Ore-Forming Fluid Geochemistry of Yangchang Quartz Vein Molybdenum Deposit in Xilamulun Molybdenum Metallogenic Belt, Inner Mongolia
详细信息
- 责任者：Zhang Zuolun (China Railway Resources Exploration Co. Ltd. ; China Railway Resources Group ; Beijing 100039 ; China) ; Liu Jianming
- 刊名：Acta Petrologica Sinica
- 出版年：2012
- 卷期：28(2)
- 关键词：钼矿 ; molybdenum ores ; 内蒙古 ; Inner Mongolia
- 页码：p.391-400
- 图表：4 illus., 3 tables, 41 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Yangchang Mo deposit is located in the Xilamulun molybdenum metallogenic belt on northern margin of North China Craton,Inner Mongolia.The mineralization is occurred within the NW-to NNW-trending faults and fractures hosted by the Yanshanian biotite monzogranite.The ore-forming hydrothermal process can be subdivided into four stages:quartz vein stage(Ⅰ) ,quartz-pyrite stage(Ⅱ-1) ,quartz-pyrite-molybdenite-chalcopyrite-galena-sphalerite stage(Ⅱ-2) and carbonate stage(Ⅲ) .Three types of fluid inclusions are observed in quartz crystals,i.e.liquid-rich(VH2O<50%) inclusion,gas-rich(VH2O=50%～90%) inclusion and vapor inclusions.Homogenization temperatures of Ⅰ,Ⅱ-1,Ⅱ-2 stages are 173～280℃,180～467℃,151～366℃,respectively.From Ⅰ stage to Ⅱ-1 stage the temperatures become higher,suggesting the magmatic water was introduced into the mineralizing system.Salinities of Ⅰ,Ⅱ-1,Ⅱ-2 stages are in the range of 4.03%～10.61% NaCleqv,2.07%～10.36% NaCleqv,2.41%～9.98% NaCleqv,respectively.The composition of the hydrothermal fluids at different stages are mainly H2O(>94.39mol%) ,with minor CO2,N2,CH4,C2H6,Ar,H2S,and Na+,HS-,Cl-ions.These suggest the Yangchang Mo deposit was formed in reduction condition and the ore-forming fluids were of the NaCl-H2O±CO2 system.Hydrogen and oxygen isotopes of fluid inclusions in various mineralization stages are-119.66‰～-98.79‰ and-0.08‰～1.90‰ respectively,indicating that the ore-forming fluids were the mixture of magmatic water and meteoric water.It is suggested that the mixing of different fluids with distinct natures might be responsible for the precipitation of molybdenite.