Purana basins of peninsular India: a review

Abstract

AbstractSeven supracratonic, Proterozoic basins, occupying more than a fifth of the Precambrian exposures in the Indian Peninsula, comprise the Purana basins. A comprehensive review of the current status of knowledge of these voluminous orthoquartzite‐carbonate‐shale suites in the context of their contemporary lithostratigraphy, depositional environments and structural disposition is presented. Stromatolite biostratigraphy and available geochronological data are compared, to discern their age limits.These basins contain perhaps one of the most elaborate records of Middle to Late Proterozoic (Riphean‐Vendian) sedimentation preserved in an unmetamorphosed and only slightly deformed state. Further sedimentological and structural studies could lead to a better understanding of the Proterozoic craton‐margin processes. Their close association with the Middle Proterozoic Mobile Belt of peninsular India is that of two contrasting tectonic regimes, contemporaneously adjoining each other. The existing lithostratigraphic classifications of many of these sequences may not stand the test of process ‐ response considerations as demonstrated by the recent revisions in the stratigraphy of the Cuddapah and Bhima basins. The prolific stromatolitic, micro‐organic and trace‐fossil communities preserved in them require much more detailed, but cautious study, and may yield information on the Riphean‐Vendian biota. However, these studies must be undertaken in association with elaborate geochronological determinations which are sparse at present.Inadequacy of the existing knowledge of these basins is highlighted, with the view of inviting the attention of the geological community to these unique basins from peninsular India.