Redox reactions, biological processes, evaporation and precipitation processes, adsorption, and Rayleigh distillation mechanisms have been proposed to account for the fractionation of antimony (Sb) isotopes in natural materials. However, only one paper was published to support and characterize the Rayleigh distillation induced Sb isotopic fractionation in a hydrothermal system. Therefore, the Sb isotopic fractionation mechanism research in the epithermal system is still negligible, which severely restricts future application. The Zhaxikang Sb–Pb–Zn–Ag deposit is the only super-large deposit within the North Himalayan Metallogenic Belt (NHMB), which comprises two episodes of mineralization (First episode: Pb–Zn mineralization, Stages 1 and 2; Second episode: Sb mineralization, Stages 3 to 6). Herein, we measured the δ¹²³Sb_{NIST 3102A} values of stage 4 sulfosalt minerals and stage 5 stibnite from the Zhaxikang Sb–Pb–Zn–Ag deposit, to resolve the fractionation direction and relative magnitude of Sb isotopes caused by these aforesaid geologically prominent mechanisms in the epithermal systems with an auxiliary investigation of Fe–Cu isotopes. The second episode of Sb-containing hydrothermal fluid has leached metals (e.g., Pb, Ag, Fe, Cu) from pre-existing Pb–Zn orebodies, to initiate the formation of stage 4 sulfosalt minerals. According to XPS (X-ray Photoelectron Spectroscopy) analyses, the Cu isotopic variation of stage 4 bournonite (0.08‰ – 0.89‰) must be controlled primarily by the reduction reaction (Cu²⁺ + e⁻ → Cu⁺) during leaching and precipitation. Keeping in mind a good linear correlation between δ¹²³Sb and δ⁶⁵Cu values (R² = 0.99) for bournonite, the same mechanism was used to decipher the variation in δ¹²³Sb values (0.10‰ – 0.48‰) of bournonite (Sb⁵⁺ + 2e⁻ → Sb³⁺). Abundant native sulfur within the orefield allowed for the overall reaction equation of CuFeS₂ + FeS₂ + PbS + Sb⁵⁺(aq) = CuPbSbS₃ + Fe²⁺(aq) + 2S to describe the bournonite formation. Accordingly, the Sb isotopic variations (−0.27‰ to 0.48‰) of Sb-bearing minerals (boulangerite, bournonite and stibnite) were empirically attributed to redox reactions. The Rayleigh distillation model indicated that the observed fractionation was most likely induced by redox reactions, while the related theoretical calculations revealed a great antimony exploration potential in deeper parts of the orefield. Overall, the Sb isotopes could be used to identify redox changes in the epithermal system, and exhibit great potential in tracing metal sources, monitoring fluid evolution and ore formation, and providing insights into mineral exploration.

已提出氧化还原反应、生物过程、蒸发和沉淀过程、吸附和瑞利蒸馏机制来解释天然材料中锑 (Sb) 同位素的分馏。然而，仅发表了一篇论文来支持和表征热液系统中瑞利蒸馏诱导的 Sb 同位素分馏。因此，在超热液系统中Sb同位素分馏机制的研究还可以忽略不计，严重制约了未来的应用。扎西康 Sb-Pb-Zn-Ag 矿床是北喜马拉雅成矿带 (NHMB) 内唯一的超大型矿床，包括两个矿化阶段（第一阶段：Pb-Zn 矿化，阶段 1 和阶段 2；第二阶段： Sb 矿化，第 3 至 6 阶段）。在这里，我们测量了 δ ¹²³扎西康 Sb-Pb-Zn-Ag 矿床第 4 阶段_硫盐矿物和第 5 阶段辉锑矿的Sb _{NIST 3102A}值，用于解析由上述这些地质显着机制在低温热液系统中引起的 Sb 同位素分馏方向和相对量级Fe-Cu同位素的研究。第二次含 Sb 热液流体从预先存在的 Pb-Zn 矿体中浸出金属（例如，Pb、Ag、Fe、Cu），开始形成第 4 阶段硫盐矿物。根据 XPS（X 射线光电子能谱）分析，阶段 4 硼硅石的 Cu 同位素变化（0.08‰ – 0.89‰）必须主要受还原反应（Cu ²⁺ + e ^-  → Cu ⁺) 在浸出和沉淀期间。记住，在 δ ¹²³ Sb 和 δ ⁶⁵ Cu 值 (R ²  = 0.99)之间存在良好的线性相关性，我们使用相同的机制来破译 δ ¹²³ Sb 值 (Sb)的变化(0.10‰ – 0.48‰) ⁵⁺ + 2e ⁻  → Sb ³⁺ )。矿区中丰富的天然硫使得整个反应方程式为 CuFeS ₂  + FeS ₂  + PbS + Sb ⁵⁺ (aq) = CuPbSbS ₃  + Fe ²⁺(aq) + 2S 来描述钙铝石的形成。因此，含锑矿物（硅铝榴石、钙铝石和辉锑矿）的 Sb 同位素变化（-0.27‰ 至 0.48‰）根据经验归因于氧化还原反应。瑞利精馏模型表明，观察到的分馏很可能是由氧化还原反应引起的，而相关的理论计算表明，在矿田更深的部分具有巨大的锑勘探潜力。总的来说，Sb同位素可用于识别超热系统中的氧化还原变化，并在追踪金属来源、监测流体演化和矿石形成以及为矿物勘探提供见解方面具有巨大潜力。