A detrital zircon U–Pb and Hf isotopic transect across the Son Valley sector of the Vindhyan Basin, India: Implications for basin evolution and paleogeography

Abstract

The Vindhyan Supergroup, located in central peninsular India, is one of the largest and thickest Precambrian sedimentary successions of the world, outcropping over an area of over 104,000km2. The Vindhyan is the largest of the so-called “Purana” (Hindi for “ancient”) basins in India. The Vindhyan Supergroup is subdivided into the upper Vindhyan and the lower Vindhyan. The age of the Lower Vindhyan is reliably constrained to the Paleo-Mesoproterozoic interval whereas the age of the Upper Vindhyan sedimentary sequence is the subject of considerable controversy. This study provides a very large and integrated detrital zircon database that provides constraints on the age of the Upper Vindhyan sequence and its relationship to the nearby Marwar Supergroup. In some scenarios, these two basins are considered as coeval and Neoproterozoic in age whereas in other models the basins are thought to have evolved during different time intervals. Multiple hypotheses have been proposed concerning basin closure: some argue for an early Neoproterozoic to late Mesoproterozoic closure (~1050Ma) of Upper Vindhyan sedimentation whereas others argue for an Ediacaran–Cambrian age. Our study indicates that although both the Marwar and Vindhyan basins share some similar source regions, their evolutionary histories cannot be reliably linked. We argue that deposition of the Upper Vindhyan sequence closed near the end of the Mesoproterozoic (~1000Ma) whereas deposition in the Marwar basin was confined to the Ediacaran–Cambrian interval (~570–521Ma). This argument is indirectly supported by previously published paleomagnetic data from both the Upper Vindhyan and the Marwar sequences. Although the basins have distinct depositional histories, Hf isotopic data show that the Vindhyan and Marwar shared similar sources, most likely from the Aravalli region. We conclude that the so-called “Purana Basins” of India formed during distinct intervals of Precambrian time (Paleo-Mesoproterozoic, Mesoproterozoic and Ediacaran-Cambrian). The formation of these sedimentary basins may be related to the supercontinents of Columbia (Lower Vindhyan), Rodinia (Upper Vindhyan) and Gondwana (Marwar). The sedimentary sequences in the Marwar Basin may be part of a large trans-Gondwana series of basins that include the ‘nearby’ Salt Range (Pakistan), Huqf Supergroup (Oman) and Molo Group (Madagascar).