Indian National Gas Hydrate Program Expedition 01 report

Collett, Timothy S.; Riedel, Michael; Boswell, Ray; Presley, J.; Kumar, Pushpendra; Sathe, A. V.; Sethi, A. K.; Lall, M.V.; Scientists, Nghp Expedition

doi:10.3133/sir20125054

Cited by 50 publications

(116 citation statements)

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“…The calculated BGHSZ for the site MD161-8 based on the estimated geothermal gradient of 44 o C/km is ~150 mbsf which is close to the observed depth of BSR (~160 mbsf; Collett et al, 2008).…”

Section: Base Of Hydrate Stability Zonementioning

confidence: 90%

“…A geothermal gradient of 44°C/km has been reported by Collett et al(2008) for the NGHP site 10D near to our coring location (MD161-8) in the K-G basin.…”

Section: Methodsmentioning

confidence: 99%

“…Smectite bearing Godavari Clay Formation constitutes the Holocene-Pleistocene deposit of the K-G basin (Rao, 2001). The seismic reflection data off K-G basin (Collett et al, 2008;Dewangan et al, 2010;Shankar and Riedel, 2010) show regional presence of gas hydrates manifested in the form of bottom simulating reflectors (BSR) observed at depth of 125 mbsf (water depth: 945m) to 220 mbsf (water depth 1146 m). BSRs represent a phase boundary, where the low-velocity, gas-charged sediments occur below the high-velocity gas hydrate bearing sediments (Singh and Minshull, 1993).…”

Section: Geological Settingmentioning

confidence: 99%

“…Recently, paleo-cold seepage associated authigenic carbonate and chemosynthetic clam (Calyptogena sp.) shells have been reported from this site (Mazumdar et al, 2009b and and nearby site NGHP-10D (Collett et al, 2008). Based on 14 C and U/Th age dating of foraminiferal tests and authigenic carbonates respectively, a minimum age of 46 to 58 kyr was suggested for the methane expulsion events (Mazumdar et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

Joshi¹,

Mazumdar²,

Peketi³

et al. 2014

Marine and Petroleum Geology

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Methane release events have been linked to global warming, alteration of the carbon cycle and influence on biota. However, unequivocal evidence of paleomethane release events are limited. We report several negative carbon stable isotope excursions in planktic and benthic foraminifera in a core (MD161-8) from the Krishna-Godavari (K-G) Basin, Bay of Bengal. The most negative δ 13 C spikes are recorded during the marine isotope stages MIS-4 and at the transition of MIS-5 to 4. Occurrence of highly 13 C depleted (average δ 13 C = -48±2.4 ‰ VPDB) authigenic high magnesian calcite are also reported within this time window from the core MD161-8. In the present work an unequivocal explanation for the observed 13 C depletion in the marine planktic and benthic foraminifera is difficult to achieve solely from the optical/ electron microscopy or C-O stable isotope ratio analyses due to possible influence of diagenetic alteration. We attribute the observed episodic methane expulsion events, as inferred from the negative δ 13 C excursions and earlier reports on the occurrence chemosynthetic bivalves and Mo concentration anomaly to the destabilization of the base of gas hydrate stability zone (BGHSZ). Sea level drop and shale tectonics induced focused fluid flow are the two possible causes of hydrate destabilization discussed here. Shale tectonics were possibly responsible for creating fault systems which acted as the conduit for gas flow through the sediment column and subsequent seepage. Shale and salt tectonics in the passive continental margins being a globally observed phenomenon, its role as an important driving force for enhanced methane emission needs detailed investigation to understand the climatic perturbations through geologic time. Additional evidence of methane emission from site MD161-15 further supports the link between shale tectonics and methane emission.

