西秦岭降扎地区寒武系层控金矿床中Au-Se共同富集成矿机制

Mechanism of Au and Se co- enrichment in Cambrian Stratabound Gold Deposits in Jiangzha, Western Qinling Mountains, China

西秦岭降扎地区寒武系中的层控金矿床，产于由碳质硅岩和碳质板岩组成的硅岩建造中。研究表明，无论是围岩还是金矿石，均普遍含有较高的硒，达到工业综合利用的要求，在局部地段甚至可以圈出独立的硒矿体。在金矿石中，硒主要呈独立矿物和以类质同象形式存在于硫化物中，且硒与金呈密切的正相关关系。尤为重要的是，在金矿石中常常见到自然金与一些硒矿物紧密共生，说明 Au、 Se可能以 Au- S- Se或 Au- Se络合物形式进行迁移。由于沸腾的成矿流体与下渗的富氧冷水混合而发生氧化还原作用，导致了 Au和 Se的共同富集成矿。

The Cambrian stratabound gold deposits in Jiangzha, western Qinling Mountains are hosted in the silicalite formation composed of black chert and carbonaceous slate. Studies have shown that Se is so high in abundance either in wall rocks or in gold ores as to reach the grade of industrial value for comprehensive utilization. In local places some independent Se orebodies can even be delineated. In gold ores Se is present mainly as independent minerals, or isomorphously in sulfides. In addition, Se is closely positively correlated with Au. What is more important is that in the gold ores native gold is commonly observed ultimately intergrowing with some selenium minerals. On the basis of this unique phenomenon, it is thought that gold and selenium are possibly transported by Au- S- Se or Au- Se complex. The co- enrichment of Au and Se is attributed mainly to boiling of ore fluids and their mixing with shallow- seated oxygen- bearing water.