赞比亚铜带省谦比希铜矿床成因:来自流体包裹体和H-O-S同位素地球化学证据

为揭示谦比希铜矿床的成矿流体性质、成矿物质来源及其演化特征，对其矿石和脉石矿物展开了流体包裹体和H-O-S同位素地球化学研究.结果显示，热液型脉状矿化石英流体包裹体均一温度变化于100~350 ℃，盐度变化于11%~19%NaCl_eqv；δD_V-SMOW值为-64.0‰~-52.6‰，δ18O_H2O值为1.57‰~2.97‰.热液型脉状和沉积型层状铜矿体δ34S_CDT值分别变化于5.5‰~12.1‰和6.0‰~21.0‰.分析表明，热液型成矿流体属Cl-Na-Ca型水溶液，属中低密度流体；成矿流体受幔源和壳源岩浆混合，导致铜发生沉淀.沉积型层状矿化硫主要来自成岩硫化物和海水硫酸盐，硫酸盐以热化学还原为主，导致SO₄2-较彻底的变为H₂S.整体看来，谦比希铜矿床热液型脉状矿化与新元古代中期岩浆活动密切相关，沉积型层状矿化主要与新元古代晚期大规模造山运动和区域变质作用有关. 

Genesis of Chambishi Copper Deposit in Copperbelt Province of Zambia:Evidence from Fluid Inclusions and H-O-S Isotope Geochemisty

Fluid inclusions study and H-O-S isotopic geochemical analysis of ore and vein minerals were carried out in this study in order to reveal the characteristics of ore-forming fluid and material of the Chambishi copper deposit. The results of microscopic measurement of temperature show that the homogenization temperature and salinity of the fluid inclusions from hydrothermal fluid filling deposit mainly range from 100 to 350 ℃ and 11% to 19% NaCl_eqv, respectively. Analyses of H-O isotopic composition of the hydrothermal fluid filling deposit show that the values of δD_V-SMOW and δ18O_H2O are -64.0‰ to -52.6‰ and 1.57‰ to 2.97‰, respectively. Analyses of S isotopic composition show that the values of δ34S_CDT from hydrothermal fluid filling orebodies and depositional orebodies are 5.5‰ to 12.1‰ and 6.0‰ to 21.0‰, respectively. The above data indicate that the ore-forming fluid of the hydrothermal fluid filling deposit is of medium-low temperature, low-middle salinity and density, and belongs to Cl-Na-Ca-type aqueous solution. The fluid is a mix of mantle and crust-derived magmas. Fluid mixing is the main reason for copper precipitation. Sulfur of the hydrothermal fluid filling deposit is similar to those of mantle-derived sulfur, whereas the sulfur of the depositional ore deposit is mainly sourced from diagenetic sulphide and seawater sulfate. The mechanism of sulfate reduction for both deposits is thermochemical reduction which resulted in the change of sulfur from SO₄2- to H₂S. The mixed sources of ore-forming fluid and material indicate that mineralization of the hydrothermal fluid filling deposit is closely related to the middle Neoproterozoic magmatism, whereas mineralization of the depositional ore deposit is mainly related to the strong Late Neoproterozoic orogenesis and regional metamorphism.