【摘要】 桐峪金矿床位于华北地台南缘小秦岭金矿带的西段。矿体多呈薄板状、脉状和透镜状产出。赋矿围岩为太古代太华群变质岩系。围岩蚀变主要有绢云母化、硅化、碳酸盐化等。文章对该矿床的流体包裹体进行了岩相学研究,并开展了显微测温、流体成分及氢、氧同位素测试,模拟估算了密度、压力、深度。结果表明,第Ⅰ、Ⅱ、Ⅲ阶段流体包裹体的均一温度、盐度分别为:280~360℃,3%~11%;190~330℃,3%~15%;150~290℃,1%~11%。包裹体液相成分中阳离子以Na+、K+、Ca2+为主,阴离子以Cl-为主,SO2-4次之;气相成分以H2O、CO2和N2为主,含少量O2、CH4。流体为弱还原性。成矿温度属中(高)温,低盐度,成矿压力为78~220 MPa,成矿深度大约为3~8km。包裹体水的δDV-SMOW值为-44.4‰~-81.8‰,δ18O水值为0.01‰~6.65‰。成矿流体成矿初期为岩浆水或者混有少量变质水的混合水,成矿后期有大气降水的混入。Au在成矿流体中主要是以Au(HS)-2的形式进行迁移,其次为Au2S(HS)2-2。更多还原

【Abstract】 The Tongyu gold deposit,lying in southern North China platform,is tectonically located in western Xiao Qinling gold metallogenic belt.Ore bodies,hosted in metamorphic rocks of Achaean Taihua Group,occur as sheets,veins and lenses.Wall rock alteration is well developed in the gold deposit;there are carbonatization, sericitization,silicification,choritization etc.The authors approximately calculated the density,pressure,depth on the basisof studiesof petrography and microscopic differential thermometry of fluid inclusions as well as components and H-O isotopic compositionsof the fluids.Homogenization temperaturesof fluid inclusionsof the three stages are 280~360℃,190~330℃and 150~290℃respectively,with salinitiesof 3%~11%,3%~15%and 1%~11%.The liquid part of the fluid inclusion mainly contains Na+,K+,Ca2+.Cl-is the anion of the highest value,and SO2-4takes the second place.The gas phase composition primarily contains H2O,CO2and N2,followed by a small amount of O2and CH4.The fluid inclusions are characterized by slight reduction. Mineralization took place at intermediate temperature.Based on fluid inclusion studies,the authors consider that the ore-forming hydrothermal fluid is of low salinity.The ore-forming pressures are from 78 MPa to 220 MPa,suggesting that the depth ranges from 3 km to 8 km.(D values vary in the range of-44.4‰ ~-81.8‰,and δ18O(H2O)in the range of 0.01‰ ~6.65‰.TheδD-δ18O isotopic diagrams show that the early stage was dominated by magmatic water or mixed magmatic water,whereas at the late stage there was some addition of atmospheric precipitation.The authors have reached the conclusion that Au in the ore-forming fluid mainly migrated in the form of Au(HS)-2,followed by Au2S(HS)2-2.更多还原