with various surface expressions being spatially confined to gas 

deposits and faults. This kind of relationship has been confirmed by many other studies from different mud 

volcano regions. 

This study summarizes the occurrences of mud volcanoes in the Transylvanian Basin with special attention to 

the diversity in morphology, the evolution and dynamics from 1932 (Banyai, 1932) to 2002-2008. By shallow 

drillings we gained insight into the structure of these small size mud volcanic manifestations. On this basis we 

propose a new morphological classification for the mud volcanoes in the Transylvanian Basin.


A relationship between Holocene sea-level change and shallow gas generation 

S. García-Gil 1 , C. Muñoz Sobrino 2 , J. Iglesias 1 , A. Judd 3 , B. Diez 1 

1 Dpt. Geociencias Marinas, University of Vigo, Spain 

2 Dpt. Biología Vegetal y Ciencias del suelo, University of Vigo, Spain 

3 Alan Judd Partnership, High Mickley, Northumberland, NE43 7LU, UK 

Analysis of pollen from cores collected from the inner Ría de Vigo, NW Spain combined with seismic sequence 

stratigraphy has: 1) revealed a history of changing marine and terrestrial influences, 2) made it possible to 

determine the history of sea level changes over the last few thousand years, and 3) enabled the determination of 

the age and environment of deposition of sediments in which shallow gas has been generated. 

Fig. 1: Ría de Vigo: the extent of acoustic turbidity (shallow gas) is indicated in yellow, the core locations in red, 

and the bathymetric profile (below) in white. 

The sediments of the ría were deposited on a basement of granitic and metamorphic rocks. Water depths 

decrease from the open sea towards the inner ría (see figure), which was exposed (and crossed by river channels) 

during the main periods of lower sea level (late glacial maximum – the Würm – and the Younger Dryas). During 

the climatic amelioration, the coastline transgressed into the ría eventually flooding the innermost part, San 

Simon Bay where the post-glacial record is restricted to the most recent sediments. 

The sediments of San Simón Bay are characterised by shallow gas which obscures all seismic detail, except in 

the coarse sediments of the Rendondela River delta. The Cesantes beach sediments include an organic horizon, 

ancient alluvial fan sands, and the modern sand and gravel beach. Gas bubbling from the intertidal zone is 

thought to be derived both from peat which lies directly on weathered granite, and also from Holocene organicrich 

muds. 

Pollen analysis was undertaken on four cores, two collected outside the Rande Strait (see figure), and the other 

two on a beach in San Simón Bay. The first two sites were flooded since 8,000 yrs BP, and the other within the 

last 4,000 years. Core VIR94 was taken from a gas-free location where the sediment sequence is compressed, so 

the core was able to reach sediments deposited before the flooding of San Simón Bay (Fig. 1b). The beach cores 

contain marine palynomorphs deposited at the end of the middle Holocene (

28 


Acoustic detection of gas emissions and active tectonics within the submerged section of the 

North Anatolian Fault zone in the Sea of Marmara 

L. Géli 1 , P. Henry 2 , T. A. C. Zitter 2 , S. Dupré 1 , M. Tryon 3 , M. N. Çağatay 4 , B. Mercier de Lépinay 5 , X. Le 

Pichon 2 , A. M. C. Şengör 4 , N. Görür 4 , B. Natalin 4 , G. Uçarkuş 4 , S. Özeren 4 , S. Bourlange 6 , 

D. Volker 7 and the Marnaut Scientific Party 

1 Ifremer, Marine Geosciences Department, 29280, Plouzané, France 

2 CEREGE and Collège de France, Europôle de l'Arbois, BP80, Aix-en-Provence, France 

3 Scripps Institution of Oceanography, La Jolla, CA, 92093-0244, USA 

4 Istanbul Technical University, Faculty of Mines, Geology Department, Maslak, Istanbul, Turkey 

5 Geosciences Azur, Université de Nice-Sophia Antipolis, Valbonne,, France 

6 CRPG, 15 Rue Notre Dame des Pauvres, 54501 Vandoeuvre Les Nancy, France 

7 IFM-GEOMAR, Wischhofstr. 1-3, D-24148 Kiel, Germany 

We here present results of acoustic surveys and Nautile submersible dives in the Sea of Marmara, and show that 

most gas emissions in the water column are found near the surface expression of known active faults. In the Gulf 

of Izmir at the eastern end of the Sea of Marmara, expulsion of gas through seafloor fault ruptures was observed 

after the 1999 Kocaeli earthquake on the North Anatolian Fault (Alpar, 1999; Kuscu et al., 2003). In September 

2000, acoustic reflectivity images of the deeper parts of the Sea of Marmara were obtained with a 180 kHz side 

scan sonar towed by R/V Le Suroit, ~75 m above seafloor. Echoes produced by gas plumes were observed 

before the first seafloor arrival. In May-June 2007, during the Marnaut cruise of R/V L’Atalante, a SIMRAD 

EK60 echo sounder operating at 38 kHz and mounted on a fish towed at approximately 10 m depth was used for 

plume detection. All sites where acoustic anomalies were detected in 2000, were still active when revisited seven 

years later. Gas emissions are unevenly distributed. The linear fault segment which crosses the Central High 

exhibits relatively less gas emissions and scenarios for historical seismicity suggest that this segment connecting 

the Cinarcik Basin to the Central Basin forms a seismic gap -as it has the longest time elapsed since the last 

earthquake. In the eastern Sea of Marmara, active gas emissions are also found above a buried transtensional 

fault zone, which displayed microseismic activity after the 1999 event. Remarkably, this zone of gas emission 

extends westward all along the southern edge of Cinarcik basin, well beyond the zone where 1999 aftershocks 

were observed. Our findings suggest that, at least in some settings, the distribution of gas seeps may provide an 

indication of recent fault activity and even help identify buried structures. 

Spatial methane-bubble flux quantification from seeps into the atmosphere 

on the Black Sea shelf 

J. Greinert 1,2 , D. F. McGinnis 2 , L. Naudts 1 , P. Linke 2 and M. De Batist 1 

1 Renard Centre of Marine Geology (RCMG), Ghent University, Krijgslaan 281 s8, B-9000 Gent, Belgium 

2 Leibniz-Institute of Marine Science IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel, Germany 

Particularly free gas fluxes at seeps are transient in time and space, triggered by external forces (wind, tides) as 

well as internal properties, e.g. gas reservoir sizes or gas supply from deeper sediment horizons. In 2003 and


2004, multibeam and single beam surveys and the deployment of the hydroacoustic lander system GasQuant 

were carried out in an active seep area west of the Crimea Peninsula within the CRIMEA project. Multibeam 

data (bathymetry and backscatter mapping) and single beam data (bubble seep localization) were used for 

mapping the seep distribution and for determining the relation of seeps/m 2 and backscatter values. Backscatter 

data are used to quantify the amount of active seeps in the entire mapped area based on the full coverage 

backscatter maps derived from the multibeam survey (Fig. 1). 

Fig. 1: Backscatter data from the 

study area and seep positions (red 

dots). The very good correlation 

allows using the backscatter data to 

calculate the number of seeps/m2 

for specific back scatter values and 

to extrapolate the number of seeps 

for the entire area (21.8 km 2 ). 

Flux measurements using the submersible JAGO yielded very accurate single spot fluxes but do not provide 

information about the temporal variability of bubble release. To analyse this, the GasQuant lander was deployed. 

The data gained show that by far the majority of bubble releasing seeps is only active for less than 10% of the 

time (Greinert, JGR 2008). Distinct release patterns could be observed, varying from frequent and periodic 

releases to sporadic and periodic, to erratic or single bursts. These patterns are related to the filling and emptying 

of gas reservoirs, e.g. underneath bacteria mats or carbonate slabs triggering periodic bubble release on a minute 

basis. Tidal cycles were not observed as the Black Sea does not have prominent sea level changes (< 20 cm). 

Using the average bubble release activity (only 12% of the time) together with the directly measured fluxes (0.24 

to 0.63 mmol/s), the total number of seeps in the study area (2709), and correcting this flux with the mean 

activity measured by GasQuant results in a methane flux of 14043 mol/d (224 kg of C). 

To estimate the maximum amount of methane that could be transported to the sea surface, we applied a bubble 

dissolution model (McGinnis at al., JGR 2006). The amount of methane that reaches the sea surface was 

modeled by assuming different bubble size spectra and taking the changing water depth condition in the study 

area into account. Based on the most likely initial Gaussian bubble size distribution we can estimate that only 0.2 

to 3.3 % (110 and 70m water depth, respectively) of the initially released methane reaches the sea surface 

(Figure 2). For the entire study area this sums up to only 1680 mol/d or 20.16 kg of carbon. 

Gas hydrate induced fluid flow alteration 

J. Hauschildt 1 , V. Unnithan 1 , J. Vogt 1 

1 Jacobs University, Bremen 

The formation of sub-seafloor gas hydrates in marine environments can be described as a coupled transport and 

thermodynamic process inside a host sediment matrix undergoing structural evolution. The transport processes 

are driven by the sedimentary load and induced overpressure gradients, controlled by the sediment permeability. 

For accurately modelling the resulting fluid flow profile, the alteration of the sediment permeability during 

hydrate precipitation has to be taken into account, which affects both the transport of solutes and the sediment 

compaction. 

We investigated the effect of the flow deflection due to local permeability reduction on the total hydrate 

abundance in scenarios of a laterally varying thickness of the hydrate stability field. 

The predicted results of the coupled system of the sediment and fluid transport, of the thermodynamic 

equilibrium and of the pore pressure were obtained using a semi-implicit two-dimensional Finite Volume

30 


Model. The large range of time scales involved requires a solver for stiff differential equations, and the 

Numerical Differentiation Formulae turned out to provide an efficient solution. 

Assumptions on the microscopic structure of gas hydrate crystals in the host sediment matrix can influence the 

permeability reduction depending on whether a moderate hydrate saturation can already clog fluid pathways. We 

present the resulting sensitivity of hydrate abundance and solute profiles to the underlying porosity-permeability 

model assumption. 

water depth m 

water depth m 

bubble diameter mm CH fraction of initial amount % 

4 

N fraction of bubble % 

2 

CH fraction of bubble % 

4 

Fig. 2: Model runs for 

the bubble dissolution 

clearly show that 

bubble size and release 

depth have a great 

impact on the amount 

of methane that is 

finally transported to 

the sea surface (CH4 

fraction of initial 

amount). During their 

rise through the water 

column bubbles strip 

nitrogen and oxygen 

from the water and 

methane is dissolved. 

The stripping effect is 

greater with smaller 

bubbles so that quite 

large bubbles with 

12mm initial diameter 

transport 15% (from 

90m depth) to 25% 

(70m depth) of the 

initial methane to the 

atmosphere. 

This flux is in very good agreement with geochemically measured sea surface fluxes by Schmale et al. (GRL 

2005). However, compared to other methane sources as e.g. sheep, each of which burps out about 20 g of 

methane per day, the studied seep site, which has been classified as highly active (Naudts et al., Marine Geology 

2006), is negligible as an atmospheric methane source compared to e.g. the about 40,000,000 sheep that 

discharge methane in New Zealand alone. 

When a pockmark is not a pockmark: Large pockmark-like features on the Landes Plateau (Bay 

of Biscay) 

J. Iglesias 1,2 , S. García-Gil 1 , A. Judd 3 and G. Ercilla 2 


2 CSIC, Instituto Ciencias del Mar, Barcelona, Spain 


Pockmark-like seabed depressions have been found in the deep (1200 to 2000 m) waters of the Landes Plateau, 

Bay of Biscay (Fig. 1). This plateau lies between the Capbreton and Cap Ferret Canyons which provide 

sediment transfer routes to the deep ocean from the Spanish and French continental shelves.


The seabed depressions are 800 to 1500 m across and 10 to 50 m deep according to multi-beam echo sounder 

data (Fig. 2). Some are isolated, others occur in groups aligned NE-SW; these groups create elongate depressions 

up to 4 km long. Seismic (air-gun and TOPAS) profiles show that each feature comprises a stack of identical 

features which extend to the base of the Quaternary sequence. They are located above diapiric features, and 

faults extending upwards from these salt diapirs almost to the seabed provide migration pathways for any 

buoyant fluids. 

This study provides an explanation for the formation of these features, involving the influence of the collision 

between the Iberian and Eurasian Plates during the Tertiary Alpine Orogeny, diapiric activity which affected the 

Miocene sequence, and Neogene and Quaternary sedimentary regimes, but not the erosion of seabed sediments 

by escaping fluids. 

Fig. 1: Landes Plateau study area. 

Fig. 2: Multibeam bathymetry and seabed slope map, Landes Plateau. Inset: multibeam bathymetry showing 

examples of pockmark-like features.

32 


Gas presence in the sediment pile – Black Sea case 

G. Ion 1 , E. Ion 1 , F. Dutu 1 , A. Popa 1 , V. Radulescu 1 

1 GeoEcoMar, 23-25 D. Onciul, 024053-Bucharest, Romania 

Black Sea is one of the most researched areas in terms of gas presence, in the sediment pile. This is mainly due 

to its very specific characteristics: an almost enclosed basin, 93% of its depth being anoxic and a geologic 

history marked by successive states of fresh and saline waters. Large amounts of sediments have been 

accumulated in some parts of the black sea (more than 12000 m in some areas). 

The water level dynamics specific to the evolution of the Black Sea in glacial time, produced best environments 

(deltas, marshes, migrating shoreline and river channels, etc.) for the production of important spots or even belts 

of large amounts of organic matter that produced biogenic gas. Oil and gas proven provinces exists in the Black 

Sea. Some methane originating from deep parts of the sediment pile ascends and reaches the shallow sediments 

and even the water column. The fluids follow the most permeable structures and conduits, as tectonic features or 

mud volcanoes. 

Specific seismo-acoustic facies can be attached to characteristic geological structures. Contrasting facies are 

specific for the presence of gas in the sediment pile (as wipe outs and acoustic turbid zones, etc) and a correct 

geological interpretation requires great care and experience. 

The mixing of biogenic and thermogenic methane can exist on all specific areas of the sea: continental shelf, 

shelf break, continental slope and the deep sea. The possible bio-geochemical reworking of methane makes 

difficult to distinguish between biogenic and thermogenic gas. 

On the continental slope gas hydrate accumulations are present. Double BSR structures are quite common on the 

western part of the continental slope and a unique and a strange feature made by four stacked BSRs has been 

reported for the first time in the same area by Ion G. et. al., in 2002. 

It is thought that Prokaryote organisms play a major role in mediating the methane production and consumption 

in the sediment pile. In the last years Black Sea has been and still is a huge natural laboratory to study the 

complex processes related to the microbiology and geology of the methane gas. 

Mapping and main characteristics of multiple BSR reflectors in the Tuapse Trough (Black Sea) 

M. Ivanov 1 , V Blinova 1, 2 , N. Malyshev 2 , R. Pevzner 3 , A. Volkonskaya 1 , S. Bouriak 3 

1 UNESCO Centre for Marine Geology and Geophysics, Geological department, Moscow State University, 

Moscow, Russia. 

2 Corporate Research and Technology Centre, Rosneft oil company, Russia 

3 Deco Geophysical, Moscow, Russia 

Large numbers of the multichannel commercial 2D seismic records were analyzed to reveal a distribution of 

BSR reflectors in sedimentary cover of the Tuapse Trough. Special set of seismic processing methods oriented 

on detailed study of uppermost sedimentary section (until 500 m bsf) have been applied. It allows ensuring 

maximum resolution and dynamic characteristics of seismic records at this depth interval. 

BSR type reflectors have been detected in the most of seismic sections and map of gas hydrate bearing deposits 

was created. Two areas of gas hydrate distribution: North-western and Central have been definitely identified. In 

N-W area BSR reflector is very well traced in Quaternary deposits simulating complex relief of channel-levee 

system. In Central area BSR reflectors are coincide with Maikopian folds. They are discontinuous and crossing 

discordant with layers of different ages. Total area of BSR distribution in the Tuapse Trough is not less than 

5100km 2 . 

Maps of temperature gradients and heat flow were built on the base of BSR distribution map. They demonstrate 

very high heat flow variations in this area ranges between 15 and 60 mW/m2, while highest values coincide with 

outer, probably, most active folds. These data are in accord with direct measurements of heat flow at this area 

and allow to give reasonable explanation for big variations of heat flow on relatively limited area. 

Multiple BSR’s (from 2 to 4) have been revealed on several seismic lines. By simple modeling of P-T conditions 

it was concluded that uppermost BSR in this vertical succession coincide with present-day bottom of gas hydrate 

stability zone. 

Comparison of these data with multiple BSR’s in N-W part of the Black Sea (Danube deep=sea fan) demonstrate 

that they have similar nature and most probably reflect some local regional climatic changes influenced warming 

of sea bottom water temperature in whole Black sea during last 10 m.y. due to opening of Bosporus Strait.


Marine pore fluid profiles of dissolved sulfate; do they reflect in situ methane fluxes? 

M. Kastner 1 , M. Torres 2 , E. Solomon 1 , A. Spivack 3 

1 Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA 

2 College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA 

3 Graduate School of Oceanography, Narragansett, RI 02882, USA 

To establish the structural and lithological controls on gas hydrate distribution and to asses the associated 

methane fluxes in the Indian Ocean, non-pressurized and pressurized cores were recovered from the Krishna- 

Godavari (KG) and Mahanadi deepwater Basins (900-1170 meters) offshore southeast India, and from an 

Andaman Sea site (1600 meters water depth). The pore fluids were analyzed for a large range of chemical 

species and isotopic ratios; the significance of the dissolved sulfate and δ 13 C-DIC (dissolved inorganic 

carbonate) proiles are emphasized below. Evidence for gas hydrates was obtained at each of the sites. 

A main objective was to use sulfate gradients and δ 13 C-DIC values as proxies for sub-seafloor hydrocarbon 

fluxes and to identify the nature of the sulfate reduction reactions. In anoxic sediments methane is produced in 

the subsurface by organic matter diagenesis, and DIC is present mainly as the HCO3 - ion. The reaction of organic 

matter oxidation linkd to sulfate reduction produces 2 moles of bicarbonate per mole sulfate reduced. In high 

methane flux areas in the sulfate-methane transition (SMT) zone, the coupled reaction of anaerobic methane 

oxidation (AOM) with sulfate reduction, produces one mole of bicarbonate per one mole of sulfate reduced, 

shown in the two equations. 

1. 2 (CH2O) + SO4 -2 → 2HCO3 - + H2S 

2. CH4 + SO4 -2 → HCO3 - + HS - + H2O 

The δ 13 C–DIC values provide a clear distinction between these two reactions, because the δ 13 C of methane is 20 

to 75‰ more negative than of organic matter. 

The SMT zone separates sulfate-bearing and methane depleted sediments and sulfate-depleted and methane-rich 

sediments. This is a biogeochemical redox boundary in methane-rich sediments with methane hydrate. In this 

redox transition zone the sulfate reduction and AOM reactions are mediated by a marine microbial consortium. 

Significant variations in sulfate concentration gradients were observed in the KG Basin, with both the shallowest 

and deepest SMT zone at ~9 and 30 mbsf; the highest concentrations of gas hydrates were observed in the KG 

Basin. At six of the 8 sites analyzed the δ 13 C of the DIC is controlled by organic matter oxidation linked to 

sulfate reduction, with δ 13 C-DIC values that range from -12‰ to - 26‰. Only, at two of the sites (14 and 10) 

AOM dominates, with δ 13 C-DIC values of -36‰ and -47‰, respectively. At these two sites the SMT as well 

ccurs at ~20 mbsf. At the Mahanadi Basin, with just minor disseminated gas hydrates, and in the Andaman Sea, 

with methane hydrates only below ~250 mbsf the SMT occurs at ~20 mbsf. The δ 13 C-DIC values at these sites 

are -38‰ and -46‰, respectively, indicating the predominance of the AOM reaction. These results indicate that 

shallow depths of the SMT zone do not necessarily indicate that AOM is the responsible reaction for sulfate 

reduction. Hence, the steepness of the sulfate concentration profiles does not automatically reflect that AOM is 

the dominant reaction; analysis of δ 13 C-DIC is required to distinguish between the dominant reaction responsible 

for the sulfate concentration profile. Furthermore, there is no correspondence between the depth of the SMT, or 

the steepness of the sulfate profile, and the depth or amplitude of the BSR, suggesting that these two interfaces 

are reflecting different aspects of the subsurface methane hydrology. 

Preliminary modeling of fluid advection rates, based on Cl concentration profiles, indicate that fluid flow rates 

are as well considerably higher in the KG Basin, following by the Andaman Sea site and lowest in the Mahanadi 

Basin. 

Is heat flow probing a direct measure for gas hydrate stability boundary conditions? 

N. Kaul 1 and H. Villinger 1 

1 Universität Bremen, Department of Geosciences 

Exchange processes of gas hydrates with pore water and finally with sea-water have often been postulated but 

rarely been observed. Especially at the upper boundary of gas hydrate hosting sediment layers at the sea floor 

and in some distance beneath, stability of gas hydrates is controlled not only by temperature and pressure but 

additionally by solubility of methane, salinity of pore water and other parameters. This sensitive balance is 

probably destroyed during coring, making observations on core material difficult. Therefore in-situ measurement 

techniques should be applied to investigate this sensitive boundary. 

In numerous temperature profiles, measured with a heat probe in the upper 4 to 6 m of gas hydrate prone shelf 

sediments from the Arctic to the equatorial Pacific we observe unusual and characteristic deviations from linear

34 


positive temperature gradients. Strong excursions and even negative partial gradients occur. Collocated in-situ 

measurements of thermal conductivity show jumps to lower values which is easily possible if gas is present in 

the pore space. These observations are most likely associated with the dissociation of gas hydrate which may be 

caused by locally very steep methane concentration gradients in the pore water. 

We expect, that the temperature anomalies are an expression of the dynamic equilibrium of the upper boundary 

of gas hydrate layers. 

Thermodynamic and kinetic control on anaerobic oxidation 

of methane and sulfate reduction 

N. J. Knab 1,2 , A. W. Dale 3 , B. B. Jørgensen 1 

1 Max-Planck Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany 

2 University of Southern California, Department of Biological Sciences, Los Angeles, USA 

3 Utrecht University, Department of Earth Sciences, Utrecht, The Netherlands 

Biologically mediated anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SRR) in marine 

sediments has a very low standard free energy yield of ΔG° = -33 kJ mol -1 . The free energy yield of microbial 

respiration reactions can only be exploited by organisms if it is sufficient to be conserved as biologically usable 

energy in the form of ATP. The in situ energy yield that the organisms gain from performing AOM-SRR 

therefore strongly depends on the concentrations of substrates and products in the pore water of the sediment. In 

this work ΔG for the AOM-SRR process was calculated from the pore water concentrations of methane, sulfate, 

sulfide, and dissolved inorganic carbon (DIC) in sediment cores from different sites of the European continental 

margin in order to determine the influence of thermodynamic regulation on the activity and distribution of 

microorganisms mediating AOM-SRR. In the sulfate methane transition zone (SMTZ) the energy yield of the 

coupled process was favorable for the microorganisms with energy yields between ca. 19 and 42 kJ mol -1 . 

Theoretical calculations confirm that under the pore water concentrations prevailing in a typical SMTZ of 

sediments dominated by diffusive transport ΔG of AOM-SRR is not becoming significantly less exergonic than - 

20 kJ mol -1 . In most cases the energy yield was surprisingly constant over the entire interval of the SMTZ but the 

occurrence of rates was restricted to the bottom of this thermodynamically favourable zone. The distribution of 

SRR and AOM rates was reflected in the profile of the kinetic drive, calculated from a dual Michaelis Menten 

equation using the measured substrate concentrations. The maximum AOM rates closely matched the peak of the 

kinetic drive at the bottom end of the SMTZ, where methane concentrations were high and sulfate was almost 

depleted. 

The observed dependence of the main AOM activity on the kinetic conditions in the sediment might results from 

methane concentrations being much lower than the half-saturation constant KM(CH4) whereas sulfate 

concentrations are higher or in the same range as KM(SO4 2- ). Yet, such a strong kinetic influence can be only 

expected when the concentration of one of the substrates has the same magnitude or is even lower than its KM. If 

the in situ concentration is much higher than the KM the FK becomes close to 1 and therefore insignificant. The 

influence of the kinetic drive on AOM in the cores investigated in this study explain the restricted occurrence of 

the major AOM-SRR activity at the bottom of the SMTZ. and also the often observed strong dependency of 

AOM rates on methane concentrations.


3D modelling of a gas hydrate accumulation based on thermal, acoustic and coring data 

M. Kulikova 1 , T. Matveeva 1 , J. Poort 2 , Y. Jin 3 , H. Shoji 4 

1 VNIIOkeangeologia, Angliyskiy pr. 1, 190121, St-Petersburg, Russia 

2 Renard Centre of Marine Geology, Gent University, Krijgslaan 281, B9000, Gent, Belgium 

3 Korea Polar Research Institute, 503 Get-Pearl Tower, Yeonsu-gu Incheon, 406-840, Korea 

4 Kitami Institute of Technology, 165 Koen-cho, 090-8507, Kitami, Japan 

During the 31 st and 32 nd cruises of the R/V ‘Akademik M. A. Lavrentyev’ carried out in the framework of the 

CHAOS (Hydro-Carbon Hydrate Accumulations in the Okhotsk Sea) International Project (Shoji et al. 2005, 

Matveeva et al. 2005), more than sixty structures related to fluid venting were discovered using the SONIC-3 

deep-towed system (side scan sonar (SSS) combined with 3.5-kHz subbottom profiler). On the SSS records these 

flare locations correspond to structures of enhanced backscatter with an isometric and concentric form. The 

acoustic anomalies occupy a floor space of 27.9 km 2 (up to 14%) from the total area of about 200 km 2 covered by 

SSS. 

Acoustic, coring and thermal modeling data for the CHAOS seep were analyzed and compared. As a result we 

built 3D model of gas hydrate (GH) accumulation associated to the CHAOS seep. Comparison of sediment 

coring data with those on backscatter intensity for the CHAOS structure has shown that this GH occurrence 

confines to zone of very high backscatter (110-140 conventional units) (Fig. 1). The zone of maximal backscatter 

in its turn corresponds to that of high temperature gradient suggesting discharge of gas-saturated water. Based on 

the thermal modeling it was established that within the CHAOS both free gas and gas-saturated water are 

discharged (Kulikova et al. 2007). Sediment recovered from the zone of high temperature gradient (0.1 K/m) 

represented by massive and vein GH-induced sediment structures. These structures suggest GH precipitation 

from gas-saturated water in those locations where the presence of high temperature gradient is responsible for 

the decrease of gas solubility in the pore water. The zone of backscatter intensity of 75-110 conventional units 

corresponds to average temperature gradient values suggesting GH formation during water segregation by 

diffusing gas along free gas venting front (Ginsburg, Soloviev, 1998). Thus, our 3D model may serve as a useful 

tool for prediction of a mechanism of GH formation and probably by phase state of the discharging fluid (free- 

and dissolved in water gases). 

Fig. 1. CHAOS seep on SSS record – from the left; 3D model of GH accumulation within the CHAOS seep – 

from the right. 

Based on the calculated velocity of ascending fluid flux (0.15 m/year; Kulikova et al. 2007), it is possible to 

estimate a volume of the discharging fluid (water and dissolved gas) as a whole and gas dissolved in the water 

separately. According to our estimations, 3·10 3 m 3 /year of the fluid will discharged from the active zone of the 

CHAOS structure with 80 m radius. Since methane concentration in the fluid at a given temperature and 

calculated pressure can not exceed 2 cm 3 /g (Ginsburg, Soloviev, 1998), the amount of dissolved methane 

discharging through the active zone of the CHAOS seep should nor exceed 6·10 3 m 3 /year. It should be noted that 

we did not consider the volume of free gas discharging at the studied structure that implies increase of the total 

amount of discharging gas in several times.

36 


Good opening of oil-and-gas-content of Azov Sea are result of 3D modeling 

E. Lavrenova 1 , B. Senin 1 , M. Kruglyakova 1 , A. Gorbunov 1 

1 Chernomorneftegaz, Gelendzhik, Russia 

3D Modeling of sediment cover and transition complex Azov Sea was performed. Results of modeling describe 

general elements of petroleum system and estimate prospect of oil-and-gas-content. Prospects of oil-and-gascontent 

may be connected with sediment of transition complex (PZ-early MZ). Sediment rocks of Paleozoic are 

sours rock in our case. Sediment rocks of Mesozoic (T-J) are sours rock for MZ trap of Timashevskaya Step 

and north flange of Indolo-Kubanskiy Trough. 

Generation of oil-and-gas in Paleozoic sediment takes place in trough to the south and north of Azov Ridge. 

The beginning of generation applies to Triassic period and gets out of oil-window by the end of the Middle 

Jurassic. Paleozoic petroleum system was realized about half potential on the Azov Ridge and in full potential 

on the Indolo-Kubanskiy Trough and Timashovskaya Step by the end of the Late Jurassic. 

Mesozoic sours rock beginning generation is not yet observed by present day on Azov Ridge and it reached to 

oil-window by maykopian period (P3-N1mk) on Indolo-Kubanskiy Trough. 

Accumulation of oil-and-gas on Paleozoic and Early Mesozoic reservoir sediment began occur at the time of 

Triassic-Jurassic on highlands of Azov Ridge. 

Accumulation of oil-and-gas on Upper Paleozoic and Low Triassic reservoir rock of Indolo-Kubanskiy Trough 

and Timashevskaya Step occur by Early Triassic. The result of thermal creaking are distraction this 

accumulation by Late Jurassic. Accumulations of oil-and-gas were formed on trap of Low Jurassic reservoir 

sediment dated by Cretaceous. 

Large-scale spatial and temporal trends in seep emissions in the Coal Oil Point seep field – Using 

a seep resistance model to understand geologic and environmental control 

I. Leifer 1 , M. Kamerling 2 , B. Luyendyk 3 , D. Wilson 3 , C. Stubbs 3 , T. Lorenson 4 

1 Marine Science Institute, University of California, Santa Barbara, USA 

2 Venoco, Inc. 

3 Department of Earth Sciences, University of California, Santa Barbara, USA 

4 US Geologic Survey, 345 Middlefield Rd., Menlo Park, CA USA 

Sonar surveys of marine seep fields provide an ideal opportunity to map the number of seeps and qualitatively 

map the spatial distribution of seep intensity. These data, when repeated over time can be studied with respect to 

better understanding the controlling environmental parameters of marine hydrocarbon seepage. Repeated surveys 

of the Coal Oil Point (COP) seep field spanning a decade have revealed both large-scale spatial evolutionary 

changes, and persistent seep spatial distributions. Here, hydrocarbons migrate from the Monterey Formation, a 

Miocene-age shale, to the seabed through the Sisquoc Formation, a late Miocene-Pliocene-age siltstone. Oil 

production from some of the Monterey Formation underlying the seep field has affected reservoir pressures and 

as a consequence the spatial distribution of seepage. Thus, this hydrocarbon production can be considered as a 

massive perturbation experiment on natural processes affecting hydrocarbon seep migration. 

Significant changes were noted, specifically, a decrease in the spatial extent of seepage, and a relative increase in 

the importance of intense, focused seeps relative to small, dispersed seeps. Moreover, these changes were on a 

field-wide length scale, and because surveys required 4 days, could not result from tidal time scale or shorter 

variability. Based on evidence of long-term, persistent seepage (more than 500kA), these trends suggest 

significant recharge events on 100-year time-scales. 

Seepage spatial distributions were linked to a 3D seismic data set of the geology underlying the seep field. 

Analysis revealed close spatial correlation and control between anticlines and faults and trends in seepage. For 

example, in several cases, the hanging wall of a fault clearly delineated seepage areas. Data also suggested a 

correlation between areas of intense seepage and the slope of the Monterey-Sisquoc contact. In some cases, 

intersecting faults were identified that were co-located at the seabed with areas of intense seepage. 

The seep spatial-distribution and the temporal changes in the distribution were investigated through an electrical 

network, conceptual model of seepage. Previously, the model has been used to better understand seepage 

changes on meter scale and hourly time scales. Interpretation of the analysis with the model was consistent with 

the observed changes throughout the seep field, including areas affected by decreased reservoir pressure due to 

production.


Fig. 1 Map of sonar return for the Coal Oil Point seep field, Sept 2005. All seep names are informal. Contours 

and color map are logarithmically spaced, normalized sonar return. Inset shows southwest US, with small box 

indicating study area. Data key and length scale on figure. Sonar spatial resolution is 100 m x 100 m for the 

deep seeps, and 50 x 50 m for the Coal Oil Pt Seeps, respectively. North-south low-pass filter applied to sonar 

returns. 

Thiotrophic mats and their association with methane seeps 

- comparison of different cold seep sites 

A. Lichtschlag 1 , J. Felden 1 , F. Wenzhöfer 1 , A. Boetius 1,2 , D. deBeer 1 

1 Max-Planck-Institute for Marine Microbiology, Bremen 

2 Jacobs University Bremen, 28759 Bremen 

A typical feature of cold seeps is a rich benthic community fuelled by methane, sulfide and often higher 

hydrocarbons rising upwards from a deep source. Within zones where sulfate penetrates from the water column 

into the sediment, the methane is consumed by anaerobic methane oxidation (AOM) coupled to sulfate reduction 

(SR). This process is mediated by a consortium of methane oxidizing archea and sulfate reducing bacteria. 

Sulfide as one main product of this reaction can either be precipitated geochemically or it can nourish the highly 

adapted seep community, which often consists of chemosynthetic siboglinid tubeworms, bivalves or thiotrophic 

bacteria. Prominent representatives of the bacteria are for example Beggiatoa, Thioploca or Arcobacter that often 

build up extensive mats using the oxidation of sulfide with oxygen or nitrate as energy source. 

This study aims to provide an overview on differences and similarities of various cold seep structures in terms of 

sulfide production and its consumption by thiotrophic bacteria on a regional as well as on a global scale. We 

compare several seep sites with dense thiotrophic mats i) with each other and ii) with sediments where no mats 

have developed. Selected target areas are seep structures in the Nyegga area of the coast of Norway, the Håkon 

Mosby Mud Volcano (Barents Sea) and the Nile Deep Sea Fan, where numerous seeps have been found. The 

biogeochemistry of these seeps is compared to that of the Dvurechenskii Mud Volcano (Black Sea) where 

permanent anoxia in the water column prohibits the occurrence of thiotrophic bacterial mats. Clear differences 

are detectable between the systems: those with high sulfide fluxes are associated with dense thiotrophic mats and 

extremely high oxygen consumption rates. The thiotrophic mats control sulfide emission, and certain bacteria are 

associated with certain sulfide fluxes: I) Arcobacter is associated with high sulfide fluxes and fluidic sediments, 

II) Beggiatoa mats are found at medium to high sulfide fluxes and III) Thiomargarita are associated with low 

fluxes. In contrast, in oxygen depleted environments like the Black Sea large quantities of sulfide are exported to 

the water column due to the absence of thiotrophic mats.

38 


The authigenic chimney formation in the Gibraltar diapiric Ridge 

(NE Atlantic) 

E. Logvina 1 2 , A. Krylov 1 , T. Matveeva 1 , A. Stadnitskaia 3 , T.C.E. van Weering 3,4 , M. Ivanov 5 and V. Blinova 2 

1 All-Russia Research Institute for Geology and Mineral Resources of the Ocean (VNIIOkeangeologia), 190121, 

1, Angliyskiy ave., St.Petersburg, Russia 

(e-mail: Liza_Logvina@mail.ru) 

2 St.Petersburg State University (SPbSU), Universitetskaya nab. 7/9, St.Petersburg, Russia 

3 Royal NIOZ, Landsdiep 4, 1797 SZ, ’t Horntje, Texel, the Netherlands 

4 Department of Peloclimatology and Geomorphology, Free University of Amsterdam, de Bolelaan 1085, 1081 

HV Amsterdam, the Netherlands 

5 Moscow State University (MSU), 119899, Vorobjevy gory 1, Moscow, Russia 

Dredging on the Gibraltar diapiric Ridge during TTR14 cruise onboard R/V “Professor Logachev” yielded a 

large amount of carbonate chimneys. Two of them conventionally named as “Big” and “Small” were studied 

during this work. The area, where the studied chimneys were sampled, situated on the modern boundary of gas 

hydrate stability zone, thus their formation during the Early Pleistocene (Ivanov et al., 2004) might be related to 

formation of gas hydrates. 

Subsamples for isotopic δ 13 CVPDB, δ 18 OVPDB and XRD analysis were picked out from the chimneys using the 

scheme presented on figure 1. The main goal of the study was to reveal possible sources of carbon and oxygen 

incorporated into the bulk carbonate material. More than 70 subsamples were measured for δ 13 CVPDB and 

δ 18 OVPDB isotopic compositions at the Stable Isotope Laboratory in the Free University of Amsterdam. 

Mineralogical composition of carbonates was studied by powder X-ray diffraction (XRD) analyses on apparatus 

Rigaku Rint 1200. 

Fig. 1 Sketch representing subsamples (1-24) position on the (A) “Big” and (B) “Small” chimneys. The dotted 

curves represent inner canals of the chimneys; numbers I-V indicate cross sections position. 

