Microscale Geochemical Characteristics of Pyrite from the Shuikoushan Gold Deposit

水口山金矿床作为南岭成矿带内重要的多金属矿床，其成因类型长期存在着争议。文章通过黄铁矿微区地球化学分析(电子探针EPMA)及硫同位素示踪，系统探讨成矿物质来源与热液演化过程。结果显示：黄铁矿呈现显著S亏损(S/Fe原子比1.13~1.76)、高Co/Ni比值(0.52~12.83，均值2.47)，显示出水口山金矿床的形成与中温岩浆热液活动密切相关。Au以晶格金(Au1+)形式赋存于富As黄铁矿中，As通过晶格缺陷促进Au固溶。硫同位素组成(δ34S = −1.5‰~3.5‰)与岩浆源矿床(如朝山、双旗山金矿)相似，显著区别于地层来源矿床(如黄金洞金矿)，表明成矿物质主要源于晚侏罗世岩浆热液。矿石铅同位素组成较为均一，206Pb/204Pb = 18.10~18.63，207Pb/204Pb = 15.32~15.85，208Pb/204Pb = 38.745~39.35，μ = 9.50，显示深源特征。综合表明，水口山金矿床成矿作用与区域岩浆活动密切关联，为深部找矿提供了地球化学标志。The Shuikoushan gold deposit, as a significant polymetallic deposit within the Nanling Metallogenic Belt, has long been debated regarding its genetic classification. This study systematically investigates the sources of metallogenic materials and hydrothermal evolution processes through microscale geochemical analysis of pyrite (electron probe microanalysis, EPMA) and sulfur isotope tracing. Results reveal that pyrite exhibits significant sulfur depletion (S/Fe atomic ratio = 1.13~1.76), high Co/Ni ratios (0.52~12.83, mean = 2.47), these features indicate that the deposit formed in association with intermediate-temperature magmatic-hydrothermal activity. Gold occurs as lattice-bound Au1+ in As-rich pyrite, where arsenic promotes Au solid-solution by inducing lattice defects. The sulfur isotopic composition (δ34S = −1.5‰ to 3.5‰) aligns with magmatic-source deposits (e.g., Chaoshan and Shuangqishan gold deposits) but distinctly differs from strata-sourced deposits (e.g., Huangjindong gold deposit), suggesting that the ore-forming materials were primarily derived from Late Jurassic magmatic-hydrothermal fluids. Ore-related lead isotopes exhibit homogeneous compositions (206Pb/204Pb = 18.10~18.63, 207Pb/204Pb = 15.32~15.85, 208Pb/204Pb = 38.745~39.35) with a μ value of 9.50, indicating a deep-source affinity. Collectively, these findings demonstrate a close genetic link between mineralization and regional magmatism, providing critical geochemical indicators for deep exploration.