Geochemistry of metasedimentary clastic rocks from Dhanjori and Badampahar Groups, Singhbhum Craton, Eastern India: implications for tectonic setting and Archean–Proterozoic boundary

This work intends to present a comprehensive geological and geochemical study of the metasedimentary clastic rocks from Dhanjori and Badampahar Groups, Singhbhum Craton, Eastern India. It is a contribution for understanding the source area weathering, tectonic setting, and to define the Archean–Proterozoic boundary in eastern India for the first time in the study area. The sediments from three stratigraphic levels in Dhanjori and Badampahar Groups of Singhbhum Craton display great diversity in major, trace, and rare earth element geochemistry. In bivariate diagrams of TiO2 vs. Zr, and discriminant function 1 vs. discriminant function 2 (DF-1 vs. DF-2) were used for depicting the provenance of these sequences, and all the samples of the study area fall in the felsic igneous rocks and granites and gneisses field. Besides, the values of Pb, U, Th, Y, La, Ce, and low Sc with high critical trace elemental ratios of Th/U, Th/Sc, Zr/Y, and La/Sc in quartz-pebble conglomerate (QPC) indicating their derivation from the felsic igneous source. The QPC-quartzite sequence of Dhanjori Group is characterized by light rare earth element (LREE) enrichment, nearly flat heavy rare earth element (HREE) (Gd/Yb)N, and enrichment of Eu anomaly, corroborating felsic province in the source area. The quartzite of the Badampahar Group is formed in depleted mantle source or mafic–ultramafic rocks which are supported by the presence of low concentrations of Th and Sc, low values of Zr/Y, La/Sc, Th/Sc, Th/Co, La/Co, and Th/U ratios, enrichment of Co + Cr + Sc and depletion of HREE. The values of (La/Sm)N, (Gd/Yb)N, and Eu anomaly is also attributed to a provenance from mafic–ultramafic source rocks. In Al2O3/SiO2 vs. Fe2O3 + MgO, TiO2 vs. Fe2O3 + MgO, and SiO2 vs. K2O/Na2O diagrams, all the samples of the study area dominantly come in the field of passive margin tectonic setting except few samples fall in the active continental margin, oceanic island arc, and continental arc fields, respectively. Based on the above-mentioned geochemical data and field observations, the erosional unconformity signed by conglomerates at the base of Dhanjori Group represents the transition between the crustal composition from dominantly mafic–ultramafic to granitic–granodioritic. Therefore, occurrences of QPC may define the Archean–Proterozoic boundary between the Singhbhum Granite Phase-B and the Dhanjori Group.