ORE-FORMING FLUIDS AND GENESIS OF QIYIMUCHANG LEAD-ZINC DEPOSIT IN ERGUNA AREA, INNER MONGOLIA
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摘要: 七一牧场矿床是内蒙古额尔古纳成矿带内新发现的一个铅锌矿床，具有大中型矿床的成矿潜力.为确定该矿床的成矿流体特征及成因类型，对主成矿阶段的石英开展了流体包裹体岩相学观察、显微测温和激光拉曼光谱分析.结果表明，石英中主要发育富液相、富气相、CO2三相和少量含子矿物三相包裹体；包裹体的均一温度为132~342℃，大致集中在130~200℃和240~320℃；两相包裹体的盐度范围在0.5%~9.9%，含CO2三相包裹体的盐度为3.0%~11.9%，属低盐度.根据子矿物熔化温度得出含子矿物三相包裹体的盐度为42.4%和44.2%.激光拉曼光谱分析显示，包裹体中气相成分主要为H2O和CO2.认为流体的沸腾作用是矿质沉淀的重要机制，该矿床属赋存于中生代火山岩中与浅成-超浅成岩浆作用有关的中低温热液脉型矿床.Abstract: The Qiyimuchang lead-zinc deposit, newly discovered in the Erguna metallogenic belt, Inner Mongolia, has the ore-forming potential of middle-large scale. The petrographic observation, microthermometry and Laser Raman spectrum analysis of fluid inclusions in quartz formed in the major metallogenic stage are carried out to determine the characteristics of ore-forming fluids and the genesis of deposit. The results indicate that three main types of fluid inclusions are developed in quartz, including two-phase (liquid-rich and vapor-rich), CO2-bearing three-phase, and a few daughter mineral-bearing three-phase inclusions, with the homogenization temperatures ranging from 132 to 342℃, generally concentrated in 130-200℃ and 240-320℃, and the salinities of three types being 0.5%-9.9%, 3.0%-11.9%, 42.4% and 44.2%, respectively. The Laser Raman spectrum analysis shows that the gaseous compositions are mainly H2O and CO2. The fluid boiling plays an important role in the deposition of mineral materials. The deposit, hosted in the Mesozoic volcanic rocks, belongs to the epi-mesothermal vein-type related to hypabyssal-ultra hypabyssal magmatism.
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Key words:
- fluid inclusion /
- fluid boiling /
- Qiyimuchang Pb-Zn deposit /
- Erguna area /
- Inner Mongolia
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