The Lizi gold deposit, a representative gold deposit in the West Qinling Orogen of China, has ongoing debates regarding its ore-forming material sources, enrichment and precipitation mechanisms, and metallogenic age. This study combines geological characteristics with in situ U-Pb rutile dating, trace-element of pyrite, and S-Pb isotope analyses to determine the metallogenic age and constrain the sources and processes of ore formation. Based on crosscutting relationships and mineral paragenesis, the mineralization process of the Lizi gold deposit can be divided into four stages: (1) quartz-sericite-pyrite (Stage I), (2) pyrite-gold (Stage Ⅱ), (3) chalcopyrite-gold (Stage Ⅲ), and (4) quartz-calcite (Stage IV). Gold primarily occurs in Stage Ⅱ and Ⅲ coexisting with pyrite and chalcopyrite, respectively. Rutile from Stage Ⅱ yielded a metallogenic age of 211.1 ± 6.3 Ma, indicating gold mineralization is associated to the Late Triassic hydrothermal activity. Three generations of pyrite were identified from Au-bearing quartz-sulfide veins, i.e., Py1 from Stage I, Py2 from Stage Ⅱ, and Py3 from Stage Ⅲ. Py2 is further divided into Py2a and Py2b according to growth zoning. From Py1 to Py3, the contents of elements such as Au, Ag, Cu, Pb, and Bi increase, and Au concentrations in pyrite remain below 10 ppm, indicating gold predominantly precipitated as visible gold (e.g., native gold, electrum, sylvanite), with only minor solid-solution incorporation in pyrite. The strong positive correlations between Au and Cu, Pb, Te, and Bi in pyrite, coupled with native gold coexisting with minerals containing these elements, collectively suggest a magmatic contribution to gold mineralization. The δ 34 S values of Py1 (1.78–2.57 ‰) reveal mixing sulfur characteristics of the Liziyuan Group strata (–10.47 to 1.80 ‰) and syenitic rocks (2.90–9.09 ‰), whereas the δ 34 S values of mineralization-related Py2 and Py3 (5.59–12.18 ‰) indicate a dominant syenitic magmatic source. In situ Pb isotopic compositions of galena intergrowing with gold ( 206 Pb/ 204 Pb = 17.971–18.312, 207 Pb/ 204 Pb = 15.553–15.654, and 208 Pb/ 204 Pb = 38.01–38.42) further support a mixed source involving Liziyuan Group strata and syenitic magmatic rocks for metallogenic materials. Collectively, this study provides compelling evidence that the formation of the Lizi gold deposit was primarily associated with late Triassic magmatic-hydrothermal activity.
Jin et al. (Mon,) studied this question.