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.
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The Proterozoic aeon involved at least three major continental readjustments. India and Antarctica appear in most models of supercontinent reconstructions, but their relative position has been the subject of debate. High-resolution petrological and geochronological data, especially from the Proterozoic mobile belts, provide the principal means of resolving this issue. The ice-covered nature of Antarctica allows only limited access to the rocks, and then only in coastal tracts, so detailed studies in more accessible Proterozoic terrains in India assume added significance.
This volume, a follow-up to the XII International Symposium on Antarctic Earth Science, Goa (a SCAR symposium), provides new data from selected locations in east Antarctica (Enderby Land and Dronning Maud Land) and from India, including the Eastern Ghats Mobile Belt (EGMB), Chota Nagpur Gneissic Complex, the Khasi Hills and the Aravalli–Delhi Mobile Belt. The presented geochronological data, constrained by petrological studies, are expected to provide new insights, especially into the EGMB–east Antarctica connection and the rate of continental readjustments in the post-Rodinia break-up.