Inferring a Neoproterozoic orogeny preceding the Rodinia break-up in the Sirohi Group, NW India
Devsamridhi Arora, Naresh C. Pant, Fareeduddin, Surbhi Sharma, Raghuram, Mohd. Sadiq, 2017. "Inferring a Neoproterozoic orogeny preceding the Rodinia break-up in the Sirohi Group, NW India", Crustal Evolution of India and Antarctica: The Supercontinent Connection, N. C. Pant, S. Dasgupta
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Recent studies indicate the Delhi Orogeny to be a Grenvillian-age collision event in the NW Indian Shield. West of the southern part of the South Delhi Fold Belt, aeromagnetic anomalies show a high-angle relationship with the Delhi Fold Belt trend. We examined an argillaceous–calcareous metamorphosed sequence exposed within and adjacent to this aeromagnetic anomaly. This sequence, deposited over a granitic basement, is reported as the Sirohi Group. The basement granite is dated to be 892 ± 10 Ma (Erinpura age) and this was partially reset at 815 ± 43 Ma. The metapelites preserve a low- to medium-grade metamorphic assemblage (peak temperature of c. 460°C) and the metamorphism took place at 822 ± 29 Ma, which was partially reset at 723 ± 65 Ma. The partial resetting can be ascribed to the Malani eruption. Control of accessory minerals on the garnet trace element chemistry is evident in the Y distribution of the two analysed garnets.
It is contended that the Rodinia break-up, marked by Malani Igneous Suite, was preceded by an orogenic event (the Sirohi Orogeny) which marked the culminating mountain-building event in the cratonization of the NW Indian Shield.