ON ASSESSING THE METAL-BEARING POTENTIAL OF KASHPIR SHALES (SAMARA REGION) USING LINEAR GEOCHEMICAL SPECTRA

This study investigates the metal-bearing potential of Upper Jurassic (Tithonian stage) combustible shales from the Kashpir deposit (Volga Basin) using linear geochemical spectra methodology. Samples from mine workings and natural outcrops were analyzed by energy-dispersive X-ray fluorescence spectrometry (ED-XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results reveal elevated concentrations of Ca (27.5-38.6%) and Fe (20.3-24.3%), indicative of a carbonate-clay composition with pyrite inclusions, characteristic of reducing sedimentation conditions. Excesses over the Clarke values were revealed for Ba, Co, Sr, Ni, and Mo, confirming the industrial potential of these shales as a source of rare and non-ferrous metals. The authors have developed a novel analytical approach based on reference concentrations (maximum and minimum values), enabling assessment of metal enrichment without identifying a dominant ore-forming element-particularly valuable for multi-element systems. The observed differences between mine and surface samples are attributed to post-sedimentary processes (leaching and oxidation). Our findings demonstrate a consistent lithological-geochemical shale type and highlight prospects for their comprehensive exploitation.