Abstract Sulfur content at sulfide saturation (SCSS) is a critical parameter that controls the consumption of sulfide during partial melting as well as potential exsolution of sulfide during magma evolution. Natural magmatic systems involve H2O in silicate melt and NiS in FeS-dominated sulfide, but the combined effects of melt H2O and sulfide composition on SCSS have not been well constrained. We carried out 18 phase equilibrium experiments between anhydrous or hydrous basaltic melt and FeS-NiS sulfide at 1.0–2.5 GPa and 1523–1673 K in a piston cylinder apparatus. Experimental results demonstrate an increase of SCSS of approximately 104 ppm per wt% melt H2O and a proportional increase of SCSS with the mole fraction of FeS in sulfide (XFeS). In combination with literature data, we find that the effects of melt H2O and sulfide composition are independent and additive. A new model of SCSS for natural basaltic melt is developed: SCSS ( ppm ) = X FeS ⋅ exp 13.88 − 9744 T − 328 P T + 104 w H 2 O , where T is temperature in K, P is pressure in GPa, and wH2O is melt H2O content in wt%. This model not only fits our own data well but also reproduces literature data of SCSS in basaltic melt within 20% off. Application of this SCSS model to ridge magmatism shows that the observed S contents in MORBs corresponds to ~15% melting of mantle (after sulfide exhaustion). The higher S contents in some sulfide-saturated MORBs require a mantle source containing high-NiS sulfide (XNiS ≈ 0.4). Comparison of SCSS with S contents in melt inclusions from primary arc magmas suggests that sulfate is not required to be present for a majority of sub-arc mantle.

中文翻译：

---

硫化物成分和熔体水对玄武岩熔体硫化物饱和时硫含量的影响

摘要 硫化物饱和度（SCSS）的硫含量是控制部分熔融过程中硫化物消耗以及岩浆演化过程中硫化物潜在出溶的关键参数。天然岩浆系统包括硅酸盐熔体中的 H2O 和 FeS 主导的硫化物中的 NiS，但熔体 H2O 和硫化物成分对 SCSS 的综合影响尚未得到很好的限制。我们在活塞缸装置中在 1.0-2.5 GPa 和 1523-1673 K 下进行了 18 次无水或含水玄武岩熔体与 FeS-NiS 硫化物之间的相平衡实验。实验结果表明 SCSS 增加约 104 ppm/wt% 熔体 H2O，SCSS 随硫化物 (XFeS) 中 FeS 的摩尔分数成比例增加。结合文献资料，我们发现熔体 H2O 和硫化物成分的影响是独立的和相加的。开发了天然玄武岩熔体的新 SCSS 模型：SCSS ( ppm ) = X FeS ⋅ exp 13.88 − 9744 T − 328 PT + 104 w H 2 O ，其中 T 是以 K 为单位的温度，P 是以 GPa 为单位的压力，以及 wH2O是熔体 H2O 含量（wt%）。该模型不仅很好地拟合了我们自己的数据，而且还重现了玄武岩熔体中 SCSS 的文献数据，折扣幅度在 20% 以内。将此 SCSS 模型应用于山脊岩浆作用表明，在 MORB 中观察到的 S 含量对应于约 15% 的地幔熔化（硫化物耗尽后）。一些硫化物饱和 MORB 中较高的 S 含量需要含有高硫化 NiS (XNiS ≈ 0.4) 的地幔源。