Crustal evolution of the Aravalli and Bundelkhand Archean nuclei, North Indian Block: recent advances and perspectives

The North Indian Block comprises two important Archean nuclei, the Aravalli and Bundelkhand cratons. The existence of early Paleoarchean crust (3.59–3.54 Ga) in both nuclei is supported by zircon xenocrysts in 3.44–2.55 Ga tonalite-trondhjemite-granodiorite (TTG) gneisses, although the oldest rock records in the Aravalli and Bundelkhand cratons are represented by scarce exposures of ca. 3.31 and 3.55 Ga TTGs, respectively. The Archean crust in these cratons is largely composed of 2.58–2.50 Ga K-rich granitoids and sanukitoids. A synthesis of literature published during the last four years on these north Indian cratonic blocks revealed several new and important findings, which enabled us to improve our understanding of the evolution of the Archean crust. Integrated microstructure, petrological, geochemical, and latest phase equilibrium modelling and isotopic data have not only provided robust evidence for the Archean antiquity of the central Aravalli-Banded Gneissic Complex but also revealed many aspects of the metamorphic evolution of this terrane. For the Bundelkhand Craton, these data show craton-wide exhumation from 2.4 to 2.3 Ga, two discrete phases of Neoarchean TTG magmatism (ca. 2.71 and 2.68 Ga), deposition of the banded iron formations between 3.44 and 2.80 Ga and their peak metamorphism at ca. 2.5 Ga. The data also provide a better understanding of the anatomy of the intraterrane shear zones and the Paleo– to Mesoarchean supracrustal metavolcanics and metapelites.