Utilization of high resolution satellite geoid data for estimation of lithospheric thickness in the Bay of Bengal

Abstract

Very high-resolution database generated from Seasat, Geosat GM, ERS-1 and TOPEX/ POSEIDON altimeters data of the northern Indian Ocean has been used for the first time for preparation of geoid and free-air gravity maps. In the present work, geoid height anomalies have been analyzed across the Ninetyeast and 85°E Ridges within the Bay of Bengal. Present data sets are more accurate and detailed (off-track resolution: about 3.33 km and grid size: about 3.5 km). Observed geoid height - age and geoid height derivative (with respect to age) - age relationships have been established and compared with the plate model of lithospheric cooling to determine. The present endeavor is to determine the lithospheric plate thickness beneath both ridge structures. Attempts have been made to match the observed value with the computed value over the Bay of Bengal. The lithospheric plate cooling model correlates convincingly with the observed value. It has shown the efficacy of a plate model according to which geoid observations of the Bay of Bengal are better explained by a larger plate thickness of 90 - 125 km for the oceanic crust of age older than 30 Ma.