广东长坑-富湾金、银矿床流体地球化学特征及其意义  

GEOCHEMICAL CHARACTERS AND SIGNIFICANCE OF THE FLUID INCLUSIONS FROM THE CHANGKENG-FUWAN GOLD-SILVER DEPOSITS, GUANGDONG PROVINCE

作　　者：毛晓冬[1] 黄思静[1] 刘云华[2] 

机构地区：[1]成都理工大学"油气藏地质及开发工程"国家重点实验室 [2]中国地质大学

出　　处：《成都理工大学学报（自然科学版）》2003年第2期111-119,共9页Journal of Chengdu University of Technology: Science & Technology Edition

基　　金：中国地质调查局资助项目 ( 2 0 0 1 1 0 2 0 0 0 2 6)

摘　　要：在广东长坑 -富湾金、银矿床的金矿石矿物中观察到单相盐水溶液包裹体和两相盐水溶液包裹体 ,银矿石矿物中除此还有单相气体包裹体和两相气液包裹体。测得包裹体均一温度 :金矿 1 2 8～ 2 0 0℃ ,银矿在 1 85～ 2 80℃之间 ,均为中 -低温 ;包裹体盐度 :金矿 6.0 %～ 9.5 %( Na Cl,个别高于 1 0 % ) ,银矿 6.0 %～ 8.2 % ( Na Cl)和 9.7%～ 1 5 .9% ( Na Cl,个别低于 6% ) ;包裹体密度 :金矿 0 .878～ 0 .991 g/cm3 ,银矿 0 .83 3～ 1 .0 1 8g/cm3 ;成矿压力在 2 7.0～ 3 1 .0 MPa左右 ,银矿化较金矿化高 ;金矿成矿流体属 K-Na-Cl型 ,银矿是 Na-Ca-Cl型 ,它们的流体成分不同于现代海底喷流和海水环境中的成矿流体 ;Na Cl-H2 O体系的 T-S-D相图反映金、银矿床的成矿流体介于临界和饱和曲线之间 ;金矿成矿流体介质水为大气降水或建造水 ,银矿的成矿流体水是大气降水与火山 -岩浆水的混合水。说明长坑 -富湾金、银矿床成矿不是在海盆中由热水沉积作用形成的 ,而是热液交代作用的产物 ;成矿流体属亚临界、中 -低温、中 -低盐度的高密度流体 ,要形成如此大规模金、银矿床 。Fluid inclusions are observed and tested in the minerals, such as quartz, realgar, barite, sphalerite and calcite from the orebodies of the Changkeng Fuwan gold silver deposits. The fluid inclusions from the gold deposit comprise single phase brine dissolution (L H 2O ) and two phases brine dissolution (L H 2O +V H 2O ). The fluid inclusions from the silver deposit consist of the above two types and single phase gas inclusion (V CO 2 or V H 2O ). The homogenization temperatures are measured to be 128~200℃ for the gold deposit and 180~280℃ for the silver deposit. This indicates that the metallogenic temperatures for the silver deposit are higher than those for the gold deposit. The metallogenic temperatures for both gold and silver are low to middle, and the metallogenic fluid for both are low to middle salinity [6.0%~9.5%(NaCl) for gold deposits, 6.0%~8.2%(NaCl) and 9.7%~15.9%(NaCl) for silver deposits] but high density one (0.878~0.991 g/cm 3 for gold, 0.833~1.018 g/cm 3 for silver). The metallogenic pressure is within 27.0~31.0 MPa and higher for forming gold deposits than for forming silver. The metallogenic depth is about 900~1200 m. The fluid components for metallogenesis of gold belong to K Na Cl type, and Na Ca Cl type for silver. According to the diagram of the T S D of NaCl H 2O, the metallogenic fluid for both gold and silver deposits indicates to be sub critical fluid. The fluid inclusion contents are also quite different from that of the modern sea floor exhalation and that of the metallogenesis fluid in the sea environment . All the above evidences indicate that the mineralization of the Changkeng Fuwan gold and silver deposits is not the hot water depositional mineralization but is the hydrothermal replacement. To be formed such large scale gold and silver deposits, the metallogenesis system must be hydrothermal circulation mechanism under a certain high pressure.

关 键 词：金矿 银矿 包裹体 均一温度 盐度 密度 热液交代作用 

分 类 号：P618.5[天文地球—矿床学]