Gas-charged sediments on the inner continental shelf off western India

Abstract

High resolution seismic reflection profiles on the inner continental shelf (less than 60 m water depth) off India from 10°N to 22°N show 5–35 m of weakly stratified acoustically transparent clays. At water depths of 15–50 m, the subbottom profiles are characterized by anomalous seismic signatures in the form of acoustic maskings. These extend from the underlying Late Pleistocene unconformity, often stretching along the bedding planes, and occasionally surfacing on the sea bed. These acoustic maskings could be due to shallow hydrocarbon gases (mainly methane) which might have been derived from biogenic sources or geothermal processes, or both.