甘肃省文县阳山金矿床流体包裹体的地球化学特征

甘肃省文县阳山金矿床是近年来在陕甘川交界地带发现的一个产于泥盆系浅变质岩系的特大型金矿床。流体包裹体的系统分析结果表明:(1)镜下石英和方解石中流体包裹体的类型丰富多样。据室温状态下流体包裹体的相态、加热状态下流体包裹体的性状及产出特征,鉴别出2种成因类型及7种物理状态类型;(2)流体包裹体显微测温结果显示本区的均一温度在105～310℃之间,主要集中在260～310℃、220～240℃、150～190℃3个区间,成矿流体组分体系接近于NaCl H2O CO2体系,成矿流体密度估计在0 35～1 02g/cm3之间,成矿压力估计在400×105～800×105Pa之间,流体包裹体盐度估计在2 5%～10 4%NaCl之间;(3)从流体包裹体成分分析获得的pH值为6 91～7 1,还原参数n(CH4+CO+H2)/n(CO2)的摩尔数比值在0 009～0 050之间,表明具有浅成中偏碱性和弱还原环境成矿的特点;(4)石英中流体包裹体的δDSMOW值为-92 4‰～-62 9‰,δ18O石英SMOW值在-3 09‰～+0 41‰之间,δ18OH2OSMOW值在-12 13‰～-8 48‰之间。综合分析认为成矿可能主要与低温热液作用有关。

FLUID INCLUSION GEOCHEMISTRY CHARACTERISTICS OF THE YANGSHAN GOLD DEPOSIT IN WEN COUNTY,GANSU PROVINCE,CHINA

Yangshan gold deposit is a supper large gold deposit,located in the border area of Shanxi-Gansu-Sichuan,occurs in Devonian epimetamorphised,phyllite or limestone,found by Gold Geological Party of CAPF in recent years.Fluid inclusion geochemistry characteristics were deduced by samples in this area.Microthermometry of fluid inclusions in quartz indicates seven types of inclusions,and two types of inclusions in calcite.Fluid inclusions in quartz have homogenization temperatures from 105℃ to 310℃,pressure ranges from 400×10~5 Pa to 800×10~5 Pa,salinity ranges from 2.5 to 10.4 NaCl equivalent wt percent,and density ranges from 0.35 g/cm~3 to 1.02 g/cm~3).Ore-forming fluids are basically from the NaCl-H2O-CO2 system.pH values of ore-forming fluid range from 6.91 to 7.10,CH4+CO+H2/CO2 values range from 0.009 to 0.050,_δ_DSMOW) values of inclusions in quartz range from -92.4‰ to -62.9‰,_δ_OSMOW) values of quartz range from -3.09% to +0.41%,and _δ_OH2O SMOW) values range from -12.13% to -8.48%.In this paper,based on the studies of fluid inclusions trapped in quartzes and calcites,the ore-forming fluid geochemistry characteristics are described,and the role of fluid inclusions in exploration and the ore genesis of this deposit is revealed.