Журнал дистанционного зондирования и ГИС

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A Gravity and Bathymetric Study in the South East Continental Margin ofIndia

Ayaz Mohmood Dar, Lasitha S, and Rammiya K

The Eastern Continental Margin of India (ECMI) has formed as an upshot of separation of India from Antarctica during the early cretaceous period and subsequent seafloor spreading led to the evolution of Bay of Bengal. The study area, which lies between latitude 8° to 14°N and longitude 77.5° to 81°E, has been selected to delineate the width of the continental shelf region of the south east coast of India. GEBCO bathymetry data and Satellite gravity data has been used for the present study. The bathymetry contour map generated by GEBCO bathymetry data shows gradual increase in the depth from the coastal region (~100 m) to the central basin (~3700 m) and nearly follows a N-S trend from Karikal to Chennai. 24 profiles were extracted from the bathymetric as well as satellite gravity grid. The profiles were created perpendicular to the coastal margin. The maximum width of shelf (~45 km) is observed along the coast near Mamallapuram which is the river mouth of Palar River. Shelf width is gradually decreasing from Chennai to Karikal and the continental slope is also very steep. On the southern part of it, the continental shelf of India merges with that of Srilanka. Further south, in the Mannar basin, the shelf width ranges from 25 to 33 km. The continental shelf region is marked by a relatively high (-40 to 40 mGal) compared to the low gravity anomaly (-40 to -180 mGal) observed towards the basinal area. A local gravity high compared to the surroundings centered at 80.6˚E and 11.8˚N can be associated with the offshore extension of Moyar- Bhavani shear zone, which dissects south Indian terrain.