Genesis of the Mandongshan gold deposit (Xinjiang, NW China): T-P-fS(2) and phase equilibria constraints from the Au-As-Fe-S system
Genesis of the Mandongshan gold deposit (Xinjiang, NW China): T-P-fS(2) and phase equilibria constraints from the Au-As-Fe-S system
复制标题
满东山金矿床（中国西北部新疆）的成因：T-P-fS(2) 和 Au-As-Fe-S 体系的相平衡约束
DOI：
10.1016/j.oregeorev.2016.11.032
复制
发表时间：
2017
影响因子：
3.3
通讯作者：
Zhu Yongfeng
中科院分区：
文献类型：
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作者：
Zhang Huichao;Zhu Yongfeng
曼东山金矿床位于西准噶尔（中国新疆），赋存于早石炭世玄武岩和凝灰岩中。矿体主要由含金热液脉、矿化玄武岩和含浸染硫化物的凝灰岩组成。热液过程可以根据矿石岩相研究来确定：石英-钠长石-硫化物-自然金（第一阶段）、毒砂-方解石-自然金（II）和黄铁矿-方解石（III）。对石英中流体包裹体的显微测温和激光拉曼光谱分析表明，第一阶段的成矿流体温度适中（360-398°C），低盐度（0.5-5.1 wt% NaCl 当量），以 H2O-CH4 为主，随后演化为低盐度（0.2-1.2 wt% NaCl 当量），CH4at 含量微乎其微。 219–267°C（第三阶段）。矿化玄武岩中矿石元素（As、Au、Cu、Sb、Ba、Cs、Rb）含量均高于新鲜玄武岩。使用SUPCRT92软件包和更新的slop98.dat数据库对Au-As-Fe-S体系进行物相分析表明，相分离和流体-岩石反应引起的H2S活度和氧逸度的降低导致了第一阶段的自然金沉积。毒砂结晶引发的H2S活度的降低导致了第二阶段的自然金沉积。
The Mandongshan gold deposit, located in the west Junggar (Xinjiang, China), is hosted in Early Carboniferous basalt and tuff. Ore bodies mainly consist of gold-bearing hydrothermal veins, mineralized basalt and tuff with disseminated sulfides. Hydrothermal process could be identified based on ore petrographic studies: quartz-albite-sulfide-native gold (stage I), arsenopyrite-calcite-native gold (II), and pyrite-calcite (III). Microthermometric and laser Raman spectroscopic analysis of fluid inclusions in quartz demonstrate the ore-forming fluid at stage I was moderate temperature (360–398 °C), low-salinity (0.5–5.1 wt% NaCl equiv), and H2O-CH4-dominant, which evolved to low-salinity (0.2–1.2 wt% NaCl equiv) with insignificant content of CH4at 219–267 °C (stage III). Contents of ore elements (As, Au, Cu, Sb, Ba, Cs, Rb) in mineralized basalt are higher than those in fresh basalt. Phase analysis for the Au-As-Fe-S system using SUPCRT92 software package with the updated database of slop98.dat indicates that a decrease of H2S activity and oxygen fugacity, caused by phase separation and fluid-rock reactions, induced native gold precipitation at stage I. The decrease of H2S activity triggered by arsenopyrite crystallization caused native gold deposition at stage II.