Geochemical characteristics and uranium mineralization exploration potential of late Miocene molasse sediments of NW Himalayan foreland basin Pakistan

Abstract

This study has defined the provenance, tectonic settings, paleo-weathering, sediment-recycling, and sandstone-type uranium mineralization potential of late Miocene mid-Siwalik Dhok Pathan Formation from Surghar-Shingar Range of NW-Himalayan foreland Fold-and-Thrust-belt. Twenty-six sandstone samples were analyzed on XRF and ICP-MS to determine concentrations of different geochemical species. These Himalayan molasse sediments are moderately rich in quartz. The other framework gains include igno-metamorphic and sedimentary lithic fragments (second in abundance after quartz), feldspars, and dominance of ferroan phlogopite (biotite) over white mica. Garnet, epidot, amphibole, magnetite, tourmaline, rutile, zircon, monazite, and uranothorite are present as common accessory minerals. These sandstones are generally classified as lithic arenite, greywacke, and arkose on the basis of geochemistry. These molasse sediments have recorded the signatures of first-cycle detritus mainly contributed by felsic-igneous rocks in collision-arc tectonic settings. Chemical index of weathering and alteration (CIW and CIA) revealed slight/low weathering of source areas. The REE patterns and Eu/Eu* values are also supporting felsic-igneous provenance for the studied samples. The median high concentrations (ppm) of vanadium (V 79.57), thorium (Th 10.08) and uranium (U 33.05) in sandstone, positive correlation of U with Al2O3 (r = 0.22), deposition in strong anoxic environments are the characteristic features of uranium enrichment/accumulation processes in sandstone-type environments thus signifying good potential for uranium exploration.