江西金山矿区硅质岩的发现及其地质意义

通过野外地质调查和系统的岩石学及常量元素、微量元素、稀土元素地球化学特征的研究，探讨了金山矿区硅质岩的成因和大地构造环境。通过测试分析，显示区内硅质岩贫Al₂O₃、TiO₂，富As、Sb、Hg、Au、Ag、W、Pb，贫∑REE，δ(Eu)为负异常，δ（Ce）为弱正异常，HREE相对富集等热水沉积物的特征，同时也表明在硅质岩的形成过程中有陆源物质的介入。在判别硅质岩的形成与作用的一系列图解上，样品均落在热水沉积作用和形成于大陆边缘环境的范围内，这与一些特征值w(Fe)/w(Ti)、w(Fe+Mn)/ w(Ti)、w(Al)/w(Al+Fe+Mn)、w(MnO)/w(TiO₂)、δ(Ce)等的分析结果相吻合。这种硅质岩的发现与对比结果说明了该区域构造演化的复杂性。在晚古生代加里东运动使赣东北地区壳体断裂拉张，形成断陷盆地，并发生了热水喷流沉积成岩成矿作用。金山金矿床在形成过程中还经历了古生代热水成矿作用的叠加改造。

Genesis and Geological Significance of Cherts in Jinshan Mine,Jiangxi Province

Based on the detailed field geological survey and comprehensive petrology and major elements, trace elements, REE composition studies, the authors discuss the genesis and the tectonic environment of cherts in the Jinshan mine. The results of analysis indicate that cherts show hydrothermal sediment characteristics of relatively low contents of Al_2O_3,TiO_2 and relatively abundant elements of As, Sb, Hg, Au, Ag, W and Pb. Rare-earth elements are characterized by a low content, Eu negative anomaly, Ce low positive anomaly and HREE relative enrichment, which suggest that there exists an entry of terrigenous constituent during the formation of these cherts. In a series of discriminant diagram of cherts, the samples fall into the hydrothermal sedimentation field, showing that they are formed in a continental margin environment. Several ratio values of Fe/Ti,(Fe+Mn)/Ti, Al/(Al+Fe+Mn), MnO/TiO_2 and δ(Ce)also indicate the same characteristics. The hydrothermal sediment cherts, which suggest that the complex tectonic evolution once occurred in the area, are found. There are a series of fault basins, which were formed by Caledonian tectonic event in Late Palaeozoic in the northeast of Jiangxi Province. At the same time there came into being hydrothermal exhalative mineralization in the Jin(shan) gold deposit. The Jinshan gold deposit suffered superposed reconstruct by hydrothermal mineralizing process in the Palaeozoic era.