XRD shows that both studied chimneys as whole consist of dolomite, calcite, quartz and some amount of 

goethite. “Small” chimney characterizes by predominance of dolomite. The highest concentrations of dolomite 

observed in the top of the “Small” chimney (section I-II). Calcite concentration is increased to the canal of the 

chimney (subsample No1). The “Big” chimney consists predominantly of calcite with some admixture of 

dolomite around the canal (subsamples No11&20). The quartz content in the “Small” chimney is higher as 

compared to “Big” one. Goethite was identified in different parts of both studied chimneys. Highest content of 

goethite in the “Big” chimney observed in the periphery part (subsample No15) and in bottom of the “Small’ 

chimney (section IV-V, subsamples No6,1). 

The obtained δ 13 CVPDB values vary from -2.37 to -27.9‰. There is no significant difference in carbon isotopic 

compositions between two studied chimneys. At the same time, negative trend in δ 13 CVPDB distributions from 

canal to periphery of the chimneys is remarkable. The variations in measured carbon isotopic values may be 

explained by different sources of carbon inherited by carbonate: (a) carbon depleted in 13 C deriving after AOM, 

(b) CO2 enriched in 13 C released during methane generation, (c) carbon of ambient sea-water (δ 13 CVPDB ~0‰), 

(d) carbon of the autochthonous organic matter (δ 13 CVPDB ~-27‰). 

The measured values of δ 18 OVPDB vary from +1.63 to +4.8‰ (+3‰ on average). Most of the measured values are 

typical for MDAC (+3…+6‰). The δ 18 OVPDB of the studied chimneys is controlled by combination of the 

following factors: (a) the temperature of formation, (b) the carbonate mineralogy, and (c) δ 18 OVPDB composition


of discharged fluid. Theoretical δ 18 O values for the dolomite were calculated according to the equation from 

Fritz and Smith (1970) for bottom water with δ 18 OSMOW=0‰ and measured T=13 o C (Diaz-del-Rio et al., 2003). 

Our calculations show that the oxygen isotopic composition of the dolomite precipitating in the present-day 

environment is 3.7‰ (PDB), which is in the good agreement with the measured values. The differences between 

the calculated and measured values one can explain by the variations in the temperature and isotopic 

composition of the ambient water. An extremely light value of -3.39‰ (VPDB) measured in the top of the «Big» 

chimney suggests either anomalous high temperature of carbonate formation or light isotopic composition of 

original fluid. 

Thus, the data obtained testify formation of studied chimneys at the water temperature over 13 o C during venting 

of gas (perhaps thermogenic origin). The carbonate precipitation of the chimneys occurred from the canal 

(around gas flux) to the outer side. 

Methane seepage from the Arctic Shelf – Origin from permafrost, gas hydrate, 

or river-borne organic matter? 

T. D. Lorenson 1 

1 U.S. Geological Survey 345 Middlefield Rd. MS-999 Menlo Park CA, 94025 USA 

The Arctic shelf is currently undergoing warming related to Pleistocene and Holocene sea level rise starting 1.6 

M.Y. ago. Recent global warming has dramatically increased the temperature of the Arctic region over the last 

30 years. During the Holocene transgression warmer waters flooded the relatively cold permafrost of the Arctic 

Shelf. The thermal pulse is still propagating down into the submerged permafrost resulting in thawing from both 

above and below. Gas hydrates, if present in and beneath permafrost, may become thermally unstable, resulting 

in methane emission into the water column and atmosphere. 

A recent assessment of the Arctic region identified 1000 - 2000 Pg C of stored carbon that is vulnerable to 

climate change over the next century. It appears that northern high latitude regions are a sink for atmospheric 

carbon dioxide of approximately 0.5 Pg C per year and a source of atmospheric methane of approximately 50 

Tg C per year. Gas hydrates and drowned permafrost were identified as having the greatest potential to release 

methane. 

Several studies conducted cooperation with the USGS during the past 20 years have attempted to find 

geochemical evidence for gas hydrate dissociation on the Beaufort Sea shelf where a variety of overlapping 

geologic scenarios exist: 1) drowned permafrost, 2) known petroleum systems of Prudhoe Bay and the 

Mackenzie River, 3) submerged pingo-like features (PLF’s), 4) pockmark fields, and 5) several river deltas 

entering the Arctic Ocean, the largest of which in the Mackenzie River. The results of these studies show that 

methane source and location in the geosphere are variable. 

On the Alaskan Beaufort Shelf, methane in seawater is elevated in water depths less than about 10 m, This 

methane appears to be can be associated with drowned permafrost, and likely originates from microbial 

degradation of organic matter deposited by rivers. Deeper on the shelf, north of the Prudhoe Bay oil field, some 

exceptionally high bottom water methane concentrations were measured with carbon isotopic signatures very 

similar (~ -46 to -48‰) to gas hydrate sampled from the Mt. Elbert 01 gas hydrate test well drilled in 2007. It is 

clear that this methane is associated with the Prudhoe Bay petroleum system resulting in compelling but not yet 

conclusive evidence that gas hydrate dissociation is occurring on the shelf. 

Gas venting in and around the Mackenzie River delta is associated with offshore PLF’s and pockmarks. PLF’s 

resemble onshore pingos, however their genesis is uncertain. The region is underlain by an active petroleum 

system and drowned permafrost. Methane concentrations are elevated in cores from the PLF’s and remote 

ocean vehicle (ROV) surveys revealed streams of microbial – sourced methane bubbles (-76 to -80‰) 

emanating from at least two PLF’s. These PLF’s are associated with an exceptionally thick area of submerged 

permafrost and are may be produced by upward-migrating, overpressured gas and water. It has been suggested 

that the gas and water originate from decomposing, intra-permafrost gas hydrate, however migration of methane 

from decomposition of deeply buried organic matter water in sequestered in permafrost cannot be ruled out. 

Microbial methane (-72 to -99‰) from the Kugmallit pockmark field, near the mouth of the Mackenzie delta is 

isotopically similar to methane emanating from sampled PLF’s. Methane in deeper gas hydrates of the 

Mackenzie delta is thermogenic (mean value -42.7‰). Inland, gas seeps occur in shallow ponds and streams, 

resulting in steep-sided pockmarks. This methane is thermogenic, has been venting vigorously for at least 45 

years, and is very similar in composition to deeper gas hydrate and thermogenic gas in nearby gas fields.

40 


Environmental constrains on anaerobic methane oxidation and microbial community structure 

in marine sediments: The case of Cadiz mud volcanoes 

L. Maignien 1 , J. Parkes 2 , B. Cragg 2 , N. Boon 1 , and the RV James Cook JC10 shipboard scientific party. 

1 Laboratory of microbial ecology and technology (LabMET), Ghent University, Belgium 

2 Laboratory of Geomicrobiology, School of Earth, Ocean and Planetary Sciences, Cardiff University, UK 

Anoxic oxidation of methane (AOM) in marine sediments is a widespread microbialy mediated reaction, with 

high environmental impact. It locks methane carbon in the sediment while promoting the development of 

thriving chemosynthetic ecosystems on the continental margins. 

The aim of this study is to identify possible environmental controls on the amplitude of this reaction, and on the 

structure of the AOM microbial community. During a recent RV “James Cook” cruise, we therefore targeted 

three mud volcanoes (mv’s) in the Gulf of Cadiz, which differ in term of structure and geochemical 

environments, with the aim to measure methane turnover, its potential controls and associated microbial 

diversity. Sulphate reduction and methane oxidation activities were measured using radio-labelled substrates 

immediately upon sediment recovery, whereas diversity survey was carried by mean of Fluorescence In Situ 

Hybridisation and 16s rDNA libraries. 

Typical Methane and sulphate gradients associated with AOM where present in these sediments except at 

MERCATOR mv, where dissolution of Gypsum (CaSO4) maintained high sulphate concentration along the 

entire core. At MERCATOR, DARWIN, and CARLOS RIBEIROS mv’s, we found maximum methane 

oxidation activity ranging from 6 to 300 nmol/cm 3 /d. The lowest activities were measured at MERCATOR mv, 

where high salts concentration (up to 10 times sweater concentration) may inhibit the AOM reaction. At 

DARWIN mv, discrete AOM near-surface hot-spots sampled with the Remote Operated Vehicle ISIS resulted in 

highest activities and thus revealed the very heterogeneous structure of this mv. Archaeal and bacterial 16s clone 

libraries revealed that AOM communities differed considerably in between these three ecosystems. At DARWIN 

and CARLOS RIBEIRO mv’s, these communities where relatively diverse and dominated by ANME-2, ANME- 

3 and associated Sulfate Reducing Bacteria phylotypes, whereas microbial diversity at MERCATOR was much 

lower and dominated by the ANME-1b phylotype. These results where confirmed by direct observation of 

ANME-2-DSS shell-type clusters and ANME-1 “filaments” respectively. Overall, these results demonstrate the 

influence of several environmental parameters such as sediment geochemistry, seep relocalization following 

carbonate crust development and methane flux on the microbial activity and community structure at these cold 

seep sites. 

Gas hydrates on the Sakhalin slope (the Sea of Okhotsk): Origin, formation control, and gas 

resources 

T. Matveeva 1 , L. Mazurenko 1 , E. Prasolov 1 , M. Kulikova 1 , E. Beketov 1 , J. Poort 2 , H. Shoji 3 , Y. К. Jin 4 , A. 

Obzhirov 5 , E. Logvina 1 , A. Krylov 1 , H. Minami 3 , A. Hachikubo 3 

1 All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (VNIIOkeangeologia), 

St-Petersburg, Russia 

2 Renard Centre of Marine Geology, Gent UniversityBelgium 

3 Korea Polar Research Institute, Yeonsu-gu Incheon, Korea 

4 Kitami Institute of Technology, Kitami, Japan 

5 PV.Ilyichev’s Pacific Oceanographical Institute, Vladivostok, Russia 

The Sakhalin shelf and slope towards the Derugin Basin (the Sea of Okhotsk) form a remarkable active methane 

seep region provided by deep hydrocarbon source layers through active fault systems. An area of focused fluid 

venting off NE Sakhalin, was investigated in 2003-2006 during expeditions within the framework of the CHAOS 

(Hydro-Carbon Hydrate Accumulations in the Okhotsk Sea) (Shoji et al., 2005, Matveeva et al., 2005; 

Mazurenko et al., 2005; Jin et al., 2005, 2006) and later in 2007 in the frame of the SSGH (Shoji et al., 2008) 

International Projects. Numerous structures related to seafloor gas venting were discovered and gas hydrates 

were sampled from ten of them. As a result a large hydrochemical (major element geochemistry and oxygen and 

hydrogen isotope determinations of over 500 samples) and geophysical (acoustic profiling with various 

frequencies) dataset was obtained and supplemented with geothermal investigations. 

With this extensive dataset, we were able to draw a picture of the gas hydrate occurrence over the area and at the 

separate gas hydrate accumulations (GHA). The following key parameters were considered: mechanisms of gas 

hydrate formation; hydrate-forming fluids (water and gas) and their compositions and origin; distribution of 

GHAs and their structural control; dynamics of the discharging fluids in respect to gas hydrate formation; the 

thickness of GHSZ over the area and at separate GHAs; the quantity of methane captured by gas hydrates in 

separate GHAs and within the area as a whole.


Geochemical analysis of the interstitial fluids was used to define the mechanisms of GHA and spatial 

distribution pattern of gas hydrates in the seeps sediment. The principal significance of the mechanisms is the 

existence of the gas diffusion halo which also associated with the infiltration of gas saturated water through the 

gas hydrate stability zone. Segregated and precipitated gas hydrates occur in vicinity of upward free gas flows, at 

the contact zones of dissolved gas flows, and in the intervals with different sediments permeability and gradients 

of pore water salinity. 

Combination of chemical and isotopic analyses of the interstitial and hydrate waters allowed to conclude that in 

different GHAs hydrates were formed either in-situ pore water or from seawater and an ascending fluid enriched 

in salts. The gas hydrate-forming water consists of about 70% pore water derived from the host sediment and 

30% from the ascending fluid. The overall isotopic composition of the ‘fluid’ taking part in hydrate formation 

was calculated as δ 2 H ~ -11‰ and δ 18 O ~ -1.5‰. 

A model of the ascending fluid discharge along the seeps was made based on the measured chlorinity (salinity 

function) of the pore waters and calculated chlorinity gradients (Fig.1). The chloride ion distribution profiles 

with depth represents alike increasing and decreasing trends both in hydrate-bearing and hydrate-free cores. The 

model testifies an upward water infiltration of more saline water and/or relatively desalinated water along free 

gas flux. Revealed dynamic of the fluid discharge together with thermal field obviously control the gas hydrate 

formation. 

Consideration of geophysical, geothermal data, and coring results suggests that studied GHAs controlled by 

morphological features of Sakhalin slope (venting sites location at canyons, junctions of faults, close to shelf), by 

the presence superficial faulting or land slides from slope instabilities, and structurally deeper faulting. The 

bottom of GHSZ depends from the geothermal gradient whereas the top is function of gas flux intensity. 

Based on our calculations, the total methane content in the proved and potential GHAs occurring off NE 

Sakhalin ranges from 3·10 10 to 10 11 m 3 . The comprehensive study allows us to conclude that the area of gas 

venting -related GHA is large gas hydrate-bearing province. 

Fig. 1. Map of chlorinity (Gcl) gradient (mM/cm) distribution within the southern part of the CHAOS structure. 

The structure boundary is shown by a dotted line. The cores that recovered gas hydrates are represented by 

circles, hydrate-free cores are represented by squares. The gas-hydrate-bearing cores are focused at locations of 

intensive ascending flows of water enriched/depleted with salts. In conditions if a gradient of water salinity exist 

under conditions of hydrate stability, diffusion of methane induces hydrate formation by segregation on the 

outside a boundary fresher/saline water.

42 


Methane budget of the down-current plume from Coal Oil Point seep field, Santa Barbara 

Channel, California. 

S. Mau 1 , M. Heintz 1 , D. L. Valentine 1 

1 University of California, Santa Barbara 

Previous research indicates that 5.5-9.6 x 10 6 mol/d (90-150 t/d) of methane are emitted from the seafloor into 

the coastal ocean near Coal Oil Point (COP), Santa Barbara Channel (SBC), California. Methane concentrations 

and biologically-mediated oxidation rates were quantified at 12 stations in a 198 km 2 area down-current from 

COP during the SEEPS’07-Cruise with the R/V Atlantis. A ship-board Acoustic Doppler Current Profiler 

(ADCP) recorded current velocity patterns simultaneously with water sampling. The observed methane 

distribution matches the cyclonic gyre which is the normal current flow in this part of the Santa Barbara Channel 

- pushing water to the shore near the seep field and then broadening the plume while the water turns offshore 

further from the source. A methane budget was calculated using a box model, with budget terms including 

methane burden, sea-air flux, oxidative loss, and flux in and out of the 51 km 3 box. The results indicate a 0.3% 

loss via sea-air exchange and a 0.8% loss due to microbial oxidation. The majority of the methane is advected in 

and out of the box. This data enables a calculation of the amount of dissolved methane emitted from the COP 

seep field, and when combined with published measurements of bubble flux, allows for a revision of the total 

methane flux from the COP seeps. Revised estimates for the dissolved methane flux for COP are 9.6 x 10 6 

mol/d, raising the total COP methane release to 11.5-15.6 x 10 6 mol/d (180-250 t/d). These results represent a 

snapshot, but serve as a base for the first complete dissolved methane budget of the water column above a seep 

site in the marine realm. 

Multidisciplinary approach to the study and environmental implications of two large pockmarks 

on the Malin Shelf, Ireland 

X. Monteys 1 , X. Garcia 2 , M. Szpak 3 , S. Garcia-Gil 4 , B. Kelleher 3 , E. O’Keeffe 5 

1 Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4, Ireland 

2 Dublin Institute for Advanced Studies,5 Merrion Sq., Dublin 2, Ireland 

3 School of Chemical Sciences, Dublin City University, Dublin 9, Ireland 

4 Dpto. Geociencias Marinas, Facultad de Ciencias, University of Vigo, 36310-Vigo, Spain 

5 Martin Ryan Institute, National University of Ireland, Galway, Ireland 

Shallow geophysical datasets and ground truthing have been used in this research to characterise in detail two 

large gas related depressions in a recently discovered pockmark field on the Malin Shelf, northwest Ireland. 

Pockmarks are aligned to the main fault of the region, the SW-NE Skerryvore Fault. High resolution multibeam 

echosounder (MBES) bathymetry reveals the surface morphology of these seabed features to the meter scale. 

They appear as subcircular depressions and are composite (presenting several units) within a generally smooth 

seabed (Fig. 1). Pockmark A is c. 650 m in diameter and 6 m deep, and presents two subunits (c. 100 m in 

diameter); Pockmark B, is c. 750 m in diameter, 8 m deep, and has three subunits (c.120m in diameter). Shallow 

seismic and single-beam echosounder (SBES) records reveal evidence of gas related activity within the 

subsurface strata; such as masking, gas accumulation, disturbed sediments and enhanced reflectors; in 

association with these pockmarks. Pockmark B is observed to be near an igneous intrusion dyke (c. 20 m below 

seabed), it has a higher gas accumulation facies suggesting that the dyke, and associated steeper dipping 

reflectors, influenced the gas migrating upwards to the seabed. Based on the marine electromagnetic data, there 

is a good correlation between pockmarks and low electrical conductivities. There seems to be an increase in the 

electrical conductivity on the edges of the pockmarks and a drop below regional levels within. This could be 

caused by the presence of gas or by changes in physical properties of the sediment arising from sediment 

structure collapse due to escaping gas which in turn caused a redistribution of sediments, resulting in a more 

heterogeneous physical environment. Records of SBES (12 kHz) confirm the disturbance of the subsurface 

structure underneath the pockmark (Fig. 2). MBES backscatter (95 kHz) levels are homogenous within and 

around the pockmarks, suggesting a similar sediment cover. This is confirmed by the analysis carried out on a 

number of sediment cores taken around the pockmarks that show two distinctive lithological units. The top unit 

(0.5 -1m in thickness), is primarily composed of fine sand, which is underlained by at least 2.5 m of cohesive 

muddy sediments. Radiocarbon dating from core BS-21, indicate that the entire sediment record (2.6 m) is 

Holocene (between 2.9 – 5 ky BP). Recent planktonic foraminifera assemblages suggest temperate waters The 

seafloor captured on video showed a large number of burrowing systems belonging to Nephrops norvegicus. 

Numerous occurrences of hermit crab, sea pens and anemones were also recorded. No carbonate crusts or gas 

plumes were observed on the video footage.

100 


Fig. 1: Multibeam bathymetry shaded relief images around pockmarks features with associate depth profiles. 

Dots represent sample locations. Dotted lines symbolize navigation track lines. 

a 

b 

c 

1 

2 

1 2 

1 

100 m 

1 2 

Fig. 2: a) Multibeam bathymetry shaded relief image around pockmark B (plan view). b) Shallow seismic 

profile (3.5 kHz) imaging the gas accumulation front and the igneous intrusion. c) SBES profile showing thinlayered 

strata and acoustic scattering beneath the pockmark (12 kHz). 

Methane-derived carbonate concretions as proxies of an 

ancient gas hydrate stability zone: 

Evidences from Upper Miocene sediments of the Tertiary Piedmont Basin (NW Italy) 

M. Natalicchio 1 , F. Dela Pierre 1,2 , L. Martire 1 , C. Petrea 1, P. Clari 1 and S. Cavagna 1 

1 Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, 10125 - Torino 

2 C.N.R., Istituto di Geoscienze e Georisorse, Sezione di Torino, Via Valperga Caluso 35, 10125 - Torino 

In present day settings gas hydrates are commonly observed both cropping out at the sea floor or buried below it. 

They are frequently associated to authigenic carbonates characterized by negative δ 13 C and positive δ 18 O values. 

On the contrary the past occurrence of gas hydrates in ancient sedimentary successions has been only rarely 

hypothesized on the basis of distinctive isotopic values of peculiar carbonate concretions, supposedly related to 

gas hydrate formation and dissociation. 

Several carbonate concretions, embedded in lower Messinian slope deposits (Sant’Agata Fossili Marls = SAF) 

have been recently recognized in the Tertiary Piedmont Basin (NW Italy). All of them show negative δ 13 C values 

B 

20 m 

500 m 

2

44 


(-15,11 to -59,64 ‰ PDB) and positive δ 18 O ones (from +1,56 to +8,11 ‰ PDB) suggesting that carbonate 

precipitation was induced by bacterial degradation of methane sourced by gas hydrate destabilisation. 

Two major groups of concretions have been recognized: 1) Lucina-bearing concretions consisting of a lensshaped 

body (chemoherm) of cemented mud breccias, rich in chemosymbiotic macrofauna (Lucina bivalves and 

tube worms). The chemoherm is enclosed in the lower part of SAF and represents the sea floor products of an 

ancient venting site; 2) Lucina-free concretions, in which the lack of chemosymbiotic fossil remains and of 

traces of exposure at the sea floor suggest that their formation occurred below the sea floor, within the 

sedimentary column. Within this group, that occurs in the upper part of SAF, two subtypes can be distinguished 

on the basis of their shape: a) stratiform concretions, 20 to 60 cm thick and up to 20 m wide. Some of them are 

characterized by an intricate network of septarian-like fractures and veins, filled both with different generation of 

fine–grained sediments and with complex polyphase carbonate cements. Others appear brecciated and contain 

mm to cm - sized angular clasts separated by polyphase carbonate cements. Unusual petrographic features (e.g. 

collapse breccias, pinch out of cements in open cavities) indicate that these rocks record formation and 

successive destabilization of gas hydrates in the sub-seafloor. In particular, the brecciated concretions resemble 

the collapse breccias that, in present day settings, are frequently reported in gas hydrates stability zone. 

b) Cylindrical concretions, showing a visible maximum height of 120 cm and a diameter of about 50 cm. These 

concretions crop out at different levels of SAF, both above of the stratiform ones and below the chemoherm. 

They corresponds to ancient fluid conduits originated by the localized cementation of sediments by focused 

methane rich-fluids, sourced by gas hydrate destabilisation and ascending toward the seafloor. A network of 

mesoscopic fractures and faults sub-perpendicular to bedding controlled their distribution. 

The relative timing of all the concretions found shows that, in the Early Messinian, at least two phase of 

methane-rich fluid expulsion occurred. During the first one, methane-rich fluids sourced by gas hydrate 

destabilisation reached the sea floor, forming the chemoherm embedded in the lower part of SAF. The ascending 

fluid pathways in the subsurface is marked by the cylindrical concretions located below the chemoherm. The 

second phase is showed by stratiform and cylindrical concretions enclosed in the upper part of the SAF. 

In conclusion, type 1 concretions document sea floor seeping, whereas type 2, consisting of subsurface products, 

provide a reliable evidence of the past formation of gas hydrates in the sedimentary column, of their 

destabilisation and of the migration of the resulting hydrocarbon-rich fluids toward the seafloor. 

Submeter mapping of methane seeps by ROV observations and measurements at the Hikurangi 

Margin, New Zeeland 

L. Naudts 1 , J. Greinert 1 , J. Poort 1 , J. Belza 1 , E. Vangampelaere 1 , D. Boone 1 , P. Linke 2 , 

J.-P. Henriet 1 , M. De Batist 1 

1 Renard Centre of Marine Geology (RCMG), Universiteit Gent, Krijgslaan 281 s8, B-9000 Gent, Belgium 

2 Leibniz-Institut für Meereswissenschaften, Wischhofstrasse 1-3, 24148 Kiel, Germany 

During R.V. Sonne cruise SO191-3, part of the “New (Zealand Cold) Vents” expedition, RCMG deployed the 

CHEROKEE ROV “Genesis” at the Hikurangi Margin . This accretionary margin, on the east coast of New 

Zealand’s North Island, is related to the subduction of the Pacific Plate under the Australian Plate. Several cold 

vent locations as well as an extensive BSR, indicating the presence of gas hydrates, were found at this margin 

(Lewis & Marshall, 1996; Henrys et al., 2003; Faure et al., 2006). The aims of the ROV-work were to precisely 

localize active methane vents, to conduct detailed visual observations of the vent structures and activity, and to 

perform measurements of physical properties and collect samples at and around the vent locations. 

The data obtained during the seven ROV dives has been integrated with data from other TV-guided equipment 

deployed or towed over the covered areas. Two areas were investigated (Faure Site & LM-3 site); both generally 

have a flat to moderately undulating sea floor with soft sediments alternating with platform-like areas consisting 

of carbonates (Fig. 1). Active bubble-releasing seeps were observed at the Faure and LM-3 areas. These were the 

first ever visual observations of bubbling seeps at the Hikurangi Margin. At Faure Site six different seep clusters 

were discovered within a 2500 m 2 active area during three separate dives. Bubble-releasing activity was very 

variable in time, with periods of almost non-activity alternating with periods of violent outbursts (Fig. 2). Over a 

period of 20 minutes 6 outbursts were observed with each a duration of 1 minute and with an interval 3 minutes 

between the outbursts. These violent outbursts were accompanied by the displacement and resuspension of 

sediment grains and the formation of small depressions showing what is possibly an initial stage of pockmark 

formation. Bottom-water sampling at the seep sites revealed methane concentrations of up to five volume 

percentage of the extracted total gas volume and methane with microbial signature (δ 13 C=66.6‰VPDB). At the 

LM-3 site only one very small, single bubbling seep was observed during one of the two dives at this site. At 

both sites, bubble release occurred mainly from prominent depressions in soft-sediment sea floor away from the 

carbonate platforms. Comparable depressions, but without bubble release, were observed throughout both areas. 

The presence of the carbonate platforms together with the depressions indicates that seepage is probably much


more common on longer time scales than we have observed. Both sites are covered with dense fields of shell 

debris and with local sponges and/or soft tissue corals in association with carbonate platforms. Only at the LM-3 

site, which consists of a large carbonate platform, live clams occur, often in association with tube worms (Fig. 

1). Sediment-temperature measurements, in both areas, were largely comparable with the bottom-water 

temperature except for one LM-3 site that was densely populated by polychaetes, where anomalous low 

sediment-temperature was measured (Fig. 1). 

Fig. 1: Screenshots taken from the ROV footage; clams and tubeworms at the carbonate platforms of the LM-3 

site, sediment-temperature measurement at a ‘raindrop site’ (LM-3) and bubble release at a ‘raindrop site’ (Faure 

Site). 

Fig. 2: Screenshots taken from the ROV footage, showing the temporal variability of bubble release at the Faure 

Site. 

The analysis of the ROV data together with the integration of other datasets leads to a complete characterization 

of the seep structure and environment which shows the real extent of the present active seep areas. Overall it is 

clear that the present seeps areas are very confined in space and that the active seep sites have shifted in location 

over time. 

References: 

Faure, K., Greinert, J., Pecher, I.A., Graham, I.J., Massoth, G.J., De Ronde, C.E.J., Wright, I.C., Baker, E.T. and 

Olson, E.J., 2006. Methane seepage and its relation to slumping and gas hydrate at the Hikurangi 

margin, New Zealand. N. Z. J. Geol. Geophys., 49, 503-516. 

Henrys, S.A., Ellis, S. and Uruski, C., 2003. Conductive heat flow variations from bottom-simulating reflectors 

on the Hikurangi margin, New Zealand. Geophys. Res. Lett., 30, 1065–1068. 

Lewis, K.B. & Marshall, B.A., 1996. Seep faunas and other indicators of methane-rich dewatering on New 

Zealand convergent margins. N. Z. J. Geol. Geophys., 39, 181-200.

46 


Underwater acoustics in marine seeps research 

A. Nikolovska 1 , H. Sahling 1 and G. Bohrmann 1 

1 MARUM – Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, 

Leobener Str., 28359 Bremen, Germany 

Detailed acoustic investigation of bubble streams rising from the seafloor were conducted during R/V Meteor 

Cruise-M72/3a at a deep submarine hydrocarbon seep environment. The area is located offshore Georgia 

(Eastern part of the Black Sea) at a water depth between 840 m and 870 m. The sediment echosounder 

PARASOUND DS-3/P70 was used for detecting bubbles in the water column that causes strong backscatter in 

the echographs (“flares”). Employing the swath echsounder KONGSBERG EM710 flares in the water column 

were mapped along the entire swath width of approximately 1000 m at high spatial resolution. The exact location 

of the flares could be extracted manually despite the rudimentary possibilities of acquiring and analysing the 

water column data of the system. Subsequently, the horizontally looking sonar KONGSBERG Digital Telemetry 

MS1000 mounted on a remotely operated vehicle (ROV) was utilized to quantify the flux of bubbles. A model 

was developed that is based on the principle of finding the ‘acoustic mass’ in order to calculate the volume flux 

from the backscatter data. 

The acoustic approach resulted in bubble fluxes in the range of approximately 0.01 to 5.4 L/min at in situ 

conditions. Independent flux estimations using a funnel-shaped device showed that the acoustic model 

consistently produced lower values but that this bias is low with differences of less than 12 %. Furthermore, the 

deviation decreased with increasing flux rates. A field of bubble streams was scanned three times from different 

directions in order to reveal the reproducibility of the method. Flux estimations yielded consistent fluxes of about 

2 L/min with variations of less than 10 %. 

Although gas emissions have been found at many sites at the seafloor in a range of geological settings, the 

amount of escaping gas is still largely unknown. With this study presenting a novel method of quantifying 

bubble fluxes employing a horizontally-looking sonar system it is intended to contribute to the global effort of 

better constraining bubble fluxes at deep-sea settings. 

The origin of hydrocarbons and fluids at North Alex and Giza mud volcanoes, West Nile Delta 

(Egyptian margin) 

M. Nuzzo 1 , F. Scholz 1 , A. Reitz 1 , C. Hensen 1 , M. Elvert 2 , K.-U. Hinrichs 2 , V. Liebetrau 1 and the RV-Poseidon 

P362/2 Scientific Party 

1 IFM-GEOMAR, Institute for Marine Sciences, Kiel, Germany 

2 MARUM, Organic Geochemistry Group, University of Bremen, Bremen, Germany 

Interstitial fluids, hydrocarbon gases and sediment samples were collected along transects across Giza and North 

Alex mud volcanoes (MVs) in the western Nile Delta in the ambit of the West Nile Delta (WND)-Project (RWE- 

DEA/IFM-GEOMAR) in February 2007. Giza and North Alex MVs are located at a water depth of about 700 

and 500 m, and have a diameter of about 2500 and 1500 m, respectively, and show evidence for recent mud 

flows and fluid/gas advection. Here we combine the analysis of molecular and isotopic geochemistry of 

hydrocarbon gases, geochemistry of sedimentary lipids, and inorganic geochemistry of pore fluids to investigate 

their origins. 

In the Nile Deep Sea Fan (NDSF), intense seepage activity is related to salt tectonics, the presence of wide 

wrench faults and high sediment instability across the delta. Data from drill holes revealed that thermogenic 

gases and petroleum pooling in Mio-Pliocene reservoirs have migrated from deeper source rocks underlying 

Mesozoic strata (Vandré et al.; 2007). 

Extruded sediments at Giza and North Alex MVs are saturated in thermogenic hydrocarbon gases and enriched 

in petroleum. However, the thermal maturity and extent of biodegradation of the petroleum is highly variable, 

with the occurrence of mature and non-degraded oil at Giza MV and of overmature and/or highly biodegraded 

oil at North Alex MV (Fig. 1). This suggests that at Giza MV, petroleum adsorbed on the sediments may 

originate from Mio-Pliocene reservoirs, whereas at North Alex MV it may have a deeper origin. The origins of 

sedimentary organic matter are highly variable, with a predominance of terrestrial sources at Giza MV and of 

marine and mixed sources at North Alex MV. The fluids venting at the geographical centre of both MVs are 

highly depleted in chloride (up to 140 mM; normal bottom water (BW): ~600 mM) and highly enriched in boron 

(up to 2.7 mM; BW: 0.4 mM), typical for fluids advecting from deep strata and consistent with a thermogenic 

origin of the gases. This is also in agreement with elevated ammonium concentrations in these fluids, 

presumably released during the thermal degradation of organic matter at depth. In order to substantiate our 

knowledge on the origin/age of the fluids, 87 Sr/ 86 Sr ratios will be determined to approximate the age/origin of the 

source strata. Overall, the comparative analysis of the geochemistry of the fluids, gases and sediments across


Giza and North Alex MVs yields insights into multiple origins and transport mechanisms of the products 

expelled at these cold seeps. 

Fig. 1: Total Ion Current chromatograms showing the distribution in apolar lipid compounds extracted from 

sediments of North Alex (GC36 and GC46) and Giza (GC34) mud volcanoes. 

Reference 

Vandré C., Cramer B., Gerling P., and Winsemann J. (2007) Natural gas formation in the western Nile delta 

(eastern Mediterranean): thermogenic versus microbial. Organic Geochemistry 38, 523-539. 

Mapping and sampling seafloor seeps to prove hydrocarbon prospectivity in Indonesia’s 

Frontier Basins 

D. L. Orange 1 , P. A. Teas 1 , J. Decke 1 , P. Baillie 2 , Widodo 1 , A. Hamdani 1 , Widjanarko 3 , B. B. Bernard 4 , J. M. 

Brooks 4 , M. Levey 5 , AOA Geophysics Shipboard Reps 5 

1 Black Gold Energy LLC, Jakarta, Indonesia 

2 TGS-NOPEC Geophysical Company, Perth Australia 

3 MIGAS, Jakarta, Indonesia 

4 TDI-Brooks International Inc., College Station, Texas, USA 

5 AOA Geophysics Inc., Moss Landing, California, USA 

Seafloor seeps can provide direct information about a basin’s petroleum system, and, in particular, charge, 

source, and maturity. The goal of a seep-based exploration program is to rapidly and efficiently delineate and 

high grade prospects and prospective areas in previously under-explored basins. This exploration approach 

(which we refer to as SeaSeep TM ) combines large volumes of high resolution multibeam bathymetry and 

backscatter, sea bottom coring, gravity, magnetics, 2D seismic and hydrocarbon geochemistry information in one 

data suite to explore a basin via traditional detection of oil and gas seeps juxtaposed with robust structures. 

The primary tool we used to identify sites of potential seafloor seepage was multibeam sonar (bathymetry and 

backscatter). Anomalous bathymetric features of interest included mounds, mud volcanoes, pockmarks, and fault

48 


zones. Anomalous high backscatter targets were present on some bathymetric anomalies, but also occurred in 

areas with no anomalous relief. 

The multibeam survey covered 400,000 square kilometers in water depths ranging from 200m to 3500m. 

Bathymetric grids (25m bin) and backscatter mosaics (5m pixel) were integrated with all of the other data sets in 

order to come up with a suite of potential targets. A final suite of targets was selected for each basin that would 

sample a wide range of target types, interrogate targets of interest for petroleum exploration (leads), evaluate 

multiple sub-basins, and provide areal distribution even if some parts of the survey area showed fewer or less 

charismatic seep targets. 1300 targets were sampled using 6m (and rarely 3 or 9m) piston cores. By accurately 

tracking the position of the piston cores in 3D in real time using Ultra-Short Baseline navigation (USBL), we 

were able to place the core barrel within meters of the intended target and precisely sample the seafloor feature 

of interest. The cores were then subsampled for detailed geochemical analysis. In some of the survey areas, 

piston cores on high backscatter features yielded no recovery, or at best, fragments of authigenic carbonate or 

outcrop; in other survey areas, piston cores on high backscatter targets yielded near-complete recovery and 

excellent geochemistry. As such, we could not predict with whether the first high backscatter core target in basin 

would be conducive to recovery. We did find, however, that in any given basin similar features behaved a similar 

fashion. 

Survey operations began in early December, 2006, and were completed by early April, 2008, with the last 

geochemical results received by late April. 11% of the cores contain evidence of migrated liquid petroleum, and 

46% of the cores contain thermogenic gas. Over 400 isotope pairs, and 20 biomarker (molecular fingerprinting) 

suites provide insight into the maturity and source of multiple gas and oil petroleum systems. Live 

chemosynthetic communities were sampled with the piston core in numerous locations; at several of these sites 

we re-deployed a box core, using USBL navigation, to sample within meters of the piston core in order to obtain 

large quantities of chemosynthetic fauna for later study. 

The large number of geochemical hits, both oil and gas, in a project on the scale of this survey is unprecedented. 

We attribute the high success rate to a combination of factors: (1) the presence of thermogenic oil and gas 

charge, (2) the quality of the high resolution survey program used to identify potential seep targets, and (3) the 

quality of the navigation that allowed precise sampling of the targets by the piston core. The distribution of the 

oil and gas ‘hits’, and their composition information, are being tied back to the exploration data volume in order 

to identify areas where we will go forward with additional exploration activity. 

Shallow gas hydrates in an Eastern Black Sea high intensity gas seepage area – quantification by 

autoclave technology 

T. Pape 1 , A. Bahr 1,2 , F. Abegg 1,2 , H.-J. Hohnberg 1 , S.A. Klapp 1 , and G. Bohrmann 1 

1 MARUM – Center for Marine Environmental Sciences, University of Bremen 

2 IFM-GEOMAR, The Leibniz Institute of Marine Sciences, Kiel 

(tpape@uni-bremen.de / phone +494212183918) 

During R/V METEOR cruise M72/3 in 2007, in situ inventories of low-molecular-weight hydrocarbons 

(LMWHC) were determined in shallow sediments of one of the largest seep sites in the southeastern Black Sea 

(Klaucke et al., 2006). The Batumi seep area is located offshore Georgia, in about 835 m water depth close to the 

upper boundary of the nominal gas hydrate stability field. It is characterized by sea bottom features typical for 

intense hydrocarbon seepage (e.g., rough topography, authigenic carbonates forming pavements and slabs, 

pockmark-like structures). 

