Plume and Plate Tectonics Model for Formation of some Proterozoic Basins of India along Contemporary Mobile Belts: Mahakoshal — Bijawar, Vindhyan and Cuddapah Basins

Abstract

Proterozoic basins in India mostly belong to two periods, viz. Paleo-Mesoproterozoic (~1.9–1.6 Ga) and Meso-Neoproterozoic (1.1–0.7 Ga) periods that show a long hiatus of ~0.5 Ga between the upper and the lower groups. We have considered Mahakoshal — Bijawar, lower Vindhyan and lower Cuddapah (Cuddapah Supergroup) basins in the former group while the latter consists of upper Vindhyan, and upper Cuddapah (Kurnool) basins. They mostly occur along the contemporary Proterozoic collision zones and are sub parallel to them. The Mahakoshal and Bijawar Supergroups occur along the Satpura Mobile Belt (SMB) and Bundelkhand craton, respectively with Bundelkhand craton as basement and are overlain by the Vindhyan Supergroup of rocks along the SMB. They are almost sub-parallel to the mobile bet, SMB. The Cuddapah Supergroup of Paleoproterozoic period and the Kurnool Group of Neoproterozoic period of Cuddapah basin occur along the Eastern Ghat Mobile Belt (EGMB). Based on the exposed contemporary dyke swarms and sills of mafic and ultramafic rocks that are exposed far apart and their extent sub-surface based on geophysical data, it is suggested that a large plume/superplume existed during Paleoproterozoic period (~1.9 Ga) under the Indian continent. It was responsible for the breakup (rifting) of the then cratons and provided margins for deposition of the former older group of rocks with shelf type of sediments and large scale mafic/ultramafic intrusives. The latter younger groups formed during subsequent convergence in Meso-Neoproterozoic period (~1.1–0.7 Ga) as foreland basins on the stable platform of the rifted cratons. That largely explains their undisturbed nature and absence of magmatic rocks. This convergence also caused large scale deformation as folds and faults in the former group of rocks as they collided with adjoining cratons and formed orogenic belts of that time. In the above examples, the Mahakoshal, Bijawar, lower Vindhyan and lower Cuddapah basins of Paleoproterozoic period formed during the rifting phase due to the plume/ superplume while the upper Vindhyan and upper Cuddapah (Kurnool) basins of Neoproterozoic period formed during subsequent convergence as foreland basins. As they formed during different stages of plate tectonics viz. rifting and convergence, they show long hiatus of 0.5–0.6 Ga between the older and the younger groups. The same plume/superplume at 1.9 Ga might also be responsible for the breakup of the contemporary Columbia supercontinent as rocks of similar ages have been reported from other parts of this supercontinent.