Geochemical Characterization and Constraints on Provenance, Tectonic setting and Paleoweathering of the Miocene Bhuban Sandstone Exposed in Sakhan Anticline, Tripura Fold Belt, Surma Basin, India

Abstract

ABSTRACT The petrography of sandstone, major oxides, trace and REE compositions of the Bhuban formation, exposed in the Sakhan Anticline of Tripura Frontal Fold Belt have been studied to determine the source rock, depositional tectonic setup and paleoweathering conditions. The average modal composition of the Bhuban Sandstone (Q89.27F4.40L6.33) classified them as quartz arenite and sub litharenite types. The modal composition data (Q-F-L) indicates a craton interior and recycled source for these sediments and deposited in an active continental basin margin as suggested by the bivariate plot of SiO2 vs. K2O/Na2O. The binary discrimination plot of Hf vs. La/Th suggests acidic and older sedimentary component as source for the studied sandstone. The ternary plot of V-Ni-Th×10 pointed towards felsic igneous provenance. Trace and rare earth elemental ratios, chondrite-normalize REE plot suggests the source of the Bhuban sediments are derived from felsic terrain. The CIA values (66.48-75.41), A-CN-K plot (A=Al2O3, CN=CaO+ Na2O, K=K2O) and distinct depletion of Na2O, CaO, U, Sr and Ba suggests moderate degree of chemical weathering of the source rocks which may indicate humid climatic conditions in the source area.