THE PALAEODELTA OF THE PROTO VATRAK AND PROTO MAHI RIVERS OF NORTHEASTERN GUJARAT, INDIA - A REMOTE-SENSING INTERPRETATION

Detailed remote sensing studies carried out in northeastern Gujarat, I ndia, suggest that there has been a major change in the drainage syste m as evidenced by the presence of a large palaeo-delta system. The are a is drained by two major rivers, the Mahi and Vatrak originating from the Aravalli Hills to the east, which discharge into the Gulf of Camb ay, in the Indian Ocean. Major lineaments, palaeodrainage patterns and palaeodeltas of the Vatrak and Mahi rivers were delineated. These wer e large rivers in the past with a high discharge and floodplains which were 5-10 km wide. Most of the palaeodrainage follows the NE-SW Preca mbrian lineaments/faults indicating their structural control. Reactiva tion of these lineaments and differential uplift of the Aravalli Hills resulted in increased transportation of the eroded sediments and depo sition of more than 5 km thick sediments into the Tarapur block of the Cambay Basin. The Gulf of Cambay extended up to the Limbasi-Sojitra-P etlad area during the Quaternary. There are implications for petroleum exploration in the sense that the results when integrated with subsur face geological and geophysical data help to delineate the reservoir f acies suitable for petroleum exploration along the eastern margin of t he Tarapur block.