A Geophysical Appraisal of the Purana Basins of India

Out of the six Purana basins, namely Cuddapah, Kaladgi, Bhima, Pakhal, Chattisgarh and Vindhyan, Cuddapah, Pakhal and Chattisgarh appear to be filled with rocks of higher than normal density, whereas the other three comprise low density rocks. Their gravity picture, however, are not found to be simple highs or lows as to be expected from their densities but are distorted by both deepseated causes as in the case of Cuddapah, Chattisgarh and Vindhyan basins, as well as the overlying sediments as in the case of Pakhal basin. Major earth movements appear to have been associated with Cuddapah, Pakhal, Vindhyan and Chattisgarh basins whereas Kaladgi and Bhima basins represent mere depressions. The thickness of sediments in these basins is estimated to vary from 2 to 10 km.