Abstract

An integrated geophysical strategy comprising deep electrical resistivity and gravity data to image sub-basalt sedimentary basins is presented. A 3D gravity inversion is used to determine the basement structure of the Permian sediments underlying the Cretaceous formation of the Jam River Basin, India. The thickness of Cretaceous formation above the Permian sediments estimated from modeling of 60 deep electrical sounding data agree well with drilling. The gravity effect of mass deficit between the Cretaceous and Permian formations was found using a 3D forward modeling and subsequently removed from the Bouguer gravity anomaly along with the regional gravity field. The modified residual gravity field was then subjected to 3D inversion to map the variations in depth of the basement beneath the Permian sediments. Inversion of gravity data resulted two basement ridges, running almost E-W, dividing the basin into three independent depressions. It was found that the Katol and Kondhali faults were active even during the Post-Cretaceous time and were responsible for the development of the subsurface basement ridges in the basin. The inferred 3D basement configuration of the basin clearly brought out the listric nature of the two faults referred earlier. Further, the extension of the Godavari basin into the Deccan syneclise and the fact that the source rock studies show the presence of hydrocarbons in the Sironcha block in the northern part of the Godavari basin would throw some light on the hydrocarbon potential of the Jam River Basin as well.