阳山金矿带金的赋存状态及其对成矿过程的指示意义

阳山金矿带是西秦岭金矿带已探明金储量最大的独立金矿区，其矿化样式主要为微细浸染状矿化，其次为石英脉型矿化，可见金与“不可见金”均有发育，该金矿带是研究造山型金矿金赋存状态的理想地区，其研究成果对理解金成矿作用和过程以及指导选矿工艺具有重要意义。论文在翔实的野外地质调查和显微观察基础上，将成矿期划分为早阶段(黄铁矿石英)、主阶段(黄铁矿毒砂绢云母石英)和晚阶段(辉锑矿石英方解石)，综合应用电子探针、激光剥蚀电感耦合等离子体质谱、电感耦合等离子质谱仪、高分辨率透射电镜、X射线粉晶衍射等技术，剖析阳山金矿带不同成矿阶段金的赋存状态，进而探讨其对成矿过程的指示意义。研究表明：成矿早、主阶段以微细浸染状硫化物矿化为主，金主要以晶格金的形式赋存于黄铁矿和毒砂中；而成矿晚阶段以脉状矿化为主，金主要以自然金的形式存在。金的赋存状态的变化，指示从成矿早阶段到晚阶段，成矿温度、压力逐渐降低，成矿流体成分由富As流体演化为相对贫As且富Sb的流体。

Gold occurrence in the Yangshan gold belt in the West Qinling Orogen and its implications for ore-forming processes

The Yangshan gold belt is the largest isolated gold deposit district in the West Qinling gold belt, where disseminated mineralization is dominant with lesser quartz vein type mineralization. Native visible gold and “invisible gold” are both developed in the gold belt, making the Yangshan gold belt ideal for studying gold occurrence in orogenic gold deposits. Such study is significant for understanding gold metallogeny and ore-forming processes and beneficial for guiding mineral processing. Based on detailed field investigation and micro-observations, the ore paragenesis can be divided into early (pyrite-quartz), main (pyrite-arsenopyrite-sericite-quartz) and late (stibnite-quartz-calcite) ore stages. We used a combination of electron microscope, laser ablation inductively coupled plasma mass spectrometry, inductively coupled plasma mass spectrometer, high resolution transmission electron microscopy and X-ray powder diffraction to investigate gold occurrence in different ore stages. We further discussed the implications of the gold occurrence in the ore-forming processes in the Yangshan gold belt. The results show that the early and main ore stage mineralization is dominated by micro-grained disseminated sulfides and gold occurs as lattice gold in pyrite and arsenopyrite, whereas vein type mineralization is dominated in the late ore stage and gold occurs as native visible gold. The changing of gold occurrence indicates that, from early to late ore stages, fluid temperature and pressure decreased gradually and the ore fluid evolved from As-rich to relatively As-poor and Sb-rich fluid.