| 湘西南金矿床成矿流体地球化学研究 |
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| 引用本文：.1999.Geochemical Studies of Ore-forming Fluids in Gold Deposits of Southwestern Hunan[J].Mineral Deposits,18(1):73~82 |
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| 基金项目:中国有色金属总公司地质总局资助项目（95-D-21) |
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| 中文摘要:流体包裹体地球化学和氢、氧同位素研究表明，湘西南金矿床的成矿流体显示低温、低盐度、中等密度、低氧逸度、呈中性-弱碱性的特征，成矿流体中的金主要以Au(HS)-2、AuH3SiO40等络合物形式迁移，金矿床形成于低温、低压环境条件下，成矿溶液主要来自大气降水。流体包裹体同位素测年与示踪研究表明，该区金矿床并非形成于传统认识中的武陵-雪峰期，而是加里东期成矿，金矿床的成矿物质主要来自赋矿地层而非中基性脉岩。 |
| 中文关键词:金矿床 成矿流体地球化学 湘西南 |
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| Geochemical Studies of Ore-forming Fluids in Gold Deposits of Southwestern Hunan |
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| Abstract:A systematic study is carried our on the fluid inclusions of gold deposits in southwestern Hunan. It is shown that the fluid inclusions in quartz arc mainly gas-liquid inclusions genetically dominated by primary or psudo-secondary inclsuions. The ore-forming temperature ranges from 130℃ to 230℃，and its salinity is usually lower than 6% NaCl. The gas composition of fluid are dominantly H2O, CO2, with minor CH4, H2 and N2, and the liquid composition is characterized by Na+>K+>Ca2+ >Mg2+ and SO42- >Cl->F- , which is similar to things of the modern hotspring water. The ore-forming solution is characterized by low-temperature, low-salinity, low-oxygen fugacity, medium-weak alkalinity, and gold is transported mainly in the forms of Au(HS) 2- and AuH3SiO40 in the ore-forming fluid. Based on the compositional features of ore-forming fluid and its H2O isotope composition as well as the geological features of gold deposits in this area, it can be concluded that the ore-forming solution mainly originated from meteoric water rather than from metamorphic water as traditional opinion considered. The Rb-Sr isochron ages of fluid inclusions in gold deposits are 412×106 a and 435×106 a respectively, suggesting that gold mineralization in this area took place in Caledonian period rather than in Wuling-Xuefeng period. Rb, Sr isotopic features of ore-forming fluid indicate that the ore-forming materials are of crustal origin, mainly derived from the host strata rather than from the intermediate-basic dikes. |
| keywords:gold deposit, gelochemistry of ore-forming fluids, southwestern Hunan |
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