Skarn-hosted deposits can be important high-grade resources for a variety of metals, but Sn skarns are still of subordinate importance for global mining because of their complex mineralogy and evolution. As part of recent exploration efforts, the economic potential of the Sn–Zn–In mineralization at the Hämmerlein skarn-hosted deposit is currently being re-evaluated. The temporal and spatial evolution of the ore-forming hydrothermal system is still debated. We analyzed fluid inclusion assemblages (FIA) in ore and gangue minerals using conventional and infrared microthermometry and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We further estimated alteration temperatures with chlorite thermometry and compared the fluid inclusion (FI) record at Hämmerlein with a mineralized greisen sample of the nearby Eibenstock granite. Cassiterite in skarn forms the major mineralization at Hämmerlein during stage I and hosts FIs showing homogenization temperatures of up to 500 °C and salinities between 30 and 47 wt% NaCl eq. Cassiterite from schists and the additional greisen sample from the Eibenstock granite of the later stage II show lower homogenization temperatures (350–400 °C) and considerably lower salinities varying from 1.9 to 6 wt% NaCl eq. Despite the different homogenization temperatures and salinities, the chemical compositions of FIs hosted in both generations of cassiterite show that both (cassiterite in skarn and in schist and greisen) are similar, which points to a common source. The gangue minerals mainly contain low-temperature FIA (max. 330 °C and 2–9 wt% NaCl eq.) and are interpreted to form during further cooling of the system in stage III. Intergrown chlorite has compositions indicating similar temperatures of around 260 °C and is thus also related to stage III. FIA in sphalerite homogenize around 200 °C with salinities between 2 and 6.7 wt% NaCl eq. and show decreasing trace element contents despite having the same salinity range as the gangue minerals, indicating dilution of the ore-fluid during stage IV as a possible precipitation mechanism. Stage I inclusions are solely hosted in cassiterite from skarn, which shows the importance of fluid inclusion analyses in ore minerals, and record remarkable high mineralization temperatures, exceeding the typically temperature range reported in other studies by at least 100 °C. Our results suggest that this main ore stage is related to the early expulsion of a high-salinity brine phase from an underlying magmatic intrusion at depths greater than 3 km, which likely is a relatively short-lived event within the evolution of the hydrothermal system.

中文翻译：

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从矿石和脉石矿物中的流体包裹体，德国 Erzgebirge 以矽卡岩为主体的 Hämmerlein 矿床 Sn-Zn-In 矿化的顺序演化

矽卡岩矿床可以是多种金属的重要高品位资源，但由于其复杂的矿物学和演化，Sn 矽卡岩在全球采矿中仍处于次要地位。作为近期勘探工作的一部分，目前正在重新评估 Hämmerlein 矽卡岩矿床中 Sn-Zn-In 矿化的经济潜力。成矿热液系统的时空演化仍存在争议。我们使用传统和红外显微测温法以及激光烧蚀电感耦合等离子体质谱法 (LA-ICP-MS) 分析了矿石和脉石矿物中的流体包裹体组合 (FIA)。我们使用绿泥石温度计进一步估计了蚀变温度，并将 Hämmerlein 的流体包裹体 (FI) 记录与附近 Eibenstock 花岗岩的矿化 greisen 样本进行了比较。矽卡岩中的锡石在 I 阶段形成了 Hämmerlein 的主要矿化，并且宿主 FI 显示出高达 500 °C 的均质温度和 30 至 47 wt% NaCl eq 之间的盐度。来自片岩的锡石和来自后期 II 阶段 Eibenstock 花岗岩的额外 greisen 样品显示出较低的均质温度 (350–400 °C) 和相当低的盐度，从 1.9 到 6 wt% NaCl eq。尽管均质化温度和盐度不同，两代锡石中的 FI 的化学成分表明两者（矽卡岩中的锡石以及片岩和灰岩中的锡石）是相似的，这表明了一个共同的来源。脉石矿物主要包含低温 FIA（最高 330 °C 和 2-9 wt% NaCl eq.），并被解释为在阶段 III 的系统进一步冷却过程中形成。共生亚氯酸盐的组成表明温度接近 260 °C，因此也与阶段 III 相关。闪锌矿中的 FIA 在 200 °C 左右均匀化，盐度在 2 到 6.7 wt% NaCl eq 之间。尽管具有与脉石矿物相同的盐度范围，但显示出微量元素含量下降，这表明在第四阶段矿液的稀释是一种可能的沉淀机制。阶段 I 包裹体仅存在于矽卡岩的锡石中，这表明流体包裹体分析在矿石矿物中的重要性，并记录了显着的高矿化温度，比其他研究报告的典型温度范围高出至少 100 °C。