云南哀牢山老王寨大型造山型金矿成矿流体地球化学  

Ore-forming fluid geochemistry and genesis of Laowangzhai large scale orogenic gold deposit in Ailaoshan gold belt,Yunnan Province,China

作　　者：梁业恒[1,2] 孙晓明[1,2,3] 石贵勇[1,2] 胡北铭[3] 周峰[3] 韦慧晓[3] 莫儒伟[3] 

机构地区：[1]中山大学海洋学院,广州510006 [2]广东省海洋资源与近岸工程重点实验室,广州510275 [3]中山大学地球科学系,广州510275

出　　处：《岩石学报》2011年第9期2533-2540,共8页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划(973)项目(2009CB421006;2002CB412610);国家自然科学基金(40830425;40873034;40673045);高等学校博士学科点专项科研基金(200805580031);中央高校基本科研业务费专项资金(09lgpy09)联合资助

摘　　要：云南哀牢山金矿带是我国最重要的喜马拉雅期金矿带,而老王寨是其中最大的金矿。流体包裹体研究显示:老王寨金矿含金石英脉中流体包裹体类型主要为NaCl-H2O型和CO2-H2O型,其均一温度为102～302℃,峰值为160～180℃;流体盐度范围变化较大,介于2.5%～12.9%NaCleqv之间,峰值为6.0%～7.5%NaCleqv,显示老王寨成矿流体具有中低盐度和中低温度的特征。氢氧同位素测定显示成矿流体δDH2O=-115‰～-90‰,δ18OH2O=5.2‰～6.8‰,显示其组成主要为岩浆水,可能与有机沉积物发生过同位素交换。流体包裹体碳同位素组成(δ13C为-6.5‰～-3.9‰)基本落在幔源碳变化范围之内,说明其中CO2可能来自地壳深部,甚至上地幔。综合成矿地质特征和成矿流体的证据,提出老王寨金矿为喜马拉雅期造山型金矿。Ailaoshan gold deposit belt formed during Himalayan orogenisis in Yunnan Province is one of the most important gold deposits belts in China,within which the Laowangzhai gold deposit is the biggest one.Fluid inclusion microthermometry,Laser Raman analysis and carbon,hydrogen and oxygen isotope measurements are carried out in fluid inclusions of auriferous quartz veins from Laowangzhai gold deposits.The fluid inclusions are mainly NaCl-H2O and CO2-H2O types.Microthermometric measurements show that the homogenization temperatures range from 102℃ to 302℃,with peak values of 160~180℃,the salinities are 2.5% NaCleqv to 12.9% NaCleqv,with peak values of 6.0%~7.5% NaCleqv,indicating that the ore-forming fluids are characterized by low salinity and mid-low temperature.Isotopic analyses show that δDH2O and δ18OH2O of the ore-forming fluids are-115‰^-90‰ and 5.2‰~6.8‰,respectively,implying that the ore-forming fluids are mainly composed of magmatic fluid,with isotope interference of organic sediments.Carbon isotopic composition of the fluid inclusions lays within the range of mantle-derived carbon,suggesting that CO2 in the ore-forming fluids was probably derived from the deep crust,even the upper mantle.Geologic and geochemical features show that the Laowangzhai gold deposit is an orogenic gold deposit formed during the Himalayan orogenisis.

关 键 词：成矿流体 造山型金矿 老王寨金矿 哀牢山金矿带 

分 类 号：P618.51[天文地球—矿床学]