Sulfide assemblages, precious metals, transition metal alloys, and associated accessory phases were characterized throughout the Skaergaard intrusion to better constrain the sulfide saturation history of the intrusion and the role of late magmatic volatiles in modifying the Skaergaard metal budget and distribution. Sulfides in and below the Middle Zone of the Layered Series of the intrusion are readily replaced by low-Ti magnetite. The ratio Σ(low-Ti magnetite mode)/Σ(sulfide mode), indicating oxidation of sulfides, reaches maximum values in the Lower Zone of the Layered Series. Sulfide assemblages below the Middle Zone are typically accompanied by minor biotite, apatite, and rare calcite as well as trace compositionally distinctive clinopyroxene and orthopyroxene. The occurrence of Ag, Au, Pt, Cu, and metal alloys outside of the Middle Zone is further evidence of the Skaergaard intrusion parental magma being S-poor. Native Ag, commonly accompanied by trace amounts of Cl, occurs both in and below the Middle Zone. Evidence of coexisting precious metal + brine assemblages exists where native metals are accompanied by sylvite ± halite and Ag is accompanied by Ag halides. Ag occurrences in the Middle Zone are of irregular morphology with trace Cl ± S ± calcite. Further evidence supportive of a metal + brine assemblage is observed where Ag + quartz is found in an apparent open clinopyroxene-hosted fluid inclusion consisting of Na, Si, Cl, Ca, K, and S. Ag is used to model the behavior of precious and transition metals in the presence of an exsolving fluid phase. Numerical modeling suggests that, in a sulfide-bearing system, residual Ag concentrations and concentrations in the exsolved fluid are most affected at the point where sulfide is lost to a separating volatile fluid phase. It is suggested that, owing to the low-S nature of the Skaergaard system, fractional crystallization and early fluid saturation produced enrichment of Ag, with other precious and transition metals, in the interstitial silicate liquid much higher than normal due to delayed sulfide saturation. As this interstitial liquid evolved, Ag was lost to an exsolved volatile phase of high salinity and migrated upward. A similar process likely occurred for Au and other elements with high affinities for Cl.

中文翻译：

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格陵兰 Skaergaard 侵入体的硫化物、天然金属和相关微量矿物：晚期热液流体的证据

硫化物组合、贵金属、过渡金属合金和相关的辅助相在整个 Skaergaard 侵入过程中被表征，以更好地限制侵入的硫化物饱和历史和晚期岩浆挥发物在改变 Skaergaard 金属收支和分布方面的作用。侵入体层状系列中区及其下方的硫化物很容易被低钛磁铁矿取代。表示硫化物氧化的比 Σ（低钛磁铁矿模式）/Σ（硫化物模式）在层状系列的下部区域达到最大值。中带下方的硫化物组合通常伴有少量黑云母、磷灰石和稀有方解石，以及微量成分独特的单斜辉石和斜辉石。Ag、Au、Pt、Cu、中带以外的金属合金是 Skaergaard 侵入母岩浆贫 S 的进一步证据。原生银，通常伴随着微量的氯，出现在中带内部和下方。存在贵金属 + 盐水组合共存的证据，其中天然金属伴随着钾盐 ± 盐酸盐，而 Ag 伴随着卤化银。中区银矿呈不规则形态，微量 Cl±S±方解石。观察到支持金属 + 盐水组合的进一步证据，其中在由 Na、Si、Cl、Ca、K 和 S 组成的明显开放的单斜辉石流体包裹体中发现了 Ag + 石英。Ag 用于模拟贵重的行为和过渡金属在存在溶出流体相的情况下。数值模拟表明，在含硫化物的系统中，残留的 Ag 浓度和溶出液中的浓度在硫化物损失到分离的挥发性流体相的那一点上受到的影响最大。这表明，由于 Skaergaard 系统的低硫性质，分步结晶和早期流体饱和产生了 Ag 与其他贵金属和过渡金属的富集，由于延迟的硫化物饱和，间隙硅酸盐液体中的含量远高于正常值。随着这种间隙液体的发展，Ag 失去了高盐度的挥发相并向上迁移。Au和其他对Cl具有高亲和力的元素可能会发生类似的过程。由于 Skaergaard 系统的低硫性质，分步结晶和早期流体饱和产生了 Ag 与其他贵金属和过渡金属的富集，由于延迟的硫化物饱和，间隙硅酸盐液体中的含量远高于正常值。随着这种间隙液体的发展，Ag 失去了高盐度的挥发相并向上迁移。Au和其他对Cl具有高亲和力的元素可能会发生类似的过程。由于 Skaergaard 系统的低硫性质，分步结晶和早期流体饱和产生了 Ag 与其他贵金属和过渡金属的富集，由于延迟的硫化物饱和，间隙硅酸盐液体中的含量远高于正常值。随着这种间隙液体的发展，Ag 失去了高盐度的挥发相并向上迁移。Au和其他对Cl具有高亲和力的元素可能会发生类似的过程。