Eoarchean to Mesoarchean crustal evolution in the Dharwar craton,India: Evidence from detrital zircon U-Pb and Hf isotopes

The formation and evolution of continental crust in the Early Earth are of fundamental importance in understanding the emergence of continents, their assembly into supercontinents and evolution of life and environment. The Dharwar Craton in southern India is among the major Archean cratons of the world, where recent studies have shown that the craton formation involved the assembly of several micro-continents during Meso- to Neoarchean through subduction-accretion-collision processes. Here we report U-Pb-Hf isotope data from detrital zircons in a suite of metasediments (including quartz mica schist, fuchsite quartzite and metapelite) from the southern domain of the Chitradurga suture zone that marks the boundary between the Western and Central Dharwar Craton. Morphology and internal structure of the zircon grains suggest that the dominant population was derived from proximal granitic (felsic) sources. Zircon U-Pb data are grouped into Paleo-Mesoarchean and Neoarchean to Paleoproterozoic with peaks at 3227 Ma and 2575 Ma. The age spectra of detrital zircon grains, in combination with the Lu-Hf isotopic analyses indicate sediment provenance from magmatic sources with model ages in the range of ca. 3.67 to 2.75 Ga. A transition from dominantly juvenile to a mixture of juvenile and recycled crustal components indicate progressive crustal maturity. The results from this study suggest major crustal growth events during ca. 3.2 Ga and 2.6 Ga in Dharwar. Our study provides insights into continental emergence, weathering and detrital input through river drainage systems into the trench during Eoarchean to Mesoarchean.