Abstract A genetic link between Sb mineralization and magmatism has previously been proposed, yet little is known about the mobility of Sb during magma degassing. We have carried out a series of experiments to understand the effects of fluid composition, oxygen fugacity (fO2), pressure and temperature on the partitioning of Sb between magmatic fluids and a rhyolitic melt at crustal conditions (T = 850 °C, P = 200 MPa). The experiments were carried out in Molybdenum - Hafnium Carbide (MHC) pressure vessel assemblies at T = 850 to 1000 °C, P = 100 to 200 MPa and logfO2 from 1.64 log units below to 1.78 log units above the Ni-NiO buffer. Antimony partitions into aqueous chloride-bearing fluids weakly, with the fluid/silicate melt partition coefficient of Sb (DSbfluid/melt) increasing from 0.48 ± 0.11 (1σ) to only 0.85 ± 0.17 (1σ) as the total chlorine concentration in the fluid increases from 0.99 to 16.24 m, indicating the lack of significant Sb-chloride species in the fluid. In contrast, DSbfluid/melt increased from 0.89 ± 0.19 to 1.49 ± 0.19 as the aluminum saturation index (ASI) of the melt increased from 1.02 to 1.24. The moderate increase in DSbfluid/melt with increasing ASI of the melt (and HCl/metal chloride in the fluid) most likely relates to decreasing Sb solubility in the melt and further demonstrates the lack of significant chloride complexing of Sb. We also found that DSbfluid/melt is only slightly influenced by fO2 suggesting that Sb does not change oxidation state (Sb3+) at redox conditions typical of arc magmatism. Furthermore, the presence of reduced S species in the fluid phase caused only a minor increase in DSbfluid/melt indicating that Sb-sulfide complexes are not particularly stable in magmatic fluids. Our data also show that pressure and temperature, within the range of 100 to 200 MPa and 850 to 1000 °C, do not significantly influence DSbfluid/melt. Thus it is apparent that at most possible conditions at which rhyolitic melts degas in the upper crust, Sb will only weakly partition into the fluid phase and it is likely that the Sb budget of large epithermal Sb deposits is not directly derived from primary magmatic fluids.

中文翻译：

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岩浆深度脱气能否贡献大型热液锑矿床的金属预算？

摘要 先前已提出 Sb 矿化与岩浆活动之间的成因联系，但对岩浆脱气过程中 Sb 的流动性知之甚少。我们进行了一系列实验来了解流体成分、氧逸度 (fO2)、压力和温度对地壳条件下 Sb 在岩浆流体和流纹质熔体之间分配的影响 (T = 850 °C, P = 200兆帕）。实验在钼 - 碳化铪 (MHC) 压力容器组件中进行，T = 850 至 1000 °C，P = 100 至 200 MPa，logfO2 从低于 Ni-NiO 缓冲液的 1.64 log 单位到高于 Ni-NiO 缓冲液的 1.78 log 单位。锑较弱地分配到含氯化物的水溶液中，Sb 的流体/硅酸盐熔体分配系数（DSbfluid/melt）从 0.48 ± 0.11 (1σ) 增加到仅 0.85 ± 0。17 (1σ) 随着流体中总氯浓度从 0.99 m 增加到 16.24 m，表明流体中缺乏显着的 Sb-氯化物种类。相反，随着熔体的铝饱和指数 (ASI) 从 1.02 增加到 1.24，DSbfluid/melt 从 0.89 ± 0.19 增加到 1.49 ± 0.19。DSbfluid/熔体随着熔体（以及流体中的 HCl/金属氯化物）的 ASI 增加而适度增加，这很可能与 Sb 在熔体中的溶解度降低有关，并进一步证明 Sb 缺乏显着的氯化物络合。我们还发现 DSbfluid/melt 仅受 fO2 的影响很小，这表明 Sb 在弧岩浆作用的典型氧化还原条件下不会改变氧化态 (Sb3+)。此外，流体相中减少的 S 物质的存在仅导致 DSb 流体/熔体的轻微增加，表明 Sb-硫化物复合物在岩浆流体中不是特别稳定。我们的数据还表明，压力和温度在 100 到 200 MPa 和 850 到 1000 °C 的范围内，不会显着影响 DSbfluid/melt。因此，很明显，在流纹岩在上地壳中熔化脱气的大多数可能条件下，Sb 只会微弱地分配到流体相中，并且大型超热液 Sb 矿床的 Sb 预算很可能不是直接来自原生岩浆流体。