Gravity anomalies and crustal structure of the Bay of Bengal

The Bengal Fan is covered afresh by systematic geological and geophysical i nvestigations by National Institute of Oceanography (NIO), India and a deta iled free-air gravity map of the fan is prepared. The map shows two strong gravity lows - one corresponding to the continental shelf and the other to the WE Ridge. The Ninetyeast Ridge is brought out as a gravity high, The an omalies are inverted to determine the anomaly-producing interfaces, which s uggest that the 85 degreesE Ridge anomaly could not be explained by an isol ated geophysical model invoking a negative density contrast for the ridge m aterial. The WE Ridge anomaly and several other isolated gravity lows are a ttributed mostly to the depression-like structures in the Moho. Each depres sion of the Moho is associated with a basement high. The depression beneath the WE Ridge is about 6 km deep from the regional Moho boundary, which is at variance to the earlier results. It is suggested that the depressions ma y possibly have developed due to the surface volcanic loads emplaced on alr eady evolved oceanic crust of the Bay of Bengal. (C) 2001 Published by Else vier Science B.V.