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Metamorphic evolution of the Chotanagpur Granite Gneiss Complex of the East Indian Shield: current status

By
S. Sanyal
S. Sanyal
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P. Sengupta
P. Sengupta
Department of Geological Sciences, Jadavpur University, Kolkata 700032, India
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Published:
January 01, 2012

Abstract

Geological information on the Chotanagpur Granite Gneiss Complex (CGGC) has been reviewed with a view to: (a) identifying the different metamorphic episodes; (b) developing an event stratigraphy in the high-grade blocks; and (c) correlating the different metamorphic episodes with the globally extensive orogenic processes. Integrating the existing geological information, the geological evolution of the high-grade block of the CGGC has been divided into four stages associated with four distinct metamorphic events (MIMIV). The earliest metamorphic event (MI) that is recorded in granulite enclaves in the regionally extensive felsic gneisses culminated in ultrahigh temperatures (>900 °C at c. 5–8 kbar) at around 1.87 Ga. In the second stage, voluminous felsic magmas were intruded – the MI granulites – and were metamorphosed to form migmatitic felsic gneisses (MII) within about 1.66–1.55 Ga. The third stage witnessed intrusions of a suite of anorthosite and porphyritic granitoids (c. 1.55–1.51 Ga), followed by high-grade metamorphism (700±50 °C, 6.5±1 kbar, MIII) during approximately 1.2–0.93 Ga. The fourth stage (MIV) is marked by the intrusion of a suite of mafic dykes, followed by infiltration-driven metamorphism (600–750 °C at 7±1) during 0.87–0.78 Ga. The proposed metamorphic events have been correlated with the supercontinental cycles in the Proterozoic time.

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Contents

Geological Society, London, Special Publications

Palaeoproterozoic of India

R. Mazumder
R. Mazumder
Geological Studies Unit, Indian Statistical Institute, Kolkata, India
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D. Saha
D. Saha
Geological Studies Unit, Indian Statistical Institute, Kolkata, India
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Geological Society of London
Volume
365
ISBN electronic:
9781862396135
Publication date:
January 01, 2012

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