Fluid conditions of shallow marine hydrothermal vent sites (200 mbsl) and mid-ocean ridge-related environments (>2000 mbsl). At Calypso Vents in the Bay of Plenty and Paleochori Bay at the coast of Milos Island, fluids with temperatures <200°C are emitted through volcaniclastic sediments in water depths <200 mbsl. The hydrothermal mineralisation from these fluids is dominated by pyrite and marcasite showing diverse textures, including colloform alternations, semi-massive occurrences surrounding detrital grains, vein-type pyrite, and disseminated fine-grained assemblages. Pyrite and marcasite from Calypso SE show elevated concentrations of volatile elements (e.g., As, Sb, Tl, Hg) implying a vapour-rich fluid phase. By contrast, elements like Zn, Ag, and Pb are enriched in hydrothermal pyrite and marcasite from Calypso SW, indicating a high-Cl liquid-dominated fluid discharge. Hence, vapour-liquid element fractionation induced by fluid boiling is preserved in the seafloor mineralisation at Calypso Vents. Hydrothermal mineralisation at very shallow vent sites (<10 mbsl), like Paleochori Bay, are affected by wave action causing a seasonal migration of the seawater-fluid interface in the sediment cover. The δ34S composition of native S crusts and crystalline S (0.7 to 6.7 ‰) is indicative for host rock leaching and thermochemical reduction of seawater sulphate. By contrast, the highly negative δ34S signature of native S globules in sediments (-7.6 to -9.1 ‰) is related to microbial sulphate reduction or a subordinate magmatic fluid influx. Alunite-jarosite alteration (Paleochori Bay) and a mineral assemblage consisting of orpiment, realgar, and native S (Calypso Vents) may also suggest a contribution by an oxidised (sulphate-rich) low pH fluid of potential magmatic origin. However, fluid boiling is pervasive at Calypso Vents and Paleochori Bay, and the condensation of vapour-rich fluids in a steam-heated environment may produce a similar alteration and mineralisation assemblage without a significant magmatic fluid influx, as known from some subaerial epithermal systems.

中文翻译：

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浅海岛屿弧相关热液喷口，新西兰卡里普索喷口和希腊帕莱奥霍里湾的硫铁矿和黄铁矿中的痕量元素特征

浅层海洋热液喷口部位（200 mbsl）和大洋中脊相关环境（> 2000 mbsl）的流体条件。在米洛斯岛沿岸的丰盛湾的卡里普索通风口和米洛斯岛海岸的帕莱奥乔里湾，温度<200°C的流体通过水深<200 mbsl的火山碎屑沉积物排放。这些流体的热液矿化作用以黄铁矿和镁铁矿为主，表现出不同的质地，包括共晶状蚀变，碎屑颗粒周围的半大量出现，脉状黄铁矿和散布的细粒组合。来自Calypso SE的硫铁矿和镁铁矿显示出较高浓度的挥发性元素（例如，As，Sb，Tl，Hg），这意味着富含蒸气的液相。相比之下，来自Calypso SW的热液黄铁矿和镁铁矿中富含Zn，Ag和Pb等元素，表示以高Cl液体为主的液体排放。因此，在Calypso Vents的海底矿化中保留了由流体沸腾引起的汽液元素分馏。像Paleochori湾这样非常浅的排泄点（<10 mbsl）的热液矿化作用受到波浪作用的影响，引起沉积物覆盖物中海水-流体界面的季节性迁移。天然S壳和结晶S（0.7至6.7‰）的δ34S组成指示了宿主岩的浸出和海水硫酸盐的热化学还原。相比之下，沉积物中天然S小球（-7.6至-9.1‰）的高度负δ34S特征与微生物硫酸盐的减少或次要岩浆流体的涌入有关。铝矾土-铁矾石蚀变（Paleochori湾）和由雌黄，雄黄，天然S（Calypso通风孔）也可能暗示了潜在岩浆来源的氧化（富含硫酸盐）低pH流体的作用。但是，Calypso通风孔和Paleochori湾普遍存在流体沸腾现象，蒸汽加热环境中富含蒸气的流体的凝结可能会产生类似的蚀变和矿化作用，而没有明显的岩浆流体涌入，这是从一些航空地下超热系统得知的。