摘要
热液矿床中金主要以包体金和裂隙金两种赋存状态产出，裂隙金构成富矿石。金的两种析出形式，分别为热液演化过程中金的两组成矿化学反应的结果。同时，金的活化和沉淀作用与热液流体中铁的活动有密切关系。为阐明热液富金矿石形成的机理，进行了含金黄铁矿的模拟合成实验。实验是在自紧式冷封高压釜（石英管衬套）中完成的。实验的物理化学条件模拟胶东玲珑等金矿的实测成矿参数ｔ＝４００～２００℃；ｐ＝５０～１０ＭＰａ；ｃ（ＮａＣｌ＋Ｎａ２Ｓ）＝０５～１ｍｏｌ／Ｌ；ｐＨ＝２～６５。装填物料为Ｆｅ２Ｏ３＋６Ｓ＋ＡｕＣｌ３·ＨＣｌ·４Ｈ２Ｏ或金粉。恒温时间为７～１２ｄ。合成黄铁矿具有完好的立方体或五角十二面体晶形。盐酸分步提取法实验证明，在黄铁矿晶体的核心部分含９０×１０－６～６０×１０－６的分散包体金，而黄铁矿边缘部分及以外的残余Ｆｅ２Ｏ３中仍含有大量的反应残余金粒。实验结果证明，在合成反应体系中只有少量的金与黄铁矿同时析出；而更多的金在残余溶液中富集，在自然热液成矿过程中这部分金可形成晚期裂隙金。实验结果与在胶东等地区热液金矿床观察到的事实吻合。
There are two important existing forms of gold in hydrothermal deposits: inclusion and “fissure” gold in pyrite, and the latter forms rich ores. The formation of these two forms of gold in hydrothermal mineralization is controlled by the tectono dynamic environment and thermodynamic evolution of ore forming system. A series of synthetic experiments of gold bearing pyrite have been carried out in order to investigate the mechanism of the formation of rich gold ores. The experiments were accomplished by using self tightening cold seal pressure vessel with quartz tube. The physical chemical conditions for experiment system are modeled after those determined in Linglong hydrothermal gold deposit of Jiaodong district: t =400～200℃, p =50～10MPa, c (NaCl+Na 2S)=0.5～1mol/L, pH=2～6 5. Loaded reagents are Fe 2O 3+6S+AuCl 3·HCl·4H 2O or gold powder. Time for constant temperature is 7～12days. The synthetic pyrite has a perfect cubic or pentagonal dodecahedron crystal forms. Partial leaching tests demonstrate that in the central parts of pyrite crystal, dispersion inclusion gold with contents of 90×10 -6 ～60×10 -6 is present. A lot of gold grains have also been measured out in the margin of pyrite and in residual Fe 2O 3 materials by means of partial leaching and electron probing. This fact indicates that in the experimental reaction system, only a small amount of gold deposits with pyrite simultaneously, whereas much of it remains in the residual solution, forming fissure gold in the later fracturing activities. Experimental results are in good agreement with observed facts in hydrothermal gold deposits of Jiaodong and other districts.
出处
《地学前缘》
EI
CAS
CSCD
1998年第2期301-310,共10页
Earth Science Frontiers
基金
国家自然科学基金
地质矿产部重要基础地质研究项目
关键词
含金
黄铁矿
模拟合成实验
热液成矿
金富集
gold bearing pyrite, synthetic experiment, hydrothermal differentiation of Au and Fe, ore forming reaction system
