Geochemical Assessment and Resource Potential of the Critical Minerals in Sardhai Formation, Punjab, Pakistan

Abstract

This study presents a geochemical characterization and mineral potential of the Sardhai Formation, an Early Permian clay dominated unit of the Nilawahan Group exposed within the Salt Range fold and thrust belt of Pakistan. Twenty-two clay samples collected from two outcrop localities near Kallar Kahar were analyzed by inductively coupled plasma mass spectrometry to evaluate the formation's critical mineral inventory. Because the unit is lithologically uniform, the dataset offers a controlled framework in which elemental variability can be attributed primarily to post depositional processes rather than primary depositional differences. Results show mean values of; lithium (0.26398 ppm), vanadium (1.06501 ppm), manganese (2.19484 ppm), beryllium (0.04840 ppm), gallium (0.12050 ppm), niobium (0.07946 ppm), nickel (0.11183 ppm), chromium (0.34034 ppm), zirconium (0.03512 ppm), hafnium (0.00723 ppm), titanium (0.35212 ppm), the light rare earth elements (0.56496 ppm), and lastly uranium at (0.28650 ppm), they occur at the highest and are most consistently quantifiable concentrations. Non oxidized samples consistently retain higher concentrations of these elements than their oxidized counterparts, indicating that oxidative weathering, structurally driven fluid rock interaction, and the formation's position within the fold and thrust belt, rather than original sedimentary composition, govern present day critical mineral distribution. One sample constitutes a distinct multi element, rare earth enriched anomaly. Despite these detectable patterns, absolute concentrations remain below economic threshold throughout, and the dataset is best characterized as reconnaissance level rather than indicative of economic mineralization. The findings nonetheless demonstrate that fine grained clay successions in the Salt Range can act as meaningful repositories of critical elements and establish a baseline for future investigation. Recommended follow up work includes denser, non-oxidized patch focused sampling, clay phase identification, sequential extraction, fluid inclusion and isotopic studies, and structural mapping, all of which are necessary before any assessment of resource potential can be responsibly made