Analysis of multi-channel seismic reflection and magnetic data along 13� N latitude across the Bay of Bengal

Rao, D. Gopala; Bhattacharya, G.C.; Ramana, M.V.; Subrahmanyam, V.; Ramprasad, T.; Krishna, K. S.; Chaubey, A.K.; Murty, G.P.S.; Srinivas, K.; Desa, M.; Reddy, S. I.; Ashalata, B.; Subrahmanyam, C.; Mital, G. S.; Drolia, R. K.; N., S.; Ghosh, Sumit; Singh, R. N.; Majumdar, R. K.

doi:10.1007/bf01237515

Cited by 33 publications

(13 citation statements)

References 16 publications

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“…The KG Basin is in a passive margin setting that shows a thick alluvium sediment accumulation deposited since the Miocene in a growth fault environment (13). Sediment input in this region has been dominated by the Krishna and Godavari River systems producing sedimentation rates of ϳ20 to 25 cm ka Ϫ1 (37). The high sedimentation rate and rich source of organic carbon (1.5 to 2.0 wt% total organic carbon) make the site a good candidate for methane generation in shallow subsurface sediments (22).…”

Section: Methodsmentioning

confidence: 99%

Macroscopic Biofilms in Fracture-Dominated Sediment That Anaerobically Oxidize Methane

Briggs

Pohlman

Torres

et al. 2011

Appl Environ Microbiol

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Methane release from seafloor sediments is moderated, in part, by the anaerobic oxidation of methane (AOM) performed by consortia of archaea and bacteria. These consortia occur as isolated cells and aggregates within the sulfate-methane transition (SMT) of diffusion and seep-dominant environments. Here we report on a new SMT setting where the AOM consortium occurs as macroscopic pink to orange biofilms within subseafloor fractures. Biofilm samples recovered from the Indian and northeast Pacific Oceans had a cellular abundance of 10 7 to 10 8 cells cm ؊3 . This cell density is 2 to 3 orders of magnitude greater than that in the surrounding sediments. Sequencing of bacterial 16S rRNA genes indicated that the bacterial component is dominated by Deltaproteobacteria, candidate division WS3, and Chloroflexi, representing 46%, 15%, and 10% of clones, respectively. In addition, major archaeal taxa found in the biofilm were related to the ANME-1 clade, Thermoplasmatales, and Desulfurococcales, representing 73%, 11%, and 10% of archaeal clones, respectively. The sequences of all major taxa were similar to sequences previously reported from cold seep environments. PhyloChip microarray analysis detected all bacterial phyla identified by the clone library plus an additional 44 phyla. However, sequencing detected more archaea than the PhyloChip within the phyla of Methanosarcinales and Desulfurococcales. The stable carbon isotope composition of the biofilm from the SMT (؊35 to ؊43‰) suggests that the production of the biofilm is associated with AOM. These biofilms are a novel, but apparently widespread, aggregation of cells represented by the ANME-1 clade that occur in methane-rich marine sediments.

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Section: Methodsmentioning

confidence: 99%

Macroscopic Biofilms in Fracture-Dominated Sediment That Anaerobically Oxidize Methane

Briggs

Pohlman

Torres

et al. 2011

Appl Environ Microbiol

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“…Correlation of this unconformity off the ridge into the fan section is possible along some but not all seismic lines (e.g., Gopala Rao et al, 1994Rao et al, , 1997Krishna et al, 1998;Schwenk and Spiess, 2009). Leg 22 sites sampled the older unconformity.…”

