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Evidence of paleo-cold seep activity from the Bay of Bengal, offshore India

DRS at CSIR-National Institute of Oceanography

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Title Evidence of paleo-cold seep activity from the Bay of Bengal, offshore India
 
Creator Mazumdar, A.
Dewangan, P.
Joao, H.M.
Peketi, A.
Khosla, V.R.
Kocherla, M.
Badesab, F.K.
Joshi, R.K.
Roxanne, P.
Ramamurty, P.B.
Karisiddaiah, S.M.
Patil, D.J.
Dayal, A.M.
Ramprasad, T.
Hawkesworth, C.J.
Avanzinelli, R.
 
Subject gas hydrates
authigenic minerals
palaeo studies
methane
 
Description Evidence of paleo–cold seep associated activities, preserved in methane-derived carbonates in association with chemosynthetic clams (Calyptogena sp.) from a sediment core in the Krishna-Godavari basin, Bay of Bengal is reported. Visual observations and calculations based on high-resolution wet bulk density profile of a core collected on board R/V Marion Dufresne (May 2007) show zones of sharp increase in carbonate content (10–55 vol %) within 16–20 meters below seafloor (mbsf). The presence of Calyptogena clam shells, chimneys, shell breccias with high Mg calcite cement, and pyrite within this zone suggest seepage of methane and sulfide-bearing fluid to the seafloor in the past. Highly depleted carbon isotopic values (delta sup(13)C ranges from -41 to –52 ppt VPDB) from these carbonates indicate carbon derived via anaerobic oxidation of methane. Extrapolated mean calendar age (approx. 58.7 ka B.P.) of the clastic sediments at a depth of 16 mbsf is close to the upper limit of the U-Th based depositional age (46.2 plus or minus 3.7 and 53.0 plus or minus 1.6 ka) of authigenic carbonates sampled from this level, thereby constraining the younger age limit of the carbonate deposition/methane expulsion events. The observed carbonate deposition might have resulted from the flow of methane-enriched fluids through the fracture network formed because of shale diapirism
 
Date 2009-12-21T06:46:47Z
2009-12-21T06:46:47Z
2009
 
Type Journal Article
 
Identifier Geochemistry Geophysics Geosystems, vol.10(6); 15 pp, doi:10.1029/2008GC002337
http://drs.nio.org/drs/handle/2264/3492
 
Language en
 
Rights Copyright 2009 by the American Geophysical Union. All efforts have been made to respect the copyright to the best of our
knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher American Geophysical Union