Depositional history of the Mesoproterozoic Chhattisgarh Basin, central India: insights from geochemical provenance of siliciclastic sediments

Abstract

ABSTRACT The Chhattisgarh Basin is one of the most important Proterozoic basins of peninsular India. Owing to its deposition in the Mesoproterozoic, the largely undeformed and unmetamorphosed sedimentary sequence of this basin is believed to hold vital clues to our understanding of the evolution of the Indian craton subsequent to the disintegration of the supercontinent Columbia. Despite its importance, only limited studies have been carried out to decipher the depositional history of the basin and to correlate various litho-units in it. Here, we present results of quantitative provenance analysis of the sediments in the basin using trace element and Nd isotopic ratios and discuss their implications for the evolution of the basin in the context of regional tectonics. The sediment provenance analysis reveals that the spatially extensive ~2.5 Ga old granitoids of the Bastar craton were the major contributors (45% to 65%) of the total sediment budget into the basin during its initial stage of evolution. As sedimentation progressed the contribution from the Bastar granitoids was restricted to less than 30% of the total budget with the remaining supplied by younger 1.6–1.7 Ga magmatic rocks. The overall provenance of sediments appears to have remained constant throughout the evolutionary history of the basin; however, the relative contributions of various sources did change with time. The latter is highly conspicuous across the stratigraphic boundary between the Singhora and Chandarpur groups, in the lower part of the Chhattisgarh Supergroup. The geochemical data suggest that the basin developed as a result of either rift or sag into which the sea incursion occurred through the adjacent grabens during the Mesoproterozoic marine transgression.