山东莱州新城金矿床流体包裹体

山东新城金矿是胶东焦家-新城成矿带上重要的蚀变岩型金矿床。矿体主要赋存在焦家断裂带下盘靠近主裂面的黄铁绢英岩和黄铁绢英岩化碎裂岩内，严格受焦家断裂构造控制。矿石矿物主要有黄铁矿、黄铜矿、方铅矿、闪锌矿、自然金、银金矿和辉银矿等。区内围岩蚀变类型主要有黄铁绢英岩化、绢英岩化、绢云母化、硅化、钾化和碳酸盐化等，且矿化主要与黄铁绢英岩化和硅化关系密切。本次研究主要针对新城金矿床深部矿石中的流体包裹体进行了岩相学、显微测温、单个包裹体成分激光拉曼光谱及氢、氧同位素分析研究。研究表明：该矿床深部矿石中纯CO₂包裹体数量有明显增加现象，同时发育含CO₂包裹体和气液两相包裹体;成矿流体具有低盐度(w(NaCl))（2.06%~10.24%）、低密度（0.54~0.97 g/cm³）的特点;主成矿温度为260~300 ℃，成矿压力为65~113 MPa，成矿深度为6.51~8.82 km。成矿过程中流体经历了CO₂-NaCl-H₂O体系的不混溶作用。氢、氧同位素分析认为，成矿流体δD_SMOW为－75.1‰～－61.4‰，δ¹⁸O_水为4.80‰～6.40‰，并将新城金矿床与典型“焦家式”金矿床成矿流体特征及来源进行对比，认为新城金矿成矿流体主要以幔源流体为主。综合研究表明，新城金矿床成因类型为幔源流体参与成矿的中温热液脉型金矿床。

Fluid Inclusions of the Xincheng Gold Deposit of Laizhou City in Shandong Province

Xincheng gold deposit of Shandong Province is a typical altered rock type gold deposit in the Jiaojia-Xincheng gold ore belt. The ore body is mainly located in the footwall of the Jiaojia-Xincheng fault zone within the pyrite phylic and the cataclasite of pyrite phylic near the fracture surface and it is significantly controlled by the fractured zone. The main ore minerals are pyrite, chalcopyrite, galena, sphalerite, native gold, electrum and argentit, etc. The main types of wall-rock alteration zone contain pyrite phyllic, phyllic, sericite, silicification, potassium and carbonate, etc., and the gold mineralization has a close relationship with pyrite phyllic and silicification alteration. The petrographic, microthermometric, laser Raman microspectroscopic in the single fluid inclusion were studied here, results showed that the hydrogen and oxygen isotope analysis on fluid inclusions were developed in auriferous ore of Xincheng gold deposit in the deep position. Also, it indicated that the numbers of the pure CO₂ fluid inclusions are conspicuously increased in the deep position of the deposit, with the existence of the CO₂-bearing fluid inclusions and the aqueous two-phrase fluid inclusions at the same time. The ore-forming fluids show the characteristics of low salinity (2.06%-10.24%), low density (0.54-0.97 g/cm³). Mineralization temperature is concentrated in 260-300 ℃, and the pressure ranges from 65 to 113 MPa, which equals to a depth of 6.51-8.82 km. And fluid immiscibility occurred in CO₂-NaCl-H₂O system in the ore-forming process. The hydrogen and oxygen isotope analysis indicated that the δD_SMOW of the ore-forming fluids is -75.1 ‰--61.4‰ and the δ¹⁸O_H2O is 4.80‰-6.40‰. Compare the characteristics and source of fluid to the typical “Jiaojia style” gold deposit, it showed that the ore-forming fluids of the Xincheng deposit are mainly from deep mantle fluids. Comprehensive study shows that the genesis of the deposit is the type of mantle-derived fluid mineralization in mesothermal type gold deposits.