Controlled on-board degassing of pressurized sediment cores allowed for accurate quantifications of gas and gas 

hydrates present in the shallow subsurface. Using our Dynamic Autoclave Piston Corer (DAPC), seven 

pressurized cores of up to 264 cm core length were recovered from a seafloor area of about 0.2 km 2 . The mean 

gas composition of sub-samples taken during core degassing was strongly dominated by methane (up to 99.97 

mol % of ΣC1-C4 LMWHC, CO2) followed by ethane, carbon dioxide and trace amounts of C3 and C4 LMWHC. 

Molecular ratios of LMWHC (C1/[C2+C3] > 1,000) and mean stable isotopic compositions of methane (δ 13 C = – 

53.5‰ VPDB; D/H = –175‰ SMOW) suggest a gas mixture of biogenic and thermogenic origin. Total methane 

concentrations in five pressurized cores strongly exceeded theoretical equilibrium concentrations of dissolved 

methane with the hydrate phase of about 93 mM (after Tishchenko et al., 2005), demonstrating the presence of 

substantial amounts of shallow-buried gas hydrates. 

Pressurized and non-pressurized cores generally contained sediments belonging to the Black Sea stratigraphic 

Units 1, 2, and 3. A positive correlation between the thickness of the stratigraphic Unit 3 in pressurized cores and 

gas amounts released during degassing suggests preferential precipitation of gas hydrates below Unit 2. This 

interpretation is corroborated by computerized X-ray tomographic imaging and visual observations of 

conventional gravity cores. Gas hydrates were found to precipitate as distinct, massive layers at the base of Unit


2 and as widespread, disseminated chunks in Unit 3. The presence of hydrate structure I was deduced from the 

LMWHC composition and confirmed by X-ray diffraction techniques. 

Comparative calculations including all pressurized cores were performed to assign nominal Unit-specific 

concentrations of dissolved methane. The results confirm that highest nominal methane concentrations occur in 

Unit 3 deposits. Respective in situ concentrations of dissolved methane in Unit 3 deposits ranged between about 

770 and 2,400 mM. To the best of our knowledge, this is the first high-resolution investigation of in situ amounts 

of gas and gas hydrates in a high-intensity seepage area. The results obtained allow for an estimation of the total 

amount of gas hydrates and methane-bound carbon in shallow deposits of the entire Batumi seep area. 

References 

Klaucke I., Sahling H., Weinrebe W., Blinova V., Bürk D., Lursmanashvili N., Bohrmann G., (2006) Acoustic 

investigation of cold seeps offshore Georgia, eastern Black Sea. Marine Geology, 231, 51-67. 

Tishchenko P., Hensen C., Wallmann K., Wong C.S. (2005) Calculation of the stability and solubility of 

methane hydrate in seawater. Chemical Geology, 219, 37-52. 

Direct petrographic evidence of the past occurrence of gas hydrates in Oligo-Miocene sediments 

of the Tertiary Piedmont Basin (NW Italy). 

C. Petrea 1 , L. Martire 1 , M. Natalicchio 1 , P. F. Dela Pierre 1 , S. Cavagna 1 , P. Clari 1 

1 Dipartimento di Scienze della Terra, Torino University, Italy 

The Tertiary Piedmont Basin (TPB) and in particular the Monferrato region are among the first areas in the 

world where CH4-derived authigenic carbonates have been described. Methane-derived rocks occur at different 

stratigraphic levels in a succession consisting mainly of clastic sediments and spanning in age the Oligocene and 

Miocene. They include both classical chemoherms, characterized by richness of chemosymbiotic mollusc 

remains, and other products of methane oxidation, devoid of seep fossils, that are interpreted to result from 

carbonate precipitation in the pores of buried sediments at some metres or tens of metres below the sea floor. All 

the investigated carbonates share very depleted δ 13 C values (down to -52 ‰ PDB) and some samples also show 

positive δ 18 O values (up to + 8 ‰ PDB). Such positive O values suggest that dissociation of clathrates could be 

the source of methane-rich fluid flow to the surface as observed on many present day continental margins. 

A detailed study of the TPB CH4-derived rocks, conducted with a multidisciplinary approach (petrography, 

cathodoluminescence, UV epifluorescence, SEM-EDS, isotope geochemistry, fluid inclusion analysis, Raman 

microspectrometry) allowed to identify unusual diagenetic features that point to the possible past occurrence of 

gas hydrates. Different kinds of features may be distinguished in several samples coming from different 

localities: (1) antigravitational structures: cm-sized cavities are filled with concentrically arranged laminated 

microcrystalline carbonates separated or even floating in limpid calcite spar. Microcrystalline carbonates mainly 

consist of dolomite and display spherulitic and peloidal fabric referable to microbial activity. (2) irregular 

distribution of sparry and fibrous calcite cements within cm-sized cavities corresponding to syneresis cracks or 

gas conduits. Cathodoluminescence evidences that cements do not make isopachous rims but pinch out on cavity 

walls giving rise to very asymmetric authigenic fillings. (3) complex, irregular, crusts of mm thickness occurring 

at fissure walls: they consist of very thin stromatolitic-like microcrystalline microbial laminae with a very large 

open framework now centripetally filled with dolomite spar. (4) geopetal fills of secondary pores: sharp-edged 

mm-sized cavities within muddy sand dykes are geopetally filled with mud and authigenic pyrite on the bottom 

and by sparry dolomite. 

The genesis of the first three puzzling fabrics can be explained with the former presence of a solid compound 

prone to a progressive volume reduction that gave rise to increasingly larger new open spaces. Gas hydrates, that 

may form at the sea floor or within buried sediments and short after dissociate depending on P and T changes, 

are the best candidates for explaining these features. The new open spaces could occur either at the boundary 

between gas hydrate and cavity walls or within the gas hydrate mass itself and were filled with authigenic 

carbonates whose precipitation was induced by microbial oxidation of methane. Geopetal structures (4), instead, 

were generated by dissociation of small clasts of gas hydrates: sediment particles contained within the gas 

hydrate clast fell on the bottom of the resultant pore that was plugged by dolomite cement concomitantly with 

pyrite authigenesis. 

The described features may be considered a new type of diagenetic structures, that can be defined “melt and 

seal”, and provide a direct documentation of the presence and dissociation of gas hydrates in ancient sedimentary 

successions. Given the small size of these structures, their recognition requires a detailed petrographic analyses 

but the effort is rewarding because it greatly helps in reconstructing hydrocarbon and fluid migration in fossil 

systems.

50 


Authigenic carbonate crusts from active cold seep sites in the Eastern Mediterranean: New 

results from MEDECO cruise (HERMES Project) 

C. Pierre 1 , G. Bayon 2 , M.-M. Blanc-Valleron 3 , J.-M. Rouchy 3 , J. Mascle 4 , S. Dupré 1 , 

I. Bouloubassi 1 , J. Sarrazin 2 , J.-P. Foucher 2 and the Medeco scientific team 

1 UPMC, LOCEAN, Paris, France, 2 Ifremer, Brest, France, 3 Muséum National d’Histoire Naturelle, Paris, France, 

4 Géosciences Azur, Villefranche sur Mer, France. 

Active cold seeps associated to mud volcanoes and pockmarks are widely distributed in the Eastern 

Mediterranean.Sea. In situ studies on these geological structures initiated ten years ago in the frame of the 

french-dutch MEDINAUT survey and of the ESF-MEDIFLUX program during which two oceanographic 

cruises (NAUTINIL and BIONIL) were realized. These operations have demonstrated the importance to use a 

submersible to obtain in situ observations, sampling and measurements at precise locations of fluid seepage. 

During fall 2007, MEDECO cruise, onboard the « R.V. Pourquoi Pas ? », has allowed to investigate, during two 

months, deep Mediterranean ecosystems using the ROV-Victor. A large part of the time was devoted to study 

several active cold seeps already known on the Mediterranean Ridge, Anaximander Mountains and the Nile deep 

sea fan. 

At cold seep sites, special attention was given to sample authigenic carbonate crusts covering the sea floor either 

as massive and indurated large pavements, or as thin and highly porous laminated crusts. These carbonate crusts 

represent hard substrates where abundant fauna are living either fixed or sheltered within cavities. 

The carbonate mineralogy indicates low-Mg calcite that originates from the pelagic sediment, whereas the 

authigenic carbonate cement is composed of Mg-calcite, aragonite and dolomite. No obvious difference was 

observed in carbonate composition of the crusts from the different sites, with the exception of the absence of 

dolomite in the crusts from Cheops mud volcano located in the western Nile deep sea fan. 

The oxygen and carbon isotopic compositions of the carbonate crusts vary within wide ranges : 2.47< δ 18 O ‰V- 

PDB


Microbial activity in the south-eastern Baltic Sea (Russian sector) with special reference to the 

methane and sulfur cycling 

N. Pimenov 1 , M. Ulyanova 2 , T. Kanapasky 1 , E .Veslopolova 1 , V. Sivkov 2 

1 Winogradsky Institute of Microbiology, RАS 

2 Atlantic Branch of Shirshov Institute of Oceanology, RAS 

The geographical position and the hydrological regime of the Russian sector of the Gdansk basin of the Baltic 

Sea make it a zone of excessive influx of both natural allochthonous and anthropogenic OM and biogenic 

elements. Low depths of this area result in incomplete destruction of OM; the suspension reaching the bottom 

contains therefore labile OM, which is actively utilized by microorganisms of various physiological groups. Due 

to intensive microbial processes, oxygen is rapidly consumed; sulfate-reducing and methanogenic 

microorganisms are therefore activated in the upper sediment layer. Seasonal observations revealed significant 

oxygen limitation in the near-bottom water of the Gdansk Basin at depths over 65 m; methane concentrations 

increase to 90–500 nmol/l, while its usual concentration in Baltic waters does not exceed 35 nmol/l. During 

autumn, H2S - (up to 60 nmol/l) was revealed in the pre-bottom water of the stations deeper than 95 m. 

Radioisotope measurements revealed high rates of sulfate reduction (SR) in the upper sediment layers (up to 0.6 

mmol dm -3 day -1 ). In autumn, SR (up to 8 µmol l -3 day -1 ) was detected also in the near-bottom water column. 

СН4 content in the aleuric and pelitic silts increased sharply with depth, reaching 190–900 mmol dm -3 20–30 cm 

below the surface. In spite of high CH4 content, intensive methanogenesis (MG) was not revealed. The highest 

MG rate in anaerobic surface sediment layers was 2.5 µmol dm -3 day -1 . 

Significant anomalies in the content of gaseous hydrocarbons in the Baltic Sea near-bottom waters revealed in 

early 1970s by the scientists of Shirshov Institute of Oceanology, are associated with discharge of gas-containing 

fluids localized in the regions with specific geomorphological structure of the sea bottom (Craters=pockmarks). 

We have investigated several pockmarks in the Russian sector of the Gdansk Basin. Microbiological, 

biogeochemical, and isotopic investigation of the near-bottom water and surface sediments of the pockmarks 

revealed their significant differences from other regions of the deep-water zone of the Gdansk Basin. We found 

out anomalies of methane concentration (up to 2.5 m from the bottom) above the crater. This zone was also 

characterized by increased microbial numbers, rates of dark CO2 fixation and methane oxidation. Increased 12 С 

content in POC was observed in the near-bottom water of the pockmark area; this finding confirms our results on 

increased microbial activity and suggests that in the near-bottom horizon above the pockmark, apart from 

methanotrophs, a sulfur-oxidizing bacterial community is formed, oxidizing the reduced sulfur compounds 

derived from highly reduced bottom sediments. 

Analysis of the data on integral SR rates in the upper 30 cm of the sediments revealed that the typical rate of 

formation of reduced sulfur compounds via OM decomposition was 2-3 mmol m -2 day -1 . In the pockmark 

sediments, where significantly higher methane content was detected, anaerobic methane oxidation (AMO) 

played the major role in formation of reduced sulfur compounds. SR rate there was 8.4 mmol m -2 day -1 , and 

AMO rate, 6.4 mmol m -2 day -1 . The origin of methane can not be determined unequivocally from the δ 13 С-СН4 

values. At 10–20 cm depth, in the zone of the highest AMO rate, δ 13 С-СН4 varied from -53.2 to -56.6 ‰; in 

deeper layers of the sediment, it became heavier (from -40 to -45‰). Obviously apart from contemporary 

microbial methane, isotopically heavier methane of deep sediment layers is accumulated in the surface sediments 

of pockmarks. 

Magnetic iron-sulphides as methane proxies in southern Hydrate Ridge sediments 

(ODP Leg 204): Preliminary results 

E. Piñero 1 , J. Cruz Larrasoaña 2 , F. Martínez-Ruiz 3 , E. Gràcia 1 

1 Unitat de Tecnologia Marina, Centre Mediterrani d’Investigacions Marines i Ambientals, Barcelona, Spain 

2 Institut de Ciències de la Terra Jaume Almera (CSIC), Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain 

3 Instituto Andaluz de Ciencias de la Tierra, Universidad de Granada, Granada, Spain 

Southern Hydrate Ridge (SHR) is a structural high located in the Cascadia Accretionary Complex (Oregon 

margin), which has been exhaustively studied since the identification of gas hydrates. During Leg 204 of the 

Ocean Drilling Program, nine sites were drilled in SHR sediments (Fig. 1) in order to evaluate the role of gas 

hydrates as a trigger of slope failures, their potential impact on climate change and its contribution as a carbon 

budget on the global cycle. 

The presence of magnetic minerals in methane-rich environments has already been related to gas hydrate 

formation and preservation (e.g. Larrasoaña et al., 2006). Thus, sulphides form during the early diagenesis as a 

consequence of the biological mediated reaction between the ascending methane and sulphate (Anaerobic 

Oxidation of Methane - AOM). This reaction also controls the precipitation of authigenic carbonates.

52 


Fig. 1. Location of Hydrate Ridge in the Cascadia Margin. a) Plate tectonic setting of the Cascadia accretionary 

complex. Black outlined box shows the location of Hydrate Ridge. b) Detailed bathymetric map (20 m contour 

intervals) of SHR. Location of ODP Leg 204 Sites 1244 to 1252, from where the samples presented in this study 

were collected. 

The main objectives in this work are: to characterize the magnetic minerals present in SHR sediments, to 

evaluate their possible mechanisms and environments of formation and to study the relationship between their 

distribution with depth and the variation of the position of the sulphate-methane transition (SMT) in the 

sedimentary column with time. 

Previous textural analyses reveal that SHR is composed by hemipelagic silty-clay sediments interbedded with 

numerous mass-transport deposits including turbidites and debris flows. The magnetic mineralogy of these gas 

hydrate-rich sediments (revealed by remanent magnetization data) is dominated by magnetite and two magnetic 

iron sulphides: greigite and pyrrhotite (Larrasoaña et al., 2006). Magnetite is more abundant in coarse-grained 

sediments and therefore it is interpreted to be detrital in origin. Greigite and pyrrhotite have been recognized as 

diagenetically produced during microbial reduction of sulphate in 3 zones: the sulphate zone (above SMT), the 

anaerobic oxidation of methane zone (SMT), and the methanic zone (below SMT). Electronic scanning 

microscopy analyses were performed in order to study the paragenetic sequence of the different magnetic 

sulphide minerals in every ambient of SHR. Results show that greigite forms above and at the SMT zone, while 

pyrrhotite preferentially forms below this depth (Larrasoaña et al., 2007). 

The formation of magnetic sulphide minerals depends on the proportion of Fe versus Fe extractable in the 

sediments, which controls the completion of the pyritization reaction in marine sediments. In order to study the 

chemical conditions in which these magnetic iron sulphides (greigite and pyrrhotite) are produced and preserved, 

we have measured the total Fe (TFe), reactive_Fe, total organic carbon (TOC) and total S (TS) of a set of ca. 100 

samples with distinctive magnetic assemblages (magnetite+greigite, greigite-, and pyrrhotite-dominated). TOC 

and TS were analysed by an elemental analyser and, TFe and reactive_Fe were measured by atomic absorption 

spectrometry. 

TS contents vary between 0.2 and 0.9%. TFe values range between 4.3 and 7.3%, in which the reactive_Fe 

represents the 23-39%. TS/TOC ratio values are near the oxic and normal marine seawater conditions (TS/TOC 

= 0.36), except for two magnetite+greigite and greigite-dominated samples that show higher TS contents. All the 

samples show TS/reactive_Fe ratios considerably lower than of saturated pyrite (1.15), which implies a low 

degree of pyritization in the environment. 

These preliminary S and Fe results suggest that pyritization reactions at the different diagenetic zones in SHR are 

not driven to completion (Figure 2), and formation and preservation of greigite and pyrrhotite meta-stable 

minerals are favoured by a low H2S flux or by high reactive-Fe contents in their local micro-environments of 

formation. In this situation, the net consumption of available sulphide would be used in producing new greigite 

or pyrrhotite rather than evolving into pyrite. 

A reaction model will be applied to all the dataset in order to constrain the necessary time to form the magnetic 

sulphide minerals in every environment, and thus, modelling changes of the SMI depth and methane flux over 

time.


Fig. 2. Left: Reactions of pyritization in marine sediments evolving to different iron sulphides. Right: Plot of 

Sulfur versus Extractable Iron in selected SHR sediment samples. Lines of the saturation ratios of the different 

iron sulphides are also depicted. 

References 

Larrasoaña, J.C., Gràcia, E., Garcés, M., Musgrave, R.J., Piñero, E., Martínez-Ruiz, F., Vega, M.E., 2006. Rock 

magnetic identification of magnetic iron sulfides and its bearings on the occurrence of gas hydrates, 

ODP Leg 204 (Hydrate Ridge). In: Tréhu, A.M., Bohrmann, G., Torres, M.E., Colwell, F.S. (Eds.), 

Proc. ODP, Sci. Res., vol. 204. Ocean Drilling Program, College Station, TX, pp. 1–33. 

Larrasoaña, J.C., Roberts, A.P., Musgrave, R.J., Gràcia, E., Piñero, E., Vega, M., Martínez-Ruiz, F., 2007. 

Diagenetic formation of greigite and pyrrhotite in gas hydrate marine sedimentary systems: results from 

ODP Leg 204 (southern Hydrate Ridge). Earth Planet. Sc. Lett. 261 (3-4), 350-366. 

Evidence of gas hydrates on the central Nile deep-sea fan 

D. Praeg 1 , J. Mascle 2 , R. Geletti 1 , V. Unnithan 3 , L. Loncke 4 , F. Harmegnies 5 

1 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy 

2 Géosciences Azur, B.P. 48, 06235, Villefranche-sur-Mer, France 

3 Jacobs University Bremen, Germany 

4 Université de Perpignan, France 

5 IFREMER Centre de Brest, Plouzané, France 

Gas hydrates have been found at seabed at one location in the eastern Mediterranean Sea, but bottom simulating 

reflections (BSRs) that might indicate their wider presence have not been documented. Here we present evidence 

for a BSR indicative of gas hydrates on the Nile deep-sea fan, based on a re-examination of multichannel seismic 

(MCS) profiles held by academic institutes. The MCS data include profiles acquired by OGS in 1973 (using 

explosive sources and a 2.4 km long streamer), reprocessed for this study; and MCS profiles acquired by 

Géosciences Azur from 1998-2002 (using airgun sources and streamers 0.3 to 4 km long). Geothermal 

measurements obtained during the recent MEDECO2 campaign of the Pourquoi pas? were used to constrain the 

theoretical hydrate stability zone. The BSR is observed as a reflection of inverse polarity that can be traced over 

a depth range of 2000-2500 m on the central Nile fan, deepening from c. 220-330 ms below seabed and in places 

cross-cutting (discontinuous) stratal reflections. Comparison with the modeled methane hydrate stability zone 

(MHSZ) indicates the BSR to be consistent with free gas at the base of a hydrate occurrence zone up to 250 m 

thick. These findings provide public confirmation of what is known to those engaged in exploration offshore 

Egypt, i.e. that the central Nile Fan hosts a gas hydrate system. 

The central Nile fan is a slope with a history of large-scale mass failures, and contains numerous cold seeps that 

are venting gases, derived in part from underlying hydrocarbon systems. Modeling of hydrate stability for

54 


conditions representative of the last glacial stage in the Mediterranean Sea, when sea levels were lower and 

bottom waters cooler (by up to 4°C), shows that the MHSZ would have been up to 50% thicker and its upper 

limit up to 300 m shallower. The glacial to interglacial transition therefore corresponded to a significant 

reduction in hydrate stability, with implications for slope stability along the upper limit of the MHSZ as it 

migrated downslope (across a depth range of c. 900-1200 m), as well as for the supply of gas to the many cold 

seeps that lie within the area of gas hydrate occurrence. An improved understanding of the dynamics of the gas 

hydrate system on the Nile fan may thus be relevant both to studies of its sedimentary evolution and to the 

functioning of its cold seep systems. 

Bacterial symbionts related to hydrocarbon degraders in mussels from the asphalt cold seep 

Chapopote, Gulf of Mexico 

L. Raggi 1 , F. Schubotz 2 , K.-U. Hinrichs 2 , H. Sahling 2 , N. Dubilier 1 

1 Max-Planck Institut for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany 

2 MARUM, University of Bremen, Leobener Str., 28359 Bremen, Germany 

Chemosynthetic life was recently discovered in the southern Gulf of Mexico (GoM) where lava-like flows of 

solidified asphalt cover a large area at 3000 m depth that also includes oil seeps and gas hydrate deposits 

(MacDonald et al. 2004). This site, called Chapopote, is colonized by animals with chemosynthetic symbionts 

such as vestimentiferan tubeworms, mussels, and clams. 

Two mussel species are present at Chapopote, Bathymodiolus heckerae and B. brooksi based on morphological 

and molecular analyses (COI gene). As many other deep-sea bathymodiolin mussels, these hosts harbor cooccurring 

sulfur- and methane-oxidizing bacteria in their gills, based on comparative analyses of genes providing 

information about the phylogeny and metabolism of their symbionts (16S rRNA, pmoA, aprA, RubisCO genes) 

combined with fluorescence in situ hybridization (FISH). Unexpectedly, we discovered a novel symbiont in B. 

heckerae that is closely related to hydrocarbon degrading bacteria of the genus Cycloclasticus. Stable carbon 

isotope analyses of lipids typical for heterotrophic bacteria were consistently heavier by 3‰ than other lipids 

indicating that the novel symbiont might use isotopically heavy hydrocarbons from the asphalt seep as an energy 

and carbon source. 

The discovery of a novel symbiont that may be able to metabolize hydrocarbons is particularly intriguing 

because until now only methane and reduced sulfur compounds have been identified as energy sources in 

chemosynthetic symbioses. The large amounts of hydrocarbons available at Chapopote would provide these 

mussel symbioses with a rich source of nutrition 

Where Mother Earth runs a lab for us – investigating carbon storage in the deep sea by looking 

at natural CO2 seepage in the Okinawa Trough hydrothermal system 

G. Rehder 1 , A. Boetius 2 , D. de Beer 2 , M. Häckel 3 , F. Inagaki 4 , C. Mertens 5 , K. Nakamura 6 , V. Ratmeyer 7 , 

J. Schneider 1 , K. Yanagawa 8 

1 Baltic Research Institute, Seestraße 15, 18119 Rostock-Warnemünde, Germany 

2 Max Planck Institute for Marine Microbiology, Celsiusstr.1, 28359 Bremen, Germany 

3 Leibniz-Institute for Marine Sciences IFM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel, Germany 

4 Kochi Institute for Core Sample Research, JAMSTEC, Monobe B200, Nankoku, Kochi 783-8502, Japan 

5 University of Bremen, Institute of Environmental Physics, Otto Hahn Allee, NW1, 28334 Bremen 

6 National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan 

7 MARUM Zentrum für Marine Umweltwissenschaften, Leobener Strasse, 28359 Bremen 

8 University of Tokyo, Dept. of Earth and Planetary Sciences, 7-3-1 Hongo, Tokyo 113-0033, Japan 

From March 3 rd to 26 th , 2008, a German-Japanese research consortium ventured on a field expedition to some 

sites of known hydrothermal activity in the Okinawa Trough, South China Sea, using RV “SONNE” as a 

platform to deploy the remotely operated vehicle (ROV) “Quest 4000”. The Okinawa Trough is one of only two 

known marine geological settings worldwide where liquid CO2 is accumulated in – and emanating from - the 

seafloor. The condensed CO2 is generated by complex phase separation processes of the hydrothermal fluids, and 

shows varying concentrations of other gas components. The hydrothermal generation of liquid CO2 is a 

scientifically fascinating phenomenon on its own. However, the general scope of the expedition was to use this 

setting to evaluate the potential reactions of the marine system to deliberate storage of manmade liquefied CO2 in


the deep sea and deep-sea sediments. This scenario is currently discussed as an option to mitigate further rise of 

atmospheric CO2 concentrations. 

The talk will present the observation of multi-component gas mixtures with varying ratios of the gas 

composition, describe the phase transition processes and transport mechanisms of liquid CO2-rich phases, 

discuss the buffering effect of weathering reactions in silicate-bearing sediments, report on observations of the 

distribution of CO2-seep-specific and non-specific deep sea fauna, show some first results on in situ 

measurements of benthic fluxes and turnover, and demonstrate the propagation of CO2 in the water column by 

larger scale CTD/rosette surveys. It will also emphasize the great potential as well as some caveats of the use of 

natural CO2-emitting sites as natural analogues for future deliberate marine carbon storage scenarios. 

Methane fluxes in diffusion-controlled marine sediments: 

Consequences for the global methane cycle 

N. Riedinger 1 and B. B. Jørgensen 1,2 

1 Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany 

2 Center for Geomicrobiology, Department of Biological Sciences, University of Aarhus, Århus C, Denmark 

Biogenic methane from the microbial decay of buried organic matter plays an important role in the global marine 

carbon cycle. Anaerobic oxidation of methane (AOM) coupled with sulfate reduction is a major control on the 

upward migrating methane fluxes which basically control the depth of the sulfate/methane transition (SMT). To 

determine the global diffusive methane flux and the loss of methane in the sediment due to AOM, we established 

an extensive marine data base on methane, sulfate and other relevant parameters. Diffusion fluxes were 

determined from the concentration profiles. The results of multivariate data analyses show, inter alia, that the 

global relationship between sedimentary methane and sulfate fluxes is linear over several orders of magnitude. 

Yet, most flux ratios between methane and sulfate do not show a 1:1 relation as would be expected from a simple 

stoichiometry (SO4 2- + CH4 + 2H + → H2S + CO2 + 2H2O) but rather indicate a lower methane flux relative to the 

sulfate flux. 

Our compilation of data aims at a global methane flux budget for marine sediments. By comparison to global 

data on methane emission and methane storage we will analyze the role of methane for the global carbon and 

sulfur cycles. 

Gas bubble streams at Vodyanitskii Mud Volcano, Sorokin Trough, Black Sea 

H. Sahling 1 , G. Bohrmann 1 , Y. G. Artemov 2 , A. Bahr 3 , M. Brüning 1 , S. A. Klapp 1 , I. Klaucke 3 , E. Kozlova 4 , 

A. Nikolovska 1 , T. Pape 1 , A. Reitz 3 , K. Wallmann 3 

1 MARUM – Center for Marine Environmental Sciences and Faculty of Geosciences, Bremen, Germany 

2 Institute of Biology of the Southern Seas, National Academy of Sciences of Ukraine, Sevastopol, Ukraine 

3 IFM-GEOMAR – Leibniz-Institute of Marine Sciences, Wischhofstr. 1-3, 24148 Kiel, Germany 

4 UNESCO-MSU Center for marine Geosciences, Geological Faculty, Moscow State University, Russia 

Vodyanitskii mud volcano is one of many mud volcanoes located in the Sorokin Trough, Black sea. It is a 500 m 

wide and 20 m high cone surrounded by a depression located at a water depth of about 2070 m. A sidescan sonar 

profile shows different generations of mud flows. Gravity corer sampling revealed of the mud flows yielded mud 

breccia, authigenic carbonates and gas hydrates. The fluids that flow through or erupt with the mud are enriched 

in chloride suggesting a deep source, which is similar to the fluids of the close-by Dvurechenskii mud volcano. 

Direct observation with the ROV QUEST revealed gas bubbles emanating at two distinct sites at the crest of the 

mud volcano, which confirms earlier observations of bubble-induced hydroacoustic anomalies in echosounder 

records. The sediments at the main bubble emission site show a thermal anomaly with temperatures at ~60 cm 

sediment depth that were 0.9°C warmer than the bottom water. Chemical and isotopic analyses of the emanated 

gas revealed that it consists primarily of methane and that it is of microbial origin. The gas flux was estimated 

using the video observations of the ROV. Assuming that the flux is constant with time, about 1.1 ± 0.5 * 10 6 mol 

of methane is released every year. This value is in the same order of magnitude as reported fluxes of dissolved 

methane that is released with advecting pore water at other mud volcanoes, suggesting that bubble emanation is a 

significant pathway transporting methane from the sediments into the water column.

56 


About relation between seismicity and anomalies of thermal field in the eastern part of the 

Black Sea water area 

E. Sakvarelidze 1 , I. Amanatashvili, V. Meskhia 1 , L Glonti 1 

1 Centre of the Seismic Monitoring, Tbilisi, Georgia 

The Caucasus represents one of the active regions of Alpine-Himalayan continental collision. Seismicity of this 

region is conditioned by movement of the Arabian plate from south towards the Eurasian plate. On the Caucasus 

territory earthquakes of 7 magnitude can take place and their effect reaches 9 points. 

South-east part of the Black Sea water area and adjoining sea coast line are characterized by quite high 

seismicity. Within paleoseismic researches of the zone, several ranges of paleoseismic dislocation structures are 

revealed, which originate from strong earthquakes. Seismicity map of western Georgia gives us opportunity to 

judge about strong earthquake epicenters’ saturation in the south-east part of the Black sea water area. These 

seismic events point to the fact, that western Georgia territory and the Black Sea basin are seismically active. 

Therefore, the region seismicity study and researches of the earthquakes’ distribution regularity in space and 

time, determination of relation between seismicity and modern geotectonic processes in the crust are of current 

importance. 

It is now determined that hypocenters of all perceptible earthquakes are related to the depth cracks. Region 

seismicity naturally evokes change of the resilient characteristics of the earth crust, which can become apparent 

in oscillations of speed attitudes of longitudinal and transverse waves (Vp/ Vs) and correspondingly in variations 

of Puasson coefficient. These variations in their turn can be evoked by those thermo resilient tensions, which 

appear due to the anomalies of thermal field. 

Data analysis of thermal flows available in the eastern part of the Black Sea shows large-scale dispersion of flow 

values. The biggest values of thermal flows are noted in the comparably narrow area in the south-east part of the 

sea, elongated from Batumi traverse westward, where flow values reach (81-84) mWt/m 2 . Apparently, this area 

is continuation of Adjara-Trialeti plicate system, also characterized by analogue flows’ values. Northward from 

the area of anomalous high values, field flow is characterized by temperate values around 40-50 mWt/m 2 . 

Calculation of depth temperatures on the crystal fundament, Conrad and Moho surfaces, performed by us for the 

eastern part of the Black Sea, showed that on Conrad and Moho surfaces had been zones of high temperatures 

corresponding to the zones of maximum thermal flows. Temperatures in these zones are equal: 500-700 0 C for 

Conrad surface and 1600 0 C for Moho surface. If we take into account that temperatures of the adjoining zone 

from north are equal correspondingly 150-200 0 and 350 0 C, then it can be concluded that due to the presence of 

big horizontal temperature gradients here thermo resilient strains can be evoked, which cause anomalous values 

of Puasson coefficient, and as a result earthquakes take place in this region. 

Our future researches are going to be dedicated to the estimation of Puasson coefficient in the concerned region. 

Dispersion of biomarker in the AOM dominated upper sediment of Quepos slide offshore 

Costa Rica 

F. Schellig 1,2 , O. Schmale 2 , H. Niemann 3,4 ,G. Rehder 1,2 

1 Sonderforschungsbereich 574 (SFB 574), Christian-Albrechts-Universität Kiel (Germany) 

2 Leibniz-Institut für Ostseeforschung Warnemünde (IOW), Sektion Meereschemie, Rostock (Germany) 

3 Max Planck Institut für Marine Mikrobiologie, Bremen 

4 Institute for Environmental Geosciences, Basel 

Enormous quantities of methane are stored in marine sediments but just a little is released into the water column 

due to the microbial process of anaerobic oxidation of methane (AOM). Microbial and biogeochemical 

investigations have shown that a consortium of methane oxidizing archaea and sulfate reducing Bacteria (SRB) 

are responsible for this highly efficient methane-sink (BOETIUS et al., 2000). Apart from these kind of 

investigations specific biomarkers can be used to identify the process of AOM in the sediment. These biomarkers 

are archaeal and bacterial cell membrane lipids which can give insights into the diversity of organisms involved 

in AOM (Hinrichs et al., 2002). 

Our study area is located in a water depth of nearly 400 m offshore Costa Rica and is part of the subduction zone 

of the Middle American Margin. The Cocos Plate is subducted beneath the Caribbean Plate at a rate of nearly 88 

mm yr -1 (KIMURA et al., 1997) whereas methane rich fluids from the underthrust oceanic sediments ascend 

through high-permeability conduits to the seafloor. On Meteor cruise M66/2 a remote operating vehicle (ROV) 

was used for detailed sampling of fluid and gas releasing seep sites. Three different study sites were chosen, 

which were indicated by differently colored microbial mats and different fluid flow rates. To get a spatial 

impression of the microbial distribution on these sites, the marine sediment was sampled by 20 cm push cores 

along transects crossing the microbial mats. . These samples were investigated for biomarkers and nutrients.


Our biomarker examinations show a variety of different components. Known fatty acids from C14 to C18 like 

C16:1w5c , C16:1w7c , C18:1w7c as well as higher molecular components like the C30 five rings hopanoid diploptene or 

hop-22(29)-ene have been identified. A final comparison with geochemical pore water data and genetic studies 

will offer a perfect 2D-insight in the running processes in the upper sediment. 

References: 

Boetius, A., K. Ravenschlag, et al. (2000). A marine microbial consortium apparently mediating anaerobic 

oxidation of methane. Nature 407: 623-626. 

Hinrichs, K. U. and A. Boetius (2002). The Anaerobic Oxidation of Methane: New Insights in Microbial 

Ecology and Biogeochemistry. Ocean Margin Systems. G. Wefer, D. Billett, D. Hebbelnet al. Berlin 

Heidelberg, Springer Verlag: 457-477. 

Kimura, G., Silver, E.A., Blum, P., Blanc, G., Bolton, A. and Clennell, M. (1997). Costa Rica accretionary 

wedge. Ocean Drilling Program. 

Application of membrane inlet mass spectrometry for online analysis of seafloor emissions to the 

water column and the atmosphere at pockmarks in Lake Constance 

M. Schlüter 1 , T. Gentz 1 , I. Bussmann 1 , M. Wessels 2 , S. Schlömmer 3 

1 Alfred-Wegener-Insitute for Polar and Marine Research, Bremerhaven, Germany 

2 Institute for Lake Research, Langenargen, Bodensee 

3 Federal Institute for Geosciences and Natural Resources, Hannover, Germany 

Methane concentrations around pockmarks were investigated in Lake Constance. The pockmarks are located in 

water depths of 13m and 80m. Intense release of gas bubbles from sediments was observed by visual inspection 

even from board of the research vessel. For a detailed mapping of gas concentrations in bottom waters as well as 

surface waters we applied the membrane inlet mass spectrometer (MIMS) Inspectr 200-200. The Inspectr 200- 

200 is designed for in situ measurements down to water depths of 200m and allows gas analysis (AMU 1-200) 

with a scan rate of 1.3 seconds (Fig. 1). 

During cruises with the RV Kormoran we applied the Inspectr 200-200 onboard of the vessel and used a 

submersible pump system for water sampling. By this means we analysed the concentration field of methane, 

oxygen, argon, nitrogen as well as carbon dioxide for different water depths along transects crossing the 

Pockmarks. For studies of methane in surface and bottom waters we designed a simple and reliable volumetric 

calibration technique for the quantification of CH4 over a wide range of concentrations. Furthermore, a cool-trap 

system was developed to minimize interferences caused by the high water vapour content, permeating through 

the membrane inlet into the vacuum section of the mass spectrometer. By application of the cool-trap the 

detection limit was lowered to less than 16 nmol/L CH4. Analyses by this rather new technique were compared 

with CH4 concentrations derived by “classical” water rosette sampling and subsequent head space analysis by 

gas chromatography. Around pockmarks very steep horizontal gradients of methane concentrations were 

observed in bottom as well as surface waters. An increase in CH4 concentrations by a factor of more than 5 were 

observed within a distance of less than 10 meters (Fig. 2). By compilation of gas analyses obtained for different 

waters depths a kind of 3D visualisation of the methane concentrations field is presented. This allows estimates 

on gas emissions from the seafloor. Based on gas concentrations measured in surface waters (~1.2 m bsl) along 

transects from the harbour to the pockmarks sites as well as at pockmark sites gas emission to the atmosphere 

were estimated for different seasons of the year. 

