Mineralogy and geochemistry of clastic sediments of the Terani Formation, Cauvery Basin, southern India: implications for paleoweathering, provenance and tectonic setting

Mineralogical and geochemical (major, trace and rare earth elements) studies were carried out on the clay samples of the Terani Formation, South India to investigate the paleoweathering, source rocks characteristics and tectonic setting. The chemical index of alteration (CIA), plagioclase index of alteration (PIA) values and A-CN-K diagram indicate that clays were generated from source rocks of the upper continental crust affected by intense chemical weathering. The chondrite-normalized REE patterns show considerable LREE enrichment, HREE depletion with significant negative Eu anomalies. The REE patterns, elemental ratios like Al2O3/TiO2Cr/Ni, Eu/Eu*, (La/Lu)cn, La/Sc, Th/Sc, La/Co, Th/Co, and Cr/Th, discriminant function diagram, various bivariate and ternary plots indicate the contribution of sediments from felsic and intermediate source rocks. The discriminant-function-based tectonic setting diagrams reveal passive margin setting for the source area of the Terani Formation.