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新西兰怀特岛的火山热液系统被认为足形成高硫化Cu—Au矿床化学条件的典型代表。1万年以上的活动周期产生的Cu和Au的总量(主要来自脱气岩浆)计算结果分别是100万吨和45吨。从近代火山通道喷出的蚀变安山岩中含有明矾石、硬石膏和黄铁矿。它们的硫同位素组成表明矿脉充填时的温度为近380℃。在此温度下,Cu和Au在酸性溶液中高度溶解,这一点可以解释喷出物中为何贫Cu缺Au。然而,质量平衡计算结果表明,在酸性溶液排出地表之前Cu和Au已在较冷的带内沉淀了。
The volcanic hydrothermal system on the Isle of Wight, New Zealand, is considered to represent a typical representative of the chemical conditions of high-Cu-Cu deposits. The total amount of Cu and Au (mainly from de-aerated magma) produced over a period of more than 10,000 years is 1 million tons and 45 tons, respectively. The altered andesite emanating from the modern volcanic channel contains alunite, anhydrite and pyrite. Their sulfur isotopic composition indicates that the temperature at the filling of the veins is nearly 380 ° C. At this temperature, Cu and Au are highly soluble in acidic solutions, which explains why Cu is depleted of Au in the effluent. However, mass balance calculations show that Cu and Au have precipitated in colder bands before acid solution exits the earth’s surface.