Magnetic basement in the central Bay of Bengal

Abstract

Analyses of about 6000 km of processed magnetic data in the central Bay of Bengal using Analytical Signal Processing and Werner Deconvolution techniques revealed that the depth to top of the magnetic basement varies between 5 and 12 km from the sea surface, where the water column thickness is about 3.4 km. These inferred depths are comparable to the reported acoustic basement depths. The basement map derived from magnetic interpretation defines the general configuration of the central Bay of Bengal. The N10-12°W trending subsurface 85°E Ridge buried under 2 to 3 km thick sediments is a prominent tectonic feature. Offshore basins characterised by deeper magnetic basement (∼9 km) and 100-200 km wide are present on either sides of the ridge. These basins were filled with 6-8 km thick lower Cretaceous to recent sediments. Integrated geophysical study depicts that the magnetic basement is characterised by NW-SE, NE-SW, NNE-SSW, N10-12°W and E-W trending structural features that are associated with the lower Cretaceous ocean floor. The Analytical Signal Processing and Werner Deconvolution techniques proved to be effective in determining the depth to the basement in areas covered by thick sediment overburden and characterized by a complex geologic/tectonic framework.