Detection of gas-charged sediments and gas hydrate horizons along the western continental margin of India
Veerayya, M.; Karisiddaiah, S.M.; Vora, K.H.; Wagle, B.G.; Almeida, F. (1998). Detection of gas-charged sediments and gas hydrate horizons along the western continental margin of India, in: Henriet, J.-P. et al. Gas hydrates: relevance to world margin stability and climate change. Geological Society Special Publication, 137: pp. 239-253. https://dx.doi.org/10.1144/GSL.SP.1998.137.01.19 In: Henriet, J.-P.; Mienert, J. (1998). Gas hydrates: Relevance to world margin stability and climate change. Geological Society Special Publication, 137. The Geological Society: London. ISBN 1-86239-010-X. 338 pp., more In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719; e-ISSN 2041-4927, more |
| Keywords | Chemical compounds > Organic compounds > Hydrocarbons > Gas hydrates
Sediments
Topographic features > Submarine features > Continental margins
ISW, South Indian Ocean [Marine Regions]
Marine/Coastal |
| Authors | | Top | - Veerayya, M.
- Karisiddaiah, S.M.
- Vora, K.H.
| | |
| Abstract | High-resolution seismic reflection and sub-bottom profiling on the continental margin off western India has revealed the presence of characteristic acoustic maskings in the form of wipe-outs, reflector terminations and seep-associated features in the inner shelf. These maskings suggest the presence of gas-charged sediments. Further seaward on the outer shelf-middle slope, pockmarks and prominent plumes in the overlying water column indicate a significant seepage of gas from the slope sediments, and it is the seepage which may demonstrate the existence of source rocks. Seismic profiles also revealed the presence of bottom simulating reflectors (BSRs) in the mid-lower slope-rise regions, presumably suggesting the presence of gas hydrates. The BSRs occur at roughly 300–600 ms (TWTT) beneath the sea floor at water depths between 525 and 2200 m; they occasionally show discontinuities. Distinct blanking zones as well as acoustic voids have also been observed above the BSR. In contrast, chaotic and/or scattered hyperbolic reflectors occur in places below the BSR, which may suggest the presence of gas-charged sediments. Folds, diapiric features and faults present in the slope-rise areas may probably serve as traps and conduits for upward migration of fluids and methane gas from the deep. |
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