292 INDIAN SUBCONTINENT Table Generalised correlation of the Indian Gondwana formations (adapted from Shastri et al., 1977) Age JURASSIC Lower TRIASSIC Upper Damodar Valley PERMIAN Upper Lower Pranhita Godavari Kota Supra Panchet Middle Lower Mahanadi Son Valley Parsora Mahadeva Dharmavaram Maleri Pali Bhimavaram Yerapalli Mangali Panchet Raniganj Barren Measure Kamthi Barakar Karharbari Talchir Barakar Karharbari Umaria Talchir the similarities in sedimentary succession in several of the now-isolated basins, the presence of a master basin for the deposition of the Gondwana sediments has been suggested Faulting, as well as topographic relief during the post depositional phase, presumably caused the varying morphology of the individual basins Popular opinion, however, insists on a rift origin of the Gondwana basins, which at a later stage developed into half or full grabens The progressive, as well as repetitive movements along block faulted basement slabs underlying the basin, controlled the sedimentation in different Gondwana basins The present-day basin geometry is a combined effect of faulting in three stages, at the initiation, during, and post-dating sedimentation Between Jurassic Breakup and the Himalayan Collision The Gondwana sedimentation, which began in the Permian, continued until the Lower Jurassic The next major global event that grossly affected Indian continental block was the breakup of Gondwana at around 165 Ma The initial separation resulted in marine incursions and deposition of sediments in western Rajasthan and in the Kachch region along WNW–ESE trending rift basins The deposition of continental sediments, which had earlier stopped in different Gondwana basins before the Lower Jurassic was also resumed, at least in certain cases The Gondwana breakup event is also responsible for the development of arrays of fracture systems in the Indian Continental block (Figure 7) Geomorphologically expressed as lineaments, these fracture systems, which developed either as new sets of fractures or as reactivated old tectonic grains, helped to significantly change the geophysical character of the Indian crust in a variety of ways Kamthi Motur Barakar Talchir As the Indian continental block (along with Madagascar and Seychelles, and Antarctica remaining attached to it) moved northward following the dismemberment of Gondwana, it was affected successively by the outbursts of four plume heads centred at Marion, Reunion, Crozet, and Kerguelen Islands The manifestations of the Crozet Plume outbursts are virtually unknown The Marion Plume outbursts resulted in the separation of Madagascar from the Indian continental block during 80 to 90 Ma (Figure 8) Evidence for this comes from the occurrence of 88–90 Ma old acid as well as mafic rocks in different parts of central and North Kerala, St Mary’s Island off the Karnataka coast and also from Madagascar The Rajmahal Traps and the Sylhet Traps are the manifestations of Kerguelen Plume activities, which lasted from 130 Ma to 110 Ma The plume caused the separation of Antarctica from the Indian continental block and induced Cretaceous marine ingress both in the south-eastern part of the peninsula as well as in the south-east of the Bengal basin The timing and the passage of impingement of the Reunion Plume are well recorded in the form of different features that developed between Kohistan in the north to the Lakhsadweep-Maldive Islands in the south The important features that developed during between 70 Ma and 64 Ma include: i the formation of narrow sedimentary basins, locally having volcanic inputs (many of which turned into oil-bearing formations) in western Rajasthan and northern Gujarat; ii extensive mafic (continental tholeiite basalt) volcanicity in western and central India; iii intrusions of plutonic alkaline masses of diverse composition which were also responsible for the development of isolated patches and linear belts