radiolaria - Marum

Bibliography - 1994 Radiolaria 14
Aitchison, J.C. 1994. Early Cretaceous (Albian/Aptian)
radiolarians from Blocks in Ayer Complex Melange, eastern
Sabah, Malaysia with comments on their regional tectonic
significance and the origins of enveloping melanges. J.
Southeast Asian Earth Sc., (in press).
Aitchison, J.C. & Flood, P.G. 1994. Cenozoic
radiolarians from Ocean Drilling Program Leg 143, Site 869A
Equatorial Pacific Ocean. In: Proceedings of the Ocean
Drilling Program, Scientific Results. vol. 143. College
Station, TX (Ocean Drilling Program). (in press)
Amon, E.O. & Braun, A. 1994. Radiolarians from lower
Permian deposits of the Belskaya depression, Bashkiria (west
slope of southern Urals; Artinskian stage, Burtsevsky
horizon). In: Contributions to Eurasian Geology; Permian
Conference Papers. Eds.), vol. 9. Occasional Publications
ESRI, Columbia, USA. pp. 1-7.
From marly deposits of the Tulkas type section (Belskaya
depression, Bashkiria) a well preserved Lower Permian (Artinskian)
radiolarian faunas is figured and described: Astroentactinia speciosa
n. sp., Entactinia densissima, Entactinia aff. pycnoclada,
Helioentactinia cf. ikka, Copicyntra leviuscula n. sp., Tetracircinata
reconda Latentibifistula cf. triacanthophora, Quadriremis? sp.,
Quinqueremis clathrolobulatus n. sp. Peculiarites of fauns
compositio are briefly discussed.
Bohrmann, G., Abelmann, A., Gersonde, R.,
Hubberten, H. & Kuhn, G. 1994. Pure siliceous ooze, a
diagenetic environment for early chert formation. Geology,
22/3, 207-210.
The formation of marine opal-CT nodules or layers as early
diagenetic deposits has been documented only in Antarctic deep-sea
sediments. In contrast, porcellanites and cherts in land sections and
Deep Sea Drilling Project and Ocean Drilling Program drill sites are
usually found in sediment sections of Miocene age and older. During
R.V. Polarstern cruises ANT-IV3 and 4, young porcellanites were
recovered for the first time in contact with their host sediment in
two cores from the Atlantic sector of the southern ocean. Chemical
and mineralogical studies of these deposits and their surrounding
sediments have increased knowledge about very early chert
formation. In both cores the porcellanites are embedded in
sediments rich in opal-A with extremely low levels of detrital
minerals, an environment that seems conducive to a rapid
transformation of biogenic silica into porcellanites.
Haslett, S.K. 1994a. Plio-Pleistocene radiolaria
biostratigraphy and palaeoceanography of the mid-latitude
North Atlantic (DSDP Site 609). Geol. Mag., 131/1, 57-66.
Radiolaria were examined throughout the Plio-Pleistocene of
Deep Sea Drilling Project (DSDP) Site 609. Eight radiolarian datumlevels
(first and last appearances) were identified, some for the first
time in the North Atlantic. The recognition of these datums allows
correlation between the Atlantic, Pacific and Indian oceans, through
a previously published zonal scheme (Johnson et al. 1989). Zones
NR1 to NR11 were recognized, although some zones had to be
combined (NR1-2 and NR8-10) due to the absence of some
stratigraphically important taxa. The relative abundance distribution
of the radiolarian palaeoceanographical proxy Didymocyrtis
tetrathalamus indicated three cool phases (0/0.56-0.75 Ma, 1.2-
1.33/1.69-1.86 Ma, and 2.14 2.32/3.73-> 4.1 Ma) interrupted by
two relatively warm episodes (0.56-0.75/1.2-1.33 Ma and 1.69-
1.86/2.14-2.35 Ma). These fluctuations in sea-surface
temperature (SST) correspond with palaeoclimatic events indicated
by other proxies (e.g. Foraminifera), such as the onset of Northern
Hemisphere glaciation. This study illustrates the usefulness of
radiolaria in North Atlantic stratigraphical and palaeoceanographical
analysls .
Haslett, S.K. 1994b. Plio-Pleistocene radiolarian
biostratigraphy and palaeoceanography of the North
Atlantic. In: Tectonic, Sedimentation and Palaeoceanography
of the North Atlantic. (Scrutton, R.A. & Stoker, M.S., Eds.).
Special Publications of the Geological Society of London,
London, U.K. pp.