Fig. 1: The Inspectr200-200 underwater mass spectrometer was applied for online and in situ analysis of trace 

gases. The system consists of a roughing pump, an embedded PC, an Inficon mass spectrometer, a microcontroller 

(µC) for adjustment and control of the flow rate delivered by the gear pump as well as of the 

temperature of the Membrane Inlet System (MIS). A more detailed consideration of this system is provided by 

Wenner et al. (2004) or Short et al. (2006).

58 

CH 4 [µmol/L] 

0.30 

0.25 

0.20 

0.15 

0.10 

0.05 


0.00 

09:00:00 10:00:00 11:00:00 12:00:00 13:00:00 

Time [hour] 

Fig. 2: Methane concentrations obtained by the membrane inlet mass spectrometer Inspectr 200-200 in surface 

waters around two Pockmarks. The high scan rate of 1.3 seconds allows a very detailed consideration of the 

horizontal as well as vertical concentration field of CH4 around the pockmarks. 

References: 

Short R. T., Toler S. K., Kibelka G. P. G., Rueda Roa, D. T., Bell, R. J., Byrne, R. H. (2006). Detection and 

quantification of chemical plumes using a portable underwater membrane introduction mass 

spectrometer. TrAC, Trends Anal. Chem. 25 (7), 637–646 

Wenner P.G., Bell P. G., van Amerom, F.H.W., Toler S.K., Edkins J.E., Hall M.L., Koehn K., Short R.T. and 

Byrne, R.H. (2004). Environmental chemical mapping using an underwater mass spectrometer. Trends 

in Analytical Chemistry, 23, 288-295. 

Evidence of submarine gas hydrate deposits in context with methane seepage and active venting 

on the Hikurangi margin, NZ, from marine controlled source electromagnetics 

K. Schwalenberg 1 , I. Pecher 2 , J. Poort 3 , R. Coffin 4 , W. Wood 5 , M. Jegen 6 

1 Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, GERMANY 

2 Institute of Petroleum Engineering, Heriot Watt University, Edinburgh, EH14 4AS, UK 

3 Laboratoire de Geosciences Marines, Institut de Physique du Globe de Paris, 7505 Paris, FRANCE 

4 Naval Research Laboratory, Marine Biogeochemistry, Overlook Avenue, SW, Washington DC, 20375, USA 

5 Naval Research Laboratory, Stennis Space Center, Mississippi 39529, USA, 

6 IFM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel, GERMANY 

Methane seepage from the seafloor and the existence of submarine gas hydrates is known from the Hikurangi 

Margin on the east cost of New Zealand’s North Island. Widespread BSR’s have been observed in seismic data 

and several gas seep sites have been identified with echo sounders and video observations during expeditions on 

New Zealand’s RV Tangaroa. The first systematic investigation of methane seepage took place in 2006 on cruise 

TAN0607 and culminated in the <strong>international</strong> multidisciplinary “New Vents” project in 2007 on RV Sonne 

cruise SO191. 

Marine controlled source electromagnetics (CSEM) is an exploration method that recently gained considerable 

recognition in the offshore oil and gas exploiting industry. This is because the electrical resistivity derived from 

CSEM data is sensitive to the presence of resistive hydrocarbons such as oil, gas, and also gas hydrates. 

Submarine gas hydrates form in the available pore space of the sediment matrix and replace conductive pore 

fluid, with the consequence that the observed resistivity increases over areas, where hydrate forms in sufficient 

quantities. 

Within the “New Vents” project it was the first time that marine CSEM has been applied within a German 

project as well as in New Zealand coastal waters. Four profiles have been served in three target areas of known 

venting and methane seepage. The instrumentation used is a unique bottom-towed electric dipole-dipole system, 

capable to sense the seafloor to a depth of some hundred meters with a lateral resolution of about 100m. Three 

profiles show a strong coincidence between the location of seep sites and very anomalous resistivities. Deposits 

of concentrated gas hydrate at depth are likely the cause for these anomalies, but free gas may also play a role. In 

particular, data from the Wairarapa at the SE corner of the North Island point to considerable sources of gas 

hydrates in the first 100mbsf. There is one seep site where active venting, high heat flow, shallow gas hydrate 

recovered from cores, and seismic fault planes have been observed, but no resistivity anomaly. The reasons


could be a) the gas hydrate concentration is too low, even though methane venting is evident, b) strong temporal 

or spatial variations, and c) the thermal anomaly indicates rather temperature driven fluid expulsion that hampers 

the gas hydrate formation beneath the vent. The fourth profile across Porangahau Ridge shows an anomaly over 

a seismic high amplitude reflection band extending from the BSR to about halfway to the seafloor, which may 

constitute a gas hydrate “sweetspot” above a zone of free gas. Geochemical analysis of pore water profiles also 

support that active venting takes place at this location. Seismic profiles show significant shoaling of the base of 

gas hydrate stability indicative of larger-scale fluid-flow expulsion while surface heat flow data display a mildly 

advective signature. 

Considerable methane fluxes to the atmosphere from perennial deepwater hydrocarbon plumes 

in the Gulf of Mexico 

E. A. Solomon 1 , M. Kastner 1 , I. R. MacDonald 2 

1 Scripps Institution of Oceanography, University of California, San Diego, , USA 

2 Physical and Life Sciences Department, Texas A&M University-Corpus Christi, Corpus Christi, USA 

Methane is an important trace gas in the atmosphere playing a significant role in greenhouse warming and ozone 

destruction. The current global CH4 source strength is relatively well constrained at ~582 Tg CH4 yr -1 , but the 

methane fluxes from individual sources are not 1 . Although marine geological sources may be significant, most 

remain poorly quantified and are not included in the global oceanic CH4 flux to the atmosphere (4 Tg CH4 yr - 

1 ) 1,2 . Thus, quantitative studies of the CH4 discharge through seafloor seeps, the amount lost/consumed in the 

water column, and the flux to the atmosphere are critical for evaluating the role of the ocean in the global 

methane flux to the atmosphere. 

During two research expeditions in the northern Gulf of Mexico (GOM), water column CH4 concentration and 

isotopic depth profiles were collected by a submersible from six deepwater (~500-600 m) perennial hydrocarbon 

plumes. Navigation through the water column was based on visual identification of gas bubbles during ascent. 

Traditionally, hydrocasts have been used to sample water column CH4 concentrations above seeps; they have 

difficulty targeting these relatively narrow plumes and typically fail in sampling the seafloor source. Previous 

studies have indicated that bubble plumes emanating from water depths >200 m do not reach the mixed layer as 

a result of bubble dissolution and methane oxidation. The results of this study show that bubble dissolution and 

methane oxidation are inhibited in the GOM plumes, and, as a result, surface water methane concentrations are 

up to 2,000 times supersaturated. The calculated diffusive methane fluxes from individual plumes to the 

atmosphere range from 641-16,397 μmol m -2 d -1 . These fluxes are 3-4 orders of magnitude greater than the 

diffusive fluxes from the deepwater marine environment and 1-3 orders of magnitude greater than from shallow 

water seep areas, including the prodigious shallow seeps at Coal Oil Point, California 3 . 

These results expand the depth range where CH4 emissions from marine seeps are considered significant, and 

show that the diffusive fluxes from the mixed layer to the atmosphere above these GOM plumes are, to our 

knowledge, the highest reported to date. Considering there are ~5,000 active seep sites in the northern GOM, a 

preliminary estimate for the CH4 flux out of this small area of the global ocean ranges from 0.3 to 0.85 Tg CH4 

yr -1 . This potential CH4 flux is 21% of the current estimated global ocean flux to the atmosphere 1,2 . This 

suggests that GOM hydrocarbon plumes, and likely hydrocarbon plumes in other oil-rich basins such as the 

Persian Gulf, Caspian Sea, West African Margin, North Sea, and the Alaska North Slope represent a significant 

source of 14 C-depleted (“fossil”) methane to the atmosphere. 

References 

1 Denman, K.L. et al., in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to 

the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S.D. Solomon et al., 

Eds. (Cambridge University Press, Cambridge, UK and New York, NY, USA, 2007), chap. 7. 

2 Wuebbles, D.J., & Hayhoe, K. Atmospheric methane and global change. Earth Sci. Rev. 57, 177-210 (2002). 

3 Mau, S., et al. Dissolved methane distributions and air-sea flux in the plume of a massive seep field, Coal Oil 

Point, California. Geophys. Res. Lett. 34, L22603, doi:10.1029/2007GL031344 (2007).

60 


New discovery of mud volcanoes related to active strike-slip faults and thrusting ridges in the 

Moroccan margin (Gulf of Cadiz, Eastern Central Atlantic) 

L. Somoza 1* and MVSEIS_08 Team: 

M. Benmakhlouf 2 , D. Casas 3 , P. Esquete 4 , F. Estrada 3 , C. Falagán 4 , Y. El Frihmat 5 , A. García 4 , F. J. González 1 , 

R. León 1 , N. López 6 , P. Mata 4 , T. Medialdea 1 , S. Mosquera 7 , L. F. Pérez 7 , C. Roque 8 , J. T. Vázquez 6 . 

1 Geological Survey of Spain, IGME. Rios Rosas 23, Madrid 28003, Spain 

2 Faculté des Sciences, Universidad Abdelmalek Essaadi,Tétouan , Morocco 

3 Instituto de Ciencias del Mar ICM-CSIC, Barcelona , Spain 

4 Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Cádiz, Spain 

5 Institut Scientifique, Rabat, Morocco 

6 Instituto Español de Oceanografía IEO, Centro Oceanográfico de Málaga, Fuengirola, Spain 

7 Facultad de Ciencias del Mar, Universidad de Vigo. Vigo, Spain 

8 Instituto Nacional de Engenharia, Tecnología e Innovaccio, Alfagride, Portugal 

Preliminary results of the MVSEIS_08 cruise (May – June 2008) onboard R/V Hespérides, as part of the ESF 

EuroCORE-EuroMARGINS programme, have revealed the presence of twelve new mud volcanoes in the Gulf 

of Cádiz. The survey area corresponds to the offshore prolongation of the Betic-Rifean Arc. Two new mud 

volcanoes were discovered in the Eastern Moroccan Field (EMF) named as Al Gacel and Boabdil at water depths 

between 780 and 1100 m, close to the known Yuma and Ginsburg mud volcanoes. Mud breccia deposits with a 

strong H2S smell was recovered from these mud volcanoes. Eastwards, data acquired in Vernasdky Ridge 

indicates the presence of fault-related minor cones yielding mud breccia, bacterial mats and carbonate crusts. In 

addition, “relict” coral mounds aligned with strike-slip faults were also observed related to the Vernasdky Ridge 

as well as to the Al Arraiche mud volcano field. South of this field, new nine mud volcanoes were found at water 

depths ranging from 1300 to 1800 m in relation to active thrusting ridges, large strike-slip faults, and diapiric 

structures affecting the Allocthonous Unit of the Gulf of Cádiz (AUGC). These later area have been named the 

Moroccan Arc Field (MAF). Two main types of mud volcano morphologies have been observed in this field. 

The first type consists of “asymmetric” cones with large outflows flowing towards the deep basin as observed on 

detailed 3D swath bathymetry. This type of mud volcanoes are clearly aligned with strike-slip faults. There are 

three of them aligned along the main strike-slip fault, named as Maimonides, Almanzor and Madrid mud 

volcanoes. Several stacked deposits of mud breccia were recovered from these mud volcanoes. The second type 

is characterised by 1-2 km diameter edifices with flat top and are found at the front of the thrust ridges. The most 

characteristic mud volcano of this type has been named as MVSEIS. Cores recovered from these later mud 

volcanoes have revealed alternative layers of mud breccia and mud flow deposits, that we preliminary interpret 

as different episodes of mud eruption. Other cones surveyed at the front of the thrust ridges did not yield mud 

breccia but grey mud layers interpreted as mud flow deposits. In addition a new mud volcano, named Gazul, was 

discovered on the Spanish at only 380 m water depth, therefore being the shallowest mud volcano in the Spanish 

margin, also related to active faults. Gazul is an isolated conic-shaped mud volcano of 116 m in high, surrounded 

by a depression with scattered coral mounds. Most of new hydrocarbon seeps discovered during MVSEIS cruise 

are related to recent strike-slip faults and thrusting ridges evidencing the close relationship between fluid venting 

and recent tectonic activity in this area. 

Shallow gas accumulations and seepage in deep water on the SW African continental margin - 

Seismic and acoustic signatures 

V. Spiess 1 , N. Fekete 1 , F. Ding 1 , C. Caparachin 1 , J.-P. Foucher 2 and the M76/3 Shipboard Scientific Parties 1,2 

1 MARUM –Center for Marine Environmental Sciences, Bremen University, Germany 

2 Ifremer Centre de Brest, Marine Geosciences, Plouzané, France 

During R/V Meteor Cruise M76/3 in June/July 2008, seismic and acoustic methods were applied to study the 

distribution of seep structures and associated subsurface feeder systems. From the combination of swath 

bathymetry and backscatter, sediment echosounder, water column imaging and high-resolution multichannel 

seismics, numerous new seep sites could be identified. 

From previous studies, a few ‘giant’ pockmarks had been documented, representing deeply rooted migration 

zones and a few hundred meters wide and a few meters to more than ten meters depressions as the morphological 

expressions of fluid and gas expulsions. The new studies confirmed a widespread occurrence of such structures 

for the wider area of the continental margins of Gabon, Congo and Angola in deeper water. 

Spatial surveys have further shown that seep structures are present on different scales, in particular also with 

smaller sizes of tens of meters in diameter and a morphology on the meter scale. While these structures seem to 

be related to relatively shallow gas reservoirs, larger structures reveal roots to gas reservoirs in several hundred


meters sub-bottom depth. At some of these locations, gas flares could be identified in the water column of some 

hundred to over thousand meters height. 

In comparison of working areas north and south of the Congo Canyon, it became evident that different driving 

forces and sedimentary and tectonic boundary conditions may be responsible for fluid seepage and its 

distribution. While in the North a thick sediment cover restricts seepage to selected zones of weakness and 

higher permeability, salt diapirism in the South is massively fracturing overlying sediments, have created 

numerous promising morphological features at the seafloor. However, only few active seeps could be found in 

the area of salt diapirism. 

Future work will particularly focus on the details of seep systems, the comparison with site-specific information 

from coring and video surveys and the integrated interpretation of the acoustic and seismic data sets. 

Sources of hydrocarbon gases in mud volcanoes from the Sorokin Trough, NE Black Sea, based 

on molecular and carbon isotopic compositions 

A. Stadnitskaia 1,2 , M. K. Ivanov 2 , E. N. Poludetkina 2 , R. Kreulen 4 , T. C. E. van Weering 1,3 

1 Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands 

2 UNESCO-MSU Centre for Marine Geosciences, Moscow State University, Russian Federation 

3 Department of Paleoclimatology and Geomorphology, Free University of Amsterdam, The Netherlands 

4 ISOLAB, 1e Tieflaarsestraat 23, 4182 PC Neerijnen, The Netherlands 

Molecular and stable carbon isotope properties of hydrocarbon gases (methane through pentanes and sometimes 

hexanes) from seven sediment cores collected from five mud volcanoes (MVs) in the Sorokin Trough (NE Black 

Sea) suggest that these gases are initially derived from the comparable hydrocarbon pools and are likely initial 

products of non-microbial oil cracking processes. Our results state that dry characteristics of gas and 13Cdepleted 

signatures of methane are result of a high admixture of secondary microbial gas formed due to 

subsequent microbial anaerobic degradation of redeposited hydrocarbons in the shallow reservoirs. The wet gas 

components in all MVs and gas hydrates are related to each other. The compositional variations in C2+ content 

appear to result from a complex of secondary processes such oil cracking in the deep subsurface, migration and 

mixing of resulted gaseous and liquid hydrocarbons, biodegradation of possibly redeposited hydrocarbons 

forming shallow reservoirs, and additional alterations of hydrocarbon gases in the surface sediments due to 

currently active microbial processes, such as AOM, C2+ consumption, etc. Our data show that the most 

unaltered gas is in the mud breccia from the Kazakov MV. The gas mixture possibly represents the original 

properties of the hydrocarbons trapped in the deep subsurface of the Sorokin Trough. Analysis of the 

hydrocarbon gas data, complemented with published maturity characteristics of organic matter from Maycopian 

rock clasts and mud breccia matrix implies that the original source of gases is likely to be located below the 

Maycopian Shale Formation. 

Gas-liquid mass transfer of rising bubbles: Visualization via PLIF 

M. Stöhr 1 , J. Schanze 2 , A. Khalili 3,4 

1 German Aerospace Center (DLR), Stuttgart, Germany 

2 Massachusetts Institute of Technology, Cambridge, USA 

3 Max Planck Institute for Marine Microbiology, Bremen, Germany 

4 Jacobs University Bremen, Bremen, Germany 

We use planar laser-induced fluorescence (PLIF) technique combined with an aqueous solution of the pHsensitive 

dye Naphthofluorescein and CO2 as a tracer gas to visualize the gas-liquid mass transfer at the interface 

of rising gas bubbles. 

By obtaining high spatial resolution and frame rates of up to 500 Hz, cinematographic image sequences become 

possible. In addition, by shifting the laser light sequences of three-dimensional LIF images can be recorded. The 

technique is applied to freely rising bubbles with diameters between 0.5 and 5 mm, which perform rectilinear, 

oscillatory or irregular motions. 

The resulting PLIF image sequences reveal the evolution of characteristic patterns in the near and far wake of the 

bubbles. This technique has the potential to throw some light on the spatial and temporal dynamics of mass 

transfer of 

rising gas bubbles, and provide more insight into the estimation of bubble size and rising velocity.

62 

y [mm] 

280 

260 

240 

220 

200 

180 

160 

140 


120 t=271 ms t=412 ms t=553 ms t=694 ms t=835 ms t=977 ms 

x [mm] -20 -10 0 10 20 -20 -10 0 10 20 -20 -10 0 10 20 -20 -10 0 10 20 -20 -10 0 10 20 -20 -10 0 10 20 

The contribution to atmospheric methane from sub-seabed sources on the UK continental shelf 

L. Tizzard 1 , A. Judd 2 , R. Upstill-Goddard, G. Uher 

School of Marine Science and Technology, University of Newcastle upon Tyne, UK 

1 present affiliation: Wessex Archaeology, Old Sarum, Salisbury, UK 

2 present affiliation: Alan Judd Partnership, High Mickley, Northumberland, UK 

A detailed geographic information system (GIS) database was created showing the distribution of sub-seabed 

methane sources (microbial and thermogenic) and fluid migration pathways on the UK continental shelf 

(UKCS). This GIS was used to create spatial models, based on a 1 km 2 grid covering the whole UKCS; 

geological, seabed and water column models were developed to evaluate the fate of methane derived from the 

various sources identified in the database. 

The geological model predicted the likelihood of seabed seepage from ‘modern’ (Holocene) and ‘pre-modern’ 

(pre-Holocene) methane sources. For each model the likelihood of seeps was assessed according to a rigid 

classification scheme. The models were constrained by comparing predicted seep likelihood to known 

occurrences of seeps, shallow gas, pockmarks, and methane-derived authigenic carbonates. The geological 

models predicted that diffusive seepage is likely in approximately 8% of seabed sediments and that focussed 

seepage is likely in 72% of pre-modern sediments. Areas where pre-modern seep sources are likely are 

widespread due to the extensive occurrence of potential source rocks of Devonian to Tertiary age. Estuaries are 

dominated by modern sources; hence they are only minor contributors of pre-modern methane. Seepage of 

potentially mixed (modern and pre-modern) provenance is likely on only 6% of the UKCS. 

The seabed models predicted the likely flux of seepage methane escaping to the hydrosphere based on published 

and fieldwork data. Models were developed taking into account diffusive flux from modern sources and bubble 

flux from pre-modern seep locations. The models predicted that the total flux (diffusion and bubble transport) 

from sub-seabed sources in the UKCS amounts to between 0.087 and 2.90 Tg CH4 yr -1 seeping through the 

seabed into the water column. Approximately 94% of this flux is sourced from seeps; the remaining 6% arises 

via diffusion across the sediment-water interface. 

The water column model used existing models to estimate the methane flux direct to the atmosphere via bubble 

transport. As the results of each model were passed to the next model (geological to seabed to water column) the 

methane flux to the atmosphere has been estimated for each 1 km 2 grid square on the UKCS (Figure 1). 

A total atmospheric flux of 0.01 to 0.48 Tg CH4 yr -1 was estimated for the UKCS (Figure 2). If the true value 

lies towards the top of this range, then natural sub-seabed methane is the largest single natural source of 

atmospheric methane in the UK, and is exceeded only by emissions from landfills and agriculture according to 

UK government figures. Although the UKCS may be unusually well endowed with sub-seabed methane 

sources, these results suggest that the global contribution from such sources is considerable and should not be 

excluded from atmospheric methane budgets.

Fig. 2: Methane flux to the atmosphere from the UKCS. 


Fig. 1: Average methane flux to the water 

column from dissolving pre-modern bubble 

seeps and diffusive flux from modern sediments. 

(N.B. exponential scale has been used.) 

Gas hydrate reservoir of carbon in the global system of subsurfacial carbon reservoirs 

B. M. Valyaev 1 

1 Oil and Gas Research Institute, Moscow, Russia 

Gas hydrate (GH) reservoir of carbon takes a peculiar place in the global system of mobile subsurfacial 

reservoirs of carbone. This can be explaned not only by its huge volume – the recent estimations make up 

5·10 17 g. Carbon reservoir in the atmosphere equels to the same volume. Hovewer, these reservoirs differ 

extremly both in the nature of oxidation – the reduction of carbon (the first contains mainly CH4, the second – 

CO2) and in its isotope (δ 13 C) composition (the methane carbone of gas hydrates (GHs) varies from 45 %0 up to - 

70 %0, the carbone of the atmosphere carbone dioxide equels to – 8 %0).

64 


The gas hydrate reservoir of carbon is also characterised by some other features. It exist only in the glacial 

epochs. Warm epochs are not favorable both for the formation and conservation of gas hydrates. In the glacial 

epochs the zone of stability of gas hydrates (ZSGH) is widespread including the ocean floor. Hovewer, GHs 

turned up to be spread extremly enevenly. Large accumulations of GHs are discrete within the limits of ZSGH 

both in space and in the sediment section. The distribution of large GH accumulations is controlled by deep 

tectonic (geodynamic) factors and by the localized flows of deep hydrocarbon fluids (Dmitrievsky and Valyaev, 

1998, 2001; and others). 

In many cases these localised flows appear to be through and are manifested on the sea bottom as hydrocarbon 

discharges (mud volcanoes, seepages, etc.). In these discharge sites subbottom GH fields are formed and specific 

microbial consortiums are developed as well. According to the data of deep water drilling within hydrocarbon 

discharges microbial consortiums are discovered in the sediment sections of ZSCH on different depths. High 

intensity of deep microbial life is discovered near the bottom of ZSGH – BSR – as well (Parkes et al, 2000; and 

others). Favourable conditions for the development of deep microbial life, caused by the energy of anaerobic 

oxidation of methane (hydrocarbon) are typical not only for ZSGH bottom. 

As it has turned out in the formation of GH accumulations on the different depths of the section of ZSGH pore 

sediments are filled with GHs only partially (up to 10-20 %, sometimes more). In that way in the medium of 

pore waters, saturated by the methane, the stability of GHs is not absolute, it is relative. Typically GH 

accumulations do not form the unique stratum – monolith, but they are spread in the form of numerous specific 

inclusions (different volumes) in the interval of sediment sections of ZSGH favourable for the formation of gas 

hudrates. Thus, the processes of the formation and the destruction of GH accumulations are accomponied by the 

development of different microbial consortiums. Gas hydrate accumulations and GH reservoirs on the whole are 

formed only owing to the utilization of the residial part of the ascending localized flows of hydrocarbon fluids. 

The methane excreted as a result of the destruction of GHs may migrate either up into the sea water or may be 

utilized by the microbial consortiums of the sediments. The important role of the GH reservoir of carbone in the 

stabilization of the conditions for the existance of microbial consortiums (deep life) in the marine sediments is 

evident. Gas hydrate reservoirs of carbon in the marine sediments should be considered as the most important 

reservoir of the carbon for the deep biosphere. 

Methane emission and associated biogeochemical consumption rates: How important are cold 

seep geostructures on a local and global scale 

F. Wenzhöfer 1 , J. Felden 1 , A. Lichtschlag 1 , D. deBeer 1 , T. Feseker 1,2 , J.P. Foucher 2 , 

G. Bohrmann 3 , F. Inagaki 4 , A. Boetius 1,5 


2 Centre Ifremer de Brest, Depart. Geosciences Marines, BP7, 29280 Plouzane, France 

3 Research Center Ocean Margins, Bremen, Germany 

4 JAMSTEC, Yokosuka, Japan 

5 Jacobs University Bremen, Germany 

Cold seeps (e.g. mud volcanoes, pockmarks) are very interesting ecosystems, both from the biological and 

geological perspective. The rising fluid, mud and gas represent a window between the deep geosphere and the 

biosphere. Cold seeps can be an important natural source of the greenhouse gas methane to the hydrosphere and 

sometimes even the atmosphere. Recent investigations show that the number of active submarine cold seeps 

might be much higher than anticipated, and that gas emitted from deep-sea seeps might reach the upper mixed 

ocean. Unfortunately, global methane emission from active submarine seeps cannot be quantified because their 

number and gas emission rates are unknown. It is also unclear how efficiently methane-oxidizing 

microorganisms remove the methane. With regard to greenhouse gas effects, the study of cold seeps at 

continental margins is an important contribution to our understanding and quantification of the methane sources 

and sinks on earth. 

Concentrated around ocean margins, the focused emission of cold and often hydrocarbon-laden fluids from 

subsurface reservoirs into the oceanic hydrosphere is creating highly dynamic cold-seep ecosystems at the 

seafloor. These systems are shaped by a complex interplay of biological, geochemical, and geological processes. 

Associated with fluid outflow at seeps are chemosynthetic communities that utilize the chemical energy of 

reduced components such as H2S, CH4, and other hydrocarbons. The production of biomass by these 

communities can be several orders of magnitude greater than at non-seep sites on the nearby ocean floor. These 

chemosynthetic communities are nourished by the chemical energy – mostly methane - rising from subsurface 

sources and forming the basis of cold-seep ecosystems. In addition to these unique and highly specialized 

ecosystems, cold seeps are recognized by several morphological features, like pockmarks, hydrocarbon seeps on 

top of salt diapirs, asphalt volcanoes, brine pools, mud diapirs, and mud volcanoes. These geostructures are 

characterized by specific chemical environments, e.g. oxygen depletion within the first few millimeters of the


sediment surface, high sulfide fluxes, mineral precipitates (e.g., authigenic carbonate and gas hydrates), and 

diagnostic stable-isotope signals in inorganic and organic phases. 

Here we present fluxes and consumption rates from different cold seep systems including mud volcanoes, 

pockmarks, gas and asphalt seeps from the Arctic region (Hakon Mosby Mud Volcano), the Eastern 

Mediterranean (Amon Mud Volvano, Central Pockmarks), the Golf of Mexico (Chapopote), the Japan Trench 

(Calyptogena accumulations). We compare in situ oxygen consumption rates as an indicator for the (micro- 

)biological and chemical activities, as well as methane discharge and subsurface consumption. Our data show 

that cold seeps are heterogeneous ecosystems in which abiotic as well as biotic processes are strongly influenced 

by fluid and gas fluxes often varying in space and time. In situ measurements reveal that at geostructure scale, 

specific habitats with distinct O2 consumption and methane emission rates can be identified. Combining habitatspecific 

rate measurements with video observation enables us to estimate the spatial distribution of the different 

habitats providing first data on methane and oxygen budgets of a variety of cold seeps world wide. By scaling 

our measured rates from local to regional and global levels, we evaluate the ecological importance of cold seeps, 

which is crucial to understand the role of methane in the global carbon cycle. 

Microbial communities in sediments of Lake Baikal mud volcanoes 

T.I. Zemskaya 1 , O.V. Shubenkova 1 , S.M. Chernitsina 1 , A.V. Egorov 2 , G.V. Kalmychkov 3 , T.P. Pogadaeva 1 , 

O.M. Khlystov 1 , S. Buryukhaev 4 , B.B. Namsaraev 4 

1 Limnological Institute SB RAS, 3 Ulan-Batorskaya st., Irkutsk 664033, Russia 

2 P.P. Shirhov’s Institute of Oceanology, 36 Nachimovskii pr., Moscow 117997, Russia 

3 A.P. Vinogradov’s Institute of Geochemistry, 1а Favorskii st., Irkutsk 664033, Russia 

4 Institute of General and Experimental Biology, 6 Sach’yanovoi st., Ulan-Ude 670047, Russia 

Till now Lake Baikal is the only freshwater reservoir where methane hydrates have been discovered (Kuzmin et 

al., 1997; Klerkx et al., 2003). Subsurface deposits of gas hydrates are located in areas of mud volcanoes and 

natural oil seepage (Khlystov et al., 2007). Studies of isotopic composition of gases discharged at dissociation of 

gas hydrates in these areas show that gas is of different genesis. Methane from the mud volcano “Malenki” is of 

bacterial origin: δ 13 С(CH4) varies between -65.6‰ and -66.2‰. Gas discharged at hydrate dissociation from the 

core of the mud volcano “K-2” has the following values: (δ 13 С(CH4) = -51.6 and -52.6‰, СН4/С2Н6 = 5.66; 

δ 13 С(CH4) = -52‰, СН4/С2Н6 = 37.66 – 42.62). These high concentrations of ethane and rather heavy isotopic 

composition are attributed to considerable amounts of gas of thermogenic genesis in sediments of the mud 

volcano “K-2”. 

The analysis of chemical composition of pore waters of sediments from the mud volcano “Malenki” shows that 

there is a discharge of gas-saturated sulfate-calcium fluid with mineralization of up to 1700 mg/l. In the crater of 

the mud volcano “K-2” there is a discharge of several fluids which differ in ionic composition and level of 

mineralization: sulfate-calcium with mineralization of up to 1800 mg/l, hydrocarbonate-calcium (up to 500 mg/l) 

and chloride-sodium. The concentration of these anions in pore waters in background regions is not higher than 8 

and 0.4 mg/l. Methane concentrations in bottom sediments of background areas increase with depth, and 

especially this abrupt rise is observed in areas of mud volcanoes. Radioactive-labeled substrates revealed high 

velocities of methane oxidation and sulfate reduction not only in surface layers of bottom sediments (1-2 cm) 

where there are methanotrophic bacteria, but also in the well-recovered deep layers of sediments (Klerkx et al., 

2003; Dagurova et al., 2005). High velocities of methane oxidation (0.12-4.7 ml СН4 dm -3 day -1 ) and the 

abundance of aerobic methanotrophic bacteria (10 7 cell/ml, versus 10-10 4 cell/ml in background areas) are 

recorded on the boundary “water-bottom sediments” in areas of mud volcanoes. Molecular microbiological 

analysis shows that Baikal bacteria possess genes responsible for synthesis of methane monooxygenases which 

provide methane oxidation. It is established that methanotrophic bacteria of type I prevail in Baikal bottom 

sediments which have the highest homology with members of the genus Methylobacter. 

The archaeal component of sediments obtained from the three sites of Lake Baikal (mud volcanoes “Malenki” 

and “K-2” and the background site) has been studied with 16S rRNA gene fragment analysis. Identical 

sequences of archaea have been found in sediments from mud volcanoes. They are characteristic of sediments 

and GH crystals from both sites. Archaea are represented by 9 phylotypes belonging to the phylogenetic 

subdivision Euryarchaeota and nine phylotypes representing Crenarchaeota. The comparison of sequences of 

Baikal archaea with microorganisms which participate in anaerobic methane oxidation in marine ecosystems 

shows that they belong to the same order Methanosaeta as groups ANME-1 and ANME-2. However, Baikal 

sequences do not form a common cluster with them and are not identical in structure to groups from marine 

ecosystems. They occupy an intermediate position on the phylogenetic tree between groups ANME-2 and 

ANME-3. 

This work was supported by RAS Presidium Programme 18.10, SB RAS Integration Project No. 58, and RFBR 

Grant No. 08-05-00709-a.

66 


Fluid seepage and mass wasting processes along the North Anatolian fault 

in the Sea of Marmara 

T. A. C. Zitter 1 , P. Henry 1 , L. Géli 2 , S. Ozeren 3 , M. N. Çağatay 3 , B. Mercier de Lépinay 4 , 

M. Tryon 5 , S. Bourlange 6 , P. Burnard 6 , N. Sultan 2 , and the Marnaut Scientific Party 

1 CEREGE, Europôle de l'Arbois, BP80, 13545 Aix-en-Provence Cedex 04 -France 

2 Ifremer, Marine Geosciences Department, 29280, Plouzané, France 

3 Istanbul Technical University, Faculty of Mines, Geology Department, Maslak, 34469 Istanbul, Turkey 

4 Geosciences Azur, Université de Nice-Sophia Antipolis, Valbonne, France 

5 Scripps Institution of Oceanography, La Jolla, CA, 92093-0244, USA 

6 CRPG, 15 Rue Notre Dame des Pauvres, 54501 Vandoeuvre Les Nancy, France 

The MARNAUT cruise of Ifremer R/V L’Atalante in May-June 2007 investigated cold seeps in the Sea of 

Marmara combining visual observations, sampling and long term instrument deployments with the Nautile 

manned submersible, as well as operations from the ship (sounding, coring, yoyo piezometer, heat flux 

measurements and water column sampling). The Sea of Marmara is located along the submerged section of the 

North Anatolian fault system, and displays numerous sites of fluid venting, as well as mass wasting processes in 

association with the active deformation at this major transcurrent plate boundary. This contribution examines the 

relationship between fluid outflow and tectonic and sedimentary setting. 

Manifestations of fluid emissions in the Sea of Marmara are diverse and range from highly focussed brackish 

water outflow emitted from authigenic carbonate chimneys to more extensive and diffuse fluid seepage areas. 

Seeping sites exhibits large patches of blackish sulfidic sediments, associated with authigenic carbonate crusts, 

white or yellow bacterial mats, and chemosynthetic fauna such as shells, polychetes, corals, urchins and sea 

anemones. At some sites, gas bubbles were observed escaping through narrow conduits piercing the black 

sediments or from open fractures. Several fluid emission sites expel fluids originating from deep within the 

sedimentary basin (thermogenic gas, oil, and brines) and, possibly, mantle. 

Mapping of cold seeps distribution both on the seafloor and from the water column indicates that fluid emissions 

are primarily associated with deep-rooted active faults. Fluid seeps are localized both along the main strike-slip 

fault system and along extensional secondary fractures. On the topographic highs, compressive structures on the 

top of NE-SW anticlinal ridges at about 1 km away from the main fault trace contribute to gas emission. 

Observations also suggest that the sedimentary environment play a role to provide drain for fluid expulsion, 

mainly in the case of diffuse seepage and water outflow. The steep slopes of the Sea of Marmara, reaching more 

than 18° in some places, are affected by significant mass wasting processes, imaged with high resolution 

multibeam bathymetric data. The slopes are characterized by numerous submarine canyons, with steep flanks 

displaying slope failures and scars, and by large destabilized areas. Mass wasting deposits, such as turbidites, 

debris flows, and avalanche debris are recognized within the basins. Fluid emissions sites are observed in close 

relationship with these deposits or at the toe of destabilized slopes. In the northeastern Sea of Marmara, fluid 

seepage has been observed at the base of a scree slope with meter-sized boulders. At the water outflow sites, and 

especially within the Tekirdag Basin, pore fluid composition profiles indicate that the brackish pore fluids are 

laterally channelled by sand layers deposited at the outlet of submarine canyons. Avalanche debris and coarse 

sandy turbidites provide thus high permeable conduits to drain fluid from the basin towards the active fault 

scarp.

Poster Session on September 16 and 18, 16:30 – 18:30 

Abstracts of posters 

(alphabetic order)

Abstracts of posters 69 

Methane and organic matter as sources for excess carbon dioxide in intertidal surface sands of 

the North Sea: Biogeochemical and stable isotope evidence 

A.M. Al-Raei 1 , M. E.Böttcher 1,2 , V. Heuer 3 , Y. Hilker 4 , B. Engelen 4 , K. U. Hinrichs 3 , M. Segl 3 

1 Max Planck Institute for Marine Microbiology, D-28359 Bremen, FRG 

2 Leibniz Institute for Baltic Sea Research, FRG 

3 RCOM und FB Geowissenschaften, University of Bremen, Germany 

4 ICBM, Oldenburg University, Germany 

Reduced organic carbon as organic matter is mineralized in marine sediments by microbial activity using 

predominantly oxygen, sulfate, and metal oxides as electron acceptors. Besides this, methane can also be 

produced and oxidized aerobically or anaerobically. Both lines of oxidation produce carbon dioxide, and both 

carbon dioxide and methane are strong green-house gases that may be liberated from the intertidal surface 

sediments into the bottom waters or the atmosphere. The most important anaerobic mineralization process is 

bacterial sulfate reduction which is also accompanied by the liberation of carbon dioxide. Different carbonbearing 

substrates act as carbon sources for sulfate reduction. Methane is involved in anaerobic oxidation of 

methane. The carbon isotopic composition of dissolved inorganic carbon (DIC) is a useful tracer for the 

biogeochemical transformations of different carbon sources and is used here to identify the key reactions in the 

carbon-sulfur cycle of intertidal surface sediments. 

