Trace Element Characteristics and Indicative Significance of Sphalerite in Xiangyangshan Pb-Zn Deposit in West Qinling, China

The Xiangyangshan Pb-Zn deposit, situated in the eastern Xicheng ore field of the West Qinling region, extends the Changba-Lijiagou Pb–Zn mineralization. This deposit lies within a major Chinese polymetallic belt rich in Pb, Zn, and other metals. To clarify its poorly understood genesis, we conducted geological surveys, LA-ICP-MS trace element analysis, and sulfur isotope studies on sphalerite from different mineralization stages. Results show that later-generation sphalerite (Sp2) is enriched in Mn, Fe, Cu, Co, and In, while earlier Sp1 is richer in Cd and Ag. Geochemical indicators, including Zn/Cd and Zn/Fe ratios coupled with principal component analysis, suggest a moderate-temperature ore-forming environment, with Sp2 forming at higher temperatures (299–304°C) than Sp1 (254–263°C). Trace elements like Fe, Cd, and Ag enter the sphalerite lattice mainly via isomorphism. Sulfur isotopes indicate that sulfur originated from seawater sulfate or reduced sulfur in strata, with thermochemical sulphate reduction (TSR) as the primary reduction mechanism. The geological features of the Xiangyangshan deposit and the trace element distributions in sphalerite are consistent with characteristics of sedimentary exhalative (SEDEX) deposits. However, the ore bodies exhibit significant post-mineralization tectonic and metamorphic deformation. Taken together, the deposit is interpreted as a hydrothermal exhalative sedimentary-hydrothermal superimposed transformation deposit.