Changing pattern of continental crust generation from late Mesoarchean to early Paleoproterozoic: Record from the southeastern Bastar Craton, central India

Abstract

The Earth underwent significant changes during the late Mesoarchean to early Paleoproterozoic period, such as the advent of modern-style plate tectonics and widespread formation and emergence of continental crust. However, the details of temporal variations in mechanisms of continental crust formation during this critical period have been widely debated. The present work addresses such issue by providing comprehensive insights through field, petrographic, whole-rock elemental, and in-situ zircon LA-MC-ICP-MS U-Pb-Hf isotope data on granitoids from the previously unexplored southeastern part of the Bastar Craton, India. The study area records the formation of a ∼ 2.86 Ga high-HREE sodic granitoid, and is interpreted to be a product of shallow partial melting of a juvenile mafic crust in an intraplate setting. Detrital zircon ages from a paragneiss suggest subsequent crust generation around 2.75–2.65 Ga, with a shift from juvenile crust formation to reworking of older crust at ∼ 2.70 Ga. Thereafter, widespread high-temperature reworking of significantly older (Eo- to Paleoarchean) crust at ∼ 2.48–2.47 Ga produced voluminous ferroan, LILE- and HFSE-enriched potassic granitoids with A-type characteristics. By synthesizing craton-wide information, our results point towards the subduction and accretion of various arc-related terrains at ∼ 2.5 Ga within the Bastar Craton. It is argued that the ∼ 2.48 Ga high-temperature, ferroan potassic granitoids were formed in an extensional geodynamic setting during post-orogenic uplift. This marks the termination of the compressive forces of subduction, leading to final cratonization. Finally, granitoid exhumation shed immature clastic sediments, now preserved as paragneiss in nearby basins, likely formed by post-collisional extensional collapse. Comparison with other well-studied cratons suggests a common pattern − an initial late Mesoarchean to early Neoarchean period of juvenile magmatism associated with non-plate tectonic regime, followed possibly by the advent of modern-style plate tectonics, terrain accretion, and granitoid diversification in the late Neoarchean.