Geochemistry of Archean Radioactive Quartz Pebble Conglomerates and Quartzites from western margin of Singhbhum-Orissa Craton, eastern India: Implications on Paleo-weathering, provenance and tectonic setting

摘要

Graphical abstractArchean radioactive (+Au+PGE) Quartz Pebble Conglomerate (QPC) from Singhbhum-Orissa Craton, eastern India.Display OmittedHighlights?Radioactive QPC occur in the western margin of Archean Singhbhum-Orissa Craton, eastern India.?QPC and quartzites exhibit moderate to high paleo-weathering conditions in the provenance.?They were derived predominantly from felsic with minor mafic- ultramafic mixed source.?QPC-quartzite sequence developed in a passive margin tectonic setting during 3.3 to 2.8Ga.?Eastern Indian radioactive QPC bear resemblance to world class U +REE+Au bearing Mesoarchean QPC.AbstractLenses of radioactive Quartz Pebble Conglomerates (QPC) and associated quartzites are exposed along western margin of Archean Bonai Granite in Singhbhum-Orissa Craton, eastern India intermittently spreading over a strike length of 8–10km. QPCs are radioactive while quartzites are mostly non-radioactive in nature. The purpose of the research is to investigate and characterize the radioactive QPC and quartzites geochemically to decipher their paleo-weathering conditions, provenance characteristics and possible tectonic setting of deposition. Geochemical data suggest moderate to high chemical weathering conditions in the provenance areas of QPC and quartzites. Major, trace and REE data indicate predominantly felsic to partly mafic-ultramafic sources for the deposition of radioactive Quartz Pebble Conglomerates from the surrounding Archean terrain.Elevated values of Th, U, Pb, La, Ce, Y and low Sc with high critical trace elemental ratios of Th/Sc, La/Sc, Th/Cr and Zr/Sc in radioactive QPC indicate their derivation from felsic igneous source. Low concentration of Th and Sc in quartzites compared to QPC and their variable Th/Sc ratios indicate both felsic and mafic sources for quartzites, albeit their preferential felsic affiliation. Higher Cr/Th ratios in quartzites (18.4), moderate Cr/Th in QPC (5.42), low to moderate Y/Ni in QPC (0.36–12.4) and quartzite (0.29–1.88), along with Au ranging from 30 to 1527ppb, Pt up to 188ppb and 682ppb in QPC and quartzites respectively point towards some contribution from mafic-ultramafic source as well. REE patterns and in particular negative Eu anomalies for both QPC and quartzites further support their derivation from felsic rocks and could possibly linked to some of the phases of Archean Singhbhum Granite and Bonai