Section: Background Geological Settingmentioning

confidence: 99%

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France‐Lanord

Spieß

Schwenk

et al. 2015

International Ocean Discovery Program Preliminary Report

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International Ocean Discovery Expedition 354 to 8°N in the Bay of Bengal drilled a seven site, 320 km long transect across the Bengal Fan. Three deep-penetration and an additional four shallow holes give a spatial overview of the primarily turbiditic depositional system that comprises the Bengal deep-sea fan. Sediments originate from Himalayan rivers, documenting terrestrial changes of Himalayan erosion and weathering, and are transported through a delta and shelf canyon, supplying turbidity currents loaded with a full spectrum of grain sizes. Mostly following transport channels, sediments deposit on and between levees while depocenters laterally shift over hundreds of kilometers on millennial timescales. During Expedition 354, these deposits were documented in space and time, and the recovered sediments have Himalayan mineralogical and geochemical signatures relevant for reconstructing time series of erosion, weathering, and changes in source regions, as well as impacts on the global carbon cycle. Miocene shifts in terrestrial vegetation, sediment budget, and style of sediment transport were tracked. Expedition 354 has extended the record of early fan deposition by 10 My into the late Oligocene.

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“…Two major rivers, the Godavari and Krishna supply the clastic sediments to the K-G basin. Based on Pb-210 and Th-230 dating, a sedimentation rate approximately 20 cm/ky was suggested by Sarin et al (1979) as a minimum estimate at water depths of 2845-3145 m. Rao et al (1994) suggested an approximate sedimentation rate of 20-25 cm/ky for the Quaternary period from the multi-channel seismic reflection studies.…”

Section: Krishna-godavari (Western Bay Of Bengal)mentioning

confidence: 99%

“…2A and B) it is evident that the sedimentation in our sampling sites took place under oxygenated bottom water conditions, except for sampling sites GH4/GC2R where deposition took place in the oxygen minimum zone. Significantly, low sedimentation rates (2-6 cm/ky: Banakar et al, 2005) in Goa sediments compared to that of K-G sediments (20-25 cm ky -1 : Sarin et al, 1979;Rao et al, 1994) seems to be responsible for very limited sulfate reduction in the former owing to rapid reminerlization of organic compounds to refractory components not amenable to sulfate reducers and Krishna-Godavari (A) and Goa (B) methanogens. Depth integrated sulfate reduction rate (J) in Goa varies from 0.011 to 0.942 nmol cm -2 day -1 .…”

Section: Fig 2 Ctd Profiles From Krishna-godavari (A) and Goa Basinmentioning

confidence: 99%

Pore-water sulfate concentration profiles of sediment cores from Krishna-Godavari and Goa basins, India

et al. 2007

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Several cores from Krishna-Godavari (Western Bay of Bengal) and Goa (Eastern Arabian Sea) basins have been studied for pore water sulfate concentrations in order to understand and contrast the diagenetic processes. K-G sediments differ markedly from Goa sediments in pore water sulfate gradients and depth-integrated sulfate reduction rates. Significantly higher sulfate reduction rates in K-G sediments (3.6 to 15.8 nmol cm -2 day -1 ), compared to that in Goa sediments (0.011 to 0.94 nmol cm -2 day -1 ), can be attributed to higher sedimentation rates. Lower exposure time to oxygen for the organic matter in K-G sediments has preserved reactive organic compounds required for sulfate reducers and possibly methanogens. Authigenic carbonates with depleted carbon isotopic composition (δ 13 C = -48 to -50‰) at the base of the sulfate reduction zone in a core from K-G suggests anaerobic methane oxidation (AMO) process. The possibility, that the underlying methane gas hydrate zone is acting as a methane source for sulfate reduction can not be negated specially in light of the existing geophysical studies. Both methane and the fermentation products of organic matter degradation served as a substrate for sulfate reduction. However, a clear understanding of there relative importance needs further investigation.

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Analysis of multi-channel seismic reflection and magnetic data along 13� N latitude across the Bay of Bengal

Cited by 33 publications

References 16 publications

Macroscopic Biofilms in Fracture-Dominated Sediment That Anaerobically Oxidize Methane

Macroscopic Biofilms in Fracture-Dominated Sediment That Anaerobically Oxidize Methane

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Pore-water sulfate concentration profiles of sediment cores from Krishna-Godavari and Goa basins, India

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