山东莱西山后金矿床流体包裹体特征

根据山后金矿床的矿物组合和矿物生成顺序,将成矿阶段划分为4个阶段:黄铁矿-石英(钾化)阶段、石英—黄铁矿(绢英岩化)阶段、金-石英-多金属硫化物阶段和石英-碳酸盐阶段。对区内主成矿阶段的石英中流体包裹体进行岩相学、显微测温及氢氧同位素进行分析。结果表明:矿石中的包裹体主要有含CO2三相包裹体、气液两相包裹体和CO2包裹体三种类型,矿石中的包裹体普遍富含CO2。成矿过程中,流体经历了CO2-H2O—Na Cl体系的不混溶作用。成矿流体具有低盐度(4.0~9.0 wt%Na Cl.eqv)和低密度(0.70~0.89 g/cm3)的特点。主成矿温度为260℃~300℃,成矿压力为83~100 MPa,对应成矿深度为7.45~8.25 km。流体包裹体氢氧同位素分析结果介于地幔初生水和岩浆水之间,部分向大气降水线方向漂移,表明山后金矿成矿流体以幔源流体为主,并有大气降水和其他流体的加入,初步确定山后金矿床是受断裂构造控制的中温热液脉型金矿床。

Characteristics of fluid inclusions of Shanhou gold deposit in Laixi,Shandong

According to the mineral combination and mineral genesic sequence of Shanhou gold deposit，the ore- forming stage can be divided into 4 stages: pyrite- quartz (potassic alteration) stage，quartz- pyrite (phyllic) stage，gold- quartz- sulphides stage and quartz- carbonate stage． The authors have studied the petrographic，micro- thermometric and H- - O isotope on fluid inclusions in this ore of main mineralizing stages of Shanhou gold deposit and find there are 3 types of fluid inclusions: CO 2 - bearing three- phase fluid inclusions，aqueous two- phrase fluid inclusions and pure CO 2 inclusions． CO 2 are widespread in the fluid inclusions in quartz of this ore． The fluids of main mineralizing stages should be a CO 2-NaCl-H 2 O system and fluid immiscibility occurred in the ore- forming process． The ore- forming fluids are low in salinity (4. 0 ～9. 0 wt% NaCl. eqv) and low in density (0. 70 ～0. 96 g/cm 3 )，mineralization temperature is concentrated in 260℃ ～300℃，and mineralization pressure ranges from 83 to 110 MPa，while mineralization depth ranges from 7. 45 to 8. 25 km． The analysis of hydrogen and oxygen iso- topes of fluid inclusions shows that the data are between the mantle derived water and magmatic water and some drift to the precipitation line． It proves that the Shanhou gold ore- forming fluids derived mainly from deep mantle fluids， and accompanied by a small amount of atmospheric water and other fluids． It is preliminarily determined that the genesis of the deposit is mesothermal gold deposit in type，which was controlled by faults．