湖南凤凰铅锌矿床成矿流体特征及成矿机制

扬子地块东南缘是我国重要的铅锌成矿带，而其中凤凰矿田尚缺系统研究。以凤凰铅锌矿床为研究对象，运用流体包裹体地质学、同位素地球化学以及显微激光拉曼光谱等方法对成矿流体特征、流体来源及流体成分开展了系统研究。结果表明:矿床中闪锌矿和与成矿有关的脉石矿物中流体包裹体较发育；包裹体主要为气液两相，其均一温度介于111.2~177℃，盐度介于4.1%~25.2%，密度介于0.98~1.09 g/cm3，总体为低温、中高盐度、中等密度流体；石英、闪锌矿中单个包裹体成分拉曼光谱测试结果表明，气液两相包裹体中气相成分主要为CH₄，液相主要为H₂O，纯气相包裹体主要成分为CH₄；H-O同位素分析结果表明，成矿流体主要为建造水，表明来自盆地中的建造水萃取了深部地层中的成矿物质，并与沉积物中有机物干馏作用产生的CH₄等一起形成还原性成矿流体，沿同生断裂构造等通道向上运移，铅锌等成矿物质在浅部敖溪组白云岩中沉淀成矿。 

Ore-forming fluid characteristics and metallogenic mechanism of Fenghuang Pb-Zn deposit,Hunan Province

The southeastern margin of the Yangtze block is an important Pb-Zn metallogenic belt in China, however, the systematical research of Fenghuang ore field is still in progress. Taking the deposit as the research object, the characteristics, source and composition of ore-forming fluid were studied by means of fluid inclusion geology, isotope geochemistry and micro-laser Raman spectroscopy. The results show that LV type fluid inclusions are well developed in the deposit. The homogenization temperature, salinity and density are between 111.2-177℃, 4.1%-25.2%, and 0.98-1.09 g/cm3 respectively. Generally, it is a low-temperature, medium-high salinity and medium-density fluid. The gas phase composition of the inclusions in quartz and sphalerite is mainly CH₄, and the liquid phase is mainly H₂O. The results of H-O isotope analysis show that the ore-forming fluid is mainly formation-water. It is considered that the formation-water from the basin extracts the ore-forming materials in the deep strata, forming reducing ore-forming fluid together with CH₄ and other reducing agents produced by organic matter retorting in the sediments, and moves upward along the contemporaneous fault structure and other channels. Finally, lead and zinc precipitate in the dolomite of the shallow Aoxi formation.