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从美国西南部后生矿区产出的矿石,揭示了其银金比值具有很好的一致性。这种一致性在存在有这些矿床的两个地体中的任何一个地体中都能识别出来,不同的是两个地体中的银金比值相差一个数量级。Ahrens(1965)提出了一个地壳银金丰度的代表性比值为17.5∶1(当时,这一比值除了可以视为不同地理特征区之间的一个合理的划分值以外,并没有更多的意义)。相对富含银的矿石产在底部为厚层元古代碎屑岩和上部为古生代海相地层的地体中,相对富含金的矿石则产在以镁铁—长英质火山(岛弧)层序为主的元古代基底之上或之内。元古代花岗岩分布在两个地体中,如果不考虑含矿建造的年龄、矿床类型、相关的火成岩、控矿构造、不同解释的俯冲形式以及风化历史,那么,在每个地体内部这一比值都具有广泛的一致性。这些特点和联系证实了该地区中所有矿区的成矿作用主要与含有这些矿石的地壳有关这一成矿假说。
Ore from the epigenetic mines in the southwestern United States revealed that the silver-to-gold ratio is in good agreement. This consistency is recognized in any of the two terrains where these deposits exist, except that the ratio of silver and gold in the two terranes varies by an order of magnitude. Ahrens (1965) proposed a representative ratio of 17.5: 1 for the abundance of silver in the crust (at a time when this ratio did not have much meaning except as a reasonable division between different geographical features) ). The relatively silver-rich ores are found in thick metamorphic clastic rocks at the base and in the upper Paleozoic marine formations, while relatively gold-rich ores are produced on mafic-mafic volcanoes (island arcs) Based on the sequence of the Proterozoic basement or within. Proterozoic granites are distributed in two terrains. Without accounting for the age of ore-bearing construction, type of deposit, related igneous rocks, ore-controlling tectonics, different interpretation of subduction patterns and weathering history, then within each terrane this Ratios are broadly consistent. These features and connections confirm the mineralization hypothesis that the mineralization of all the mines in the area is mainly related to the crust containing these ores.