Active continental margins are the major sites of continental magmatism and associated hydrothermal ore deposits with a broad metal spectrum. Mineralization across active continental margins typically displays spatial zonation, with porphyry copper-(molybdenum‑gold) deposits in volcanic arcs and tin- and tungsten-dominated mineralization occurring further inland in a back-arc setting. Particularly, tin and tungsten commonly form separate deposits in back-arc regions, even though both metals exhibit similar lithophile behavior. The key factors governing this metallogenic zonation remain unclear. The world-class South China metallogenic province hosts over 50 % of the global tungsten resources, along with a significant amount of tin and copper resources distributed in different mineralization belts, making it an ideal location in which to study regional metal zonation. Here, we comprehensively integrate a very large dataset of the halogen volatile composition (F, Cl) and oxygen fugacity of granites related to tin, tungsten, and copper mineralization in the South China continental margin. Our compilation, derived from a substantial collection of zircon, apatite, mica, and whole-rock geochemistry data, suggests that lateral variations in granite magmatism (away from the trench), transitioning from chlorine-rich and oxic to fluorine-rich and reduced conditions, exert the primary control on copper versus tin‑tungsten mineralization in the arc and back-arc regions, respectively. Differences in oxygen fugacity have a minor impact on the decoupling of tin and tungsten mineralization despite tin granites being universally reduced (ΔFMQ = −1.8 to −0.1, where FMQ is the fayalite-magnetite-quartz redox buffer) and tungsten granites having a broader redox range (ΔFMQ = −1.5 to +1.2). Instead, the disparity in fluorine content plays a more crucial role in controlling the spatial separation of tin and tungsten mineralization observed in the back-arc setting. Nd-Hf and He-Ar isotopic modeling calculations suggest that magmas linked to tin mineralization have a more pronounced involvement of F-rich mantle components compared to those associated with tungsten. Elevated fluorine (ca. 650–8000 ppm) in tin-associated magmas allowed an extreme degree of magmatic differentiation and delayed fluid exsolution due to high H2O solubility in F-rich silicate melts, ensuring Sn enrichment in highly evolved melts. In contrast, early fluid exsolution under less F-rich conditions (ca. 100–700 ppm) led to early tin loss from the melts, ultimately resulting in tungsten-dominant mineralization. This work emphasizes the combined influence of halogen composition and redox state on the regional mineralization zonation in world-class metallogenic provinces, providing vectors for global metal exploration in both past and currently active continental margins.

中文翻译：

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岩浆卤素成分和氧化还原态对活动大陆边缘金属矿化分带的控制：来自世界级华南成矿省的视角


活跃大陆边缘是大陆岩浆作用和相关热液矿床的主要场所，具有广泛的金属谱。活跃大陆边缘的矿化通常表现出空间分带，火山弧中存在斑岩铜（钼金）矿床，而弧后内陆地区则出现以锡和钨为主的矿化。特别是，锡和钨通常在弧后区域形成单独的沉积物，尽管这两种金属表现出相似的亲石行为。控制该成矿分带的关键因素仍不清楚。华南是世界级成矿省，拥有全球50%以上的钨资源，大量的锡、铜资源分布在不同的矿化带上，是研究区域金属分带的理想场所。在这里，我们全面整合了华南大陆边缘锡、钨、铜矿化相关花岗岩的卤素挥发成分（F、Cl）和氧逸度数据集。我们的汇编来自大量锆石、磷灰石、云母和全岩地球化学数据，表明花岗岩岩浆作用（远离海沟）的横向变化，从富氯和含氧条件过渡到富氟和还原条件，分别对弧区和弧后区的铜矿化和锡钨矿化发挥主要控制作用。尽管锡花岗岩普遍还原（ΔFMQ = -1.8 至 -0.1，其中 FMQ 是铁橄榄石-磁铁矿-石英氧化还原缓冲剂）并且钨花岗岩具有更广泛的氧化还原，但氧逸度的差异对锡和钨矿化的解耦影响较小范围（ΔFMQ = −1.5 至 +1.2）。 相反，氟含量的差异在控制弧后环境中观察到的锡和钨矿化的空间分离方面发挥着更重要的作用。 Nd-Hf 和 He-Ar 同位素模拟计算表明，与钨相关的岩浆相比，与锡矿化相关的岩浆更明显地涉及富氟地幔成分。与锡相关的岩浆中氟含量升高（约 650–8000 ppm），由于富氟硅酸盐熔体中的 H2O 溶解度较高，导致岩浆分异程度极高，并延迟了流体的溶出，从而确保了高度演化熔体中锡的富集。相比之下，在富氟较少的条件下（约 100-700 ppm），早期流体溶出导致锡从熔体中早期流失，最终导致以钨为主的矿化。这项工作强调了卤素成分和氧化还原态对世界级成矿省的区域矿化分带的综合影响，为过去和当前活跃大陆边缘的全球金属勘探提供了载体。