Abstract

Preore metasomatites of epithermal gold–silver deposits are formed by various types of hydrothermal solutions—from highly acidic and oxidized (argillization, alunitization, secondary quartzites) and moderately acid (sericitization) to rather reduced and alkaline (adularia). The possible processes creating highly acid mineralizing fluids at shallow depths are: (a) the condensation of the acid gas phase of heterogenized fluids (including also the condensation of gaseous HCl, HF and H₂SO₄ whose water solutions possess properties of maximum boiling azeotropic mixtures); (b) the oxidation of containing SO₂ and H₂S magmatogene gases by meteoric waters rich in oxygen; and also c) possible disproportionation of sulfur from SO₂ to H₂S and H₂SO₄. The epithermal gold–silver deposits of high sulfidation type form at the upper parts of heterophase fluid systems. The major gold–silver and sulfide mineralization (except small amounts of earlier generations of pyrite, enargite, and luzonite) precipitates not synchronously with the acid metasomatites, but essentially later, when the water table of liquid and less acid fluids raise into the realm of ore deposition. At zones of flat subducting ocean crust, the deposits of copper–porphyry type are quite often found beneath the epithermal Au–Ag deposits. However, the former cannot be considered the bottom of the gold–silver ore-forming systems, because they sometimes form much earlier and in closed systems; therefore, they have their own bottom part of the ore-forming system (a zone of K-feldspathization with related molybdenum ore) and the top part (a zone of sericitization with related copper mineralization). In addition, in steep subduction zones typical of the Central West Pacific region, including Khabarovsk and Primorsky krais and Japan, epithermal Au–Ag deposits have no spatial or temporal relations to copper–porphyry deposits due to the nearly complete absence of the latter. There are the alkaline metasomatites that form in the lower, bottom parts of epithermal heterophase fluid systems, creating the major bonanza gold–silver and sulfide mineralization of the adularia (low sulfidation) type in the Russian Far East, western America, and Japan. The term high sulfidation widely used now was created by the artificial combination of the terms high sulfate and high oxidation and is very ambiguous, because it really does not imply sulfidization processes. This type of mineralization would be better named acid sulfate.

中文翻译：

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超热金银矿床的交代矿物和矿石的形成环境

摘要

超热金-银矿床的Preore交代岩是由各种类型的水热溶液形成的，从高酸性和氧化性（氩化，铝化，次生石英岩）到中度酸性（绢云母）再到还原性和碱性（金红石）。在浅深度产生高度酸性矿化流体的可能过程是：（a）异质流体酸性气相的冷凝（还包括水溶液具有最大沸点共沸特性的气态HCl，HF和H ₂ SO ₄的冷凝）混合物）; （b）富含氧气的陨石水氧化含有SO ₂和H ₂ S的岩浆生成气体；并且c）硫可能从SO _2中歧化H ₂ S和H ₂ SO ₄。高硫化度的超热金银矿床型相形式在多相流体系统的上部。主要的金-银和硫化物矿化（早期少量的黄铁矿，钠辉石和绿宝石除外）的沉淀与酸性交代岩不是同步的，而是在液态和较少酸性流体的水位上升到岩溶范围内时才基本上在后期沉淀。矿石沉积。在扁平俯冲洋壳区域，铜-斑岩型沉积物经常在超热金-银沉积物下方发现。但是，前者不能被认为是金-银矿石形成系统的底部，因为它们有时形成得更早且处于封闭系统中。因此，它们有自己的成矿系统的底部（与相关的钼矿一起钾钾长石化带）和顶部（与相关的铜矿化有绢云母化的带）。此外，在中西部太平洋地区典型的陡峭俯冲带，包括哈巴罗夫斯克和滨海边疆区以及日本，由于几乎完全没有铜斑岩沉积，超热金银沉积与铜斑岩沉积没有时空关系。在超热多相流体系统的下部，底部形成了碱性变质岩，形成了主要的富矿金-银和硫化物矿化（由于铜-斑岩矿床几乎完全不存在，因此超热金-银矿床与铜-斑岩矿床没有时空关系。在超热多相流体系统的下部，底部形成了碱性变质岩，形成了主要的富矿金-银和硫化物矿化（由于铜-斑岩矿床几乎完全不存在，因此超热金-银矿床与铜-斑岩矿床没有时空关系。在超热多相流体系统的下部，底部形成了碱性变质岩，形成了主要的富矿金-银和硫化物矿化（远东，美国西部和日本的低硫化度）类型。现在广泛使用的术语“高硫化”是由术语“高硫酸盐”和“高氧化”的人为组合产生的，并且非常模棱两可，因为它实际上并不意味着硫化过程。这种类型的矿化将更好地命名为酸性硫酸盐。