Provenance of >2.8 Ga Keonjhar Quartzite, Singhbhum Craton, Eastern India: Implications for the Nature of Mesoarchean Upper Crust and Geodynamics

AbstractWe determined the provenance, tectonic setting, and weathering characteristics of weakly metamorphosed Mesoarchean siliciclastic rocks from the Singhbhum craton, eastern India, on the basis of their petrographic and geochemical compositions. The 1.5-km-thick siliciclastic succession, formally introduced here as the Keonjhar Quartzite, unconformably overlies the Singhbhum Granite (3.1–3.4 Ga) and has been assigned a Mesoarchean depositional age on the basis of a youngest detrital zircon of 3.01 Ga and intrusive granitoids with ages of not less than 2.8 Ga. Their highly matured and recycled nature is reflected in several geochemical proxies. The highly variable chemical index of alteration (CIA) values and the pattern in the A-CN-K plot indicate variable degrees of weathering, which in turn suggest non-steady-state weathering conditions. The high CIA values also suggest a stable tectonic setting that caused the erosion rates to decrease, which in turn caused a rise in the flux of weathered materials...