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Abstract
The presence of gas hydrates along the Indian continental margins has been inferred mainly from the bottom simulating reflection/reflector (BSR) and the gas hydrate stability zone thickness map of India. Multidisciplinary investigations have been carried out in the Krishna‐Godavari offshore area along the eastern continental margin of India which is known for its hydrocarbon potential. Processed multibeam data provided a high resolution seafloor mosaic with a fine scale geomorphology. Deep tow digital side scan sonar, multifrequency chirp sonar and 3.5 KHz sub‐bottom profiler records depict various kinds of gas escape features over the regions where BSRs are prominent. Geochemical analyses of the 5 m‐long cores show a general decrease trend in the porewater sulphate concentration, while the gas chemistry reveals an increase trend of methane concentration with core depth. Total Organic Carbon varies from 0.6 to >2.0% and CaCO3 from 5.0 to >29%. Observed geophysical, geochemical and microbial proxies suggest the likely presence of gas hydrates in the Krishna‐Godavari offshore area. Recent drilling work carried out onboard JOIDES Resolution confirmed the presence of massive (>80 m thick) accumulation of gas hydrates, and fully developed gas hydrate system in the Mahanadi offshore area and the Andaman Sea.
Acknowledgements
We thank the Director, NIO, Goa, for granting necessary permission to publish this article. We thank Mr V.K. Sibal, DG, Directorate General of Hydrocarbons, for encouragement. The officers and crew of ORV Sagar Kanya and AA Sidorenko are thanked for their cooperation during data acquisition. Our colleagues at the Gas Hydrate group, NIO deserve special thanks for their cooperation. GMT software [Citation59] was used to generate the maps in this paper. This is NIO contribution 4260.