Spatially Differential Enrichment of Fluorine and Lithium in the Jiepailing Superlarge Fluorite Deposit, Southern Hunan: Constraints from Drill-Core Geochemical Profiles

The Jiepailing deposit is a superlarge fluorite deposit with lithium enrichment in the central Nanling metallogenic belt. However, the spatial relationship between fluorite mineralization and Li enrichment and the factors controlling it remain unclear, limiting integrated exploration of deep fluorite and Li resources. A total of 1696 drill-core samples from boreholes ZK134-9 and ZK134-12 along exploration line 134 were analyzed. On the basis of whole-rock CaF2 and Li2O mass fractions, borehole depth, and lithological logs, the vertical variations in the two indices were compared, and Spearman and depth-controlled partial Spearman correlation coefficients were calculated. The vertical trend comparison over the shared 0–600 m depth interval shows that the interval medians of both CaF2 and Li2O generally decrease with depth in both boreholes. Separately, correlation analyses using the complete paired dataset from each borehole, including samples below 600 m, yield CaF2–Li2O Spearman coefficients of 0.610 for ZK134-9 (n = 1078) and 0.741 for ZK134-12 (n = 618). After controlling for borehole depth using the same datasets, the partial Spearman coefficients are 0.264 and 0.696, respectively. These features indicate similar overall vertical trends in the two boreholes, although the depth trend influences their correlations to different extents. In conjunction with lithological logs and previous studies, the results suggest that wall-rock reaction and alteration minerals may influence local F and Li enrichment: granitic rocks and associated mica alteration may favor Li enrichment, whereas carbonate wall rocks are more favorable for F precipitation and fixation. Considering lithological associations, alteration, and fault structures together, the contact between granite porphyry and Shidengzi Formation carbonate rocks and associated mineralized fracture zones in western Jiepailing have favorable exploration potential.