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Some Observation to Constrain the Zone of Continent Ocean Boundary (COB) Along the Continental Margins of India

Anil K. Kaul, A. Siawal, and N. C. Lohani
KDMIPE, ONGC, DehraDun, India

The study provides a preliminary constraint for ocean ward extension of the continental basement (thinned continental crust) of the Indian Peninsula. A few seismic sections, of east coast and west coast were studied with emphasis on pattern of reflection especially with respect to oceanic and continental basement. The variation observed was also viewed with respect to the available gravity data.

It has been observed that interaction of two crusts (old & new) is varied at various places. Continent Ocean boundary (COB) is somewhat better constrained along the Eastern Continental Margin of India (ECMI) at least along some of the seismic profiles. However, it remained less constrained along the Western Continental Margin of India (WCMI) which is overprinted with few more regional tectonic / magmatic events succeeding the formation of the continental margin. Though, some signatures of oceanic crusts are observed in the area east of Laxmi Ridge.
Generation of reverse faults, as recorded here, is a striking feature of the ECMI. As a consequence, this stable margin, whose evolution was determined earlier by phenomenon of crustal extension leading to rifting and drifting of Indian subcontinent from Antarctica, has started to get altered by the effects of compression. The presence of reverse fault is viewed as marking the initiation of change of subsiding crustal blocks to future tectonic wedges and thrust sheets millions of years henceforth as commonly present at colliding margins.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery