GEOCHEMISTRY OF PAB SANDSTONE EXPOSED IN LAKI RANGE LOWER INDUS BASIN: PROVENANCE AND TECTONIC IMPLICATIONS

Abstract

Geochemistry of the late Cretaceous Pab Sandstone deposited at the Laki Range, Southern Indus basin, was carried out in order to acquire a better knowledge of the source rock and paleoclimate. The unit in the studied region comprise predominantly sandstone, with some mudstone. The major element geochemistry of Pab Sandstone suggests that the samples were composed of abundant SiO₂, Al₂O₃, CaO, and Fe₂O₃.  Other major oxides comprises less than 2 wt. %. Major element discriminatory diagrams additionally imply that Pab sediments originated from a granitic source. The idea that the Pab sediments were generated by a granitic source is further supported by the rich concentration of trace elements including Zr, La Th, Ba, and Sr, in contrast to V, Ni, Cr, Co, and their ratio. It is conceivable that the Pab Sandstone was formed by sediments from granitic rocks, as indicated by the La/Sc and Th/Co model, as well as the TiO₂ and Zr plots. The measured Plagioclase Index of Alteration (PIA) values, which range from 59.94 to 89.44, and the Chemical Index of Alteration (CIA), which ranges from 61.12 to 83.75, indicate that the studied sediments experienced moderate to strong weathering under warm, humid climate conditions. Geochemical findings indicate that the Pab Sandstone sediments originated from the vast Indian Shield (Craton); probably from the Malani Igneous Suite in India and the Nagar Parkar Igneous Complex in Pakistan.