Milliman, J.D. & Takahashi, K. 1994. Carbonate and
opal production and accumulation in the ocean. In: Global
1994
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Surficial Geofluxex: Modern to Glacial. (Usselman, T.M.,
Hay, W. & Meybeck, M., Eds.) . National Academy Press. (in
press)
Calcium carbonate and biogenically produced opal account for
the deposition of nearly 1.8 x 10 14 t of sediment annually. Recent
advances in documenting rates of production and sediment
accumulation have facilitated a greater quantitative understanding
of the carbonate and opal systems in the marine environment.
Although reefs, atolls and carbonate banks occupy less than 1
percent the area of the deep sea, they produce 25 to 250 times
more carbonate per unit surface area than planktonic organisms. As
a result, during high stands of sea level banks and reefs serve as a
major source and sink of carbonate. During low stands of sea level,
when shallow-water productivity is dramatically reduced, the locus
of deposition shifts deep water. Export of carbonate from banks
during high stands of sea level, after they have reached their
assimilative capacity, tends to modulate these extreme conditions
Because silicate is biologically active, opal flux is more
governed by upper ocean productivity than is carbonate flux.
Approximately 150 x 10 14 g SiO2 exit the surface ocean annually,
greatest flux occurring in shelf and upwelling areas, particularly on
the Antarctic shelf. Because the oceans are greatly undersaturated
with respect to silicate, opal dissolution occurs both in the upper
ocean and near the sea-floor. Less than one percent of the biogenic
opal produced in surface waters survives in the fossil record. Higher
rates of opal preservation occur in areas of high productivity, such
as upwelling and Antarctic regions, whereas in oligotrophic regions
nearly all the opal dissolves, resulting in little preservation in the
fossil record.
Montgomery, H., Pessagno, E.A.J. & Pindell,
J.L. 1994. A 195 Ma Terrane in a 165 Ma Sea: Pacific Origin
of the Caribbean Plate. GSA Today, 4/1, 2-6.
Tectonic models purporting to describe the origin of the
Caribbean plate can be divided into two broad categories conflicting
on the point of in situ origin vs. genesis in the Pacific realm followed
by eastward transport relative to the American plate. Important
elements of Caribbean geology including Cayman Trough spreading,
the presence of the Lesser Antilles and Aves volcanic arcs,
incompatible crustal juxtapositions, complicated plate geometry,
truncated structural trends, fossils that originated at higher
latitudes, and a lengthy geologic record of eastward progression
strongly suggest allochthonous origin. However, none of these is
conclusive proof. The discovery of a Caribbean plate island terrane
significantly older than the Caribbean Sea assures that in situ
models are incorrect. The Bermeja Complex of southwestern Puerto
Rico, located on the northeastern corner of the Caribbean plate,
exposes Lower Jurassic chert. Deposited on a deep ocean floor,
radiolarian chert from the Bermeja is late Pliensbachian (~195 Ma)
in age, predating an open marine connection between the North
Atlantic and the Pacific by ~30 m.y
Murchey, B.L. & Jones, D.L. 1994. The
environmental and tectonic significance of two coeval
Permian radiolarian-sponge associations in eastern Oregon.
In: Geology of the Blue Mountains Region of Oregon, Idaho,
and Washington: Stratigraphy, Physiography, and Mineral
Resources of the Blue Mountains Region. (Vallier, T.L. &
Brooks, H.C., Eds.), vol. 1439. United States geological
Survey, professional Paper, Report, pp. 183-198.
Nakazawa, K., Ishibashi, T., Kimura, T., Koike,
T., Shimizu, D. & Yao, A. 1994. Triassic
biostratigraphy of Japan based on various taxa. In: Recent
Development on Triassic Stratigraphy. (Guex, J. & Baud, A.,
Eds.), vol. 22. Mémoires de Géologie (Lausanne), Lausanne,
Switzerland. pp. 83-105.
Two different faunas belonging to two different lithofacies are
distinguished in the Triassic of Japan. The one belongs to the shelf
facies composed of terrigenous clastic rocks, and is characterized
by ammonites, bivalves, and less amount of brachiopods and
gastropods. The zonation of the lower half of the Triassic is mainly
based on ammonoids, while the upper half is founded on bivalve
fossils. The other one belonging to the oceanic facies consists of
chert, limestone, pelagic shale, and greenstone, and yields abundant
conodonts and radiolarians. Molluscan fossils are also common in
pelagic limestones. The zonation of the oceanic sequence is made by
mainly conodonts and radiolarians The comparison of the two
different zones is difficult, because the two faunas do not occur in
association. Reviewing the various zonation, it becomes clear that