Abstract

The South Rewa basin is an important Gondwana rift-sedimentary basin of the Son-Mahanadi rift system in Central India. The basin has potential hydrocarbon (coal-bed-methane) bearing Gondwana sediments hidden below the Deccan Traps. To delineate subsurface structures of the basin, we have derived 2-D P- and S-wave velocity models (Vp and Vs) down to 15 km depth using ray-trace inversion of long-offset 3-C seismic refraction and reflection data along the 155 km N-S trending Hardi-Samatpur seismic profile. The model consists of complex sediments mixed with upper Gondwana sediments, highvelocity basalt flows, low-velocity Gondwana sediments, undulating granitic basement, and a high-density upper crust. The Vp and Vs models obtained are further correlated with other geophysical models derived from magnetotelluric (MT) and Bouguer gravity data along the same seismic profile of the study area. The lithology of the model is constrained from the Vp, Vs, Vp/Vs, and Poisson’s ratio, indicating significant lateral heterogeneity, presence of faults and horstgraben structures. We have calculated elastic parameters for composition estimation of different rocks in this basin. The MT results further complement the seismic results by delineating a conductive zone associated with the presence of sub-trappean low-velocity-layer (LVL) Gondwana sedimentary rocks confined within the half-graben of the basin. The gravity modeling results also indicate the deposition of thick, low-density Gondwana sediments. Hence, the integration of different geophysical results provides an opportunity to understand the subsurface geological structures of the South Rewa basin.