Proto-India was a part of Rodinia: Evidence from Grenville-age suturing of the Eastern Ghats Province with the Paleoarchean Singhbhum Craton

Abstract

The timing of amalgamation of the Eastern Ghats Province with the Indian shield is central to the correlation between proto-India and east Antarctica in reconstructions of the supercontinent Rodinia. In this study, the metamorphic and geochronological evolution of the Malayagiri supracrustal belt in the Rengali Province, a wedge-shaped Neoarchean cratonic terrane located between the Paleo-Mesoarchean Singhbhum cratonic nucleus and the Meso-Neoproterozoic Eastern Ghats Province has been used to constrain the suturing of the Eastern Ghats Province with the Singhbhum Craton. The Malayagiri supracrustal rocks were deposited in the Neoarchean between 2.79 and 2.42Ga. The ∼2.80Ga Pal Lahara-Kamakhyanagar Gneiss served as the basement to the supracrustal sequence. The supracrustal rocks were affected by three major tectonothermal events at ∼2.42Ga, 0.98–0.94Ga, and 0.57–0.54Ga and a minor thermal event at ∼0.82Ga. The Grenville-age metamorphism reached upper amphibolite facies conditions along a clockwise P-T path. The Eastern Ghats Province granulites in the vicinity of the Malayagiri supracrustal belt are characterized by major tectonothermal events at ca. 1.22Ga, ∼0.98Ga, ∼0.81Ga, and ∼0.62–0.50Ga. The Malayagiri supracrustal rocks and the Eastern Ghats Province granulites had a common geological history since the early Neoproterozoic with both terranes sharing the 0.98–0.94Ga, 0.85–0.80Ga and 0.62–0.50Ga tectonothermal events. The earliest event shared by the two terranes corresponds to the suturing of the Eastern Ghats Province granulites with the southern margin of the cratonic Rengali Province. Thus, the docking of the Eastern Ghats Province with cratonic India first took place during the Grenvillian and not during the Pan-African orogeny implying that proto-India was welded together with east Antarctica along the Grenville-age Eastern Ghats Province-Rayner complex orogen.