Pore waters from intertidal sands of the back-barrier tidal area of Spiekeroog and Sylt islands (southern and 

eastern North Sea) have been sampled down to 40 cm using different techniques, and water samples and 

sediments are analyzed for a number of (bio)geochemical parameters as, for instance TOC, TIC, DIC, TA, 

methane, microbial sulfate reduction rates, salinity, pH, sulfate, sulfide, pyrite, AVS, reactive Fe* and Mn*, and 

the carbon isotopic composition of DIC and methane. Analytical methods include radio tracer incubation, GC 

and IC, ion-selective electrodes, extraction and titration methods, and irmMS with different inlet systems. 

In the present study, the pore water composition and stable isotopic composition of DIC is investigated to 

characterize the different biogeochemical processes in intertidal surface sands below oxic and anoxic surfaces. 

Below reduced sediment surfaces, the isotopic composition of DIC down to -36 per mil indicates methane as a 

source for the oxidized carbon pool, in agreement with chemical pore water gradients. In contrast, DIC is less 

enriched in the lighter isotope below oxidized surface sands were oxidation of organic matter via using oxygen 

and sulfate as electron acceptors dominate. 

Gas indicators in seismic data 

J. Appel 1 , R. Lutz 1 , H. Keppler 1 , C. Gaedicke 1 

1 Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany 

The term “shallow gas” defines gas accumulations in depths till 1000 m below seafloor. It consists of CO2, H2S, 

N2 and some lighter hydrocarbons. The most frequent gaseous hydrocarbon is methane, followed by ethane, 

propane, and less butane and pentane (with their equivalent alkenes). The gas indicators were examined in 2-D 

and3-D seismic data located in the German North Sea. They mostly occur in unconsolidated sediments. 

Already small amounts of free gas in pore fluids may have a visible effect in seismic images. Common effects 

are amplitude anomalies. They can be classified as enhanced reflections or bright spots. Enhanced reflections 

appear as extended amplitude anomalies with less defined boundaries. In contrast bright spots appear as spatially 

limited amplitude anomalies within consistent reflectors. In the northwestern part of the German North Sea large 

bright spot accumulations were detected. They occur above salt diapirs at depth of ~400 m to ~1000 m below 

seafloor. These accumulations are of a nearly circular shape and it seems that they are connected to the crestal 

fault systems, which developed above the diapirs. 

Furthermore gas chimneys, acoustic turbidity, and absent reflections are other possible gas indicators in the 

observed seismic data. Chimneys are vertical or near vertical columnar disturbances in seismic data. Acoustic 

turbidity is characterized by zones of chaotic reflections. The effect of absent or faint reflections is characterized 

by zones of acoustic blanking and mostly occur in high-frequency seismic data. 

All this potentially gas-indicating effects appear in seismic data of the North Sea. Based on 2-D and 3-D seismic 

data we mapped the occurrences of bright spots in the German North Sea. This map can be used to minimize the 

risks of geohazards (e.g. blow-out risk) related with shallow gas.

70 


Quantitative analysis of methane seep flares using gas bubble model 

Yu. G. Artemov 1 

1 Institute of Biology of the Southern Seas, 2 Nakhimov Prospect, Sevastopol, 99011, Ukraine 

It is extremely difficult to perform observations of evolution of methane bubbles in sea seep flares, so 

application of mathematical modelling for scrutinizing gas bubble behaviour in the water column becomes a 

standard practice. The rising speed of bubbles (vb) and the gas transfer coefficient (kb) are parameterized in most 

known gas bubble models by generalized empirical and semi-empirical formulae. The model, based on the Peng- 

Robinson EOS, is developed where vb and kb values are calculated depending on bubble residence time in the 

water column at gradual alteration of behaviour regime from “clean” to “dirty” due to adsorption of surfactants 

or clathrate hydrate shell forming [Artemov, subm.]. 

The developed model can help in better understanding of gas flare echograms at natural bubbling seep sites. 

There is presented in Figure 1a the 38 kHz echogram of gas flare above the Vodyanitskiy mud volcano (VMV) 

obtained with the use of scientific echo-sounder SIMRAD EK-500. Acoustic data were processed with the 

WaveLens software [Artemov, 2006]. The profile of flare backscattering cross-section, integrated in 10 m depth 

bins and averaged over 30 pings when gas flare crossed the axis of sound beam, is shown in Figure 1b 

(integration boundaries are indicated by black rectangle). Local peaks of the profile correspond to the resonance 

of bubbles of different sizes. The evolution of gas bubbles with initial diameters of 4.5, 6.5, 7.5 and 10.5 mm 

was calculated by the developed model. Then the backscattering cross section of bubbles along the gas flare was 

reconstructed from modeled bubble size data and plotted in the same Figure 1b. Comparing backscattering crosssection 

profiles in Figure 1 it is reasonable to assume that the main contribution to the VMV gas flare in May 

2004 owed to gas bubbles with initial sizes of 4 – 8 mm. In addition, there presented also in the gas flare some 

number of bubbles with initial equivalent diameter of about 10.5 mm. At that, VMV sporadically emitted single 

bigger bubbles which are distinguished in echogram Fig. 1 as tilted lines at the top of gas flare. It is believed that 

such an approach can be also employed for analysis of acoustic data acquired with un-calibrated single beam 

echo-sounders. 

Fig. 1. 38 kHz echogram of gas flare above the Vodyanitskiy mud volcano (left); backscattering cross-section of 

gas flare and gas bubbles of 4 size groups (right). 

References 

Artemov, Yu. G. Software support for investigation of natural methane seeps by Hydroacoustic method // 

Marine Ecological Journal. – 2006. – 5, no. 1. – P. 57 - 71. 

Artemov, Yu. G. Modeling of gas bubbles emitted from cold seeps // Marine Ecological Journal. [In Russian]


Carbon dioxide production in surface sediments of temporarily anoxic basins (Baltic Sea) and 

resulting sediment-water interface fluxes 

M. E. Böttcher 1 , A. M. Al-Raei 2 , O. Dellwig 1 , C. Lenz 1 , V. Winde 1 , T. Leipe 1 , S. Forster 3 , M. Segl 4 

1 Leibniz Institute for Baltic Sea Research, D-18119 Warnemünde 

2 Max Planck Institute for Marine Microbiology, D-28359 Bremen 

3 University of Rostock, D-18119 Rostock 

4 FB5 and MARUM, University of Bremen, D-28359 Bremen 

Organic matter is mineralized in marine sediments by microbial activity using predominantly oxygen, sulfate, 

and metal oxides as electron acceptors. Modern euxinic basins as found in the Baltic Sea or the Black Sea are of 

particular importance because they may serve as type systems for anoxia in Earth’s history. 

We present here results from biogeochemical investigations carried out in the Baltic deeps (Gotland Basin, 

Landsort Deep) during the first scientific cruise of RV M.S. MERIAN in 2006, additionally during RV Prof. 

Penck cruises in 2006 and 2007. Short sediment cores were obtained with a multi-corer and analyzed for 

particulate and dissolved main, minor and trace elements, pH, DIC, methane alkalinity, besides the stable carbon 

isotopes of dissolved inorganic carbon (DIC). Microsensors were applied to analyze steep gradients of oxygen, 

sulphide and sulphate. Pore water profiles are evaluated in terms of process rates and associated element fluxes 

using the PROFILE software. Gross and net anaerobic mineralization rates were additionally obtained from core 

incubations with 35 S. Steep gradients in DIC are associated with a strong enrichment of the light stable isotope 

resulting in the Gotland basin from oxidized OM. Element fluxes across the sediment-water interface are 

compared with literature data and show for the Baltic Sea a dependence from bottom water redox conditions, and 

sediment compositions and formation conditions (e.g., accumulation rates). 

DIC in the anoxic part of the water column in the Landsort Deep and the Gotland Deep show relatively similar 

isotope values, close to the bottom water value, but steep gradients towards heavier values above the pelagic 

redoxcline. 

Extensive methane seepage on the Makran continental slope off Pakistan 

imaged with side scan sonar 

M. Brüning 1 , T. Le Bas 2 , B. Murton 2 , H. Sahling 1 , G. Bohrmann 1 

1 MARUM, University of Bremen, PO 330440, 28334 Bremen 

2 NOC, Southampton, European Way, Southampton, SO14 3ZH, England 

Seepage of methane from the seafloor is known from several locations around the world: Hydrate Ridge, Costa 

Rica, Black Sea, Golf of Mexico, Håkon Mosby Mud Volcano. The list becomes longer with the increasing 

number of expeditions searching continental slopes. Now Makran can be added to the list above. 

The Makran subduction zone south of Pakistan has a high potential for methane generation due to a sediment 

thickness of 7 km. The subduction had pushed up a series of accretionary ridges. Early RV Sonne expeditions 

found indications for fluid seepage (von Rad et al., 1996, 2000, Wiedecke et al., 2001). In October and 

November 2007 the German RV Meteor visited Makran to conduct a large scale search for fluid seepage. The 

first leg involved high resolution multichannel seismics and deep-towed side scan sonar (NOC’s TOBI, 30 kHz), 

the second leg focused on ROV work. The strategy of geophysical reconnaissance with side scan sonar, followed 

by single beam echo sounder bubble search in the water column, and/or TV sled on backscatter anomalies 

assigned to seepage, and finally ROV work on previously confirmed seep hot-spots proved very successful. We 

found 15 bubble flares, 9 places of chemosynthetic fauna, or carbonates, out of 14 video sleds. Nine sites were 

investigated by ROV. We can translate the video observations to most backscatter anomalies found. 

In the backscatter imagery we identified the following types of anomalies attributed to fluid escape; firstly, 

higher backscatter intensities on steep slopes, linear features on flat areas close to slumps, or on slightly elevated 

areas, and, secondly, at pockmarks, possible mud volcanoes, mounds 

The first kind of anomalies represents the majority. They are mainly located at ridges. Active seepage of 

methane was present in small portions of the anomalies. The second type was found in slope basins between 

ridges. The one visited pockmark did not show seep-activity. The other features were not video checked, as they 

were discovered after post-cruise processing. Gas discharge showed zonations: around the deformation front and 

at a ridge 36 km from the deformation front seepage was more pronounced than in other areas. The Oxygen 

Minimum Zone between 300 m and 1000 m water depth limits life of carbonate precipitators in the shallow part. 

Lower amounts of solid carbonate together with the steep topography of the upper slope worsen the 

identification of seeps from side scan imagery in the shallow area.

72 


Modelling of fluid overpressure beneath a shallow marine gas hydrate province: Hikurangi 

Margin, New Zealand 

G. J. Crutchley 1 , I. A. Pecher 2 , S. Geiger 2 , A. R. Gorman 1 , S. A. Henrys 3 

1 Department of Geology, University of Otago, PO Box 56, Dunedin 9054, New Zealand 

2 Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh EH14 4AS, UK 

3 GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand 

The crest of Rock Garden, a shallow bathymetric expression within New Zealand’s Hikurangi Margin gas 

hydrate province, is eroded close to the top of the regional base of gas hydrate stability (BGHS). This suggests a 

strong link between the gas hydrate system and slope failure (Pecher et al., 2005). Ten high-resolution 2D 

seismic lines, acquired over Rock Garden in 2006 as part of a specialised gas hydrate research cruise, reveal 

numerous pockets of gas close to the seafloor. They manifest seismically as regions of anomalous amplitudes, 

and are focused mostly beneath the predicted BGHS (e.g. Figure 1 - examples from north-eastern Rock Garden). 

This suggests that gas may be at least partially trapped by a permeability contrast between sediments below (free 

of gas hydrate) and sediments above (partially saturated with gas hydrate, reducing permeability). The gas 

pockets have the potential to contribute excess fluid pressure and ultimately load pre-existing structures or intact 

sediments to failure. We are currently conducting 2D finite element modelling to determine the sensitivity of the 

system to the gas pockets and to permeability contrasts at the BGHS. Our first models are aimed at determining 

which conditions cause sufficient over-pressure for failure by hydro-fracturing. Initial results show how 

important the permeability contrast is to generation of overpressure at the BGHS. Partial saturation of free gas 

within these pockets adds only a minor contribution to the excess fluid pressure. Failure by other modes, such as 

reactivation of pre-existing faults, will also be considered. 

Fig. 1. Oblique view looking down on the north-eastern reaches of Rock Garden. (A): Sub-figure showing the 

tectonic setting of New Zealand and the position of Rock Garden - marked by the ‘X’. (B): Sub-figure showing 

bathymetry of north-eastern Rock Garden, with the seafloor reflections of five seismic lines overlain. (C): The 

main figure displaying seismic data from the lines shown in (B) by stripping away the bathymetry – the field of 

view is the same as in (B). The seafloor is highlighted white, the interpreted BGHS is marked by the broken 

black line, and major gas pockets are marked. 

A first assessment of the relationship between sedimentation rates, organic matter preservation, 

and gas generation; Ría de Vigo, NW Spain 

E. de Blas 1 , D. Zúñiga 2 , J. Iglesias 3 , F. Alonso-Pérez 2 , N. Martínez 3 , E. Anfuso 2 , C. G. Castro 2 , S. García-Gil 3 

1 Dpt. Biología Vegetal y Ciencia del Suelo, University of Vigo, Spain 

2 Instituto de Investigacións Mariñas (IIM), CSIC, Vigo, Spain 


Ría de Vigo is one of the Galician Rías Baixas, four embayments which lie near the northern boundary of the 

NW African coastal upwelling system. From May to October prevailing winds cause the upwelling of nutrientrich 

Eastern North Atlantic Central Waters on the continental shelf and into the rías, promoting a massive 

increase in phytoplankton biomass. Primary production rises to an average of 1.4 g C.m -2 .day -1 (range 0.1 to 3 g 

C.m -2 .day -1 ) according to 14 C measurements. This high primary production enables the Rías Baixas to support


the highest mussel production in Europe (~243 x 10 6 kg.y -1 of edible mussels). Mussel farming seems to alter the 

trophic network of the rías’ ecosystem, and affects the environmental conditions of the seabed providing suitable 

conditions for methanogenesis close to the seabed. 

In this study, comparisons are made between the sedimentation rates, the preservation of organic matter, and gas 

generation at two sites in the Ría de Vigo. One site is located in an area which has been occupied by mussel 

rafts for approximately the last 50 years. In the core collected adjacent to a raft there is a clear boundary 

between the normal ría sediments and the relatively under-compacted sediments resulting from mussel farming; 

this anthropogenic-mediated sediment is approximately 60-80 cm thick. Deeper within this core gas voids are 

present, supporting the interpretation of acoustic turbidity on high resolution seismic profiles as gas. At the 

control site, outside the mussel farming area, there are no such voids and there is no acoustic turbidity. 

Sedimentation rates and the rates of deposition of particulate organic carbon (POC) were estimated using 

sediment traps deployed during the autumn, winter and spring seasons (Fig. 1). Core sample data provide total 

organic carbon (TOC), and oxidation/reduction potential (Eh; Fig. 2). 

The total sedimentation rate based on sediment trap data is higher beneath the mussel rafts (~1.32 and 2.35 

cm.yr -1 during the autumn and winter, respectively) compared to the control site (~0.17 cm.yr -1 for each of the 

two seasons). Although the rate of accumulation of POC beneath the rafts (accumulation rates average: ~2,180 

mg.m -2 .d -1 ) is high compared to the control site (1,037 mg.m -2 .d -1 ), this equates to only 4.8% of the total 

sedimentation compared to 17.5% at the control site. 

At the control site the majority of the organic matter at and near the seabed is utilised under the prevailing 

sulphate reduction conditions (Eh 0 to -150 mV). In consequence the TOC preserved in the sediment is

74 


Controlling factors on the morphology and spatial distribution of hydrocarbon-related tubular 

concretions – study of a Lower Eocene seep system 

E. De Boever 1 , M. Huysmans 1 , R. Swennen 1 , P. Muchez 1 , L. Dimitrov 2 

1 K.U.Leuven, Department of Earth and Environmental Sciences. 3001 Heverlee (Leuven), Belgium 

2 Institute of Oceanology (IO-BAS), P.O. Box 152, 9000 Varna, Bulgaria 

Tubular, calcite-cemented sandstone concretions, which are exceptionally well exposed in the Pobiti Kamani 

area (Varna, Bulgaria) are the subsurface geological product of Lower Eocene methane-related fluid migration. 

Tubular concretions were classified in five field-based morphological types and the position of individual tubular 

concretions, together with their characteristics, were mapped in detail on a scale of several 100m² at three 

selected locations. Concretion growth and morphology were primarily controlled by a buoyancy-driven, 

vertically upward directed fluid flow through the rather homogeneous sandy host sediments. Their morphology 

was additionally influenced by differences in the depositional/diagenetic fabric affecting the fluid path and 

assumed changes in the fluid flux. 

GPS-mapping of the positions of tubular concretions within individual clusters (fig. 1) strongly suggests that 

focused fluid migration is controlled by the Paleogene structural framework whereby the detailed spatial 

distribution of the tubes mimics the typical geometry of deformation structures in fault damage zones in loose 

sediments. A geostatistical data analysis of tube contour data confirms the spatial cluster structure. The 

directions of maximal spatial correlation of “tube contours” (m) (over distances >100m) are interpreted as an 

indication for the continuity of fluid flow characteristics over a certain distance and time along specific 

lineations. 

Fig. 1: Strashimirovo group. (A) Cluster geometry and mapped tubular concretions with indication of tube 

type. (B) Rose diagram of the strikes of connection lines between two distinct tubular concretions. (C) 

Experimental and modelled omnidirectional variogram (n = 126; lag distance = 15m) demonstrates the 

presence of a spatial structure in the distribution of tubular concretions.


Mapping of vent-related structures with multi-frequency seismo-acoustic profiling 

at the Makran Continental Margin, offshore Pakistan 

N. Fekete 1 , M. Bruening 1 , F. Ding 1 , T. Schwenk 1 , V. Spiess 2 

1 Research Centre Ocean Margins (MARUM), Bremen, Germany 

2 Department of Earth Sciences, University of Bremen, Germany 

A multi-frequency seismo-acoustic dataset was collected offshore Pakistan in October 2007. The margin wedge, 

which is covered by a uniquely thick pile of sediments, was surveyed from the shelf edge to the abyssal plain by 

various geophysical profiling tools including sediment echosounder, side scan sonar, and a high-resolution 

multichannel seismic system. On our poster we present first results with special focus on subsurface structures 

and gas accumulation and their relevance for margin dewatering. 

The primary aim of investigations was to identify, and map, recently active fluid and gas vent locations. While 

such are well-known to occur at tectonically active areas such as the Black Sea or the Middle America 

Subduction Zone, the influence of such a thick sedimentary cover on the fate of fluids and the nature of 

expulsion has been a matter of speculation. 

Another intriguing scientific goal concerns the structure and dynamics of Makran vent sites. Their variation as a 

consequence of local seafloor features such as nearby faults, canyons, and slumps, is studied in detail. 

The data indicate the presence of over a dozen active gas and fluid seep sites on the Makran accretionary margin. 

They are manifested in form of gas flares in the water column, seafloor locations of high backscatter, shallow 

gas accumulations within the sediments, and active pathways along tectonic boundaries, often in connection with 

one another. Seeps occur along the entire surveyed area from the shelf edge to the proto deformation zone in as 

much as 3000 m water depth. Investigations show that intense deformation allows upward gas migration 

especially near the lower-slope ridges, where gas enters the gas hydrate stability field locally. 

The unique dataset of simultaneously acquired side scan and seismic profiles allows joint geological 

interpretation and thus contributes significantly to our present understanding of this tectonically unique setting. 

Mature hydrocarbons in Fe-Mn nodules from the Gulf of Cadiz: deep-seated fluids migration, 

bacterial activity and biomineralization products 

F.J. González 1 , L. Somoza 1 , T. Torres 2 , J.E. Ortiz 2 , R. Lunar 3 and J. Martínez-Frías 4 

1 Geological Survey of Spain (IGME). Madrid, Spain 

2 Laboratorio de Estratigrafía Biomolecular (ETSIM/UPM). C/ Ríos Rosas 21, Madrid, Spain 

3 Facultad de Ciencias Geológicas (UCM). Madrid, Spain 

4 Centro de Astrobiología (CAB/CSIC/INTA). Madrid, Spain 

During the Tasyo Project cruises extensive fields of ferromanganese nodules were discovered at the base and 

flanks of carbonate-mud mounds and mud volcanoes along the Guadalquivir Diapiric Ridge (Central eastern 

Atlantic). The presence of biomarkers has been detected based on semi-quantitative analyses, over powdered 

samples of the oxide layers and nuclei from ten nodules. Extracts from Fe-Mn nodules were analyzed using Gas 

Chromatography (GC) and carbon isotopic analyses were done using Gas Chromatography-Combustion-Isotope 

Ratio Mass Spectrometry (GC-C-IRMS). 

The ferromanganese nodules are tabular to irregular in shape, and show an internal structure characterised by a 

layered disposition of Fe-Mn oxides surrounding a carbonated nucleus. Only in some samples is possible 

distinguish clearly their cores and layers. Fe-Mn layers and carbonated nucleus display the same microtextural 

features, composed by zoned rhombohedral crystals (authigenic Fe-Mn oxides in layers, and siderite to 

rhodochrosite in the nuclei) surrounded by detrital grains (silicates) and framboidal associations (fresh pyrite or 

totally pseudomorphised by goethite). The centers of the rhombohedral crystals are enriched in manganese and 

their exterior edges are iron enriched for both, Fe-Mn oxides and Fe-Mn carbonates. Fe-Mn oxides exhibit 

filamentous and bulbous textures that could have been generated by microorganisms mediation. 

The nodules hold in their oxide layers hydrocarbons (n-alkanes) derived from marine bacterial activity, also with 

presence of aromatic hydrocarbons as phenanthrene and antracenes, characteristic of mature petroleum. The 

mean value for TOC in bulk samples is 1.12% with contents ranging between 0.33 and 3.85%. Both, nucleus and 

oxide layers present presence of the same biomarkers. Gas chromatograms of the total hydrocarbon fraction 

show similar pattern in all the studied samples, comprising a modal n-alkane distribution with a first 

concentration maximum at n–C18 and an important presence at n-C16 and n-C20. Pristane and phytane and/or 

crocetane (2, 6, 11, 15-tetrametilhexadecano) are present in all the samples analysed. The chromatograms show a 

convex morphology known as unresolved complex mixture (UCM), characteristic of samples which have 

underwent an intense degree of marine microbial degradation. The lack of n-alkanes with large chains (>n-C25)

76 


suggest absence or low input of terrestrial organic matter, or their intense degradation by bacterial activity. 

Moreover, the carbon preference index (CPI) ranges from 0.66 to 1.15, which is also characteristic of mature 

samples. In addition, phenanthrene and antracene were detected in all the nodules analysed, being this substance 

not biological in origin, only occurring in petroleum and coals with a high mature degree. Isotopic values of δ 13 C 

of these compounds range between -20 and -37 per mil (vs. PDB) supporting the idea of deep thermal 

maturation. 

Fatty acids are detected in all the nodule samples being composed by saturated acids (C14-C18) which indicates a 

recent bacterial origin. Organic sulphur has been detected in the nucleus of one of the two nodules analysed, 

indicating sulphate-reducing bacterial activity. Esqualene is present in nuclei and oxide layers and it is a lipid 

present in archaea. 

Bacteria-mediated oxidation of hydrocarbons and organic matter through Mn 4+ and Fe 3+ reduction, might be 

related to the precipitation of Fe-Mn carbonates, forming siderite-rhodochrosite concretions bellow the redox 

boundary within the mud-breccia extruded sediment, that later were transformed into ferromanganese-oxide 

nodules by exhumation and exposition to the sea bottom oxidising waters. Mature hydrocarbons discovered into 

the Fe-Mn nodules could be fuelled by fluid migration from deep-seated sources along the fracture systems. 

The deep water gas seeps in Lake Baikal 

N. G. Granin 1 , M. M. Makarov 1 , R. Yu 1 , Gnatovsky 1 , K .M. Kucher 1 

1 Limnological Institute SD RAS, Irkutsk, Russia 

The gas escapes from the bottom are known in Lake Baikal since the XXVII century. Some shallow-water 

methane escapes were investigated during the 1920-1970s. After the methane gas hydrates have been discovered 

in Baikal sediments in late 1990s, the interest to study gas seeps was newly recommenced. Our systematic 

observations performed during 2005-2008 allowed us discovering in the first time the deep-water methane 

escapes from the bottom. Their manifestation is exemplified by the highest gas flare shown on Fig. 1, left. 

The water depth at the sites of these seeps occurrence ranges 400 to 1400 m, the flare heights varies 100 to 900 

m. The deep-water gas seeps were found in different regions of the lake, their locations are shown by numbers 

on Fig. 1, right. During 2005-2006, deep-water gas flares were registered in Central Baikal: near the mud 

volcano “St. Petersburg” (1) and near the Ludar’ cape (2); near the Gorevoi Utes cape (3), both gas and oil 

escapes were recorded. In Southern Baikal, the deep-water gas seeps were discovered a few kilometers offshore 

opposite the mouths of the Mishikha (4) and the Snezhnaya (5) Rivers. In 2007, new deep-water gas seeps were 

found near the city of Nizhne-Angarsk (6), on S-E slope of the underwater Academician Ridge (7), on the crosssection 

the Anga River – the Sukhaya River (8), near Krasnyi Yar (9) and Kadilny (10) capes. The deep-water 

gas seeps were discovered both in the lake’s regions characterized by BSR existence and outside such areas. 

Fig. 1. Echogram of the highest (900 m) gas flare recorded near the mud volcano “St. Petersburg”(left) and a 

scheme of deep water gas seeps location in Lake Baikal (right) 

Some of the deep-water gas escapes (for example, near mud volcano “St. Petersburg”, near the Gorevoi Utes 

cape) were systematically observed during long period of time, whereas other ones were once registered (for 

example, near the Ludar’ cape). It was recorded on a satellite image that a ring structure of 6 km in diameter has 

appeared on the ice near the Krestovskii cape (Central Baikal) on April 6, 2003 (Fig. 2, left). We suggest that its 

appearance is related to substantial gas eruption from the bottom. Such eruption has to lead to rising of isopycnic


surfaces and further formation of dome-shaped density structure. As a result, ring cyclonic water current has to 

be generated under the ice. In the zone of the highest current velocities, a vertical water exchange increases and 

the ice thickness rapidly decreases (or the ice is partly destructed). This process may be reflected as a ring 

structure on the ice surface. Careful examination of available satellite images allowed us to establish similar 

structures formed on the ice at the same region on April 1999, 2005, and 2008. Analogous ring structures were 

also observed on the ice opposite the Turka River mouth (April 2008) (Fig. 2, right) and in the northern part of 

Maloe More strait (May 2004, 2005). 

Both the deep-water methane escapes from the bottom and the ring structures regularly appearing on the ice 

surface may testify to the present activity of mud volcanoes in Lake Baikal. To evaluate contribution of different 

factors (seismic activity, fluctuations of the lake level, etc.) into such activity, continuous observations need to 

be organized in the future. 

. 

Fig. 2. The ring structures on the Baikal ice recorded near the Krestovskii cape in April 2003 (left) and April 

2008 (right). 

Regional characteristics of isotopic composition of gas hydrates in Lake Baikal 

A. Hachikubo 1 , O. Khlystov 2 , T. Zemskaya 2 , A. Krylov 1,3 , H. Sakagami 1 , H. Minami 1 , Y. Nunokawa 1 , H. Shoji 1 , 

S.Nishio 4 , M. Kida 5 , T. Ebinuma 5 , G. Kalmychkov 6 , J.Poort 7 

1 Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507, Japan 

2 Limnological Institute, SB RAS, 3 Ulan-Batorskaya St., Irkutsk 664033, Russia 

3 Present address:All-Russia Research Institute for Geology and Mineral Resources 

4 Shimizu Corporation, 3-4-17 Etchujima, Koto-ku, Tokyo 135-8530, Japan 

5 Advanced Industrial Science and Technology, 2-17-2-1, Tsukisamu-Higashi, Sapporo 062-8517, Japan 

6 Vinogradov Institute of Geochemistry, SB RAS, 1-a Favorsky St., Irkutsk 664033, Russia 

7 Renard Centre of Marine Geology, Ghent University, Krijgslaan 281-S8, Ghent B-9000, Belgium 

Gas hydrates are crystalline clathrate compounds composed of water and gas molecules that are stable at low 

temperature, high partial pressure of each gas component, and high gas concentration. Ten years ago natural gas 

hydrates were retrieved for the first time from the sublacustrine sediments of Lake Baikal and since then the 

specifics of their formation process has been discussed by researchers. In an <strong>international</strong> collaborative 

investigation program of Lake Baikal with the Limnological Institute SB RAS, Russia, since 2002, we collected 

new gas hydrate samples from the lake bottom sediment in the following mud volcanoes and methane seep sites: 

Malenky, Bolshoy, Malyutka, Peschanka, Goloustnoye Flare and Kukuy K-0 & K-2. Our study focussed on the 

isotopic composition of guest gas in gas hydrates in order to understand their formation process and gas origin. 

Whiticar et al. (1986) proposed a genetic classification diagram for natural gas using δ 13 C and δD of methane. In 

the diagram, large and small δ 13 C values of methane indicate thermogenic and mic robial origins, respectively, 

and δD of methane provides information on methyl-type fermentation or CO2 reduction in the microbial region. 

Kida et al. (2006) concluded from isotopic signatures of Kukuy gas hydrates that the guest gas is of microbial 

origin due to methyl-type fermentation and contains thermogenic methane and ethane. For the isotopic analyses 

of carbon and hydrogen, a continuous flow-isotope ratio mass spectrometer (CF-IRMS, DELTA plus XP; 

Thermo Finnigan) was used. Methane δ 13 C and δD of all observation sites were in the range of -70 to -55 ‰ and 

-330 to -300 ‰, respectively, and indicated a microbial origin produced by methyl-type fermentation. Methane

78 


δ 13 C of Kukuy K-2 mud volcano was rather large (from -60 to -55 ‰) and contained much ethane. Goloustnoye 

Flare, where gas hydrate discovered in 2007, also showed high concentration of ethane and similar isotopic 

compositions of methane and ethane to those in Kukuy K-2, respectively. In the profiles of methane and ethane 

δ 13 C hydrate gas seemed to be several permil smaller than the gas in dissolved pore water, whereas Hachikubo et 

al. (2007) reported undetectable fractionation in δ 13 C at the formation of methane and ethane hydrates. We 

conclude that the hydrate gas of Kukuy K-2 and Goloustnoye Flare is mainly microbial origin and partly 

contains thermogenic methane and ethane. A new diagram of ethane δ 13 C and δD shows regional characteristics 

and provides information on how these hydrocarbons accumulate in the lake bottom sediment. 

Isotopic composition of gas hydrates obtained from offshore Sakhalin, 

the Sea of Okhotsk 

A. Hachikubo 1 , A. Krylov 1,2 , H. Sakagami 1 , H. Minami 1 , Y. Nunokawa 1 , H. Shoji 1 , Y. K. Jin 3 , A. Obzhirov 4 

1 Kitami Institute of Technology, Kitami 090-8507, Japan 

2 Present address: All-Russia Research Institute for Geology and Mineral Resources 

of the Ocean, St.Petersburg 190121, Russia 

3 Korea Polar Research Institute, KORDI, Yeonsu-gu, Incheon 406-840, Korea 

4 V.I. Ilíchev Pacific Oceanological Institute FEB RAS, Vladivostok 690041, Russia 

Gas hydrates are crystalline clathrate compounds composed of water and gas molecules that are stable at low 

temperature, high partial pressure of each gas component, and high gas concentration. New hydrate-bearing 

seepage structures offshore Sakhalin, the Sea of Okhotsk, have been investigated from 2003 to 2006 within the 

framework of the CHAOS project (hydroCarbon Hydrate Accumulations in the Okhotsk Sea). We retrieved 

hydrate-bearing sediments by using a gravity corer on October 2003, May 2005 and May 2006 (CHAOS1, 

CHAOS2 and CHAOS3, respectively). Whiticar et al. (1986) proposed a genetic classification diagram for 

natural gas using methane isotopes. In the diagram, large and small δ 13 C values of methane indicate thermogenic 

and microbial origins, respectively, and δD of methane also provides information on methyl-type fermentation or 

CO2 reduction in the microbial origin. Isotopic compositions of carbon and hydrogen were measured by using a 

continuous flow-isotope ratio mass spectrometer (CF-IRMS, DELTA plus XP; Thermo Finnigan). Methane δ 13 C 

and δD were in the range -65 to -62 ‰ and -205 to -195 ‰, respectively. These results indicate a microbial 

origin produced by CO2 reduction according to Whiticar's diagram. Regional characteristics of isotopic 

composition were also found between each seepage structures. In the depth profile of isotopic composition 

between hydrate gas and the gas in dissolved pore water seemed to be the same in the case methane δ 13 C, 

whereas less than 10 ‰ difference between them was found in methane δD. Hachikubo et al. (2007) reported 

that δD of hydrate-bound molecules of methane hydrate was several ‰ lower than that of residual gas molecules 

in the formation processes, while there was no difference in the case of δ 13 C. Ethane concentration in the gas 

samples was 30-150ppm for hydrate-bearing sediments and 10-100ppm for non-hydrate sediments, and 

depended on each seepage structure. We discussed the formation process of gas hydrate in the shallow sediment 

cores according to the experimental results of isotopic fractionation at the formation of gas hydrates. 

The origin of the Nyegga Pockmark Field on the Norwegian continental margin 

B. O. Hjelstuen 1 , H. Haflidason 1 

1 Department of Earth Science, University of Bergen, Allegt 41, 5007 Bergen, Norway 

TOPAS high-resolution seismic profiles and EM1002 bathymetric data, collected during a R/V G.O. Sars cruise 

in 2007, confirm that slope deposits in the Nyegga area on the south Vøring Plateau, Norwegian margin, are 

intensively perforated by pockmarks. More than 200 seabed depressions have been identified. The features have 

diameters of up to 200 m, maximum depths of c. 10 m, and they are situated in an area where gas hydrates and 

pre-Pliocene polygonal faults are found. The largest, and most complex, pockmarks are found along the rim of 

the hydrate reservoir. Shallow cores indicate that some of the pockmarks are active at present. The pockmarks 

have evolved within a sedimentary package that is characterized by glacimarine and hemipelagic well-layered 

deposits. Glacigenic debris flow units, deposited during shelf edge glaciations, interfinger these sediments on the 

upper slope. The well-layered sediments are delivered to the continental slope by icebergs, suspension fall-out in 

front of an ice margin and from meltwater plumes released during the disintegration of the Fennoscandian Ice 

Sheet. The sediment rates may have been as high as 35 m/ky during deposition of these sediments. Our findings 

suggest a relation between the Nyegga Pockmark Field and the observed gas hydrate reservoir. However, we 

note that the pockmarks only are found in a very limited area of the 3000 km 2 large South Vøring Plateau gas 

hydrate region. We ascribe this to local variations in sediment characteristics.


Preparative model-study for a CSEM-experiment at the North Alex mud volcano 

S. Hölz 1 and M. Jegen 1 

1 IFM-GEOMAR, CAU-Kiel, Wischhofstr. 1-3, 24148 Kiel 

Marine controlled source electromagnetic (CSEM) has proven to be a feasible geophysical method for the 

investigation of the subsurface's conductivity structure of the seafloor. The bulk conductivity of seafloor 

sediments is mainly a function of porosity and connectivity of the pore fluid, i.e. seawater, and is decreased 

where electrically insulating free gas and/or gas hydrates form in sufficient quantities. 

We plan to use CSEM to image porosity and fluid and gas contents at the North Alex mud volcano located in the 

outer reaches of the West-Nile-Delta. Due to the small scale of the mud volcano (1.5 km in diameter) and safety 

consideration (seafloor communication cables) we have opted to develop a compact transmitter which is moved 

along the seafloor by a ROV together with stationary electric field receivers on the seafloor. The design of the 

CSEM receivers is based on the existing IFM-GEOMAR OBMT (ocean bottom magnetotelluric) stations. 

We performed a straight forward 1D modeling study to derive specifications for the transmitter and to assess 

necessary modifications for the receivers. Within the study, the achievable depth of penetration for various 

measurement geometries (i.e. transmitter-receiver separations) was estimated by calculating the 1D sensitivity 

for two and three layered models. Summarizing the results, it can be stated that a small transmitter system with a 

dipole moment of approximately 200Am (20A output into a 10m dipole) is suitable to generate detectable 

signals for transmitter-receiver separations of up to 250-350m. Depending on the separation, the resulting depth 

of penetration is between a few meters up to approximately 100-200m. 

The first deployment of the new CSEM-system is scheduled during the field experiment in the West-Nile-Delta 

in November 2008. The CSEM-experiment will be complemented by a simultaneous MT- and MMRexperiment, 

which cover the deeper conductivity structure of the North Alex. 

