青海双朋西金铜矿床的成矿流体特征及流体来源

通过对双朋西金铜矿床流体包裹体岩相学、测温学及铅、硫同位素等的分析,研究其成矿流体性质和演化,并探讨矿床成矿流体来源,结果表明:①流体包裹体主要为气液两相包裹体;包裹体液相成分阳离子以Na+、K+、Ca2+为主,阴离子主要以SO2-4、Cl-为主;气相以H,2O、CO2为主.②双朋西金铜矿床成矿流体为中高温、中等盐度、中等密度、中等压力的流体.③铅同位素206Pb/204Pb为18.058～18.710,207Pb/204Pb为15.581～15.641,208Pb/204Ph为38.191～38.531;δ34S值(‰)变化范围为+3.1～+6.2,平均值为+4.42;综合分析认为,本区铅、硫同位素来源应为壳幔混合源.

Characteristics of Ore-Forming Fluid and Genesis of the Shuangpengxi Gold-Copper Deposit in Qinghai Province

Based on the study of the fluid inclusion, thermometry and isotopes analyses, the characteristics of ore forming fluid, fluid evolution and the origin of the Shuangpengxi gold-copper deposit were discussed and systematically studied. The results showed that: ①These inclusions consisted of mainly 2 phases of gas and liquid. Analysis showed that the compositions of liquid and gas in the inclusions were Na⁺,K⁺,Ca²⁺,SO₄^2-,Cl^-,H₂O,CO₂.②The homogenization temperature, salinity and density and pressure of fluid inclusions for the mineralization, ranged from 210℃ to 460℃，and 3.0％ to 6.5％，and 0.600 to 0.800（g/cm³），and 8.0 to 20.0 MPa,respectively being middle-high temperature, middle salinity, middle density and middle pressure fluid.③Pb isotope ²⁰⁶Pb/²⁰⁴Pb range from 18.058 to 18.710,²⁰⁷Pb/²⁰⁴Pb range from 15.581 to 15.641, ²⁰⁸Pb/²⁰⁴Pb range from 38.191 to 38.531, δ³⁴S value(‰) range from +3.1 to +6.2(average +4.42),indicating that the source of Pb and S from crust mantle mixed origin.
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