Proterozoic evolution of Eastern Dharwar and Bastar cratons, India-An overview of the intracratonic basins, craton margins and mobile belts

摘要

Based on critical analysis of stratigraphic succesions in the Proterozoic intracratonic basins, geochrono-logical data and possible connections or disconnections with adjacent fold belts and craton margin mobile belts, an overview of the Proterozoic evolution of the Eastern Dharwar and Bastar cratons in India is presented. The Chattisgarh and Cuddapah basins in these cratons with Archean nuclei host sedimentary successions ranging in age from the Paleoproterozoic to the Ediacaran period, and representing several silicilastic and carbonate cycles. The Proterozoic successions of the Pranhita-Godavari valley (PGV) basin along the Dharwar-Bastar join, record multiple rifting since late Neoarchean suturing of the two cratons. We postulate a first order stratigraphic correlation across the cratons and their join and discuss how major sea level fluctuations coupled with regional tectonic events shaped the development of unconformity bound successions, adjoining fold belts and the mobile belts with supposed global tectonic connections. The oldest Paleoproterozoic intracratonic sedimentation is preserved in the Cuddapah and PGV basins, while sedimentation in the Bastar craton is largely Mesoproterozoic. The fluviodeltaic to shallow marine Neoproterozoic sedimentation followed emplacement of end-Mesoproterozoic kimberlites and lamproites indicating thermal rejuvenation of the Indian continental crust. The allochthonus Nallam-alai fold belt in eastern Cuddapah basin and the early Mesoproterozoic fold belt in PGV basin point to craton margin crustal convergences which punctuated the Paleoproterozoic sedimentation. Widespread development of carbonate bearing sequences in the Mesoproterozoic to Neoproterozoic successions point to peneplanation of the cratons and stable platformal sedimentation. The Neoproterozoic sedimentation was terminated following the docking of the Eastern Ghats belt to the eastern margin of the Dharwar-Bastar ensemble and possible final tectonic hiccups in the Central Indian Tectonic zone bordering the Bastar craton. The available data and their analysis rule out any foreland basin type connection between the Eastern Ghats belt and cratonic sedimentation in Bastar and Eastern Dharwar.