湘中基底-盖层W-Au-Sb热液系统的金属分异机制综述

湘中盆地锑矿床闻名于世,成矿元素在垂直空间上呈现出上锑(泥盆系)、中金锑(震旦系)、下金钨或金锑钨(板溪群),盆地中锑、边缘锑(金/钨)的成矿分布特征。通过系统的成矿地质条件、成矿元素地球化学研究,以及矿物流包裹体地球化学数据分析表明,湘中盆地及其基底的成矿元素分带是成矿流体性质和元素地球化学行为差异等因素相互耦合的结果。湘中地区基底-盖层成矿系统:构造-岩浆岩+盆地-流体作用,基底成矿元素在流体的作用下被萃取迁移到不同部位(基底→盖层不断演化);成矿元素锑的沉淀主要受流体的温度和pH值影响,金的沉淀主要受硫逸度或总硫溶度的控制,钨的沉淀主要受流体的盐度控制,且因物化条件的变化和元素地球化学行为的控制而呈现不同元素组合沉淀成矿。

W-Au-Sb differentiation mechanism of the basement-cover hydrothermal fluid system in the Xiangzhong Basin in Hunan province

Xiangzhong basin is well known for its antimony deposit. The ore elements are vertically zoned, i.e. Sb in Devonian system at top, Au-Sb in Sinain system at middle part and Au-W or Au-Sb-W in Banxi Group at the botoom and horizontlly Sb at center of the basin and Sb (Au/W) at the margin. Systematic study on the metallogenic condition, the elemental geochemistry and quartz fluid inclusion geochemistry shows that the element zoning is coupling result of factors, such as the ore fluid property and different element geochemical behaviors etc. The basement-cover metallogenic system:structure-magmatic rock-basin-hydrothermal fluid activity in which the ore elements are extracted by the hydrothermal fluid and are transported to different positions and deposition of Sb is mainly controlled by temperature and pH value of the ore fluid and Au deposit by S-fugacity and W deposition by salinity of the ore fluid. Deposition of element or the combined elements are zoned due to change of physical and chemical conditions and control of the element geochemical behavior.