Chapter 6 Proterozoic Vindhyan Basin: configuration and evolution

Abstract

AbstractThis chapter attempts an understanding of the Proterozoic Vindhyan Basin history in the broad framework of central India. Although the entire Vindhyan Supergroup is within the scope of this work, particular attention is paid to the little-known northwestern fringe exposures. Distinctive facies assemblages and diverse palaeocurrents in these exposures of the Lower Vindhyan play a pivotal role in the interpretation. Analysis of outcrop and subsurface data that extend under the Gangetic alluvium to the north of the Vindhyan outcrops further supports the hypothesis that an east–west-elongated basement ridge initially separated the master Vindhyan Basin from smaller contemporary basins to the north. Deposition took place in isolated lacustrine and fluvial basins north of the divide and largely in a marine realm south. Dextral shear accompanying rifting generated ridges that criss-crossed the Lower Vindhyan seafloor to the south. The uniform character of the Upper Vindhyan throughout, nevertheless, testifies to later drowning of the divide and unification of all of the basins as a consequence of regional tilt northward. However, the extended Vindhyan Sea was restricted by a second east–west-elongated ridge from merger with the contemporary Proterozoic sea further north, disparate sediments of which have been encountered in a few drill cores only.