242-8 Petrogenesis of the Korba Granites: implications for Mesoproterozoic tectonomagmatic evolution of the Central Indian Tectonic Zone(CITZ)

Abstract:

Peninsular India is a result of the collision between Archean cratons during the Meso- to Neoproterozoic. The collisional belt between the cratons of southern India (Bastar, Dharwar, Singhbhum) and northern India (Bundelkhand) is referred to as the Central India Tectonic Zone (CITZ). There are a number of batholiths within the CITZ that record different stages of crustal evolution that culminated during the terminal stages of collision at 1000-850 Ma. The ‘Late Archean’ Chhotanagpur Gneissic Complex (CGC) of the CITZ includes ‘undifferentiated’ Korba granites and associated meta-sedimentary rocks, but very little is known about the granites including their petrogenesis and age. In this study, we report the first geochemical and geochronological results from the Korba granitic rocks. Granites, pegmatites, and meta-sedimentary rocks were collected from Korba District, Northern Chhattisgarh. The in situ zircon U-Pb geochronology results indicate an Early Mesoproterozoic (1565.9 ± 6.8 Ma) emplacement age. The granites (SiO₂ = 60-76 wt%) are peraluminous, alkali-calcic to calc-alkalic, ferroan in composition and have abundant LILE and slightly to moderate abundant in HFSE. The ɛ_Hf(t) values of Korba granites range between -6.6 and +4.6. Furthermore, sillimanite-bearing pegmatites zones are found throughout the upper parts of the Korba granites suggesting that there was a period(s) of late stage Al-rich fluid fluxing. Blocks (1-10 m wide) of meta-sedimentary rocks are found within the granites and may represent a roof pendant of the series. The Korba granites are mineralogically and compositionally similar to granitoids derived by partial melting of sedimentary rocks during crustal thickening associated with collision. The results of this study suggest that there was a regional collisional event ~500 million years before the Neoproterozoic terminal collision, which is also likely recorded by the Sauser group at southwest side of CITZ. We suggest that the Korba granites were emplaced within rifted continental crust from the Southern India Craton that collided with the Northern Indian Craton during the Early Mesoproterozoic.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-20016

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