Palaeoproterozoic of India
The Indian shield represents a vast repository of the Palaeoproterozoic geological record. Built over the four large amalgamated Archaean nuclei (Dharwar, Bastar, Singhbhum and Aravalli–Bundelkhand) the major and minor Palaeoproterozoic sedimentary basins and supracrustal sequences in India are comparable in scale, and perhaps also in development, to those of North America, Africa, Australia and Brazil. The deformation of these supracrustal sequences, attendant metamorphism and emplacement of plutonic bodies hold important clues to their connection with major orogenies. Research in these areas has led to investigations into global correlation, which in turn has had a direct bearing on refining models of Palaeoproterozoic supercontinent assembly and break-up. This book covers various aspects of regional geology as well as broader issues of the Indian Palaeoproterozoic geology and its global context. It is an outcome of the UNESCO-IGCP 509 Palaeoproterozoic Supercontinents and Global Evolution research project.
Reactivation of basement: example from the Anasagar Granite Gneiss Complex, Rajasthan, western India
Published:January 01, 2012
N. Chattopadhyay, D. Mukhopadhyay, P. Sengupta, 2012. "Reactivation of basement: example from the Anasagar Granite Gneiss Complex, Rajasthan, western India", Palaeoproterozoic of India, R. Mazumder, D. Saha
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Amidst the Meso- to Neoproterozoic South Delhi Fold Belt (SDFB) of Rajasthan, India, a sheet-like body of megacrystic Anasagar Granite Gneiss (AGG) embedded in a supracrustal unit consisting of metapelites, quartzite and calc gneiss is exposed. Detailed analyses of mesoscopic and microscopic structures identify four phases of deformation. Lithological relationships coupled with U–Pb dates of zircon indicate that the protolith of the AGG was emplaced within the supracrustal unit during D1 folding at approximately 1.85 Ga. This event is significantly older than the age of volcanism in the SDFB (0.99 Ga) but probably synchronous with Aravalli Orogeny. Thrusts...