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| Da Silva, R.; Mazumdar, A.; Mapder, T.; Peketi, A.; Joshi, R. K.; Shaji, A.; Mahalakshmi, P.; Sawant, B.; Naik, B. G.; Carvalho, M. A.; Molletti, S. K.. |
| The unique hydrographic setting of the Bay of Bengal (BoB) makes it an ideal tropical marine system to study the influence of regional and global forcings on productivity and [CO2aq] through the late quaternary. Enormous fresh water flux into the BoB and consequent salinity stratification significantly weaken the convective mixing and wind driven processes which are commonly responsible for transport of nutrients to the euphotic zone driving primary productivity. Here we present a high resolution organic carbon-CaCO3 MAR and δ13CTOC records for the last 300 ky from the BoB. The results show significant productivity variation at marine isotope sub-stages and millennial timescales. Colder sub-stages and stadials (Dansgard-Oeschger cycle) show a boost in... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00409/52060/52763.pdf |
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| Peketi, A.; Mazumdar, A.; Joao, H. M.; Patil, D. J.; Usapkar, A.; Dewangan, P.. |
| In the present study, we have investigated the C–S–Fe systematics in a sediment core (MD161-13) from the Krishna-Godavari (K-G) basin, Bay of Bengal. The core covers the late Holocene period with high overall sedimentation rate of ∼573 cm kyr−1. Pore fluid chemical analyses indicate that the depth of the present sulfate methane transition zone (SMTZ) is at ∼6 mbsf. The (ΔTA + ΔCa + ΔMg)/ inline image ratios suggest that both organoclastic degradation and anaerobic oxidation of methane (AOM) drive sulfate reduction at the study site. The positive correlation between total organic carbon content (TOC) and chromium reducible sulfur (CRS) content indicates marked influence of organoclastic sulfate reduction on sulfidization. Coupled occurrence of 34S-enriched... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00295/40588/39516.pdf |
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| Mazumdar, A.; Dewangan, P.; Joaeo, 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.. |
| We report 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. 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(13)C ranges from -41 to -52% VPDB)... |
| Tipo: Text |
Palavras-chave: Methane hydrate; Cold seep; Authigenic carbonate; Bay of Bengal; AMO; Chemosynthetic community. |
| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32911/31414.pdf |
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