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Origin and Distribution of Shallow Gas-Charged Sediment on the Inner Continental Shelf of Central West Coast of India


Affiliations
1 CSIR-National Institute of Oceanography, Dona-Paula, Goa 403 004, India
2 CSIR-National Institute of Oceanography, Regional Centre, Andheri (W), Mumbai 400 053, India
 

High-resolution shallow seismic investigations on inner continental shelf of Goa have been carried out to map gas-charged sediment zones and investigate origin of trapped gas. Analyses of data reveal that the gas is trapped by different stratigraphic layers and is distributed in two zones. Zone-1 is restricted up to ~30 m water depth and in the southern part of the study area. In this zone, gas is confined within the Holocene layers above the Holocene maximum Hooding surface (MFS). Whereas, zone-2 is comprised of several isolated gas-charged patches which are distributed in the entire study area mostly between ~20 m and ~45 m water depth. In this zone, gas is confined below Holocene- MFS in incised river bed or a layer just below MFS or both. Gas-charged sediment in zone-1 is formed due to degradation of organic material which is predominantly early Holocene mangrove derived, whereas, zone-2 it is formed due to degradation of organic material which were deposited by ancestral rivers during the post-glacial sea level rise of the Late Pleistocene. The distribution pattern of zone-1 is controlled by coastline configuration, long-term longshore current pattern, Holocene rapid sea level rise and lithological character of exposed inter-tidal zone. Whereas, distribution of zone-2 is controlled by palaeo-rivers of different glacial periods and their hydraulic energy condition during the base level rise.

Keywords

Acoustic Blanking, Acoustic Turbidity, Central West Coast of India, Gas-Charged Sediment, Mangrove, Shallow Seismic.
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  • Origin and Distribution of Shallow Gas-Charged Sediment on the Inner Continental Shelf of Central West Coast of India

Abstract Views: 299  |  PDF Views: 139

Authors

K. M. Dubey
CSIR-National Institute of Oceanography, Dona-Paula, Goa 403 004, India
A. K. Chaubey
CSIR-National Institute of Oceanography, Regional Centre, Andheri (W), Mumbai 400 053, India

Abstract


High-resolution shallow seismic investigations on inner continental shelf of Goa have been carried out to map gas-charged sediment zones and investigate origin of trapped gas. Analyses of data reveal that the gas is trapped by different stratigraphic layers and is distributed in two zones. Zone-1 is restricted up to ~30 m water depth and in the southern part of the study area. In this zone, gas is confined within the Holocene layers above the Holocene maximum Hooding surface (MFS). Whereas, zone-2 is comprised of several isolated gas-charged patches which are distributed in the entire study area mostly between ~20 m and ~45 m water depth. In this zone, gas is confined below Holocene- MFS in incised river bed or a layer just below MFS or both. Gas-charged sediment in zone-1 is formed due to degradation of organic material which is predominantly early Holocene mangrove derived, whereas, zone-2 it is formed due to degradation of organic material which were deposited by ancestral rivers during the post-glacial sea level rise of the Late Pleistocene. The distribution pattern of zone-1 is controlled by coastline configuration, long-term longshore current pattern, Holocene rapid sea level rise and lithological character of exposed inter-tidal zone. Whereas, distribution of zone-2 is controlled by palaeo-rivers of different glacial periods and their hydraulic energy condition during the base level rise.

Keywords


Acoustic Blanking, Acoustic Turbidity, Central West Coast of India, Gas-Charged Sediment, Mangrove, Shallow Seismic.

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DOI: https://doi.org/10.18520/cs%2Fv116%2Fi8%2F1410-1417