Most genetic models for magmatic-hydrothermal ore deposits are based on the prerequisite that the parental magmas associated with mineralization are enriched in water (> ∼4 wt%). However, it has been recognized that a number of magmatic-hydrothermal ore deposits also formed within tectono-magmatic settings that produce initially water-poor magmas such as Climax-type porphyry deposits. Here, we present a detailed reconstruction of the Tieshan magma plumbing system related to skarn-porphyry Cu–Fe–Au mineralization in the Edong district, in which primitive magmas typically show water-poor features. Applications of multiple thermodynamic calibrations on various magmatic units from the Tieshan and Tonglushan deposits provide a wealth of information regarding the structure and evolution of the transcrustal magmatic system. Petrographic observations and clinopyroxene-liquid thermobarometry calculations indicate that the Tieshan magmatic-hydrothermal system was fed by a deep crustal magma reservoir. An accurate picture of the evolution of H₂O within the magma plumbing system is presented using the plagioclase-liquid hygrometer in combination with the amphibole hygrometer. Three critical stages during the evolution of water within the plumbing system have been recognized, associated with H₂O contents of 0.8–1.7 wt%, 2.1–2.8 wt% and 3.2–4.6 wt%, respectively. The first enrichment of water in the magmas can be attributed to the separation and transfer of evolved melts from the deep magma reservoir to the shallow crust. Continuous cooling and solidification of the shallow magma body gave rise to the second enrichment of H₂O in residual melts, leading to magmas that were fertile for the formation of ore deposits. The detailed chemical evolution of the magma plumbing system was investigated using mineral trace element compositions in combination with the partition coefficients predicted by the lattice strain model. The earliest equilibrium melts are characterized by high Sr contents (the average = 658 ± 64 ppm), suggesting that high Sr/Y signatures were likely derived from their magma sources or fractionation at deeper levels in initially water-poor environments. Variations of some particular geochemical fingerprints in equilibrium melts such as, Dy/Dy* and Eu/Eu*, also provide fundamental information on the evolution of the magma plumbing system. Our study confirms the critical role of a deep crustal magma reservoir on the formation of magmatic-hydrothermal ore deposits. The fertility of magmas with respect to ore deposit formation was enhanced by the extraction and transfer of evolved magmas from the deep reservoir to shallower levels, particularly due to the enrichment of magmatic water contents. In addition, the presence of a deep magma reservoir also sustains the incremental growth of shallow magma chambers, which provide ore-forming fluids.

中文翻译：

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铁山岩浆管道系统的岩石学重建：对原本贫水的岩浆系统中岩浆热液矿床成因的启示

岩浆热液矿床的大多数遗传模型都是基于这样的前提，即与矿化有关的母岩浆富含水（≥4 wt％）。但是，已经认识到，在构造-岩浆环境中也形成了许多岩浆热液矿床，这些矿床最初会产生贫水的岩浆，例如Climax型斑岩矿床。在这里，我们介绍了与Edong地区矽卡岩斑岩Cu-Fe-Au矿化有关的铁山岩浆管道系统的详细重建，其中原始岩浆通常表现出贫水特征。在铁山和桐庐山矿床的各种岩浆单元上应用多种热力学标定，可以提供有关跨壳岩浆系统结构和演化的大量信息。岩石学观察和斜辉石-液体热压法计算表明，铁山岩浆热液系统是由一个深壳岩浆储层提供的。H演变的准确图景岩浆管道系统中的₂ O是使用斜长石-液体湿度计和闪石湿度计组合而成的。管道系统中水逸出过程中的三个关键阶段已被确认，分别与H ₂ O含量分别为0.8-1.7 wt％，2.1-2.8 wt％和3.2-4.6 wt％有关。岩浆中水的第一次富集可以归因于从深部岩浆储层到浅地壳的析出熔体的分离和转移。浅层岩浆体的持续冷却和凝固引起了H ₂的第二次富集残留熔体中的O，导致岩浆富集，形成矿床。利用矿物微量元素组成，结合晶格应变模型预测的分配系数，研究了岩浆管道系统的详细化学演化。最早的平衡熔体的特征在于高Sr含量（平均值= 658±64 ppm），这表明高Sr / Y签名很可能源自其岩浆源或最初处于贫水环境中更深层的分馏。平衡熔体中某些特殊地球化学指纹的变化，例如Dy / Dy *和Eu / Eu *，也为岩浆管道系统的演化提供了基本信息。我们的研究证实了地壳深部岩浆储层在岩浆热液矿床形成中的关键作用。岩浆相对于矿床形成的肥力通过将演化的岩浆从深层储层中提取和转移到较浅的水平而得到增强，特别是由于岩浆含水量的增加。此外，深部岩浆储层的存在还维持了浅岩浆室的增量增长，浅岩浆室提供了成矿流体。