Anatomy of an Intracratonic Son-Mahanadi Gondwana Rift Basin in Peninsular India: an Integrated Gravity, Magnetic and Remote Sensing Approach

The NW-SE trending Son-Mahanadi basin is one of the largest intra-cratonic Gondwana rift basins of Peninsular India covering an area of approximately 48,000 sq. km. Here we employed a combined analysis of gravity and magnetic (GM) and remote sensing (RS) techniques to delineate the subsurface structures to tracing the tectonic evolution of the Son-Mahanadi basin. Landsat remote sensing data, ground gravity, and EMAG2 magnetic data were used to understand the surface and subsurface structures. The Bouguer gravity anomaly map of the region shows short wavelength gravity lows and highs due to depressions and upwarps in the basement. Interestingly, short wavelength gravity anomalies are superposed on a long wavelength regional gravity low centered over the basin. The regional gravity low bears an inverse correlation with the regional topography suggesting that the excess topographic load is compensated at depth and the required buoyancy might be due to thinning of the lithosphere as a consequence of Deccan volcanism. The ENE-WSW structural grain inferred from remote sensing data coincides with the trend of dyke swarms and the WNW-ESE trend possibly corresponds to the rift boundary faults in the south. The lineament trends show preferred spatial distribution in three sub-basins (Son, Hasdo-Arand, and Mahanadi), each separated by basement ridges. Integration of remote sensing, geological, and potential field data suggests reactivation of ENE-WSW trending structural lineaments which are associated with the dyke emplacement during Deccan volcanism. Thus, the Son-Mahanadi Gondwana basin witnessed a post-rift tectonic event associated with the Deccan volcanism.