Provenance and Paleo-weathering of the Mesozoic Rocks of Kutch Basin: Integrating Results from Heavy Minerals and Geochemical Proxies

This study investigates the composition, tectonic setting and age of source rocks of the Mesozoic Kutch Basin, along with the extent of weathering based on heavy mineral characteristics and geochemical investigations. The Mesozoic succession, divided into Jhurio, Jhumara, Jhuran and Bhuj formations, preserves sediments deposited in the Kutch Basin from the Late Triassic to Early Cretaceous. Subangular and subrounded heavy minerals indicate mixing of first cycle and recycled input in these samples. Major oxide ratios such as SiO2/Al2O3, Al2O3/TiO2, K2O/Na2O and trace elements like Zr, Th, Sc, Th/Co, Th/Sc and La/Sc indicate dominantly felsic source. LREE enrichments and negative Eu anomalies support the predominance of felsic source rocks. TheVand Ni concentrations in these sediments indicate the input from mafic sources in the older Jhurio and Jhumara formations. Weathering indices such as CIA, PIA and CIW suggest the relatively greater extent of chemical alteration for Jhumara, Jhuran and Bhuj formations in comparison to Jhurio Formation. The higher content of Hf in Jhuran and Bhuj formations suggests the input from older source rocks in younger formations, indicating erosional unroofing at the source. The concentration of Cr and Ni and ratios of Eu/Eu* and (GdN/YbN) indicate predominantly post-Archean source with inputs from older Archean rocks in younger Jhuran and Bhuj formations, and corroborate the erosional unroofing. These evidences relate possible sources of Mesozoic sediments in the Kutch Basin to Precambrian rocks of the Aravalli craton and Nagar Parkar igneous complex.