青海双朋西金铜矿床的成矿流体特征及流体来源

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

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SO24-、C l-为主;气相以H2O、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/204Pb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。

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^＋ ,Ca^2＋ ,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/cm^3 ） , 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 δ^34S value（‰） range from ＋3.1 to ＋6.2（average ＋4.42） ,indicating that the source of Pb and S from crust mantle mixed origin.