Structure of the earth's crust and upper mantle below Hindustan and the northern part of the Indian Ocean from geophysical data

Abstract

The crustal cross-section of the Indian Shield is refined on the basis of data obtained in the cooperative Indian-Soviet Deep Seismic Sounding (DSS) research and from the use of a new interpretation technique. Crustal velocity parameters are studied and the main blocks and faults are identified. The hypsometric position of the blocks is determined. Gravity field interpretation, using DSS and explosion seismology data, has made it possible to characterize the structure of the entire tectonosphere for the area: Africa-Hindustan-eastern coast of the Bay of Bengal. It is confirmed that the continents have a normal continental crust that passes into the oceanic type under the ocean. In the Somali Trough, especially in the Bay of Bengal, sediments are very thick; the Laccadiv Isles have crust which is oceanic in composition; the rift zone of the Karlsberg Ridge has deep-seated asthenospheric “roots”; the lithospheric density increases as the distance from the ridge grows; the asthenosphere is developed everywhere, but it is thinner and denser below the continent than below the ocean.