Hydrocarbons of Lake Baikal (Eastern Siberia) 

O. Khlystov 1 

1 Limnological Institute, SB RAS, 664033 Irkutsk, Russian Federation 

Lake Baikal is the largest and oldest water body on the globe. During its long geological development (>25 My), 

more than 7 km of sediments saturated with organic matter accumulated. This matter was transformed with time 

into hydrocarbons of different types. Natural gas in free, dissolved and solid (gas hydrates) state, as well as oil 

are found in the lake sediments. 

Gas and oil seeps in shallow water in Lake Baikal are known since its first descriptions in XVII-XVIIIth 

centuries. First laboratory investigations in the last century showed that methane occurs more often than other 

gases. The oil from Lake Baikal is heavily biodegraded, which makes it difficult to determine its age and 

genesis. The idea on possible availability of gas hydrates in lake sediments was declared for the first time in 

1980. In 1989, geophysical indications for gas hydrates (BSRs) were found. In 1997, first proofs of hydrate 

occurrence were obtained by deep drilling at subbottom depths of >120 m. In 2000, first agglomerations of gas 

hydrates were found in the near-bottom sediments (subbottom depth of

80 


experience in gas hydrates research and investigations allow us to continue not only large-scale basic research, 

but also testing of instruments and equipment for their studies and technology of gas exploration from subaquatic 

nearsurface hydrates. 

References 

Kalmychkov G. V., Egorov A. V., Kuz’min M. I.., Khlystov O.M. Genetic Types of Methane from Lake Baikal 

// Doklady Earth Sciences, 2006. V. 411A. No. 9. P. 1462–1465. 

Kida M., Khlystov O., Zemskaya T., et al Coexistence of structure I and II gas hydrates in Lake Baikal 

suggesting gas sources from microbial and thermogenic origin // Geophysical Research Letter, 33. 

L24603. 2006. doi:10.1029/2006GL028296. 

Khlystov O. M., Gorshkov A. G., Egorov A. V. et al. Oil in the Lake of World Heritage // Doklady Earth 

Sciences, 2007. Vol. 415. No. 5. P. 682–685. 

Crystal size distributions of naturally occurring gas hydrates 

S. A. Klapp 1 , S. Hemes 2 , H. Klein 2 , G. Bohrmann 1 , W. F. Kuhs 2 and F. Abegg 1 

1 MARUM, University of Bremen, PO Box 330440, 28334 Bremen, Germany 

2 GZG, Abt. Kristallographie, Universität Göttingen, Goldschmidtstrasse 1, 37077 Göttingen 

Gas hydrates are considered to host a large reservoir of volatile hydrocarbons. Hydrates crystallize at sites of gas 

seepage both from gases percolating through pore space as well as from pore waters. 

Many gas hydrate-related processes involve the hydrate surface area or grain boundaries, for instance gas 

exchange reactions, mass transport or hydrate dissociation. But due to experimental difficulties, size distributions 

of gas hydrate crystallites are largely unknown in natural samples. 

Here, we report on crystallite size distributions of several natural gas hydrates for samples retrieved from the 

Gulf of Mexico, the Black Sea and from Hydrate Ridge offshore Oregon from varying depth below the sea floor. 

High-energy synchrotron radiation provides high photon fluxes as well as high penetration depth and thus allows 

the investigation of bulk sediment samples. The gas hydrate crystallite sizes measured with a newly developed 

diffraction technique, utilizing the excellent beam collimation, appear to be (log-) normally distributed in the 

natural samples and to be of roughly globular shape. This could be confirmed by measurements conducted on 

differently positioned and rotated samples. 

The mean crystallite sizes are typically in the range from 200-300 µm for hydrates recovered from near the sea 

floor while a tendency for bigger grains was noticed in greater depth for the Hydrate Ridge samples, indicating a 

difference in the formation age or formation process. Laboratory produced methane hydrate, starting from ice 

and aged for 3 weeks, shows half a lognormal curve with a mean value in the order of 40µm. This one order-ofmagnitude 

smaller grain sizes suggests that care must be taken when transposing crystallite-size sensitive (petro- 

) physical data from laboratory-made gas hydrates to natural settings. 

Regulation of anaerobic oxidation of methane in diffusive sediments of the Black Sea 

N. J. Knab 1,2 , B. Cragg 3 , E. Hornibrook 4 , R. J. Parkes 3 , C. Borowski 1 , B. B. Jørgensen 1 

1 Max-Plank Institute for Marine Microbiology, Department of Biogeochemistry, Bremen, Germany 

2 University of Southern California, Department of Biological Sciences, Los Angeles, USA 

3 Cardiff University, School of Earth, Ocean & Planetary Sciences, Cardiff, Wales, U.K. 

4 University of Bristol, Department of Earth Sciences, Bristol, U.K. 

Anaerobic oxidation of methane (AOM) and sulfate reduction (SRR) were investigated in sediments of the 

western Black Sea, where methane transport is controlled by diffusion. To understand the regulation and 

dynamics of methane production and oxidation in the Black Sea, rates of methanogenesis, AOM, and SRR were 

determined using radiotracers in combination with pore water chemistry and stable isotopes. On the shelf of the 

Danube paleo-delta (P771GC) and the Dnjepr Canyon (P806GC), AOM did not consume methane effectively 

and upwards diffusing methane created an extended sulfate-methane transition zone (SMTZ) that spread over 

more than 2.5 m and was located in formerly limnic sediment. Measurable AOM rates occurred mainly in the 

lower part of the SMTZ, sometimes even at depths where sulfate seemed to be unavailable. The incomplete 

oxidation of methane in the major AOM zone and resulting methane tailing is a common feature of diffusion 

dominated methane rich sediments of the western Black Sea. The reason for the sluggish and inefficiency 

oxidation seems to be related with the location of the SMTZ inside the sediment with a limnic history (below the


marine deposits shaded in grey in the figure) since in all cores methane was completely oxidized at the limnicmarine 

transition. 

The upward tailing of methane was less pronounced in a core from the deep sea in the area of the Dnjepr Canyon 

(P824GC), the only station where the SMTZ was located close to the marine-limnic boundary and where the 

limnic sediment was covered by a thick layer of marine deposits. The importance of the limnic-marine boundary 

depth from top of core in cm 

P806GC 

SO 4 2- in mM 

0 5 10 15 20 

CH4 in mM 

0.0 0.5 1.0 1.5 2.0 

0 

50 

100 

150 

200 

250 

300 

CH4 

SO4 2- 

H2S in mM 

0 1 2 3 4 5 

DIC in mM 

0 5 10 15 20 25 

H2S 

DIC 

depth from top of core in cm 

was further indicated by the restriction of heterotrophic SRR to the marine deposits in P824GC. Sulfate 

reduction rates were mostly extremely low, and in the SMTZ they were even lower than AOM rates. 

Rates of bicarbonate-based methanogenesis were below detection limit in two of the cores, but δ 13 C values of 

methane indicate a biogenic origin. In contrary to the typical increase in δ 13 C-CH4 due to δ 12 C CH4 utilization in 

the AOM zone the stable isotopes became lighter in the SMTZ of the core from the deep sea suggesting that 

methanogenic recycling of δ 13 C-depleted CO2, derived from AOM, occurred in this core in contrast to P771GC 

and P806GC. Such a methane cycling in the AOM zone might be based on higher levels of organic matter at the 

site of P824GC. In contrary, at the sites where the SMTZ is located in the originally limnic sediments it might be 

suggested that methanogenesis above the AOM zone could result in a tailing of the methane profile, which 

would be consistent with the data from P806GC but could not be confimed at P771GC. 

Occurrence of authigenic gypsum, pyrite and carbonate mineralization in the sediments of 

Mahanadi off shore basin eastern continental margin of India: An indirect proxy to locate the 

presence of sub-surface gas hydrates in unknown marine sediments? 

M. Kocherla 1 

1 National Institute of Oceanography, Goa, India. 

About10 sediment cores (~30m length) in the gas hydrate prone sediments have been collected in the water 

depths between 400 and 1866 m in the off shore regions of Mahanadi basin in Eastern continental margin of 

India using Marion Dufresne in April 2007. Microscopic examination of 110 sub-samples from 10 selected 

sediment cores showed the occurrence of authigenic gypsum crystals, micro concretions, crystal aggregates, inter 

growths along with abundant pyrite and carbonate mineralization. 

XRD patterns and EDS analyses show that, all the crystals have typical peaks, and the typical main chemical 

compositions of gypsum. Microscopic and SEM observations show that the gypsum crystals have clear crystal 

boundaries, planes, edges and cleavages of gypsum in form either of single crystal or of twin crystals. 

In view of the fact that there are abundant pyrite nodules, slabs, tubes, and chimneys interspersed with authigenic 

gypsums cemented with authigenic carbonates, it could be inferred reasonably that the gypsums also formed 

authigenically in the gas hydrate-prone environment, most probably due to pyrite oxidation, and anaerobic 

methane oxidation. Striking authigenic morphology of gypsum crystals, along with abundant pyrite, and 

authigenic carbonates, accompanied with detrital components, indicate that they are precipitated most likely in 

same sulfate rich interstitial water dynamic environments. So, the distinct authigenic gypsum crystals found in 

gas hydrate-prone sediments from Gas hydrate survey area could also be considered as one of the parameter 

which could be used to indicate the presence of sub-surface gas hydrates in an unknown marine environment. 

Further studies are in progress for comprehensive understanding of the process involved in the Indian continental 

margins of India. 

100 

200 

300 

400 

P824GC 

SO 4 2- in mM 

0 5 10 15 20 

CH4 in mM 

0.0 0.5 1.0 1.5 2.0 

0 

SO4 2- 

CH4 

H2S 

H 2 S in mM 

0 1 2 3 4 5 

DIC in mM 

0 5 10 15 

DIC

82 


Fig. 1: Typical Characteristic crystals of Gypsum: Gypsum (Selenite) with Lenticular shape (a), Gypsum 

(Selenite) Variety (b), Gypsum Rosette with euhedral crystals (C), Intergrowths of Gypsum crystal (d), Cluster 

of Bladed Gypsum crystals (e), Complex aggregates Gypsum crystals (f). 

Fig. 2: Typical Characteristic crystals of Gypsum: Gypsum (Selenite) with Lenticular shape, with authigenic 

carbonate cements (a&b), cubical pyrite crystals in anaerobic sediments (c), co-occurrence of authigenic 

gypsum, pyrite with carbonate cementations (c). 

New data of fluids migrations on Shatskiy ridge in the Black Sea 

R. Kruglyakova 1 , V. Artemenko 1 , N. Shevtsova 1 

1 Federal Scientific Centre "Yuzhmorgeologiya", Ministry of Natural Resources, Russia 

In the East of Shatskiy ridge the wide complex of works including seismo-acoustic method (NSAP-OGT), 

gravity and magnetic prospecting, geothermy, geochemical studying of bottom sediments is executed. 

Gases. The seismicity of high resolution has given the opportunity of observing breaks, which are the channels 

of transit of hydrocarbon fluids from perspective complexes of a section and areas of burrowed highs to a surface 

of bottom and to plan points of sampling. At geological sampling by gravity corer (up to depth of 340 cm) 

novochernomorskie, drevnechernomorskie and novoevkinskie sediments are revealed. 100 stations with the 

analysis of hydrocarbonic gases (HCG) in two intervals are tested. Methane is prevailing among HCG in 

structure of a gas phase of deposits with the content on 3÷5 orders higher, than its homologues. The content of 

methane changes from 0,005 up to 71,7 cm 3 /kg, average value – 4.8 cm 3 /kg. The area as a whole is characterized


by high content of methane. Deposits of the Black Sea abyssal are characterized by low content of all 

homologues of methane. The total content of light homologues of methane averages 0,276x10 -3 cm 3 /kg (a 

maximum-1,37x10 -3 cm 3 /kg), heavy homologues - 0,045x10 -3 cm 3 /kg (a maximum - 0,44x10 -3 cm 3 /kg). Among 

light homologues ethane prevails. 

Attributes of oil and gas presence are expressed in geochemical anomalies of methane of the "mixed" type where 

with methane of biogenic origin, migrated to a surface of bottom, thermogenic methane is present, and also by 

anomalies of easy and heavy methane homologues. Large breaks are emphasized by a lot of attributes of fluids 

migration. Except for geochemical anomalies, anomalies of the increased thermal stream, and also seismic 

anomalies of "bright spot" type are marked. The most numerous and contrast seismic anomalies of "bright spot" 

type are marked in the West of Shatskiy ridge. Less contrast, but more extensive seismic dynamic anomalies are 

in the East-Black Sea basin. We assume a deep gas seep at station 49, dated for a deep break, and on station 84 

(CH4=71,2 cm 3 /kg, reef high). 

Pore waters. For the first time on Shatskiy ridge pore waters research (182 samples) is carried out, deposits with 

mineralized (20÷22 g/l) and strongly freshened (12÷15 g/l) pore water are distinguished. Areas with anomalous 

high content of methane homologues are characterized by strong freshening of pore waters of sediments. It is 

possible to assume, as the freshened waters together with deep hydrocarbonic fluids rise from depths of 

sedimentary thickness. Hence, the chemical content of pore waters is an indirect attribute of migration of fluids 

from possible deposits of hydrocarbons. 

Thermal stream. Among structures of the Black Sea Shatskiy ridge have a high thermal stream (q), background 

value q exceeds on 30 %÷ 40 % the values known for Western and East deep-water basins. On Shatskiy ridge 

northwest and southeast areas are detected, the average thermal stream of which is more than 52 mV/m 2 . Local 

areas are marked by anomalies exceeding 65÷70 mV/m 2 . Two types of anomalies of thermal stream are notable. 

The first type represents the usual localized increase of thermal stream. Anomalies which in a contour of the 

increased thermal stream have an area of their lowered values (q=34÷43 mV/m 2 ) concern to the second type. The 

most contrast low geothermal parameters are in the East-Black Sea basin. Gas saturated sedimentary thicknesses 

and direct gas-bearing traps, being thermal barriers on a way of distribution of a deep thermal stream, cause 

presence of negative anomalies of geothermal parameters. 

Isotopic composition of dissolved inorganic carbon in the subsurface sediments of the gas 

hydrate-bearing mud volcanoes, Lake Baikal. 

A. A. Krylov 1,2 , O. M. Khlystov 3 , A. Hachikubo 1 , H. Minami 1 , Y. Nunokawa 1 , H. Tomaru 1 , K. Hyakutake 1 , T. I. 

Zemskaya 3 , T. V. Pogodaeva 3 , H. Shoji 1 


2 Present address: VNIIOkeangeologia, 1 Angliyskiy pr., St. Petersburg 190121, Russia 


Lake Baikal, eastern Siberia, is the largest freshwater basin in the world with a maximal depth of 1642 m (De 

Batist et al., 2002) and the only freshwater lake known to contain gas hydrates. First near-bottom methanehydrates 

were sampled at the Malenky mud volcanoes in March 2000 (Van Rensbergen et al., 2002; Klerkx et 

al., 2003; Matveeva et al., 2003). Investigations of Kida et al. (2006) indicate that the main portion of methane 

was produced due to methyl-type fermentation. The authigenic siderites were found in subsurface gas hydratebearing 

sediments of the Malenky, K-2 and Irkutsk mud volcanoes. The δ 13 C values of the siderites (+3.3 to 

+21.9‰ PDB) indicate that their formation is due to methanogenesis (Krylov et al., 2008). 

The isotopic composition of dissolved inorganic carbon (DIC) was measured in the several mud volcanoes 

(Malenky, Peschanka, Irkutsk, Goloustnoe). The δ 13 C values of the DIC are varied from the -10‰ PDB in the 

uppermost part of sedimentary section up to +20‰ PDB at the layers deeper than 1 m below lake floor. 

The oxidation of the rising CH4 in the uppermost sediments is associated with a kinetic isotope effect for carbon 

which tends to concentrate the lighter 12 C isotope in the produced CO2. As a result, the 13 C theoretically should 

be concentrated in the residual CH4. However, it is not the case for investigated sites where the DIC and CH4 

have the general tendency to be depleted in 13 C in the uppermost sedimentary layers. The reason for observed 

phenomena is not clear. Since the sulfate-reduction zone in the Lake Baikal freshwater environment is 

insignificant, we speculate that the anaerobic methane-oxidation in the near-bottom sediments is, probably, 

overwhelmed by the processes of the methane generation. 

The strong enrichment of DIC in 13 C at the layers deeper than 1 m below lake floor indicates active 

methanogenesis. The methane generation is the exact reason for the enrichments of both siderites and DIC in 

13 C.

84 


Anaerobic hydrocarbon degrading communities and their influence on AOM 

and sulphate reduction 

W. D. Leavitt 1 , S. D. Wankel 1 , H. K. White 1 , S. B. Joye 2 , P. Girguis 1 

1 Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA. 

2 Department of Marine Science, University of Georgia, Athens, GA, USA. 

Anaerobic microbial oxidation of the hydrocarbons methane through pentane (C1-C5) is a dominant source of 

carbon and metabolic energy at marine seeps. Unlike methane, however, little is known about the cycling of C2- 

C5 hydrocarbons. In marine seeps, such as those on the northern slope of the Gulf of Mexico (GOM), C2-C5 

hydrocarbons are often present at high abundances, and anaerobic microbial oxidation of these compounds is 

likely more energetically favorable than methane at seeps (Orcutt et al. 2004). While the integration of 

biogeochemistry and microbial ecology over the past decade has unraveled much of what we know about 

anaerobic oxidation of methane (AOM), little is known about the microorganisms responsible for C2-C5 

oxidation in hydrocarbon seeps (Kneimeyer et al. 2007) and no study has related their distribution, abundance, 

and activity to the observed geochemistry (e.g. concentrations and isotope ratios). In this study, we lay the 

foundations to addressing this by combining molecular microbiological and geochemical techniques to study the 

microbial ecology and biogeochemistry of anaerobic C1-C4 hydrocarbon degradation in laboratory-based 

“artificial seep” experiments (as in Girguis et al. 2003). 

To carry out continuous flow incubations in the laboratory that mimic conditions at thermogenic gas seeps, we 

designed four independent anaerobic hydrocarbon incubation systems (AHIS). The utility of the AHIS resides in 

its ability to enrich for slow-growing organisms under a continuous flow regime via constant input of nutrients 

(that stimulate growth rates beyond what is achieveable in batch reactors of equal volume) and elimination of 

waste products. 

Briefly, anaerobic hydrocarbon seep sediments from the Gulf of Mexico (1900 meters water depth) were mixed 

with quartz sand and packed into gas-tight pressure housings. Seawater equilibrated with H2S and a select 

hydrocarbon (C1 – C4) is then passed through the sediment-bead matrix at a constant rate. Here we present our 

preliminary findings with respect to shifts in microbial community composition over the course of a four month 

incubation. In addition we present geochemical analyses of pore-water conditions pre- and post-reactor, as a 

proxy for microbial activity, as well as rates of anaerobic alkane oxidation. Future work will include more 

precise quantitation of hydrocarbon oxidation rates as related to the activity of dominant ecotypes from the seepenriched 

communities. 

References 

Girguis, P. R., V. J. Orphan, S. J. Hallam, and E. F. DeLong. 2003. Growth and methane oxidation rates of 

anaerobic methanotrophic archaea in a continuous-flow bioreactor. Appl. Environ. Microbiol. 69: 5472– 

5482. 

Kniemeyer, O. et al. 2007. Anaerobic oxidation of short-chain hydrocarbons by marine sulphate-reducing 

bacteria. Nature 449, 898-901. 

Orcutt, B.N., Boetius, A., Lugo, S.K., MacDonald, I.R., Samarkin, V., Joye, S.B., 2004. Life at the edge of 

methane ice: methane and sulfur cycling in Gulf of Mexico gas hydrates. Chem. Geol. 205: 239-251 

Remote sensing of atmospheric methane from a marine seep source 

I. Leifer 1 , E. Bradley 2 , R. Cheung 2 , D. Roberts 2 

1 Marine Science Institute, University of California, Santa Barbara, USA 

2 Dept of Geography, University of California, Santa Barbara, USA 

Methane is a critically important greenhouse gas that recent studies suggest may contribute 30% of greenhouse 

warming and whose concentrations have more than doubled over the last century. Central to predicting 

methane’s impact on the global climate, as well as emission monitoring objectives, are accurate and 

comprehensive assessments of local methane sources. Remote sensing provides an ideal tool for such a 

characterization due to methane’s strong absorption in the Short Wave Infrared, which can be detected with 

appropriate sensors. This study seeks to develop techniques for high resolution methane chartography using 

shallow marine seeps as an optimal natural laboratory and test bed and the Airborne Visible Infrared Imaging 

Spectrometer (AVIRIS). 

Marine seeps provide unique opportunities including a relatively homogeneous spectral background, freedom of 

movement, and the ability to locate and quantify seep emissions through sonar surveys because bubbles are 

excellent sonar reflectors. The Coal Oil Point (COP) seep field is conveniently located near shore and features 

extreme diversity in seep emission and intensity from more than 3 km 2 of seabed. Data from preliminary surveys 

using Flame Ion Detection (FID) measurements of total hydrocarbons (THC) during transects of an active seep


area were fit to a Gaussian plume. This created a 3D model of the plume from which methane column 

abundances greater than 0.5 g/m 2 Were estimated for an area covering ~1000 m 2 . Radiative-transfer simulations 

with these column abundances indicated AVIRIS could map methane within the seep-field oceanic boundary 

layer. 

Fig. 1 A. Contour map of atmospheric methane plume from an intense area of seepage. B. Methane column 

abundances from Gaussian plume model fit to data. 

AVIRIS data were collected over the COP seep field in August 2008, and methane anomalies were successfully 

mapped. To correct for albedo variations, the 2138 nm band (largely insensitive to H2O, CO2, and CH4 

absorption) was compared between AVIRIS data and a model atmosphere calculation for the appropriate solar 

and view geometry (MODTRAN 4.3, surface albedo 10%). Residuals were calculated from the AVIRIS data and 

the best fit Modtran simulation from an albedo-specific lookup table. Signal to noise was improved by 

integrating the residuals over several bands sensitive to methane to derive a single metric. Distinct methane 

plumes were identified for the largest intense, mega seeps (10 6 cm 3 /day from direct flux buoy measurements) 

down to seeps many orders of magnitude weaker. There was good spatial agreement between the location of 

atmospheric plumes and sonar-mapped bubble plumes. 

Fig. 2 Color density -slice image of the integral of residuals between 2200 and 2350 nm for the albedo-specific 

model (for all pixels with albedos greater than 5%). Residual spectra are shown for several areas that 

demonstrated strong methane signatures and several areas that did not. Contours shown are for sonar-mapped 

bubble plume data. 

Preliminary surveys used Foxboro, OVA-88 FIDs and measured THC in the air above the seeps and assumed all 

THC was methane. These instruments also had a slow response time. These limitations were overcome for 

ground validation of aerial surveys with a four-channel FID gas chromatograph configured as a dual mudlogger 

and modified for operation on small (7-m) boats. The system provides periodic speciation of the THC. Surveys 

showed that atmospheric plumes in the seep field can be locally enhanced in some areas with higher 

hydrocarbons – namely ethane and propane. Plumes contained butane and pentane as well.

86 


Engineered bubble plumes and the study of natural marine seepage 

– a natural bubble-driven buoyancy flow 

I. Leifer 1,2 H. Jeuthe 3 , S. H. Gjøsund 4 , V. Johansen 4 

1 Marine Sciences Institute, University of California, Santa Barbara, CA, 93106, US. 

ira.leifer@bubbleology.com. 

2 Institute for Crustal Studies, University of California, Santa Barbara, CA, 93106. 

3 Norwegian College of Fishery Science, University of Tromsø, NO-9073 Tromsø, Norway. 

4 SINTEF Fisheries and Aquaculture, NO-7465 Trondheim, Norway. 

Bubble plume upwelling flows were studied in the marine environment through dye releases into engineered 

plumes and natural marine seep plumes. For engineered plumes, these experiments measured the water-column 

averaged upwelling flows, , for a wide range of flows and depths. From , the local upwelling flow, 

Vup(z), where z is depth, was calculated and agreed well with published relationships between Vup(z) and flow, Q, 

Vup~Q^ 0.23 , for plumes strong enough to penetrate the near surface thermally stratified layer. 

These data were used to interpret observations at a natural marine seep, where the upwelling flow was decreased 

towards the sea surface instead of increase as observed for the engineered plumes. Data showed a significantly 

colder and more saline upwelling flow of water being lifted towards the sea surface. The increased density 

difference between this upwelling fluid and the surrounding fluid most likely caused flow deceleration. 

Comparison of dimensions of the engineered and seep bubble-plumes and Vup estimated a total seep flow of 

similar magnitude as direct flux measurements. However, application fo the results of this study to observations 

of a blowout predicted a flux many orders of magnitude too large, indicating that other processes likely are 

important for large transient emissions. 

Blind submarine valleys in the gulf of Cadiz: Fluid flow geological structures 

R. León 1 , T. Medialdea 1 , L. Somoza 1 , J. T. Vazquez 2 and F. J. Gonzalez 1 

1 Marine Geology Dv., Geological Survey of Spain IGME, Rios Rosas 23, 28003 Madrid, Spain 

2 Instituto Español de Oceanografía IEO, Fuengirola, 29640 Málaga, Spain 

During Tasyo, Mounforce and MVSEIS cruises, blind valleys have been defined as geological structures related 

to seabed fluid flow in the Gulf of Cadiz. Blind valleys are located in the Central Sector of Tasyo Field where 

several minor channels, pockmarks, mudvolcanoes and HDAC are present. Blind valleys (Fig 1) are giant 

elongated collapses, from 3 to 10 km long, without open extremes. These valleys start and finish by pockmarks 

or sub-circular collapsed structures, thus constitute whole structure of collapse generate by fluid flow. They are 

located along normal and strike slip faults, clearly distinguished on seismic and multibeam data aligned along 

NE-SW and NW-SE. Seismic profiles show as blind valleys have diapire structures below and the faults, which 

control the blind valley structure, work as fluid path ways. 

The geological study of the crater-like structures of fluid flow in the Gulf of Cadiz allows establishing an 

evolutionary model for generation of blind valleys constituted by three stages: i) initial stage ii) progress stage, 

and c) mature stage. Initial stage is defined by the presence of single depression structures resulting from fluid 

flow, locally jointed. Single structures are mainly conic and U-shaped aligned along focused fluid flow pathways 

defined by normal and strike-slip faults. In the progress stage, pockmarks and collapses trend to alienate along 

the principal direction of faulting, generating elongated asymmetric pockmarks by the growing up and union 

with the neighbours. Finally, in mature stage, fluid path-ways controlled by faults are wide-extend affected by 

collapse and pockmark processes. Fluid path-ways configure a huge elongated areas fully collapsed by the 

absence of mass below the seafloor due the ejection of fluids and sediments. The distinctive morphological type 

is the blind valley. Blind valleys present singular processes and structures such as: collapses in the extremes of 

the valleys, slumps around the flank, an irregular floor due to presence of carbonate mounds, mudvolcanoes, 

minor collapses or pockmarks. 

The evolution and consequent growth by merging with other lineal collapses produce blind submarine valleys of 

nearly 10 km long. Presently these blind valleys work in the Tasyo Field as furrows along which MOW is 

channelized. Even though blind submarine valleys can behave as channels of undercurrents they are deep-rooted 

with faults and fluid path ways and their origin is related to a gravitational collapse due to fluid flow.


Fig 1:- Blind valley located in the Central Sector of Tasyo Field (Gulf of Cadiz, Spain). This geological structure 

is an elongated collapses, from 3 to 10 km long, without open extremes, that start and finish by pockmarks or 

sub-circular collapsed structures. 

Methane-derived authigenic carbonates in modern intertidal surface sediments 

G. Liebezeit 1 , M. E. Böttcher 2 , P.-L. Gehlken 3 , G. Gerdes 4 , L. Giani 5 , A. Heinze 6 , J. Mederer 7 , 

B. Schnetger 8 and M. Segl 9 

1 Research Centre Terramare, Wilhelmshaven, Germany 

2 Leibniz Institute for Baltic Sea Research, FRG 

3 Dr. Gehlken-Analysis of Raw and Residual Materials, Ebergötzen, FRG 

4 ICBM, Meeresstation Wilhelmshaven, Germany 

5 Institute für Biologie und Umweltwissenschaften, Universität Oldenburg, FRG 

6 Museum „Leben am Meer“, Esens, Germany 

7 BGR, Hannover, Germany 

8 ICBM, Oldenburg University, Germany 

9 FB Geowissenschaften, University of Bremen, Germany 

A large number of carbonate concretions are found in the intertidal area of the drowned village Otzum in the 

backbarrier area of Langeoog Island (Lower Saxonian Wadden Sea, southern North Sea). From field 

observations they are associated with the former settlement having, however, formed in different intertidal flat 

sediments. The majority occurs as horizontal plates although in a few instances vertical positions have been 

observed, too. The latter appear to be related to mud cracks. Authigenic carbonates in modern temperate 

sediments are a rather unusual observation. Therefore, to deduce formation conditions, a detailed investigation of 

these concretions was started combining geochemical, stable isotope geochemical, sedimentological and 

microfacies analyses. 

The concretions consist to about 40 -50% calcium carbonate (essentially low-magnesium calcite with up to 9 

mol% Mg 2+ in solid-solution, and aragonite), the remainder being quartz and small amounts of chlorite, illite, 

kaolinite and feldspar. The organic carbon contents of the bulk concretions are typically low. Solid phase iron, 

magnesium, strontium, sulphur and phosphorus contents are partly associated with the carbonate and sulfide 

fraction. Calcium carbonate stable carbon has δ 13 C values down to about -36‰ vs. V-PDB, indicating that 

oxidation of methane contributed significantly to the dissolved carbonate species fixed in the authigenic 

carbonate lattice. Carbonate oxygen isotope ratios indicate formation from only slightly diluted seawater 

solutions, as found in the modern intertidal ecosystem. The carbon isotope signature is similar to the results 

observed in pore water DIC of intertidal surface sands that are under influence of methane oxidation. 

Microfacies analysis suggests that the secondary carbonates formed within primary matrices characteristic of 

both sandy as well as muddy tidal flats. The primary fabrics of the sand-flat type are composed of rounded 

quartz grains of fine to medium sand size. Included are various biogenic compounds such as diatom and mollusc

88 


shells characteristic of tidal flats, but also botanical macro-remains. The primary pore spaces are almost entirely 

occupied by carbonate crystals. In the carbonate precipitates various diatom tests have left moulds. In the mudflat 

concretion, biogenic compounds increase in number and diversity. Some of these are also furnished with 

organic coatings characteristic of biofilms. Remaining primary pore spaces as well as secondary pores are 

relatively more frequent within this type of concretion. Pyrite framboids are also present occasionally. 

Acknowledgements: The authors wish to thank Thomas Höpner for his support in the early phase of the project, 

and R. Botz and G. Bohrmann for stimulating discussions. 

Methane in water and sediments in Sevastopol Bays, Black Sea 

L.V. Malakhova 1 , T.V. Malakhova 1 , V.N. Egorov 1 , S.B. Gulin 1 , Yu.G. Artemov 1 

1 Institute of Biology of the Southern Seas 2, Nakhimov Av., Sevastopol, 99011, Ukraine 

The purpose of study was to determine the methane content in water column and bottom sediments of the coastal 

Black Sea area adjacent to Sevastopol bays (SW Crimea) where a number of shallow gas seepages have been 

found during the last years. Measurements of the dissolved CH4 were carried out in water and sediments sampled 

at monitoring stations shown in Fig. 1b. Also, the gas bubble samples were taken for methane analysis over the 

permanently functioning seepage in summer and autumn periods (Fig. 1a) 

44°40′ 

a) 

44°35′ 

b) 

1 

Black Sea 

2 

ЧЕРНОЕ МОРЕ 

Казачья бухта 

3 

4 

Бухта 

Омега 

Камышовая бухта 

5 

13 

14 

Стрелецкая бухта 

Карантинная 

бухта 

Fig. 1. (a) Location of gas seepages: ● – observed in 1989-1999, ▲ – observed in 2002 and 2006 [1], ▼– found 

in 2007, - - - is lines of geodynamic faults. (b) – Concentrations of the dissolved methane (µl·l -1 ) in water of 

Sevastopol bays area: ▌– measured in April-May 2007, – in August-September 2007. 

Measurements of CH4 were carried out using the gas chromatograph HP5890 with a flame ionization detector 

(FID), whose column was packed with sorbent Porapack 80-100 mesh. The concentration was calculated in 

comparison with an external methane standard. According to our data, the bubble gas contains methane (C1) and 

his homologous (total concentration C2+). The measured ratio of the methane and homologous has suggested its 

biological origin. Concentrations of the dissolved gas in surface waters of Sevastopol area varied from 0.47 to 

20.36 µl·l -1 , and in the bottom sediments – from 0.02 to 18.67 µl·cm -3 . It was found that concentrations of 

methane dissolved in water column over the seepages correspond with the background level. Content of methane 

12 

15 

17 

18 

7 

8 

▼ 

Sevastopol 

33°20′ 33°25′ 33°35′ 

10 

Севастопольская бухта 

Южная бухта 

6 

Севастополь 

Sevastopol 

16 

CH4, µk?l -1 CH4, µl·l -1 

20 

15 

10 

5 

0 

9


dissolved in water is correlated with methane concentration in bottom sediments with correlation coefficients of 

0.87 in summer period and 0.62 in autumn. 

Reference 

Eremeev, V.N., Egorov, V.N., Polikarpov, G.G., Artemov, Yu.G., Gulin, S.B., Evtushenko, D.B., Popovichev, 

V.N., Stokozov, N.A. Nezhdanov, A.I. (2007). New methane seeps in Sevastopol marine area. 

Proceedings (Visnyk) of the National Academy of Sciences of Ukraine, 4, pp. 47-50 (in Ukrainian). 

Key sediment properties affected by the presence of gas hydrates in the “Anaximander” deep 

sea mud volcanoes. 

D. Marinakis 1 , N. Varotsis 1 , C. Perissoratis 2 

1 Department of Mineral Resources Engineering, Technical University of Crete, Greece. 

2 Institute of Geology and Mineral Exploration, Athens, Greece. 

The present study examines some of the key properties of the marine sediments, which are affected by the 

presence of the hydrates, such as permeability and compressive strength. 

Permeability plays an important role to the rate of hydrate formation. High permeability values facilitate the 

mass transport of the gas components through the pore fluids, thus increasing the rate of hydrate formation. As 

hydrates are formed in the sediment’s pore space permeability drops, inhibiting thus any further mass transport 

through the sediment layers. On the other hand, very low permeability values could result in pore pressure build 

up and subsequently in the rupture of the sediment layers and the formation of fluid chimneys. 

Compressive strength is directly related to the mechanical stability of the sediment formation. At low values of 

the compressive strength, the sediment will behave plastically with compression, in which case severe 

deformation will occur with stress, leading to the mechanical failure of the geological formation. 

The “Amsterdam” mud volcano was considered as a case study, where gas hydrates were discovered just 40cm 

below the sea floor at water depths of 2000m and seabed temperatures between 12 and 14 o C. Previous studies 

concluded that the presence of hydrates near the seabed of the “Amsterdam” mud volcano can be explained by 

their formation either from gas dissolved in the water phase, or from the rapid cooling of hot fluid fluxes, which 

contain free gas and rise up through the sediment layers during geological events. Gas hydrates formed at such 

warm environments are notably susceptible to temperature variations: 20% of the total hydrate deposits will 

dissolve in the sea water if the sediment’s temperature increases by just 1 o C. 

Laboratory tests were conducted with gas hydrates formed in the pore space of clayish sediment sampled from 

gravity cores collected from the “Amsterdam” MV. Contrary to what was expected, hydrate formation was found 

to bear a moderate effect on the permeability of the “Amsterdam” MV sediment, by reducing it to almost a third 

of its original values (Fig.1), even at high pore saturation (45%) in gas hydrates. 

Hydrate formation bears a profound effect on the compressive strength of the sediment (Fig.2). Tests revealed 

that the stiffness of the sediment increases more than 50% of its initial value, if the in-situ temperature rises from 

14 to 18 o C. Any further temperature increase results in progressive hydrate dissociation, which in turn bears a 

strong impact on the compressive strength of the host formation. Above 22 o C in-situ temperature, the 

compressive strength of the host sediment was found to practically collapse, a consequence that could lead to 

possible subsea landslides near the foot of the mud volcano slope. 

Fig. 1: Permeability of natural sediment containing gas hydrates. The permeability of the sediment was recorded 

over a range of temperatures from 12 o C, where all hydrates are stable, up to 27 o C, where all the hydrates are 

dissociated. The sediment is confined in a core holder setup at constant pore pressure of 20MPa and at 2MPa 

confining stress. Hydrate content is 10% of the sediment volume.

90 


Fig. 2: Compressive strength of natural sediment containing gas hydrates. The sediment is confined in a piston 

cell and it is subjected to weak compressive stresses at constant pore pressure of 20MPa. The strength of the 

sediment, which is assessed by its modulus of elasticity at each temperature, increases from 5MPa at 12 o C to 

maximum value of 14MPa at 18 o C – close to the stability limit of the hydrate phase - and then reduces sharply 

down to 2MPa at 26 o C, where all hydrates are dissociated. 

A simple applicable transfer function to estimate (2D) marine gas hydrate inventories derived 

from precise geochemical modelling 

M. Marquardt 1 , T. Henke 2 , R. Gehrmann 3 , C. Hensen 1 , C. Müller 2 , K. Wallmann 1 

1 IFM-GEOMAR Kiel 

2 Federal Institute for Geosciences and Natural Resources (BGR) 

3 University of Leipzig 

Offshore gas hydrate inventories have been estimated so far either by the use of available pore water data 

(usually restricted to ODP drill sites) or by the interpretation of seismic records. However, the results derived 

from these two methods very often revealed significant differences in terms of quantity and distribution for 

identical locations. 

The project HYDRA aims at a complementary 

approach using geochemical reactive-transport 

models and geophysical rock physics modelling to 

quantify regional GH inventories. Geochemical 

transport-reaction models has been constrained on 

DSDP/ ODP drill Sites 685, 1230, 1233, 1040, 1041 

and 1043 (Costa Rica, Peru and Chile) to derive a 

simplified general transfer-function. The application 

of that general function requires incorporation of 

regional parameters i.e. sediment thickness, 

sedimentation rate, thermal conditions and SO4 

penetration depth (depends on CH4 flux and is in 

relation to the degradation of organic carbon). SO4 

penetration and sedimentation rate were derived from 

sediment and pore water data of gravity cores. 

Seismic interpretation yields both the thermal gradient 

Fig. 1: Map of Costa Ricans Pacific coast. On the 

red line (seismic line BGR-99 44) a first 

application of the transfer function has been 

performed. 

and the sediment thickness. Therefore a velocity 

analysis calculating the seismic velocities vp and vs 

from the elastic moduli and the rock density (effective 

medium theory), planar information of sediment 

thickness, and the thermal gradient has been applied. 

Imprecise parameters in the geophysical model (e.g. 

porosity) were adjusted before with the geochemical 

model in order to maintain two coherent and valid models. 

The main target of the project is the accurate estimation of margin-wide gas hydrate inventories. A first 

application has been performed on the continental slope offshore Costa Rica (see figure 1). First results include a 

2D-distribution along the seismic profile BGR99-44 across ODP sites 1040 and 1041. All data used (SO4 

penetration depth, sedimentation rate, sediment thickness and BSR distribution) are derived from ODP leg 170, 

the seismic profile BGR-99 44 and the cruises M-54 and SO-173. The resulting profile show the formation


potential of CH4 stored in GH (figure 2). The concentrations vary between 0 and 65g CH4 / cm 2 seafloor. As the 

gas hydrate zone widens with increasing sediment thickness and a subsiding BSR the potential formation of gas 

hydrate increases significantly. Integration of the GH bearing sediments along the profile and subsequent 

extrapolation onto 1 km of continental margin yield a potential of 1 x 10 13 g CH4 / km. Global extrapolation on 

the entire continental margin this would result in submarine GH inventories of about 2 x 10 18 g CH4. 

Fig. 2: The coloured bars in the seismic profile of BGR-99-44 shows the potential amount 

of CH4 bounded in the GH. The GH occurence zone begins at about 100m below the 

seafloor. The lower end is determined by the BSR (blue line) or the transition of slope 

sediments to continental crust (black dotted line). The concentration is given in g CH4/cm 2 

seafloor (see legend). 

Variations in the depth of the gas front 

N. Martínez 1 , S. García-Gil 1 , J. Iglesias 1 , A. Judd 2 



High resolution seismic surveys undertaken over recent years have shown that San Simón Bay (Ría de Vigo, 

NW Spain) is characterised by extensive acoustic turbidity indicating the presence of shallow gas. The gas front, 

the top surface of the acoustic turbidity, lies close (~80 cm) to the seabed, but the depth varies between surveys. 

To understand what causes these depth variations selected survey lines have been repeated numerous times over 

the last 6 years. This bay is semi-enclosed (see Figure 1) and the water is shallow (

92 


5 survey lines (Fig. 1) have been repeated at a total of 10 times at various times of year, at high and low tide; 

water depth, temperature and salinity, and atmospheric pressure variations have been recorded in each case. 

Although sub-seabed conditions are generally characterised by muddy sediments, the survey line closest to the 

Rande Strait is crossed by two channels in which there are coarser sediments (muddy silts). Salinity is affected 

by the introduction of fresh water from the Redondela River. Atmospheric pressure, water depth and sub-seabed 

depth have been used to calculate the hydrostatic pressure at the gas front. 

The data presented in Figure 2 represent extreme cases in which only one of the main parameters varies: 

1) salinity variations have little or no effect; a change from 18.95 to 32.89‰ was accompanied by 4 cm 

(average) change in the depth of the gas front. 

2) a change in hydrostatic pressure from 109 to 135 kPa (mainly caused by a 2.7 m change in water depth) 

was reflected by a gas front movement of 10 cm (average). 

3) the greatest change (13 cm average) was associated with a rise 4.2º in seawater temperature. 

Fig. 2: Three pairs of survey lines, each showing a significant variation in 1 of the 3 parameters: temperature 

(∆T), hydrostatic pressure (∆P) and salinity (∆S). Corresponding changes in gas front depths can be seen in the 

profiles and the average change in gas front depth (∆Dg). 

Although the water temperature had the greatest influence on the depth of the gas front, it is interesting to note 

that the gas front became closer to the seabed when the temperature was higher in the muddy sediments, but 

actually fell at those locations where the seabed sediment contains a greater proportion of gravel-sized particles 

(mainly shell material) suggesting that the sediment texture also has some influence. 

Miocene seep-carbonates as indicators of style and intensity of fluid migration 

S. Mecozzi 1 , S. Conti 1 & D. Fontana 1 

1 Department of Earth Sciences of the University of Modena and Reggio Emilia 

Miocene seep-carbonates have been reported from marine sedimentary successions of the northern Apennines. 

They are recognized by their peculiar palaeoecological, sedimentological, compositional and isotopic features as 

products of the microbial oxidation of methane-rich fluids and represent an excellent example of carbonate 

bodies interpreted as the remains of ancient cold seeps. 

These seep-carbonates occur from internal tectonic zones (Piedmont Terziary basins, epi-Ligurian and minor 

basins) to external zones of the foredeep. In the Miocene foredeep, they crop out in large turbiditic bodies (Mt. 

Cervarola and Marnoso-arenacea Formations) and in slope hemipelagites (Vicchio and Verghereto Marls, and 

Ghioli di letto mudstones). Dominant rock types are calcilutitic/marly limestones, calcareous marls and 

calcarenites. Enclosing sediments are hemipelagic/turbiditic mudstones, muddy sandstones and marlstones. 

In the Apenninic chain, the abundance and the extent of the outcrops provide a rare opportunity to study the 

geometry, facies distribution and internal structures of fossil methane-derived carbonates. 

On the basis of morphological and stratigraphic features two main types of seep-carbonates were distinguished in 

the field (type 1 and 2). 

The type 1 is composed of a horizontal repetition of decametric to heptometric carbonate bodies, lenses and 

pinnacles. They have a thickness of 5 - 30 m and an extension that ranges from 10 m to 100 m. The basal 

portions of these huge bodies are strongly brecciated, made up of intraformational polygenic breccias and rarely 

extraformational. The Sasso Streghe (Figure 1, Modena Apennines) and Monte Petra (Romagna Apennines)


carbonate outcrops are excellent examples of this type of seep-carbonates. The type 2 is made of numerous 

marly-calcareous lenses, irregular column-like bodies with a dimension ranging from some decimetres to 3 – 4 m 

and a thickness of 20- 30 cm to 3 m. Carbonate bodies are aligned along bedding strikes, or horizontally and 

vertically scattered and not related to a precise stratigraphic level. The Vicchio outcrops (Figure 2, Tuscan 

Apennines) are representative of this second type of carbonates. 

Mineralogical analyses of type 1 carbonate samples indicate that dolomite and ankerite represent the most 

dominant phases while Low-Mg calcite represents type 2 dominant carbonate phase. 

The carbon and oxygen isotopic compositions of the carbonates display very large ranges, from -10‰ to -55‰ 

Vienna PeeDee Belemnite (V-PDB) and from -3‰ to 6‰ V-PDB, respectively. Seep-carbonates type 1 appear 

significantly depleted in δ 13 C (ranging from -30‰ to -55‰ V-PDB) while seep-carbonates type 2 are only 

moderately depleted (δ 13 C varying from -10‰ to -23‰ V-PDB). Petrographic observations show complex facies 

relationships, as indicative of different stages in seep-carbonates growth. 

Our presentation will report the result of a detailed field observation of the two types of seep-carbonates coupled 

with geochemical, petrographic and mineralogical studies. In particular we discuss distinctive characters, 

geometry, isotope geochemistry and mineralogy, in relationship with precipitation and recrystallisation processes 

of the carbonates, the origin of carbon rich fluids, and with different mechanisms of seep-carbonate formation. 

Fig. 1. Panoramic view of the southern side of the “Sasso delle Streghe” type 1 seep-carbonates, Termina 

Formation Epiligurian sequence. 

Fig. 2. Small scattered type 2 seep-carbonates enclosed in marls. Fosso Riconi, Vicchio Marls 

foredeep slope-closure pelites.

94 


Early diagenetic dolomite precipitation during gas hydrate dissociation in the Peru Trench 

P. Meister 1 , M. Gutjahr 2 , M. Frank 3 , S. M. Bernasconi 4 , C. Vasconcelos 4 , J. A. McKenzie 4 

1 Max-Planck-Institute for Marine Microbiology, Celsiusstr. 1, 28359 Bremen, Germany 

2 Bristol Isotope Group, Dept. of Earth Sciences, University of Bristol, Queens Road, Bristol, United Kingdom 

3 Leibnitz Institute of Marine Sciences, IFM-GEOMAR, Wischhofstrasse 1-3, 24148 Kiel, Germany 

4 Geological Institute, ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland 

The release of CH4 from marine sediments due to dissociation of gas hydrates has been suggested to be 

responsible for some of the major climatic perturbations in Earth’s history. Since gas hydrates are commonly 

associated with diagenetic carbonates, such precipitates and their isotopic signatures may provide important 

information to understand the dynamics of hydrate formation and dissociation within the gas hydrate reservoir. 

During Ocean Drilling Program (ODP) Leg 201, dolomite layers were recovered from a 200-m-thick Pleistocene 

sequence of methane-rich and gas-hydrate-containing sediments in the Peru Trench (Site 1230). The results 

presented here allow us to correlate distribution patterns of dolomite with the subsurface biogeochemistry and to 

propose a possible linkage between gas hydrate stability and dolomite precipitation. 

The methane-rich sequence is capped by a thin layer of dolomite and underlain by several up to 20-cm-thick 

brecciated dolomite layers, whereas virtually no carbonate occurs within the gas hydrate zone. The absence of 

carbonate is unexpected considering that interstitial waters contain up to 150 mM of dissolved inorganic carbon 

(DIC), but can be explained by a drop in pH due to production of CO2 during microbial methanogenesis. Layers 

of early diagenetic dolomite typically form due to pH increase during anaerobic methane oxidation (AMO) and 

dolomite formation accompanying AMO is indicated by δ 13 C isotope values around -35‰ in the capping 

dolomite layer (Meister et al., 2007). A mass balance calculation based on δ 13 C in the deep dolomite breccia 

layer and DIC indicates a contribution of up to 18% AMO-carbon to the DIC pool. However, no SO4 2- is 

presently available at 200 m sediment depth to drive AMO and SO4 2- may have been delivered by a hydrothermal 

fluid, which, according to more radiogenic Sr-isotopes, originated from greater depth within the accretionary 

prism. 

The dolomite layer which formed at 7.5 m depth near the present AMO zone, is probably the result of elevated 

AMO activity following a recent degassing event. A release of substantial amounts of CH4 from gas hydrates is 

reflected in the CH4 profile and is also indicated by a kink in the Cl - profile at 18 m below seafloor, which is a 

common diffusion effect at the margins of gas hydrate-cemented zones. The gas hydrate stability field is now 

below 80 m depth and gas hydrates formerly present above this depth must have dissociated. Methane was 

probably largely retained as gas hydrate throughout deposition of the entire sedimentary sequence, whereby 

AMO was suppressed at the methane-sulphate interface, and hence, no dolomite was precipitated. 

Our results hence demonstrate how dolomite layers and their C isotope content can be used to trace AMO zones 

in the past. Moreover, the distribution of dolomite layers at Peru Trench Site 1226 show evidence for episodic 

AMO during phases of gas hydrate dissociation. This mechanism is capable of explaining the control of early 

diagenetic dolomite precipitation by the formation and dissociation of gas hydrates in other organic carbon-rich 

ocean margin sediments and in analogous sediments in the geological record. 

Reference 

Meister, P., McKenzie, J.A., Vasconcelos, C., Bernasconi, S., Frank, M., Gutjahr, M., and Schrag, D.P. (2007) 

Dolomite formation in the dynamic deep biosphere: results from the Peru Margin (ODP Leg 201). 

Sedimentology 54, 1007-1032. 

Modelling δ 13 C of dissolved inorganic carbon in deep-sea sediment under 

non-steady state conditions 

P. Meister 1 , K. Javadi 1 , A. Khalili 1 and T. Ferdelman 1 

1 Max-Planck-Institute for Marine Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany 

Variations and disequilibria in δ 13 C signatures measured in dissolved inorganic carbon (DIC) and early 

diagenetic carbonate recovered from sediments of the Peru continental margin (ODP Leg 201) indicate dynamic 

biogeochemical conditions throughout the Pleistocene deposition history (Meister et al., 2007). As also indicated 

by non-steady state interstitial water chemistry, variations in deep biosphere activity that are driven by past 

oceanographic conditions may lead to upward and downward migrations of the sulphate/methane interface. 

Under such conditions, a whole range of δ 13 C values can occur in the DIC and may get preserved in the 

diagenetic carbonate record. 

In order to better understand the dynamics of δ 13 C signatures in the subsurface, δ 13 C variation of the DIC was 

simulated using a numerical model. The model is run over a time period of several 100 ka and a depth domain of 

200 m below seafloor, which was divided into three subdomains for sulphate reduction, anaerobic methane


oxidation (AMO) and methanogenesis. For each reactive type, a constant C fractionation was assumed with δ 13 C 

values in the produced DIC of -15‰, -35‰, and +15‰, respectively. As source terms, the directly measured 

turnover rates from radiotracer incubations were applied. An additional downward advection term was always 

included in the diffusion equation in order to simulate sedimentation rate. 

Preliminary model runs show initially a sharp increase of δ 13 C values at the sulphate methane boundary due to 

isotopically heavy DIC produced during methanogenesis. However, this effect is rapidly outcompeted by 

downward diffusion of DIC with negative δ 13 C values that is produced at much higher rates by sulphate 

reduction. Applying the present activity rates to the model allowed to partially reproduce the trends in modern 

DIC isotopic signatures, but do not explain the more positive δ 13 C values preserved in the carbonates. In order 

to simulate the dynamics that occurred in the past, a further refinement of the model is necessary that integrates 

organic matter reactivity, sulphate and methane diffusion, and isotope specific DIC production. In particular, 

organic matter (OM) reactivity needs to be represented as an exponential decay process including a fixed decay 

constant and a distribution factor for OM reactivity. This model provides a theoretical basis necessary to 

understand δ 13 C patterns in dynamic diffusive systems and to postulate conditions of past deep biospheres from 

δ 13 C records of early diagenetic carbonate. 

Reference 

Meister, P., McKenzie, J.A., Vasconcelos, C., Bernasconi, S., Frank, M., Gutjahr,.M., and Schrag, D.P. (2007) 

Dolomite formation in the dynamic deep biosphere: results from the Peru Margin. Sedimentology 54, 

1007–1031. 

Isotopic and chemical analyses of gas hydrate- and porewater samples obtained from gas 

hydrate-bearing sediment cores retrieved from mud volcanoes in Lake Baikal 

H. Minami 1 , A. Krylov 1,2 , A. Hachikubo 1 , H. Sakagami 1 , H. Tomaru 1 , K. Hyakutake 1 , S. Kataoka, S. Yamashita, 

N. Takahashi 1 , S. Nishio 3 , H. Shoji 1 , O. M. Khlystov 4 , T. I. Zemskaya 4 , T. V. Pogodaeva 4 , and M. Grachev 4 


2 VNIIOkeangeologia, 1 Angliyskiy pr., St. Petersburg 190121, Russia 

3 Institute of Technology, Shimizu Corp, 3-4-17 Etchujima, Koto-ku, Tokyo 135-8530, Japan 


International cooperative research projects for the natural gas hydrate sampling operation and isotopic/chemical 

core analyses at the mud volcanoes such as Malenky (southern basin) and Kukuy K-2 (central basin) in Lake 

Baikal, Eastern Siberia, Russia were conducted during 2005 to 2007. The gas hydrate-bearing sediment cores 

were retrieved from the bottom of the lake floors by using steel gravity corers. The pore water sampling was 

conducted on board by a squeezer designed and constructed at Kitami Institute of Technology. The hydrate 

water sample was obtained by the dissociation of the hydrate on board. In order to clarify the origin and 

composition of the gas hydrates-forming fluid, the isotopic and chemical analyses of the gas hydrate-, pore-, and 

lake water samples were conducted. Stable isotope ratios of oxygen and hydrogen of the water samples were 

analyzed by using a mass spectrometer (Model Finnigan Delta plus XP, Thermo Fisher) equipped with a gasbench 

system (Model Gas-Bench II, Thermo Fisher). 

The δ 18 O and δD values of the hydrate water samples obtained were up to +2.7‰ (δ 18 O) and +10‰ (δD) heavier 

than those of the lake bottom water sampled from 50 cm above the lake floor. 

The concentrations of major ions in samples of water obtained by decomposition of different hydrate samples are 

broadly variable, and do not correlate with the composition of the pore water of the in-filled sediments. 

Remarkable are the extremely high concentrations of Cl - , Na + , SO4 2- in some of them. This fact suggests that the 

concentrations of salts in hydrate-forming gas-saturated fluids change in the course of upward migration of 

hydrates which carry away pure water and leave salts behind. 

Effect of methane gas phase dynamics on the coupled methane-sulfur cycles in the subsurface 

J. Mogollón 1 , I. L’Heureux 2 , A. Dale 1 , and P. Regnier 1 

1 Faculty of Geosciences, Utrecht University, Budapestlaan 4, 3508TA Utrecht, The Netherlands 

2 Department of Physics, University of Ottawa, Macdonald Hall, 150 Louis Pasteur, Ottawa, ON, Canada 

Reactive-transport models of geomicrobiological dynamics in subsurface environments have largely ignored the 

role of biogenic gas generation, transport, and dissolution. In natural systems characterized by high rates of

96 


methanogenesis of labile organic matter, methane gas ebullition can be significant. This gas may be transported 

towards the sulfate-methane transition zone (SMTZ) where biogenic methane diffusing up the sediment column 

encounters sulfate diffusing down from the sediment-water interface. Here, methanotrophic microbes may 

consume most of the biogenic methane in the presence of sulfate reduction through a process termed anaerobic 

oxidation of methane (AOM). Minimal energy yields are available for AOM to take place due, in part, to the low 

methane concentrations encountered in the SMTZ. Consequently, gaseous methane may be an effective 

mechanism which can sustain the microbial community carrying out the AOM. In this work, a generalized 

reactive transport model including mass, momentum, and volume conservation for three phases (solid, aqueous, 

and gas) coupled with an explicit representation of the methane-using microbial community (governed by 

thermodynamic and kinetic constraints) is used to explore the fate of methane gas in unconsolidated marine 

sediments. The model is able to elucidate the dynamics of methane bubbles as well as revealing important 

feedbacks between dissolved and gaseous methane transport and geomicrobial reaction rates. 

What is controlling shallow active methane seeps in Lake Baikal? 

Posolsky Bank case-study 

L. Naudts 1 , N. Granin 2 , O. Khlystov 2 , A. Chensky 3 , J. Poort 1 , M. De Batist 1 


2 Limnological Institute, SB RAS, 664033 Irkutsk, Russian Federation 

3 Irkutsk State University, 664033 Irkutsk, Russian Federation 

Active methane seeps and gas hydrates occur worldwide in the marine environment especially at continental 

margins. Lake Baikal represents a unique case to study active methane seeps and gas hydrates in an active 

tectonic, lacustrine setting. In this study we present and explain the distribution of several shallow active 

methane seeps located on the Posolsky Bank, a major tilted fault block in the central part of Lake Baikal. 

Active methane seeps were detected with a single-beam echosounder, which is able to detect gas bubbles in the 

water column due to the impedance contrast between water and free gas (bubbles). Possible fluid-flow pathways 

below the lake floor have been mapped based on the integration of the seep positions and high-resolution sparker 

seismic data. Subsurface sediment characteristics of a possible fluid pathway have been derived from BDP-99 

well data 

Fig. 1: Seismic sparker profile where the top of the gas-bearing layer (TGBL) has been traced,from the seep area 

3 (arrow) down the Posolsky Bank, to within the theoretical gas-hydrate stability zone (GHSZ), where the base of 

the hydrate stability zone (BHSZ) shows up as a series of enhanced reflections on the seismic data. 

The detected seeps occur near the crest of the Posolsky Bank above the Posolsky fault system. Seismic data 

suggest, however, that the fault does not act as a fluid conduit resulting in seepage, but rather cuts off a gasbearing 

layer (Fig. 1 & 2). This possible gas-bearing layer could be traced, down the Posolsky Bank, to within


the theoretical gas-hydrate stability zone, where it shows up as a series of enhanced reflections on the seismic 

data (Fig. 1 & 2). Enhanced reflections on seismic data are possible indications for the presence of free gas in the 

subsurface. The enhanced reflections are positioned below the theoretical base of the hydrate-stability zone. 

Sediment characteristics of the gas-bearing layer, derived from the BDP-99 well data (Bezrukova et al., 2005), 

suggest a sandy layer covered by clayey sediments. 

Fig. 2: 3D view of sparker profile SELE29 together with the INTAS bathymetry of the Posolsky Bank and seep 

positions plotted as red dots or 3D flares. The location of the seismic profile shown in Fig. 1 is also indicated, as 

well as the possible limit of the gas hydrate stability zone at 500 m water depth (Golmshtok et al., 2000). 

Our data suggest that the shallow gas seeps near the crest of the Posolsky Bank are partially supplied by methane 

from below the base of the gas-hydrate stability zone. This differs from other deep-water Baikal seeps and mud 

volcanoes, which are believed to be related to destabilizing gas hydrates under the influence of a tectonically 

controlled geothermal fluid pulse along adjacent faults (De Batist et al., 2002). 

References 

Bezrukova, E. et al., 2005. A new Quaternary record of regional tectonic, sedimentation and paleoclimate 

changes from drill core BDP-99 at Posolskaya Bank, Lake Baikal. Quat. Int., 136, 105-121. 

De Batist, M., Klerkx, J., Van Rensbergen, P., Vanneste, M., Poort, J., Golmshtok, A.Y., Kremlev, A.A., 

Khlystov, O.M. and Krinitsky, P., 2002. Active hydrate destabilization in Lake Baikal, Siberia? Terra 

Nova, 14, 436-442. 

Golmshtok, A.Y., Duchkov, A.D., Hutchinson, D.R. and Khanukaev, S.B., 2000. Heat flow and gas hydrates of 

the Baikal Rift Zone. Int. J. Earth Sci., 89, 193-211. 

Anomalous sea-floor backscatter patterns in methane venting areas, Dnepr paleo-delta, 

NW Black Sea 

L. Naudts 1 , J. Greinert 1,2 , Y. Artemov 3 , S. E. Beaubien 4 , C. Borowski 5 , M. De Batist 1 


2 Leibniz-Institut für Meereswissenschaften IFM-GEOMAR, Wischhofstrasse 1-3, D-24148 Kiel, Germany 

3 A.O. Kovalevsky Institute of Biology of the Southern Seas NAS of Ukraine, 99011 Sevastopol, Ukraine 

4 Department of Earth Sciences, Rome University La Sapienza, Piazalle Aldo Moro 5, I-00185 Roma, Italy 

5 Max-Planck-Institut für Marine Mikrobiologie, Celsiusstrasse 1, D-28359 Bremen, Germany 

During the 58 th and 60 th cruise of R.V. Vodyanitskiy, conducted in the framework of the EU-funded CRIMEA 

project, almost 3000 active bubble-releasing seeps were detected with an adapted split-beam echosounder within 

the 1540 km 2 of the studied Dnepr paleo-delta area. The distribution of these active seeps is not random, but is 

controlled by morphology, by underlying stratigraphy and sediment properties, and by the presence of gas 

hydrates acting as a seal and preventing upward migrating gas to be released as bubbles in the water column 

(Naudts et al., 2006).

98 


Fig. 1: 3D view of multibeam bathymetry overlain with backscatter data, bathymetric contours and seep 

locations (black dots). Pockmarks are characterized by high- to very-high-backscatter values with seeps located 

on their margins. The sediment dunes have higher backscatter values on the ENE flanks (Naudts et al., 2008). 

Here we present the relation between acoustic sea-floor backscatter and the distribution of more than 600 active 

methane seeps detected within a small area on the continental shelf (Fig. 1) (Naudts et al., 2008). This study is 

further sustained by visual sea-floor observations, high-resolution seismic data, pore-water data and grain-size 

analysis. The backscatter data indicate that seeps are generally not located within high-backscatter areas, but 

rather surround them. Most seeps are located within shallow pockmarks which are characterized by mediumbackscatter 

values, whereas deeper pockmarks have high-backscatter values with much lower seep densities 

(Fig. 1). The seismic data show the presence of a distinct gas front (free gas); shallow gas fronts correspond to 

high- and medium-backscatter areas, which are associated with gas seeps, whereas deep gas fronts correspond to 

low-backscatter areas without seeps. The presence of shallow gas is also confirmed by the pore-water data, 

showing higher amounts of dissolved-methane concentrations for areas with medium- to high-backscatter values. 

Visual observations showed that the high-backscatter areas correspond to white Beggiatoa mats (Fig. 2). These 

thiotrophic bacterial mats are indicators for the anaerobic oxidation of methane (AOM) which results in the 

formation of methane-derived carbonates (MDAC’s). AOM was also confirmed by the pore-water data. 

Fig. 2: Screenshots from JAGO dive 852 (METROL project) showing different stages in bacterial math growth 

and authigenic carbonate occurrences. The arrows point to bubbles being released at the center of a cluster of 

bacterial mats (after Naudts et al., 2008). 

No clear correlation with grain-size distribution could be established. Based on the integration of all datasets, we 

conclude that the observed high-backscatter anomalies are a result of methane-derived authigenic carbonates 

(MDAC’s). The carbonate formation appears to lead to a gradual (self)-sealing of the seeps, followed by a 

relocation of the bubble-releasing locations. Furthermore, the degree of MDAC-formation is directly linked to 

the backscatter intensity and seep activity which makes it possible to use the backscatter strength as a proxy for 

the seep activity and distribution (see talk J. Greinert). 

References 

Naudts, L., Greinert, J., Artemov, Y., Staelens, P., Poort, J., Van Rensbergen, P. & De Batist, M., 2006. 

Geological and morphological setting of 2778 methane seeps in the Dnepr paleo-delta, northwestern 

Black Sa. Mar. Geol., 227, 177-199. 

Naudts, L., Greinert, J., Artemov, Y., Beaubien, S.E., Borowski, C. & De Batist, M., 2008. Anomalous sea-floor 

backscatter patterns in methane venting areas, Dnepr paleo-delta, NW Black Sea. Mar. Geol., 251, 253- 

267.


Hydroacoustic study of the role of water level decline on methane emission and bottom sediment 

characteristics in Lake Kinneret (Israel) 

I. Ostrovsky 1 and J. Tęgowski 2 

1 Israel Oceanographic & Limnological Research, Migdal, Israel. 

2 Institute of Oceanology Polish Academy of Sciences, Sopot, Poland. 

Rapid changes in water level associated with unbalanced use of aquatic resources of Lake Kinneret require 

effective methods for monitoring of gas emission and bottom sediment parameters. Acoustic reflectance and 

scattering properties of bottom sediments were characterized by energetic, statistical, spectral, wavelet, and 

fractal parameters of a single beam echo envelope. A common feature of the chosen parameters is indication of 

energy distribution in the frequency domain and fractal description of the echo envelope shape. Data collected 

with a 120-kHz echo sounder along several transects were used to determine the flux of gaseous methane from 

the bottom (Ostrovsky et al. 2008), study the acoustical properties of surface sediments, and evaluate their spatial 

and temporal changes in Lake Kinneret. Some acoustical parameters showed close association with 

granulometric variables and organic matter content in the upper sediments. The observed effect of water level 

fluctuation on several echo parameters was apparently associated with changes in gas content in the sediments 

positioned in the deep part of the lake. Spatial distribution of some echo parameters were very stable with time; 

while other parameters showed large changes in the deep central part of the lake, but were nearly unchanged at 

the lake periphery. Overall, the suggested approach can be a useful tool for monitoring of fine modifications in 

surface sediments. 

A data starvation and the identification of fluid flow features: Lessons from the Alboran Sea 

M. Pérez 1 , S. García-Gil 1 , A. Judd 2 , F. Estrada 3 , B. Alonso 3 , G. Ercilla 3 



3 CSIC, Instituto Ciencias del Mar, Barcelona, Spain 

Single channel seismic profiles and low-resolution multibeam data from the Alboran Sea offer tantalising 

suggestions of shallow gas and fluid flow seismic features (Fig. 1). The indications of gas are at the distal 

domains of turbidite systems, and it is speculated that fluid migration pathways may exist within the relatively 

coarse sediments found in distributary channels and channel overbank deposits as well as associated to massflow 

deposits. 

Fig. 1: Multibeam echo sounder coverage, seismic profiles are aligned along the centre of the multibeam tracks. 

Locations of possible fluid flow features are indicated. This study provides examples of possible fluid flow 

features in order to explain the problems associated with ‘data starvation’. In some cases (e.g. Fig. 2), the 

coincidence of some features adds strength to the interpretation that they are indications of fluid/fluid flow. The 

study area partially overlies a mud diapir province where core analyses have proved the gas presence. Therefore, 

the hypothesis of gas in these flows becomes more supported.

100 


Seabed depressions, which may be pockmarks, are associated with patches of high amplitude reflections, which 

may (or may not) be gas enhancement. However, the ‘pockmarks’ are too small to be resolved on the available 

multibeam data, and the absence of parallel seismic lines makes it difficult to confirm that these features are real 

pockmarks. Similarly, attempts to confirm the true nature of fossil seabed depressions are frustrated because they 

are found only on single lines; are they buried pockmarks or small channels? 

Fig. 2: Single channel seismic profile with two possible pockmarks and enhanced reflections in two places. 

These images are insufficient to positively identify the features as pockmarks/enhanced reflections, but spatial 

coincidence supports this interpretation. 

Thermal features and gas hydrate formation in Lake Baikal mud volcanoes and other deep-sea 

seepage areas. 

J. Poort 1* , O. Khlystov 2 , M. Kulikova 3 , L. Naudts 1 , H. Shoji 4 , S. Nishio 5 , M. De Batist 1 

1 Renard Centre of Marine Geology, Universiteit Gent, Belgium 

*Currently at Institut du Physique du Globe de Paris, France 

2 Limnological Institute, Irkutsk, Russia 

3 VNIIOkeangeologiya, Saint-Petersburg, Russia 

4 Kitami Institute of Technology, Kitami, Japan 

5 Institute of Technology, Shimizu Corporation, Tokyo, Japan 

In Lake Baikal, shallow gas hydrates have already been identified in five mud volcano/seep structures through 

joint Russian, Japanese and Belgian research. These mud volcano/seep structures are found at different water 

depths (from 1380 m to as shallow as 440 m) and contain shallow hydrates of both structure I and II (Kida et al., 

2006). Bottom Seismic Reflections (BSRs), indicative for the presence of deep-seated hydrates, has been 

observed on nearby seismic profiles. We will report on detailed thermal investigations in association with gravity 

coring performed over the last three years in the following gas hydrate containing mud volcanoes: “K-2”, 

“Malenkiy” and “Bolshoy”. 

The “K-2” mud volcano is located on the flanks of the Kukuy Canyon at a water depth of 900 m water depth. 

This oval structure of 60 m in height and 800 m in diameter consists of two separate mud volcanoes 

corresponding to two culminations. Sediment cores have been retrieved in more than 75 sites (15 contained 

hydrates), with temperature sensors attached to the corer in 22 occasions. Shallow hydrates were only found in 

two zones of not more 50-100 m diameter: on the top and between the two culminations. These zones also stand 

out by anomalous low (30-43 mK/m) and high (90-113 mK/m) thermal gradients in comparison to what is 

measured outside the mud volcano (60-70 mK/m). 

Cores with hydrates were directly correlated to low thermal gradient and large non-linearity in the temperaturedepth 

profiles. This can be explained in three ways: (1) heat absorption by hydrate dissociation; (2) topographic


effect combined with a dynamic hydrate system; and (3) infiltration of cold lake water, possibly induced by local 

convection and/or water segregation. 

69 

88 

29 

43 

52 

78 85 

44 114 77 

85 

80 

80 

43 

76 

68 54 

67 

Fig. 1. (a) Lake Baikal Rift DEM view from the north with location of Kukuy mud volcano area in 

Central Basin. (b) Kukuy K-2 mud volcano with measured thermal gradients (in mK/m) and stations 

were hydrates were cored in red. Remark that sites with hydrates returned mostly anomalous small 

thermal gradients with increased thermal gradients at nearby sites. 

Fig. 2. To explain the distribution of gas hydrates and thermal gradient anomalies as observed in K-2 mud 

volcano, we propose a model were the formation of impermeable hydrate lumps locally blocks and diverts 

the upflow of warm seep fluids, while continued water segregation associated with the hydrate formation 

induces infiltration of cold sea water from above. 

The localized occurrence of hydrates within the mud volcanoes and a close relation to thermal anomalies was 

also observed in the mud volcanoes “Malenkiy” and “Bolshoy”, located at a water depth of about 1380m. More 

than 30 gravity cores in both structures indicate zones with shallow hydrates in local depressions and on 

culminations. Thermal stations show the presence of anomalous thermal gradients, up to 180 mK/m, at short 

distances of background values. 

The mud volcanoes in Lake Baikal do not display a strong activity in terms of acoustic flaring in the water 

column (almost absent) and large-scale temperature anomalies (< 1 degrees C). However, they comprise local 

shallow hydrate systems in close association with anomalous low and high thermal gradients. We will compare 

the Baikal results with thermal signatures from hydrate-containing seeps and mud volcanoes in the Gulf of 

Cadiz, the Black Sea, the Sea of Okhotsk and the Hikurangi Margin. 

This work was supported by the Bilateral Flanders-Russian Federation Project: Gas hydrate accumulations 

associated with active fluid seeps: a combined thermal and acoustic approach. 

References 

Kida, M., Khlystov, O., Zemskaya, T., Takahashi, N., Minami, H., Sakagami, H., Krylov, A., Hachikubo, A., 

Yamashita, S., Shoji, H., Poort, J. and Naudts, L., 2006. Coexistence of structure I and II gas hydrates in 

Lake Baikal suggesting gas sources from microbial and thermogenic origin. Geophys. Res. Lett., 

33(24). 

b. 

500 m 

53 

61

102 


Mud volcanic activity and anoxic ecosystems on the Calabrian accretionary prism: Results from 

the HERMES Medeco2 campaign 

D. Praeg 1* , C. Pierre 2 , J. Mascle 3 , S. Dupré 3,4 , A. Andersen 5 , G. Bayon 4 , I. Bouloubassi 1 , L. Camera 2 , 

S. Ceramicola 1 , F. Harmegnies 4 , L. Loncke 6 , V. Mastalerz 7 , A. Mostafa 8 , A. Vanreusel 9 , 

the Victor ROV Team 10 and the Medeco Leg 2 Scientific Party 

1 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy 

2 CNRS-UPMC (Université Pierre et Marie Curie), LOCEAN, Paris, France 

3 Géosciences Azur, Villefranche sur Mer, France 

4 Département Géosciences Marines, Ifremer, Brest Centre, Plouzané, France 

5 CNRS-UPMC, Station Biologique de Roscoff, France 

6 Université de Perpignan, France 

7 University of Utrecht, Netherlands 

Alexandria University, Egypt 

9 University of Gent, Belgium 

10 Genavir, La Seyne/Mer, France 

Two mud volcanic structures on the Calabrian accretionary prism were investigated during Leg 2 of the 

HERMES Medeco expedition: the Pythagoras mud pie and the Madonna dello Ionio. These structures were 

discovered in 2005 during the HERMES-HYDRAMED campaign of the OGS Explora (Ceramicola et al. 2006); 

the Madonna was briefly visited in 2006 during the HERMES M70-1 ROV campaign of the Meteor. Here we 

present results from ROV seabed video observations, sampling and geothermal measurements during Medeco2 

in November 2007, which provide evidence of extrusive activity and associated anoxic ecosystems. 

