湖南沃溪金锑钨矿床的金矿化作用研究:基于元素地球化学特征和自然金的热力学模拟分析  

Gold mineralization of the Woxi Au-Sb-W deposit in Hunan Province based on element-geochemical features and thermodynamic modelling analysis of native gold

作　　者：梁翼 葛行飞 王国刚 裴秋明 Hoshino KENICHI LIANG Yi;GE Hangfei;WANG Guogang;PEI Qiuming;Hoshino KENICHI(Department of Geological Engineering,Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu,Sichuan 611756,China;Hunan Gold Corporation Limited,Changsha,Hunan 410137,China;Department of Earth and Planetary Systems Science,Graduate School of Science,Hiroshima University,Hiroshima739-8526,Japan)

机构地区：[1]西南交通大学地球科学与环境工程学院,四川成都611756 [2]湖南黄金集团有限责任公司,湖南长沙410137 [3]日本广岛大学理学院,日本广岛7398526

出　　处：《地质学报》2023年第10期3380-3395,共16页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41702077);中央高校基本科研业务费专项资金项目(编号2682016CX090)联合资助的成果。

摘　　要：湖南沃溪金锑钨矿床是江南造山带中金、锑、钨、均达到大型规模的典型矿床,其自然金的金成色值极高(>998)。本文聚焦湖南沃溪金锑钨矿床中金矿化作用,通过ICP-MS测试和包裹体显微测温实验查明不同矿物与围岩的元素地球化学特征和成矿流体特征,并通过热力学模拟分析自然金的成矿条件,探讨金成色值及金银比值对金矿化的指示作用和研究价值。ICP-MS测试结果显示,金银比值在白钨矿(103~520)和黄铁矿(69~673)中相对较高,在辉锑矿(6~65)和围岩(0.3~35)中相对较低,在石英(6~199)中则变化较大。基于包裹体显微测温结果(200~350℃),本文建立了自然金成矿流体的热力学模型,分析并查明在黄铁矿与绢云母共生的自然金成矿流体中,硫离子浓度比温度更容易影响金溶解度,且金成色值主要与温度呈正相关,与硫离子浓度呈负相关。通过对比研究和讨论,认为沃溪矿床大量金矿化可能形成于温度较高和硫离子浓度较低的白钨矿成矿流体中,而极高成色值的自然金可能与高金银比值的白钨矿和黄铁矿共生。上述方法和结论可为其他金矿床的研究提供新思路。The Woxi Au-Sb-W deposit,located in the Jiangnan orogenic belt,represents a typical case where W,Sb,and Au mineralization occur within a large-scale single deposit.The native gold produced in the Woxi deposit is characterized by extremely high gold fineness(>998).This paper,focused on the gold mineralization,uses ICP-MS analysis and microthermometric analysis of fluid inclusions to determine geochemical features in mineralogy and characteristics of ore-forming fluids,and investigates the indication of gold fineness and Au/Ag ratios for the gold mineralization.The ICP-MS analysis shows Au/Ag ratios are higher in scheelite(103~520)and pyrite(69~673)and lower in stibnite(6~65)and host rocks(0.3~35),while Au/Ag ratios vary within a large range in quartz(6~199).Based on results of the microthermometric analysis(200~350℃),this paper uses thermodynamic modelling to simulate ore-forming fluids of the native gold associated with pyrite and sericite,demonstrating that the gold solubility is easier to be decreased by the sulfur concentration than the temperature,and the gold fineness has a positive correlation with the temperature and a negative correlation with the sulfur concentration.The native gold in the Woxi deposit is more likely to precipitate in the fluid with a higher temperature and a lower sulfur concentration,and is thus associated with pyrite and scheelite.This paper is expected to provide a new method to study other gold deposits.

关 键 词：自然金 ICP-MS 流体包裹体 热力学模拟 沃溪金锑钨矿床 

分 类 号：P618.51[天文地球—矿床学] P618.6[天文地球—地质学]