Research Projects

In many passive margins, sedimentary deposits fail by sliding over a basinward sloping detachment fault. Overpressure within rapidly deposited undrained shale is the primary cause of initiating the slide at the detachment. The resistive forces offered by sediments of greater strength at the downslope end of the landslide obstruct the gravity-driven glide. However, if the slide driving forces are strong, it overcomes the frontal obstruction leading to complete evacuation and a catastrophic tsunami. The offshore Krishna-Godavari Basin hosts spectacular deep-water-fold-and-thrust-belts (DWFTBs) over detachment faults. Seismic profiles show a stack of detachments linked with fold-and-thrusts on the continental slope, indicating multiple gravity gliding events. The DWFTBs detached on a mobile overpressured shale. There is seismic evidence of gas and gas hydrate, such as a bottom simulating reflection in the DWFTBs. Methane seeps were identified on the continental slope offshore KG Basin. In the proposed research, three-dimensional (3D) seismic data will be used to examine the structure of subsurface sedimentary layers, gas migration patterns and occurrence of gas hydrates in the DWFTBs. The 3D structure of the detachment, thrust and folds within the DWFTBs will help to unravel the evolution of the gravity-driven collapse structure. The integrated structural and stratigraphic analysis will provide insights into the role of sedimentation and overpressure generation in initiating the shale detachment. The National Gas Hydrate Expedition-01 drilled the gravity-driven structures of the KG Basin to explore the occurrences of methane hydrates. The deeper toe regions of the DWFTB have not been examined in terms of deformation, fluid focusing mechanisms, and stability of gas hydrates. The study will determine the 3D thermal state of the basin from the depth of the base of gas hydrate stability in the seismic data. The heat flow patterns can help predict the stability of hydrates, and potential hazards associated with gas hydrate dissociation and methane release. The research will bring into focus the critical state of stability of the slope, the trapped energy resources, and seafloor hazards in the DWFTBs.

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