山东省寺庄金矿床成矿流体特征

莱州寺庄金矿床位于焦家成矿带南段，是焦家金矿田的一部分，也是焦家成矿带上重要的热液脉型金矿床。区内主要有黄铁绢英岩带、黄铁绢英岩化花岗碎裂岩带和黄铁绢英岩化花岗岩带3个控矿带，位于焦家断裂带下盘。矿石矿物主要为银金矿、黄铁矿、自然金、黄铜矿、方铅矿和闪锌矿等。该矿床发育了绢英岩化、硅化、钾化、碳酸盐化等蚀变类型，且硅化和绢英岩化与矿化关系最为密切。本文从流体包裹体岩相学特征、显微测温、单个包裹体成分激光拉曼光谱分析以及氢、氧同位素分析方面对山东省寺庄金矿床成矿流体特征进行综合研究。结果显示：该矿床金矿石中主要发育含CO₂相、气液两相和CO₂相三类包裹体。在成矿过程中，流体经历了CO₂-H₂O-NaCl体系的不混溶作用。成矿流体具有低盐度（w（NaCl）为（0.53%~10.24%））、低密度（0.50~1.03 g/cm³）的特点。成矿温度为260~340℃，压力为82~116 MPa，成矿深度为中成（7.40~8.94 km）。氢、氧同位素分析成矿流体δD_V-SNOW为-76.6‰~-69.0‰，δ¹⁸O_水为2.94‰~7.24‰，说明成矿流体以幔源流体为主，并有少量的岩浆水和大气降水参与。结合该矿床地质特征与实验结果综合分析，认为寺庄金矿的矿床成因类型为受断裂构造控制的幔源流体参与成矿的中温中成热液蚀变岩型金矿床。

Characteristics of Ore-Forming Fluid of the Sizhuang Gold Deposit in Shandong Province

The Sizhuang gold deposit, located in the south section of the Jiaojia gold metallogenic belt and within the Jiaojia gold ore field, is a typical mesothermal gold deposit in the belt. There are three ore-controlling belts including the pyrite phyllic zone, the pyrite phyllic granitic cataclasite and pyrite phyllic granite zone. All the three ore-controlling belts occur in the footwall of the Jiaojia fault zone. The main ore minerals include electrum, pyrite, native gold, chalcopyrite, galena and sphalerite, etc.. The main wall-rock alteration types contain phyllic, silicification, potassium and carbonate, etc., and the gold mineralization has a close relationship with phyllic and silicification alteration. The comprehensive studies, such as the petrographic, microthermometric, laser Raman microspectroscopic analysis of the single fluid inclusion and the oxygen isotope analysis, are completed on fluid inclusions developed in auriferous ore of Sizhuang gold deposit. The results indicate that there develop three types of fluid inclusions in auriferous ore, including CO₂-bearing, aqueous two-phrase, and CO₂ fluid inclusions, existence at the same time, and fluid immiscibility occurred in CO₂-H₂O-NaCl system in the ore-forming process. The ore-forming fluids are featured by low salinity (w(NaCl) (0.53%-10.24%)), low density (0.50-1.03 g/cm³). Mineralization temperature is concentrated in 260-340℃, and the pressure ranges from 82 to 116 MPa, which equals to the depth of 7.40-8.94 km. The hydrogen and oxygen isotope analysis suggest that the δD_V-SNOW of the ore-forming fluids is from -76.6‰ to -69.0‰ and the δ¹⁸O_H2O is from 2.94‰ to 7.24‰, which shows that the ore-forming fluid are mainly from deep mantle fluids, with a small quantity of magmatic fluids and meteoric waters added. Comprehensive analysis, combined with geological characteristics of the Sizhuang gold deposit and the experimental results, suggests that the Sizhuang deposit belongs to the mesothermal type gold deposit. Moreover, this deposit was formed by the mantle-derived ore-forming fluid, and controlled by faults or fractures.