Lithospheric electrical imaging of the Deccan trap covered region of western India

摘要

We present here the results of magnetotelluric (MT) studies carried out along a 330 km long NE-SW trending traverse from Daulatabad at the northeastern end to Koyna on the southwestern end across the Deccan volcanic province (DVP) in western India. The 2-D MT modeling results obtained along this traverse together with those from other MT traverses in this area are examined and integrated with the results from deep seismic sounding, 3-D teleseismic tomography, and heat flow studies. The deep geoelectric section as deduced from MT models point out to a two layered lithospheric mantle structures with an upper very high-resistive layer (several thousands of ohm m) and a bottom relatively conductive one (a few tens of ohm m to a few hundred ohm m). The lithospheric electrical structure is inferred to be linked to compositional changes associated with a depleted lithospheric upper mantle in the Dharwar craton. An impressive feature that the study has brought out is the presence of a well-defined lithospheric upper mantle conductor in the depth range of 80–120 km limited to the middle segment of the MT traverse from Sangole to Partur over the DVP. The electrical characterization of the region including the presence of upper mantle conductor shows close similarities with that of other similar cratonic regions like the Slave and Superior cratons in northwestern Canada.