Abstract:

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  Al₂O₃,TiO₂  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/TiO₂ 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 Jinshan gold deposit. The Jinshan gold deposit suffered superposed reconstruct by hydrothermal mineralizing process in the Palaeozoic era.

Key words: hydrothermal sedimentation, chert, geochemistry, tectonic evolution, Jinshan mine