山西中条山铜矿峪铜矿流体演化特征

Evolution characteristics of Tongkuangyu copper fluid in the Zhongtiaoshan mountains,Shanxi Province

铜矿峪铜矿大地构造位置位于华北克拉通中部造山带南部,主容矿围岩为花岗闪长斑岩、二长花岗岩及变质基性火山岩。对不同阶段石英流体包裹体进行了包裹体岩相学、显微测温学和激光拉曼显微探针研究。结果表明,成矿流体包裹体可分为气液两相包裹体、含多子晶包裹体、含石盐子晶包裹体、含CO2包裹体及纯CO2包裹体。其中早阶段以富含多子晶包裹体(均一温度为436.2℃～>550℃,盐度(w(NaCl))为49.34%～>62%)和含石盐子晶包裹体(均一温度为345.6℃～>550℃,盐度(w(NaCl))为29.72%～>62%)为主。主成矿阶段主要由含石盐子晶包裹体(均一温度为169.1℃～324.9℃,盐度(w(NaCl))为30.47%～39.75%)、气液两相包裹体(均一温度介于159.9℃～242.9℃,盐度(w(NaCl))为1.56%～22.31%)组成并发现少量含CO2包裹体(均一温度为259.7℃～320.5℃,盐度(w(NaCl))为8.93%～13.16%)和纯CO2包裹体(CO2均一温度为24.3℃～27.22℃)。晚成矿阶段仅发育气液两相包裹体(均一温度为126.9℃～212.3℃,盐度(w(NaCl))为1.56%～7.44%)。激光拉曼光谱分析包裹体气相成分主要为H2O、CO2、HF组成,晚期为CO2、N2。包裹体中普遍存在CO2。早阶段流体应为高温高盐高氧逸度NaCl-H2O-CO2体系。主成矿阶段含气液两相包裹体与富CO2相包裹体共存,表明流体发生了不混溶或沸腾现象。成矿晚阶段低温低盐度气液两相包裹体可能来源于大气降水。分析认为,铜矿峪铜矿成因类型属斑岩型。

Tongkuangyu copper deposit is located in the south of North China craton medio-orogenic belt.The major ore-hosted rocks are granodiorite porphyry,monzogranite and metamorphosed mafic volcanic rocks.we made petrographic,microthermometric and laser Raman spectroscopic studies on the fluid inclusions.The results show that fluid inclusions in quartz crystals can be classified into aqueous and gas two-phase,daughter mineral-bearing multi-phase,halite daughter mineral-bearing phase,CO2-bearing and pure CO2 phase inclusions.In early mineralization stage,fluid inclusions are characterized by mainly daughter mineral-bearing multiphase type with 436.2 ℃-550 ℃ in homogenization temperatures and 49.34%-62% in NaCl salinities,and halite daughter mineral-bearing type with 345.6 ℃-550 ℃ in homogenization temperature and 29.72%-62% in NaCl salinities.In main mineralization stage,fluid inclusions are halite daughter mineral-bearing type with 169.1 ℃-324.9 ℃ in homogenization temperatures and 30.47%-39.75% in NaCl salinities,aqueous type with 159.9 ℃-242.9 ℃ in homogenization temperatures and 1.56%-22.31% in NaCl salinities,and a small amount of CO2 type with 259.7 ℃-320.5 ℃ in homogenization temperatures and 8.93%-13.16% in NaCl salinities,and pure CO2 type with 24.3 ℃-27.22 ℃ in homogenization temperatures.Inclusions of the late mineralizing stage only contain aqueous and gas two-phase type with 126.9 ℃-212.3 ℃ in homogenization temperatures and 1.56%-7.44% in NaCl salinities.Laser Raman spectroscopy of inclusions indicate that the principal gas-phase components are H2O and on the early stage the gas components are CO2 and HF,on the main mineralization stage the gas components are CO2 and N2.CO2 is prevalent in fluid inclusions.The fluids on the early mineralizing stage should be a NaCl-H2O-CO2 system with high homogenization temperature,high salinity and high oxygen fugacity.In the main mineralization stage the CO2 phase and NaCl-H2O phase inclusions coexisting indicates immiscibility or boiling of fluids.The low temperature and low salinity aqueous and gas two-phase inclusions of late mineralization stage may be derived from meteotic water.On the basis of fluid features and the geological characteristics,genetic type of Tongkuangqu copper is defined porphyry copper.