Formation of Eo-Paleoarchean continental crust through intracrustal reworking of differentiated Hadean crust in the Bastar Craton, India

ABSTRACT The generation of Earth’s earliest continental crust remains a fundamental question in understanding planetary differentiation and geodynamic evolution. Globally, Eo-Paleoarchean tonalite-trondhjemite-granodiorite (TTG) rocks record complex magmatic histories involving both juvenile mantle inputs and reworking of older crustal components. The Bastar Craton in central India consists of the Sukma and Kapsi TTG-dominated terranes, which formed in equilibrium with rutile-bearing eclogite and garnet-amphibolite residues, respectively. Here we present new zircon U–Pb–Hf isotope data from these two terranes that preserve coeval but isotopically heterogeneous TTG magmatism. Hafnium isotopic compositions (ε Hf (t)) of 3.8–3.6 Ga magmatic zircon are highly evolved (−14.4 to −1.2), with the Sukma and Kapsi terranes recording subchondritic ε Hf (t) arrays bracketed by Archean felsic crust and oceanic plateau Hf isotope evolution lines. These data suggest that Eo-Paleoarchean TTG magmatism in the Bastar Craton was driven by partial melting of differentiated Hadean sources. Collectively, our findings support intracrustal melting as the dominant mechanism for TTG generation in this region, reflecting a stagnant- or squishy-lid geodynamic regime on early Earth. Early continental crust in the Bastar Craton developed predominantly through partial melting and reworking of older crustal protoliths, indicating that intracrustal differentiation and recycling were already important components of crustal evolution in the early Earth.