New Ideas about the Structure and Nature of the Crust of the Western Bay of Bengal, Obtained Taking into Account Deep Seismic Sounding Data

A comprehensive analysis of geological and geophysical data characterizing the structure of the eastern continental margin of India and the adjacent part of the bottom of the Bay of Bengal has been carried out. According to the structural and tectonic features, three sectors are distinguished: southern, central, and northern, the natural boundaries between which are the fault zones of the Makhanadi and Godavari–Krishna aulacogens. In the central sector, the pericontinental East Indian Plateau adjoins the continental slope. In 2003, the R/V Mezen acquired deep seismic sounding data on two profiles in this region. These data and their geological interpretation made it possible to identify “reduced” continental crust, characterized by reduced thickness of the upper, middle, and lower layers. A conclusion is drawn about the continental nature of the East Indian Plateau and northern part of the 85° Ridge adjacent to it. The light sialic and effusive rocks that form the top of the ridge give a negative gravimetric anomaly in the free-air reduction, which is its distinguishing feature.