贵州遵义中南村黑色岩系黄铁矿的成分标型与成因探讨

THE CHEMICAL TYPOMORPHISM GENESIS OF THE PYRITES FROM THE ZHONGNANCUN BLACK-ROCK-SERIES

对贵州遵义中南村黑色岩系多元素矿床黄铁矿中的Co、Ni、As、Se、Te、n(S)/n(Fe)、w(Co)/w(Ni)、w(S)/w(Se)、w(Se)/w(Te)等标型进行了研究,并将其与4个胶东热液型金矿的黄铁矿的相应数据进行了对比。通过成分标型分析,并结合黄铁矿的形态、内部结构和同位素特征以及前人的研究成果,认为此黑色岩系多元素矿床应为海底热水沉积和生物沉积混合成因。该黑色岩系黄铁矿同胶东界河金矿的黄铁矿、胶东金青顶金矿中的黄铁矿、胶东玲珑金矿西山矿区中的黄铁矿和胶东三山岛金矿床中的黄铁矿等热液金矿型黄铁矿在10000×w(Co+Ni)/w(Fe)—10000×w(As+Se+Te)/w(S)—100×(n(S)/n(Fe)-1 8)三角图上的投点明显不同,前者投点甚为分散,后者投点较集中。从成因角度分析认为:后者的物质来自花岗岩,主成矿过程受单一的温度变化范围不大的岩浆热液控制;前者物质来源复杂,受高温阶段的深部循环热水和低温阶段的海水—热水混合流体甚至生物作用的制约。由此可以初步提出以下一般判据:在10000×w(Co+Ni)/w(Fe)—10000×w(As+Se+Te)/w(S)—100×(n(S)/n(Fe)-1 8)三角图上,成因简单的黄铁矿的投点较集中,成因复杂的黄铁矿的投点较分散。

The elements Fe, S, Co, Ni, As, Se, Te, and the values of n(S)/n(Fe), w(Co)/w(Ni), w(S)/w(Se),w(Se)/w(Te)of the pyrites from the black-rock-series Ni-Mo-Au-Pt deposit in Zhongnancun of Zunyi, Guizhou were studied and compared with those of four hydrothermal gold deposits in the Jiaodong region. The triangular diagrams based on the data of 10,000×w(Co+Ni)/w(Fe)?10,000×w(As+Se+Te)/w(S) and 100×(n(S)/n(Fe)-1.8), well show the differences that the data points of the pyrites from the black-rock-series of Zhongnancun are more separated, and those of the pyrites from the four gold deposits of Jiaodong region are more concentrated. It might indicate that the material resources of the latter were derived from the granite, and thereafter the mineralization was controlled by the magmatic water within a small variance of temperature; those of the former were controlled by the combination of deep-cycled hot water at the high-temperature stage, the hybrid flow of the marine water and hot water at the low-temperature stage even with the addition of biological constraints. Therefore, the pyrite in relation to the simple genesis will be corresponding to a concentrated plot on the triangular diagram, whereas the complicated genesis would be corresponding to sparse plotting. The present study indicates that the black-rock-series type pyrite is of complicated origin related with sea-floor hydrothermal-biological sedimentation.