Geochemistry of Siliciclastic Rocks from the Koira Group of Western Iron Ore Group, Singhbhum Craton, Eastern India: Implications for Provenance, Paleo-Weathering, and Tectonic Setting

The geochemical characteristics of quartz-pebble conglomerate (QPC) and quartzite from the Koira Group of western Iron Ore Group, Singhbhum Craton, eastern India have been studied in the context of provenance, paleoweathering, and tectonic setting. In the binary plots of log (SiO2/Al2O3) vs. log (Na2O/K2O) and log (SiO2/Al2O3) vs. log (Fe2O3/K2O), QPC samples occupy the fields of arkose, sub-arkose, sub-litharenite, and quartz-arenite, and quartzites fall in sub-arkose to sub-litharenite fields. In bivariate diagrams of TiO2 vs. Zr and DF-1 vs. DF-2 respectively were used for depicting the provenance of these sequences, and all the samples of QPC and quartzite fall in the felsic igneous rocks and granites and gneisses field respectively. 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 QPC indicating their derivation from the felsic igneous source. In contrast, both felsic and mafic sources are responsible for the formation of quartzites which are supported by the presence of a low concentration of Th and Sc and variable ratios of Th/Sc. Eu anomaly in QPC and quartzite varies from 0.32 to 0.67 and 0.29 - 1.63 respectively which is attributed to the presence of Eu depleted felsic igneous rocks in the provenance such as granites. Based on the Chemical Index of Alteration (CIA) values, a high degree of chemical weathering was depicted in the sequence of QPC and quartzite. In the A-CN-K diagram, the majority samples fall between the granodiorite and tonalite fields which indicate the probable source for the QPC-quartzite sequence. The value of the Plagioclase Index of Alteration (PIA), all the samples falls between oligoclase (Olg) and albite (Ab) fields of the AK-C-N ternary diagram which indicates that the plagioclase was completely altered. In Al2O3/SiO2 vs. Fe2O3+MgO, TiO2 vs. Fe2O3+MgO, and SiO2 vs. K2O/Na2O diagrams, all the samples of QPC and quartzites dominantly come in the fiel