汉阴北部吴家湾金矿地质特征及流体包裹体研究

吴家湾金矿是汉阴北部地区的一个重要的金矿床，处于南秦岭石泉-神河韧性滑脱逆冲推覆带。对其进行野外地质研究发现，吴家湾金矿赋矿层位为梅子垭组第一岩性段第四岩性层（S1m14），岩性主要为含碳绢云片岩夹硅质岩；控矿构造主要为RFa和RFb 2条顺层韧性剪切带，大致可分辨出S1、S2及S3 3期构造面理，S0几乎全部被置换，S2期变形与金矿成矿关系密切，金矿体主要于该期形成的韧性剪切带中产出。在地质研究基础上，可将吴家湾金矿区石英脉划分为3期，对流体包裹体的研究表明，包裹体类型以气液两相包裹体为主，纯气相、纯液相及三相包裹体较少见；均一温度范围介于176.8~344.4℃，集中于230~280℃。盐度范围为0.35%~13.51%，集中于2%~10%，成矿流体属于中-低温、低盐度流体。流体捕获深度在1.38~3.47 km，集中于1.5~2.8 km，于中浅部成矿。S2期石英脉流与成矿关系紧密，流体包裹体均一温度主要集中在240~280℃，为主成矿期流体。激光拉曼光谱分析表明气液两相包裹体液相成分以H2O为主，含少量CO2和CH4；气相成分主要为CO2，其次为CH4、N2及H2S；包裹体类型主要为富含CO2的H2O-CO2体系包裹体。对汉阴北部不同地区流体包裹体的性质进行对比研究后发现，流体包裹体均一温度为190~260℃，盐度为6%~10%，在这个区间内有利于成矿。

Geological Characteristics and Fluid Inclusions of the Wujiawan Gold Deposits in Northern Hanyin,Shaanxi

The Wujiawan gold deposit is an important gold deposit in northern Hanyin, Shaanxi. It is located at the Shiquan-Shenhe thrust-napped ductile shear zone in South Qinling. The field geological study found that the ore-bearing horizon of the Wujiawan gold deposit is the fourth lithological layer (S1m41) of the first lithology section of the Meiziya Formation, and this layer is mainly composed of carbon-bearing sericite schist with siliceous rocks; The structure is mainly composed of two layer ductile shear zones (RFa and RFb), which can roughly distinguish the three-phase structural facies of S1, S2 and S3. In which, S0 is almost completely replaced, and S2 deformation is closely related to gold mineralization. Gold ore body was mainly formed in the ductile shear zone during S2 deformation. Based on geological research, the quartz veins from the Wujiawan Gold Mine can be divided into three phases. The study of fluid inclusions shows that these inclusions are dominated by gas-liquid two-phase inclusions, with rare pure gas phase, pure liquid phase and three-phase inclusions. Their homogeneous temperatures range from 176.8℃ to 344.4℃, which is concentrated at 230~280℃. Their salinity vary from 0.35 wt% to 13.51 wt% and are concentrated in 2~10 wt%. The ore-forming fluid belongs to medium-low temperature and low salinity fluid. The fluid capture depth is 1.38~3.47 km and is concentrated at 1.5~2.8 km, and the mineralization is occurred in the middle and shallow parts. The fluid inclusions of quartz vein in S2 stage are closely related to mineralization, their homogeneous temperatures are mainly concentrated at 240~280℃, which are the fluid in the main ore-forming period. Laser Raman spectroscopy analysis shows that the liquid phase composition of gas-liquid two-phase inclusions is dominated by H2O, containing a small amount of CO2 and CH4. The gas phase components are mainly CO2, followed by CH4, N2 and H2S. The inclusion types are mainly H2O-CO2 system inclusions with rich CO2. Compared to the properties of fluid inclusions in different areas of northern Hanyin, it is found that the homogeneous temperatures of fluid inclusions range from 190℃ to 260℃, and their salinities vary form 6 wt% to 10 wt%, which are beneficial to mineralization.