Geochemical Characteristics and Exploration Implications of Primary Halos in the Liwu Copper Deposit, Western Yangtze Block, China

The Liwu copper deposit, located on the western margin of the Yangtze Block, is a typical metamorphic-hosted polymetallic Cu deposit with significant deep exploration potential. To constrain its mineralization-forming processes and primary halo characteristics, this study focuses on the Heiniudong ore segment. Based on portable X-ray fluorescence (XRF) data obtained from drill cores and underground samples, a comprehensive geochemical analysis of 20 elements was conducted. Elemental background values and anomaly thresholds were determined using the iterative sigma (σ) elimination method. Pearson correlation analysis and hierarchical cluster analysis were applied to identify element associations, while the Grigorian zonation index method was employed to investigate axial zoning patterns of primary halos. The results demonstrate that Cu exhibits strong positive correlations with S, Fe, Ag, Cd, Sn, and Bi, indicating a medium- to high-temperature hydrothermal sulfide mineralization system. The primary halo displays well-defined vertical zonation, with Ba–Sr–Sb–As representing the front halo, Zn–Pb–Cu–Ag–Sn–Fe–Cd the near-ore halo, and Bi–Mo–W–Th the tail halo. A clear axial zonation sequence is established. The vertical variation in the geochemical ratio (As × Sr × Sb)/(Mo × Bi × W) exhibits a characteristic “low–high–low–high” pattern, reflecting the superposition of the front halo of a deeper concealed orebody with the tail halo of the upper known orebody under multistage hydrothermal remobilization and structural overprinting. Integrated with the coexistence of front halo and tail halo anomalies and strong alteration in drill hole WT03, the results indicate that the southwestern extension of WT03 along southwest-dipping ductile–brittle detachment structures represents the most promising deep exploration target.