Abstract Fluid-rock interactions at Mid-Oceanic Ridges lead to metal deposition in the so-called seafloor massive sulfides at ultramafic-hosted systems. Due to restricted access to the seafloor and scarcity of 3D exposures, these systems are poorly understood at-depth. A way to access the vertical dimension is to focus on fossil analogs preserved on-land such as the one preserved in serpentinites from the Platta nappe (SE Switzerland). For this example, we document the element distribution in the mineralized rocks at three distinct levels in the rock column using both whole rock chemical analyses and LA-ICPMS analysis of sulfide (chalcopyrite and pyrrhotite) and magnetite. We bring, for the first time, chemical signatures of the mineralization in the root zone of ultramafic-hosted black smokers. At any given depth, the Co/Ni ratio is maximum in the most mineralized samples indicating that this ratio is linked to the intensity of hydrothermal alteration. Additionally, the Co/Ni ratio decreases in mineralized rocks towards the paleosurface, whereas the Se content increases. An episode of carbonation recorded in the highest structural level of the system was responsible for a slight remobilization of the former Cu stock. We propose a model in which the uprising mineralizing fluid mixed with seawater within the host serpentinites, before venting at the paleoseafloor.

中文翻译：

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超基性黑烟熏系统根区的元素分布：来自高山模拟的限制

摘要 大洋中脊的流体-岩石相互作用导致金属沉积在超镁铁质系统中所谓的海底块状硫化物中。由于进入海底的限制和 3D 曝光的稀缺性，这些系统在深度上知之甚少。进入垂直维度的一种方法是关注保存在陆地上的化石类似物，例如保存在普拉塔推覆岩（瑞士东南部）蛇纹岩中的化石类似物。在本例中，我们使用全岩化学分析和 LA-ICPMS 对硫化物（黄铜矿和磁黄铁矿）和磁铁矿的分析，记录了矿化岩石中岩柱中三个不同水平的元素分布。我们第一次带来了超镁铁质黑烟民根区矿化的化学特征。在任何给定的深度，Co/Ni 比率在矿化程度最高的样品中最大，表明该比率与热液蚀变的强度有关。此外，矿化岩石中的 Co/Ni 比朝着古地表降低，而 Se 含量增加。在系统的最高结构水平记录的碳酸化事件是导致前铜库存轻微再动员的原因。我们提出了一个模型，其中上升的矿化流体与宿主蛇纹岩内的海水混合，然后在古海底排放。在系统的最高结构水平记录的碳酸化事件是导致前铜库存轻微再动员的原因。我们提出了一个模型，其中上升的矿化流体与宿主蛇纹岩内的海水混合，然后在古海底排放。在系统的最高结构水平记录的碳酸化事件是导致前铜库存轻微再动员的原因。我们提出了一个模型，其中上升的矿化流体与宿主蛇纹岩内的海水混合，然后在古海底排放。