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Section: Base Of Hydrate Stability Zonementioning

confidence: 90%

“…A geothermal gradient of 44°C/km has been reported by Collett et al(2008) for the NGHP site 10D near to our coring location (MD161-8) in the K-G basin.…”

Section: Methodsmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

Joshi¹,

Mazumdar²,

Peketi³

et al. 2014

Marine and Petroleum Geology

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“…Also, resistivity values observed at marine cold vent systems worldwide have not been shown to exceed ∼200 m (e.g. Collett et al 2008;Kim et al 2011). The probability for the observed data P(d|H) is the Bayesian evidence and can be considered the likelihood of the parametrization H given the observed data.…”

Section: Bayesian Formulationmentioning

confidence: 99%

Bayesian inversion of marine controlled source electromagnetic data offshore Vancouver Island, Canada

Gehrmann

Schwalenberg

Riedel

et al. 2015

Geophysical Journal International

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S U M M A R YThis paper applies nonlinear Bayesian inversion to marine controlled source electromagnetic (CSEM) data collected near two sites of the Integrated Ocean Drilling Program (IODP) Expedition 311 on the northern Cascadia Margin to investigate subseafloor resistivity structure related to gas hydrate deposits and cold vents. The Cascadia margin, off the west coast of Vancouver Island, Canada, has a large accretionary prism where sediments are under pressure due to convergent plate boundary tectonics. Gas hydrate deposits and cold vent structures have previously been investigated by various geophysical methods and seabed drilling. Here, we invert time-domain CSEM data collected at Sites U1328 and U1329 of IODP Expedition 311 using Bayesian methods to derive subsurface resistivity model parameters and uncertainties. The Bayesian information criterion is applied to determine the amount of structure (number of layers in a depth-dependent model) that can be resolved by the data. The parameter space is sampled with the Metropolis-Hastings algorithm in principal-component space, utilizing parallel tempering to ensure wider and efficient sampling and convergence. Nonlinear inversion allows analysis of uncertain acquisition parameters such as time delays between receiver and transmitter clocks as well as input electrical current amplitude. Marginalizing over these instrument parameters in the inversion accounts for their contribution to the geophysical model uncertainties. One-dimensional inversion of time-domain CSEM data collected at measurement sites along a survey line allows interpretation of the subsurface resistivity structure. The data sets can be generally explained by models with 1 to 3 layers. Inversion results at U1329, at the landward edge of the gas hydrate stability zone, indicate a sediment unconformity as well as potential cold vents which were previously unknown. The resistivities generally increase upslope due to sediment erosion along the slope. Inversion results at U1328 on the middle slope suggest several vent systems close to Bullseye vent in agreement with ongoing interdisciplinary observations.

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South Asian monsoon history over the past 60 kyr recorded by radiogenic isotopes and clay mineral assemblages in the Andaman Sea

Ali

Hathorne

Frank

et al. 2015

Geochem Geophys Geosyst

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The Late Quaternary variability of the South Asian (or Indian) monsoon has been linked with glacial-interglacial and millennial scale climatic changes but past rainfall intensity in the river catchments draining into the Andaman Sea remains poorly constrained. Here we use radiogenic Sr, Nd, and Pb isotope compositions of the detrital clay-size fraction and clay mineral assemblages obtained from sediment core NGHP Site 17 in the Andaman Sea to reconstruct the variability of the South Asian monsoon during the past 60 kyr. Over this time interval eNd values changed little, generally oscillating between 27.3 and 25.3 and the Pb isotope signatures are essentially invariable, which is in contrast to a record located further northeast in the Andaman Sea. This indicates that the source of the detrital clays did not change significantly during the last glacial and deglaciation suggesting the monsoon was spatially stable. The most likely source region is the Irrawaddy river catchment including the Indo-Burman Ranges with a possible minor contribution from the Andaman Islands. High smectite/(illite 1 chlorite) ratios (up to 14), as well as low 87 Sr/ 86 Sr ratios (0.711) for the Holocene period indicate enhanced chemical weathering and a stronger South Asian monsoon compared to marine oxygen isotope stages 2 and 3. Short, smectite-poor intervals exhibit markedly radiogenic Sr isotope compositions and document weakening of the South Asian monsoon, which may have been linked to short-term northern Atlantic climate variability on millennial time scales.

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Indian National Gas Hydrate Program Expedition 01 report

Cited by 50 publications

References 0 publications

Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

Bayesian inversion of marine controlled source electromagnetic data offshore Vancouver Island, Canada

South Asian monsoon history over the past 60 kyr recorded by radiogenic isotopes and clay mineral assemblages in the Andaman Sea

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