Archean crustal evolution and craton formation in peninsular India: new insights from the Singhbhum, Dharwar and Bastar Cratons

This article highlights the scientific studies published during the last four years from the Paleo-Neoarchean Singhbhum, Dharwar and Bastar cratons. The geochronological and geochemical studies related to TTGs, granitoids, supracrustal sequences and dyke swarms have been documented separately. The Paleoarchean granitoids of Singhbhum Craton are sourced from reworked depleted mantle derived juvenile crust, reflecting episodic magmatic thickening and lower crustal delamination indicative of early crustal maturation in the craton. It is suggested that the continental crust in the Singhbhum Craton experienced a compositional transition from sodic TTG to more potassic transitional TTG and granites at 3.4 Ga. Isostatic modelling suggests that the Singhbhum Craton became subaerial by 3.3–3.2 Ga and favoured terrestrial to shallow marine sedimentation. The circular Simlipal Complex has been suggested as an impact structure and the volcanic rocks are dated at 2.84 Ga, while the sediments are sourced from 3.63 to 2.54 Ga granitoids. In the Dharwar Craton, the oldest Holenarsipur nucleus has been coined as cratonic core representing oceanic plateau, oceanic arc and oceanic crust accreted through horizontal tectonics. Based on the stable isotopes and the U–Pb zircon ages of the sediments, the Archean ocean composition, ocean oxygenation and initiation of biogeochemical processes have been documented. A new tectonic classification of Bastar Craton into western, eastern and central Bastar orogens has been proposed. The co-existence of Dharwar, Singhbhum and Bastar Cratons upto 3.0 Ga has been inferred based on the U–Pb ages of the detrital zircons of the metasediments from the Bastar Craton.