Exploration Effectiveness and Significance of Complementary X-ray Fluorescence–Geogas Prospecting Techniques for Pegmatite-Hosted Lithium–Beryllium Deposits in the Chakabeishan Ore District, Qaidam Basin, Northwest China

Abstract Targeting pegmatite-type lithium–beryllium (Li–Be) deposits in high-altitude, frozen regions, this study evaluates the effectiveness of integrated X-ray fluorescence (XRF) and geogas prospecting in the Chakabeishan ore district of the Qaidam Basin, northwest China, and characterizes associated ore-related anomaly fields. XRF analyses of exposed pegmatite veins detected negative iron (Fe), manganese (Mn), and nickel (Ni) anomalies directly above the pegmatites and positive rubidium (Rb), niobium (Nb), and tantalum (Ta) anomalies above the Be orebodies. For concealed orebodies, geogas prospecting detected anomalies above their horizontal projections dominated by Be ± Li, with associated Rb, Nb, Ta, caesium (Cs), uranium (U), thorium (Th), lead (Pb), and barium (Ba). Comparison with orebodies delineated by 500-m-depth control drilling showed that multiple discontinuous geogas anomalies were consistently present above their horizontal projections. These discrete anomalies clustered into zones with widths closely matched the horizontal projection widths of the concealed orebodies, confirming that geogas prospecting can identify concealed pegmatite-type Li–Be mineralization and estimate its downdip extent based on anomaly zone widths. The integrated anomalies indicated by XRF and geogas prospecting provide spatial distribution and mineralization information for the pegmatite vein zones. Along four profiles over pegmatite belts delineated by 500-m-deep drilling, geogas anomalies above the horizontal projections of these veins beyond 500 m depth and their distribution widths indicate a prospecting potential of at least 200 m in the deeper subsurface across most of the mining area. These findings provide a scientific basis for further exploration at depths exceeding 500 m.