Provenance Signature of Pre-Cambrian and Mesozoic Rocks in the Nearshore Placers of Konkan, Central West Coast of India

Heavy mineral studies of the nearshore placer deposits of the Konkan Coast reveal a dominant assemblage comprised of garnet and kyanite along with other accessory minerals like epidote, olivine and rutile. The heavy mineral assemblage of the study region shows a characteristic suite of 17 types of heavy minerals. Their abundance shows hardly any drastic variation in the four bays studied. Overwhelming presence of minerals like garnet and kyanite in the studied four bays points to the source as metamorphic rocks. The presence of etched garnets, overgrown zircons and etched kyanites corroborate the recycling of paleo-sediments into the bay. Characterization of opaques under the microscope also corroborates the influence of a metamorphic source, rather than the adjoining basaltic rocks. However, the absence of metamorphic rocks in the hinterland suggests the possibility of deposition of sediments predominantly from offshore. Factor analysis results also corroborate the overwhelming influence of metamorphic rocks in the present study region rather than the abutting basalts.