The Madonna dello Ionio mud volcanoes lies c. 40 km from the Calabrian coast in water depths of 1650-1850 m; 

the structure comprises three circular mud volcanic features 1.5-3 km wide (twin cones 140 m high and a low 

caldera-like feature forming the ‘head’), all of which were examined by the ROV. Geothermal measurements 

(using the 60 cm T_ROV probe as well as a gravity corer) indicate higher gradients near the centres of all three 

extrusive features. Fresh outflows of reduced gray (warm) mud were observed and sampled locally on two of the 

features (the SE cone and the ‘head’). The mud flows overlie more widespread pelagic sediments that in many 

places are intensely bioturbated; a blade core from the top of the SE cone contained siboglinid polychaete 

tubeworms that live in symbiosis with chemolithotrophic bacteria (generally sulfate oxidizing), indicating 

reduced conditions within 30 cm of seabed. The pelagic sediments drape an undulating relief indicative of 

former mud flows, and mud breccias are exposed in places. Normal faults were observed adjacent to and within 

the structure, as seabed escarpments up to 2 m high, suggesting recent vertical movements. 

The Pythagoras mud pie, c. 100 km from the Calabrian coast, is 8 km wide and c. 250 m high. ROV 

investigations focused on its summit, in water depths of 1960-2010 m, which includes two domes flanked by 

low-relief ‘terraces’. The northern dome includes evidence of violent, eruptive activity: an area of chaotic 

seabed, with an irregular, metre-scale relief of exposed mud breccias, bordered by a network of orthogonal 

fissures. The southern dome displays a smoother relief of undulating ridges and depressions, indicative of mud 

flows draped by pelagic mud. Geothermal measurements indicate low gradients. 

These observations indicate that the Madonna dello Ionio continues to be active, while the Pythagoras mud pie 

has been recently active; both are characterized by a low level of activity relative to the prior widespread 

extrusion of mud breccias. Geochemical and biological analyses of sediment and water samples acquired are 

underway and expected to provide more information on the functioning of these cold seep systems. 

Reference: 

Ceramicola, S., Praeg, D. & the OGS Explora Scientific Party (2006). Mud volcanoes discovered on the 

Calabrian Arc: preliminary results from the HERMES-HYDRAMED IONIO 2005 campaign. CIESM 

Workshop Monographs, n. 29, p. 35-39. 

Activity of North Alex and Giza mud volcanoes and its fluid and hydrocarbon gas genesis, West 

Nile Delta (Egyptian margin) 

A. Reitz 1 , F. Scholz 1 , M. Nuzzo 1 , C. Hensen 1 , S. M. Weise 2 , and the RV-Poseidon P362/2 Scientific Party 

1 Leibniz-Institute of Marine Sciences - IFM-GEOMAR, Kiel, Germany 

2 UFZ - Helmholtz Centre for Environmental Research, Dept. of Isotope Hydrology, Halle, Germany 

Within the framework of the West-Nile-Delta (WND) project two mud volcanoes (MVs), Giza and North Alex 

MV, were intensely investigated with respect to their pore fluid and hydrocarbon gas geochemistry. The aim is to 

decipher their activity as well as the chemical and physical changes that controlled the composition of the fluids 

and gases on their way up to the seafloor. Both MVs are located on the upper domain of the western Nile deep


sea fan, north of the Rosetta Canyon, the upper limit of the continental platform, in 500 m (North Alex MV) and 

700 m (Giza MV) water depth. Even though seepage activity in the Nile deep sea fan is induced by salt tectonics, 

besides high sedimentation rates and consequent rapid subsidence, Messinian evaporite influence on fluid 

geochemistry is absent at North Alex and Giza MVs. 

The sediments recovered from the MVs are enriched in petroleum and saturated with thermogenic hydrocarbon 

gases, interspersed with mud clasts from deeper, compacted source strata and carbonate concretions as well as a 

few carbonate chimneys, a product of subsurface authigenic carbonate precipitation related to anaerobic 

oxidation of methane in the subsurface sediments. The fluids from the centre of both MVs are conspicuously 

depleted in chloride (up to 140 mM; normal bottom water (BW): ~600 mM) and potassium (up to 0.6 mM; BW: 

~10?) with depth and show increasing boron concentrations, and B/Li and Na/Cl molar ratios with depth (Fig. 1), 

all together known as indications for fluids derived from clay mineral dehydration at depth. The decreasing K 

and the increasing Na/Cl ratio are known as indication for smectite-illite transformation during which K and Cl 

are lost from the pore fluid by integration into illite. However, to get a better understanding about the processes 

that occurred during fluid formation and migration it is vital to analyse the fluids with respect to their stable 

oxygen and hydrogen as well as the δ 37 Cl isotopic fractionation. These parameters will provide us with 

information related to chemical reactions (e.g. mineral dissolution/precipitation) and temperature conditions. 

Furthermore the element depth profiles seem to indicate a recent mud flow at Giza MV displaying a 

negative/positive spike overlying background concentrations. 

sediment depth / cm 

0 

100 

200 

300 

400 

0 40 80 120 

K 

0 4 8 12 

+ / mM; B / mM 

B/Li 

Giza MV North Alex MV 

B/Li / mol/mol 

Na/Cl 

Cl - K + 

100 200 300 400 500 600 700 

Cl- 500 

/ mM 

0.4 0.8 1.2 1.6 2 

Na/Cl / mol/mol 

sediment depth / cm 

100 

200 

300 

400 

500 

100 200 300 400 500 600 700 

Cl - / mM 

Fig. 1: Element concentrations and element molar ratios of pore fluids from the centre of Giza and North Alex 

MVs 

0 

B/Li / mol/mol 

0 40 80 120 

K 

0 4 8 12 

+ / mM; B / mM 

0.4 0.8 1.2 1.6 2 

Na/Cl / mol/mol 

Surface sediments of the Black Sea: Sink and source for methane in the water column 

N. Riedinger 1 , B. Brunner 1 , T.G. Ferdelman 1 , Y.-S. Lin 2 , A. Voßmeyer 1, B .B. Jørgensen 1,3 


2 MARUM - Zentrum für Marine Umweltwissenschaften, University of Bremen, Germany 

3 Center for Geomicrobiology, Department of Biological Sciences, University of Aarhus, Denmark 

High resolution methane concentration profiles were measured in surface sediments and at the water sediment 

transition in the Black Sea. Additionally, the stable carbon isotope composition of methane was determined. At 

the investigated sites the sulfate/methane transition (SMT) is characterized by a broad zone where methane is not 

completely consumed but shows a tailing up into sediments with high sulfate concentrations. At shallow water 

sites methane migrates from the sediment into the water column. The carbon isotope data show that the 

sediments at these sites are a source for methane depleted in 13 C relative to the isotope composition of methane 

in the water column. At deep water sites methane concentrations decrease with depth in the upper layers and 

increase again in proximity to the SMT. The minimum flux of methane from the water column into the sediment 

is between 1 and 4 µmol m -2 d -1 . Numerical modeling of the methane concentration and isotope data show a 

consumption of methane in the uppermost few cm in the sediment. This suggests that the removal of water 

column methane in the surface sediments is not related to anaerobic oxidation of methane (AOM) taking place in 

the zone of SMT. 

Na/Cl 

K + 

B/Li 

Cl -

104 


Comparison of microbial communities in sub-surface sediments from Haakon Mosby mud 

volcano and a non-seep site in the Barents Sea 

A. G. Rike 1 , E. Eribe 1 , E. Roinaas 2 , R. Orr 3 , K. S. Jakobsen 3 , T. Kristensen 2 

1 Norwegian Geotechnical Institute, P.O.Box 3930 Ullevaal Stadion, NO-0806 Oslo, Norway 

2 Department of Moleculear Biosciences, University of Oslo, Norway 

3 Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, Norway 

The archaeal and bacterial diversity in sub-surface sediments at the Haakon Mosby Mud Volcano (HMMV) site, 

located at 72.0020 o N – 14.4350 o E, and at a non-seep site (NSS) west of HMMV, at 72.0030 o N – 14.3700 o E, in 

the Barents Sea was studied. Both sampling sites are located at about 1300 m water depth. HMMV has been 

investigated by both geologists and biologists, and the microbial communities at different habitats have been 

described (Lösekann et al 2007, Niemann et al 2006). To the best of our knowledge, the microbial diversity in 

sediments not influenced by seeps in this region has not been characterized, and we were interested in studying 

the differences of these two microbial habitats. 

The bacterial and archaeal diversity at the sites was determined in sediments from 2-20 cm depth by 16S 

ribosomal DNA (16S rDNA) sequence analysis. DNA isolated from the sediments was PCR amplified, with 

universal-bacterial and -archaeal primers, and cloned into Escherichia coli. Sequences of approximately 900 

bases of cloned 16S rDNA inserts were used to determine species identity, or closest relatives, by comparison 

with sequences of known species. Geochemical parameters of sediments and pore water were determined to 

provide an environmental context of the sediment conditions. 

Altogether, 245 microbial clones (from archaea and bacteria) were sequenced from the two sites, 152 from 

HMMV and 93 from the NSS. Archaeal clones represented 36% of total clones at HMMV and 26% at NSS. 

All 79 archaeal clones sequenced were detected as novel and their sequences were organized into tree clusters of 

Chrenarchaeota (A, B and C) and two clusters of Euryarchaeota (D and E). 

The 55 archaeal clones retrieved from HMMV represent 13 different phylotypes, all belonging to the 

Euryarchaeota clade E of anaerobic methane oxidizing archaea (ANME). The phylotypes are affiliated with 

clusters of ANME-2A, ANME-2B, ANME-2C and ANME-3. No Crenarchaeota were detected in the HMMV 

sediment investigated in this study. With the exception of two clones closely related to uncultured 

Thermoplasmatales in the Euryarchaeota phylum, the other 22 clones from the NSS sample affiliated to the 

Chrenarchaeota phylum. 63% of the NSS achaeal clones were close relatives of uncultured Desulfurococcus. 

166 bacterial clones, 97 from HMMV and 69 from the NSS were sequenced. Uncultured Epsilonproteobacteria 

accounted for 49% of the total bacterial clones in the HMMV sediments. Other main bacterial phyla detected at 

HMMV were Deltaproteobacteria (12%) and Gammaproteobacteria (10%). At the NSS the dominating phyla 

were Planctomycetes (25% ), Alphaproteobacteria (23%) and Obsidian Pool 11 (OP11) (14%). Out of 17 

bacterial phyla only 4 (OP11 group, Chloroflexi I/II, Gammaproteobacteria I/II and Deltaproteobacteria I/II) 

were common to both sites but any clones were detected at both HMMV and the NSS. 

The archaeal diversity in the anaerobic methane and hydrocarbon influenced HMMV sediments was 

significantly lower than in the aerobic deep cold sediments from the NSS. The bacterial diversity, however, was 

great at both sites. This may indicate that the archaeal component of the microbial community is most suceptible 

to seep influence than the bacterial component. 

Microbial methane cycle in the Black Sea sediments and its effect on the atmosphere 

and water column 

I. Rusanov 1 , N. Pimenov 1 , S. Yusupov 1 , and M. Ivanov 1 

1 Winogradsky Institute of Microbiology, RAS 

Methane is among the major terminal products of anaerobic organic matter (OM) transformation, contributing to 

the atmospheric pool of greenhouse gases. During the period of 1990–2007, a unified procedure was applied to 

the radioisotope investigation of microbial methane production and oxidation, with short-term incubation under 

in situ conditions. 

The Black Sea area includes the following characteristic biogeochemical zones: 

(1)sediments of the highly productive shallow coastal zone, river estuaries, and river alluvial deposits; (2) 

extensive areas of shelf sediments, depths over 40–50 m; (3) sediments of the continental slope and deep basins, 

permanently covered with anaerobic water; and (4) sediments of the methane seeps and mud volcanoes. 

Methane levels of the upper 30–50 cm of the sediments from the Dnepr and Dnestr estuarine coastal zone, of the 

Danube delta and prodelta, and of the coastal shallow shelf stations were rather high for marine sediments. 

Methane concentration increased sharply from 0.01–0.5 ml/dm 3 at the surface sediments to 0.1–66.0 ml/dm 3 at 

the depth 25–30 cm. This distribution is caused by extensive microbial methane production (up to tens of µl/dm 3 

per day) in the upper 50 cm of the sediment and methane migration from the deeper sediment horizons. The


profiles of methanogenesis rates are confirmed by the numbers of methanogenic archaea in the coastal 

sediments. The measured δ 13 С values for methane of the surface sediments (from -70.7 to -81.8‰) suggest 

microbial origin of most of the shelf methane. 

Methane content in the upper sediment horizons of this area is at least an order of magnitude higher than in the 

near-bottom water. Most of the methane dissolved in seawater was found to arrive from bottom sediments. Low 

depths and insufficient methane oxidation enables methane arrival to the atmosphere. 

In the open shelf sediments (depths over 40–50 m) methane concentrations are 2–3 orders of magnitude higher 

than in the shallows (from 3–30 µl/dm 3 at the surface to 10–100 µl/dm 3 at 30–50 cm). These sediments exhibit 

significantly lower microbial methane production (up to hundreds nl/dm 3 per day). The balance of methane 

production and oxidation indicates that only a minor part of methane penetrates from the open shelf sediments 

into the water; it is there completely oxidized by the methanotrophic bacterial community and does not affect the 

atmosphere. 

Methane seeps of the shelf and the upper continental slope supply significantly higher amounts of methane to 

the water column. Most of this methane is oxidized in the water column; a minor part from the seeps at the 

depths up to 100–150 m reaches the atmosphere. 

The methane profile in the sediments of the continental slope and deep basins is radically different from its 

distribution in the shelf and shallow sediments. In the upper layer of deep-water sediments, methane content is 

2–40 times lower than in the near-bottom water (200–350 µl/l); its concentration decreases gradually to 50–70 

cm sediment layers. Thus, most of the methane of the Black Sea is produced by microorganisms of the anaerobic 

water column or supplied by numerous deep-water methane seeps and mud volcanoes. Methane distribution 

profiles in the deep basin area indicate that high methane content in anaerobic waters does not affect the oxygencontaining 

horizons; CH4 is practically fully oxidized in the water column by microbial anaerobic and aerobic 

community. 

Gas and gas hydrate in shallow sediments of the western deep-water Ulleung Basin, East Sea 

B.-J. Ryu 1 , M. Riedel 2 , J.-H. Kim 1 , R. D. Hyndman 3 , S.-C. Park 4 , Y.-J. Lee 1 , B.-H. Chung 1 

1 Petroleum and Marine Resources Division, Korea Institute of Geoscience and Mineral Resources, Korea 

2 Department of Earth and Planetary Sciences, McGilll University, Quebec, Canada 

3 Pacific Geoscience Centre, Geological Survey of Canada, British Columbia, Canada 

4 Department of Oceanography, Chungnam National University, Korea 

Geological and geophysical studies on hydrocarbons within shallow sediments of the western deep-water 

Ulleung Basin, East Sea of Korea have been carried out using piston cores, multi-channel reflection seismic 

profiles, and high resolution sub-bottom profiles and echo-sounding images. The heat-flow measurement and 

core analysis revealed high heat flow, high amounts of total organic carbon (TOC) and high sedimentation rates, 

which indicate good condition for hydrocarbon generation. If similar TOC content and sedimentation rate also 

occur at a deeper sedimentary interval, substantial amounts of hydrocarbon gas could be generated. Within the 

natural gas hydrate stability zone, hydrate would also be formed by migration of hydrocarbon gas generated. 

However, variations in the depth to the sulfate-methane interface (SMI) data suggests lateral differences in 

upward hydrocarbon gas fluxes, and thus in potential hydrocarbon gas generation and concentration at greater 

depth. The cores recovered from the southern study area showed high residual hydrocarbon gas (mainly 

methane) concentrations that favor the formation of natural gas hydrate. The lack of higher hydrocarbons and the 

δ 13 CCH4 ratios indicate that the methane is primarily biogenic. In these cores, cracks generally developed parallel to 

bedding planes were well observed. They can generally be formed by expansion of in-situ free gas upon core 

recovery. However, the in-situ conditions for the cores are within the stability zone of natural gas hydrate, cracks 

caused by the gas dissociated from in-situ hydrate are also expected. A number of near-vertical chimneys of 

reduced seismic reflectivity were well observed on the seismic profiles (Fig. 1). They may represent conduits of 

upward fluid and gas migration, and probably contain free gas and/or natural gas hydrate. Often, they are 

associated with reflector pull-up structures that are interpreted to be the result of high-velocity hydrate. Analyzed 

higher seismic velocities and natural gas hydrate recovery within the chimney structures showing pull-up 

structures support this interpretation. Natural gas hydrate discoveries by the piston coring and deep-drilling in 

2007 support the interpretation of substantial hydrate in many of these structures. The chimney structures mainly 

occur in mid-eastern part of the study area. Seismic data show also widespread bottom-simulating reflectors 

(BSRs), which generally occur on the interface between overlying natural gas hydrate-bearing sediments and 

underlying free gas-bearing sediments. However, most of the reflection amplitude is caused by the underlying 

free gas. BSRs are widespread in the southern part of the study area. However, the occurrence of BSRs in this 

area is patchy and their reflection amplitudes are generally low. Strong BSRs were observed in a few areas, 

especially over a gentle anticline structure in the mid-western study area. Decrease of seismic interval velocity 

beneath the BSR may suggest the presence of free gas below. The echo-sounding images showed the presence of

106 


distinct gas seepages in the water column. Seepages mainly occur in southeastern part of the study area, and are 

often found together with pockmarks and/or dome-like structures. Pockmarks were well observed on the high 

resolution sub-bottom profiles. They are formed by the depression of seafloor sediments by escaping fluids or 

gas. The presence of pockmarks on near-seafloor sediments may indicate the accumulation of free gas below the 

stability zone of natural gas hydrate as well. The distribution of chimneys, BSRs and seepages are generally 

limited to the regions, however, pockmarks occur sporadically in the entire study area. 

Fig. 1. Chimneys on a multi-channel seismic reflection profile. 

Processes of methanogenesis and microbial methane consumption in bottom sediments 

of arctic seas 

A. Savvichev 1 , I. Rusanov 1 , N. Pimenov 1 and M. Ivanov 1 

1 Winogradsky Institute of Microbiology RAS, Moscow 

Understanding of the scale of greenhouse effect requires investigation of methane production and oxidation rates 

in terrestrial, freshwater, and marine ecosystems. Methane is the terminal product of decomposition of organic 

matter arriving to bottom sediments. In the Arctic seas, annual average temperature are low, ice cover persists 

for most of the year, and photosynthetic activity is brief. Influx of organic matter into the sediments of the Arctic 

seas is therefore limited. However, in some areas the bottom sediments are enriched with additional organic 

matter due to river run-off and frontal phenomena at the currents’ borders. The littoral located at the sea–shore 

interface is a specific, highly productive zone. 

The goal of our investigations in various Arctic regions since 1993 was determination of methane concentrations 

in water and sediments and direct measurements of the rates of microbial methanogenesis (MG) and methane 

oxidation (MO) in these environments. Methane concentration was determined by the head space method. The 

rates of MG and MO were determined by the radioisotope method using the following 14 C-labeled compounds: 

NaH 14 CO3, 14 CH4, and 14 CH3COONa. Both the CO2 from methane oxidation and methane carbon incorporated 

into organic matter were considered. 

Organic-poor bottom sediments of low methane production, mostly gray aleuric-pelitic muds oxidized 

throughout the layer, cover significant areas (Sea of Kara, Chukchi Sea, northern Barents Sea, and central White 

Sea). Methane concentration in the upper sediment layer was 0.5-10 µl СН4 dm -3 and MG and MO rates, 0.002 - 

0.2 and 0.0005-0.05 µl СН4 dm -3 day -1 , respectively. Dark brown and gray sediments with black hydrotroilite 

inclusions form the muds of the Chukchi Sea shallows, the estuaries of Ob’, Yenisei, and Severnaya Dvina, as 

well as the White Sea small bays exhibit moderate methane production. Methane concentration in the upper 

layer was 10-1000 µl СН4 dm -3 , MG and MO rates were 0.2 -2.0 and 0.05 to 5.0 µl СН4 dm -3 day -1 , respectively. 

Both methane concentration and MO rate were usually low in the upper sediment layer and increased with depth. 

In the black reduced sediments of the White Sea small bays and in the sediments of stagnation zones of shallow 

estuaries, methane concentration in the upper layer reached 100-2000 µl СН4 dm -3 ; MG and MO rates were 2- 

100 and 5.0-100 µl СН4 dm -3 day -1 , respectively. The calculated gross methane production from 1 km 2 of the 

littoral (August), corrected for the areas with various production levels, was 300 l СН4 km -2 day -1 . 

In the sediments of most stations, acetoclastic methanogenesis constituted 10% or less of the total. Comparison 

of organic matter consumption revealed that bacterial sulfate reduction was 50-800 times more active than 

methanogenesis. 

Biogenic methane is produced by methanogenic archaea, a specific microbial group requiring anaerobic 

conditions for metabolism. In organics-rich sediments, such conditions are created due to organotrophic bacteria 

which consume oxygen by respiration. In oligotrophic muds, methanogens develop in microniches associated


with organic particles (dead planktonic organisms, zooplankton pellets). Additionally methane of both biogenic 

and thermogenic origin (formed from inorganic compounds under high pressure and temperature) arrives from 

lower horizons. Microbial methane oxidation determined by the radiocarbon method is the sum of two processes 

performed by aerobic methane-oxidizing bacteria and anaerobic methane-oxidizing archaea. Methanotrophic 

bactteria develop only in the aerobic sediment layer; their activity depends on both methane and oxygen 

concentrations. Methane-oxidizing archaea do not require oxygen but depend on the trophic partners within 

anaerobic communities. 

The transient response of the Black Sea methane budget to massive short-term submarine inputs 

of methane 

O. Schmale 1 , M. Haeckel 2 

1 Institut für Ostseeforschung Warnemünde and der Universität Rostock, 18119 Rostock, Germany 

2 Leibniz Institute of Marine Science (IFM-GEOMAR), Wischhofstrasse 1-3, 24148 Kiel, Germany 

A steady-state box model was developed to establish a revised methane budget of the Black Sea and to estimate 

the methane input into the water column from seeps and mud volcanoes (MV) at various water depths. Our 

model results suggest a total input of methane of 67.4 Tg yr-1 of CH4 and an average methane residence time 

between 0.3 and 6.4 yr. The model predicts that the input of methane is largest in water depths between 100 and 

600 m (82 % of the total input), suggesting that the dissociation of methane gas hydrates in water depths 

equivalent to their upper stability limit may represent a major source of methane into the water column. In 

addition to the CH4 depth distribution, we also analysed the stable carbon isotope signature of methane. The 

model results point towards an increasing influence of a thermogenic methane source with increasing water 

depth. Finally, we discuss the effects of massive short-term methane inputs (e.g. through deep water MV 

eruptions or submarine landslides in intermediate water depth) on the Black Sea methane budget and the 

resulting methane emission into the atmosphere. This non-steady-state model predicts that these inputs will be 

effectively buffered by intense microbial methane consumption and that the upward flux of methane is strongly 

hampered by the pronounced density stratification of the Black Sea water column. For instance, an assumed 

eruption of 1,000 submarine MVs (equivalent to 179 Tg CH4 d-1) in water depths below 1,000 m (where most 

of the Black Sea MVs occur) shows that the influence on the sea/air methane flux is negligible and increases the 

air-sea CH4 flux by only 0.01 %. 

Fig. 1: Map of gas and fluid discharge in the Black Sea. Triangles and dots represent locations of submarine mud 

volcanoes and areas of intense fluid discharge, respectively. Red areas represent regions of gas seepage and 

seabed pockmarks. Map is based on a data compilation from Kruglyakova et al. (2004) and Vassilev and 

Dimitrov (2002).

108 


Activity and composition of hydrocarbon degrading microbial communities in the 

Sumatra fore-arc basin 

M. Siegert 1 , G. Köweker 1 , A. Schippers 1 , M. Krüger 1 

1 Geomicrobiology, Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Germany 

In September 2006 sediment samples were taken during the R/V Sonne cruise SO189-2. The aim was to estimate 

the distribution and activity of hydrocarbon degrading microorganisms in the fore-arc of Sumatra suspected to 

harbour large reservoirs of oil and gas. Samples from a methane seep as well as different ‘background’ sites were 

compared. Cell counts using CARD-FISH probes for Bacteria and Archaea and DAPI total cell counts revealed 

cell numbers up to 10 9 cells cm -3 for total cells and up to 10 7 cells cm -3 for both domains at the seep location. 

Seep location cell counts resemble to non-seep locations in their order of magnitude. These results could be 

confirmed by quantitative PCR analysis. Additionally, DGGE analysis was conducted to investigate the 

microbial community with primers for Archaea as well as Bacteria. In this report we also present first results 

from enrichment cultures capable of hydrocarbon degradation under aerobic and anaerobic conditions. Growth 

conditions were set up for psychrophilic microorganisms, but mesophilic enrichments have also been studied. 

Our results indicate hydrocarbon degradation under Fe(III), Mn(IV) reducing as well as methanogenic 

conditions. The latter, observed by methane evolution, served as an indicator for anoxic hydrocarbon degradation 

in sediment enrichment cultures. 

Spreading of gas-bearing sediments in the Russian part of the Baltic Sea by acoustic data 

V. Sivkov 1 , M. Ulyanova 1 , V. Zhamoida 2 , Yu. Kropachev 2 , A. Grigoriev 2 

1 Atlantic Branch of P.P. Shirshov Institute of Oceanology, RAS (ABIORAS) 

2 A.P. Karpinsky Russian Research Geological Institute (VSEGEI) 

Gdansk Deep. In the beginning of 70 th of last century some geophysical and geochemical anomalies were 

discovered in the sediments of the Gdansk Deep by P.P.Shirshov Institute of Oceanology. Detailed study of four 

key-areas was carried out and as a result gas-bearing sediments (GBS) were contoured and few pockmarks were 

defined. It was laid a base of knowledge on gas-bearing muddy sediments in the SE part of the Baltic Sea. But 

taking into account the unsatisfactory ships positioning systems at those times and also appearance of new 

methods of investigations we decided to recommence this study. 

Last few years we have used ship parametrical sediment echosounder ATLAS PARASOUND (PARAmetric 

Sediment Survey EchoSOUNDer) with frequency 18 and 23.5 kHz; portable echosounder Simrad EA 400SP (38 

and 200 kHz); and ship echosounder ELAC (30 kHz). Zones of acoustical anomalies associated with GBS were 

defined and mapped in the eastern part of Gdansk Deep. The largest anomaly is situated in the south-eastern part 

of Gdansk Deep and has complicated freakish form and occupies about 370 km 2 . Around large anomalies there 

are a lot of small ones which weren’t studied yet. Fulfilled investigations allowed defining some anomalies 

earlier not known. For detailed study we chose one of the key-areas in the northern part of the Gdansk Deep, 

where we discovered one large pockmark (horizontal size approx. 1500 x 200 m), one medium (1000 x 120 m) 

and one small (200 x 200 m), with the maximum deep 3 m. 

Gulf of Finland. According the result of geological survey carried out by VSEGEI in the eastern Gulf of Finland 

the gas-saturated Holocene sediments are widespread. These sediments are represented by porous olive-grey and 

black silty clayey mud with a high content of dispersed organic matter. If the gas content in sediment is high, it 

might form an acoustically impenetrable horizon in the seafloor. At the same time at the sea bottom surface some 

crater-like structures up to 20 meters in diameter were found using side-scan sonar (CM2, C-MAX Ltd.). It was 

supposed that these pockmarks were formed by gas-seeping processes. Specific structures which can also be 

interpreted as pockmarks were detected in the sub-surface geological section by the method of continuous 

seismic-acoustic profiling. 

The common features of GBS are noticeable for both areas. From one side the GBS are situated at the margins of 

the mud accumulation basins and accordingly gas might be produced due to organic matter transformation. From 

the other side some tectonic faults were fixed inside studied areas and it is possible to suppose migration of deep 

earth gas to the surface along tectonic lineaments from lower levels in the earth's crust. Some of pockmarks were 

buried under the recent sediments. Presence of GBS is one of the exploring indications for hydro-carbon 

deposits. It is very actually for Gdansk Basin where the oil exploration of the structure D-6 is developed and the 

new oil prospecting is carried out. 

So our main result is a digital map of GBS and pockmarks in the Russian sector of Gdansk Deep. This map let us 

to calculate the area of GBS spreading and also it is very useful for maritime planning.


Development of a submarine gas flow monitoring system 

K. Spickenbom 1 , E. Faber 1 , J. Poggenburg 1 , C. Seeger 1 

1 Federal Institute for Gesciences and Natural Resources (BGR) Stilleweg 2, 30655 Hannover 

As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop 

innovative research and technologies for the monitoring and verification of CO2 geological storage, we are 

developing a submarine gas flow monitoring system. This system is designed to monitor CO2 storage leakage on 

submarine CO2 sequestration sites, but can also be used for monitoring of any free gas emission (bubbles) on the 

seafloor. 

Fig. 1: General design of a submarine gas flow sensor system prototype. 

The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring 

CO2 and CH4 on mud volcanoes in Azerbaijan (Delisle et al., submitted). This design was adapted for mounting 

on a buoy in the Gulf of Trieste, using a funnel on the seafloor to collect the gas, which is then guided above 

water level through a flexible tube. Sensors for CO2 flux and concentration and electronics for data storage and 

transmission are mounted on the buoy, together with battery-buffered solar panels for power supply. 

Besides some technical problems (condensed water in the tube; movement of the buoys due to waves leading to 

biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a 

buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. Therefore, a 

completely submersed system would be the optimal solution. 

The prototype of such a completely submersed system is shown in Fig. 1. It consists of a gas collector, a sensor 

head and a pressure housing for electronics and power supply. The collector is a plastic funnel (350 mm diameter 

for this prototype, but larger diameters up to 4 m are under construction), enclosed in a stainless-steel frame to 

add weight and stability. The whole unit is fixed to the sediment by nails or sediment screws. 

On top of the funnel different exchangeable sensor heads can be mounted, which allows simple adaption of the 

system to different flow rates. The pictured prototype is equipped with an “inverted tipping-bucket” sensor, 

which basically works like a turned upside-down rain gauge. It fills with the collected gas until full, then empties 

completely and starts again. It allows the calculation of the flow rate by container volume and frequency of the 

cycle. This sensor type is very robust and suitable for very low to medium flow rates. For higher flow rates 

different sensor heads using turbine wheels or pressure differences are also available. 

The pressure housing for this prototype is made of aluminium and contains a Hobo Pendant data logger with 

integrated battery supply. More evolved versions will include a multi-channel data logger, data transmission by 

acoustic modem or cable and a lithium-battery power supply. 

Laboratory tests with these setups have been very promising. A field test is currently running in Lake Constance 

(Bodensee), where the prototype shown in Fig. 1 was installed on a CH4 vent close to the Rhine estuary at a 

depth of 14 m in March 2008. It will be recovered at the end of May and we hope to be able to present the data at 

the <strong>conference</strong>. 

Reference 

Delisle, G., Teschner, M., Panahi, B., Guliev, I., Aliev, C. and Faber, E. (submitted). A first approach to quantify 

fluctuating gas emissions of methane and radon from mud volcanoes in Azerbaijan.

110 


Shallow Gas in the Baltic Sea - A multi-frequency seismoacoustic view 

V. Spiess 1 and participants on GeoB student cruises to the Baltic Sea 

1 Department of Geosciences, Bremen University, Germany 

Since 2000, several expeditions with R/V Heincke and R/V Alkor had been carried out to the Mecklenburger 

Bay and northeast of Rügen Island in the Baltic Sea as part of geophysics student courses. Different acoustic and 

seismic survey methods have been used to image the shallow and deeper sub-sea floor, namely with acoustic 

systems as side scan sonar, parametric echosounder, boomer as well as with watergun and GI Gun as seismic 

sources. Data were recorded with a 100 m long, 16-channel analog streamer or a 50 m long, 48-channel analog 

streamer. 

A specific focus was given to the processes in the Holocene sediment cover, which varies in thickness from less 

than 1 m to more than 20 meters in the regions investigated. Two areas, in the Mecklenburger Bay and northeast 

of Rügen Island, had been chosen for detailed studies of reflectivity and seismic signature of gas zones as a 

function of frequency, ranging from appx. 50 Hz to more than 2000 Hz. 

Reflections from gas zones appear mostly diffuse, which may indicate either a vertical distribution of scattering 

gas bubbles or strong backscatter from the top of the gas zone. Seismic velocities and amplitudes were analyzed 

to determine the character of gas charge and to estimate total gas volume. Furthermore, the detection of gas in 

general and the location precision of the top of the gas zone will be investigated as a function of wavelength, 

resp. source frequency. 

Sediment-microbe interactions in permeable sediments at hydrocarbon seeps in the Santa 

Barbara Channel, California 

T. Treude 1,2 , W. Ziebis 1 

1 University of Southern California, Department of Marine Environmental Biology, Los Angeles, CA, USA 

2 Present address: Leibniz Institute of Marine Sciences (IFM-GEOMAR), Kiel, Germany 

Sediments of marine cold-seep areas exhibit high rates of hydrocarbon discharge and are unique dynamic 

systems with specific microbial communities connected to methane and/or oil degradation processes. Microbial 

activity in such systems is in general tightly coupled to advective transport mechanisms of fluids and 

hydrocarbons as well as to geochemical gradients in the sediment. Seeps in coastal shallow-water areas are, in 

contrast to deep-sea mud, characterized by sandy permeable sediments, thus enabling enhanced substrate 

exchange due to accelerated pore water transport processes. We investigated sandy sediments off Coal Oil Point 

(Santa Barbara Channel, California), one of the world’s largest hydrocarbon-seep area, to study the effect of pore 

water transport processes on microbial hydrocarbon turnover rates, biogeochemical gradients as well as 

microbial community structure. Our results demonstrate that microbial activity, such as anaerobic oxidation of 

methane and sulfate reduction, is accelerated in comparison to deep-sea seep environments in areas where 

reduced fluids, rich in hydrocarbons, seep through permeable surface sediments. Biogeochemical parameters of 

vertical and horizontal sulfide, oxygen, methane, and sulfate concentration reveal gradients and small-scale 

distribution patterns that differ from cold-seep systems of the deeper oceans. We suggest that these gradients and 

the resulting microbial activity are a result of pore water transport processes, where the supply of substrates is 

not limited to diffusion. Our preliminary data indicate that fast substrate supply and removal of inhibitory end 

products is an important factor enabling efficient microbial consumption of hydrocarbons in marine sediments. 

Gas hydrate occurrence from seismic analysis, offshore south Chile 

I. Vargas 1,2 , U. Tinivella 2 , F. Accaino 2 , M. F. Loreto 2 , F. Fanucci 1 

1 Università degli Studi di Trieste, Dip. DISGAM, Trieste 

2 Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS, Trieste 

The active subduction of the oceanic crust along the Chilean Continental margin is characterized by the 

interaction between the Nazca plate and South American plate defining a complex structural domain. We use 

multichannel seismic data to explain the regional setting of the continental margin from 35°S to 45°S and to 

study the relations between tectonic and gas hydrate occurrence. 

The seismic data were acquired during the Conrad (1988) and Sonne (2001) geophysical cruises by American 

and German teams respectively. The data processing was performed by using Seismic Unix. The data processing


consisted of a standard sequence to produce stacked sections and post-stack Kirchhoff depth migration sections 

by using the interpolated and smoothed stack velocity fields. Seismic reflection profiles are characterized by the 

presence of remarkable Bottom Simulating Reflector (BSR) showing reverse phase with respect to the sea 

bottom and a very high-amplitude. To better define the seismic character of the hydrate bearing sediments, we 

selected parts of two seismic lines to perform a detailed velocity analysis by using iteratively the pre-stack depth 

migration. Then, we translated the velocity field in terms of gas hydrate and free gas concentration. 

The selected part of the line RC2901-734 is 20 km long. This seismic line is located in the southern sector, close 

to 44°S. The frontal part of the prism is characterized by an intense active accretion, realized trough thrust faults 

ocean-ward vergent, as evidenced by some anticline folds. A strong and continuous BSR was recognized and it 

is about 200 m depth (Fig. 1). 

Note that the BSR is shallower than expected in correspondence to the structural high; this feature can be 

explained supposing a lateral variability of the geothermal gradient. 

The final velocity model allowed us to recognize the high velocity layer (1700-2200 m/s) above the BSR 

associated to gas hydrate presence and the low velocity layer (1200-1400 m/s) associated to free gas presence 

(Fig. 1). We detected a reflector below the BSR that we interpreted as the base of the free gas layer (BGR). We 

estimated average concentrations of 12% and 1% of volume of gas hydrate and free gas respectively. We 

detected strong lateral variability of concentration and thickness in the free gas layer. 

Fig.1: Velocity model and pre-stack depth migrated section of a selected part of seismic line RC2901-734 (see 

position map). A strong BSR is presents; above it, a weak reflector was interpreted as the BGR. Note, above 

BSR, the high velocity layer associated to the gas hydrate occurrence and, below the it, the low velocity layer 

associated to free gas occurrence. 

Along the seismic line SO161-44 line, we selected a segment 25 km long, located close to 39°S. The continental 

slope is characterized by small slope basins located in correspondence of paleo-thrust and normal faults. The 

BSR is discontinuous and deeper than the selected part of the RC2901-734 line, and it reaches 500 m of depth, as 

expected. 

The deformational style on the accretionary prism may influence the pressure and temperature conditions, which 

allow the gas-hydrate stability condition. We associated the accretional process variability along of the Chilean 

continental margin with the BSR features and the gas hydrate occurrences.

Ninth international conference on - Marum

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