Chapter 16 - Deciphering Sedimentary Provenance and Timing of Sedimentation From a Suite of Metapelites From the Chotanagpur Granite Gneissic Complex, India: Implications for Proterozoic Tectonics in the East-Central Part of the Indian Shield

Abstract

Zircon populations from a suite of metapelites from parts of the poly-metamorphosed Chotanagpur Granite Gneiss Complex of the east Indian shield show complex internal morphology with U-Pb isotopic compositions that are reminiscent of their source characters and thus put tight constraints on the age of sedimentation of their protolith. The 207Pb/206Pb apparent dates of the detrital cores of zircon grains suggest that protoliths of these sediments were sourced from the ∼2700–1700Ma old domains in the adjoining cratonic areas and also from the rocks of comparable age now occurring in the Lesser Himalayan region. The ages of the youngest analyzed detrital zircons and the oldest metamorphic overgrowth constrain the age of sedimentation of the precursor of metapelites within a narrow age bracket of 1696–1678Ma. Combining the published information with the new findings reported here, it is argued that in response to disintegration of Columbia Supercontinent extensive sedimentary basins developed on the Archaean-early Paleoproterozoic basements of the Indian shield, a part of these sediments got subsequently metamorphosed by later tectonothermal events.