The Central Indian Tectonic Zone: A Rodinia supercontinent-forming collisional zone and analogy with the Grenville and Sveconorwegian orogens

Abstract

Abstract In the paleogeographic reconstructions of the Rodinia supercontinent, the circum-global 1.1–0.9 Ga collisional belt is speculated to skirt the SE coast of India, incorporating the Rodinian-age Eastern Ghats Province. But the Eastern Ghats Province may not have welded with the Indian landmass until 550–500 Ma. Instead, the ~1500-km-long, E-striking Central Indian Tectonic Zone provides an alternate option for linking the 1.1–0.9 Ga circum-global collisional belt through India. The highly tectonized Central Indian Tectonic Zone formed due to the early Neoproterozoic collision of the North India and the South India blocks. Based on a summary of the recent findings in the different crustal domains within the Central Indian Tectonic Zone, we demonstrate that the 1.03–0.93 Ga collision involved thrusting that resulted in the emplacement of low-grade metamorphosed allochthonous units above the high-grade basement rocks; the development of crustal-scale, steeply dipping, orogen-parallel transpressional shear zones; syn-collisional felsic magmatism; and the degeneration of orogenesis by extensional exhumation. The features are analogous to those reported in the broadly coeval Grenville and Sveconorwegian orogens. We suggest that the 1.1–0.9 Ga circum-global collisional belt in Rodinia swings westward from the Australo-Antarctic landmass and passes centrally through the Greater India landmass, which for the most part welded at 1.0–0.9 Ga. It follows that the paleogeographic positions of India obtained from paleomagnetic data older than 1.1–0.9 Ga are likely to correspond to the positions of the North and South India blocks, respectively, and not to the Greater India landmass in its entirety.