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    河南洛宁段河金矿流体包裹体研究和矿床成因

    Study of fluid inclusions and ore genesis of the Duanhe gold deposit in Luoning County, Henan Province

    • 摘要: 提要:河南省洛宁县段河石英脉型金矿主要包括石寨沟和岭东两个矿区,分别由3~4条含金石英脉构成。矿化过程从早到晚包括石英-黄铁矿、石英-多金属硫化物和石英-碳酸盐等3个阶段,其中中阶段金矿化最强,次为早阶段。各阶段石英中流体包裹体以气液两相包裹体为主,次为纯液体包裹体。激光拉曼测试表明,气液两相包裹体的液相为H2O,气相主要为H2O和CO2混合、纯H2O,次为纯CO2;纯液体包裹体为纯H2O。石寨沟矿区包裹体均一温度从早到晚依次为240.9~315.9℃,188.7~304.5℃,137.3~259.3℃;流体盐度变化依次为(6.74~12.85) wt% NaCl.eq,(2.41~8.68) wt% NaCl.eq,(2.24~7.86) wt% NaCl.eq。岭东矿区均一温度从早到晚依次为303.7~343.1℃,251.8~325.4℃,305.7~355.0℃;流体盐度变化依次为(5.11~11.70) wt% NaCl.eq,(2.74~10.11) wt% NaCl.eq,(0.53~6.74) wt% NaCl.eq。两矿区主成矿期流体均为中温、低盐度,早阶段流体为改造热液和变质热液的混合体,含一定量CO2,且流体CO2含量和盐度从早到晚逐渐降低。石寨沟矿区包裹体均一温度逐渐降低,而岭东矿区包裹体均一温度先降后升,加之岭东矿区各阶段成矿温度均高于石寨沟矿区,表明成矿流体系统主要受岩浆热驱动,岭东矿区更靠近岩体,且在晚阶段又有脉动性的岩浆加热,段河金矿区南部存在隐伏岩体。

       

      Abstract: Abstract:The Duanhe gold deposit is a quartz-vein type gold deposit, located in Luoning County, Henan Province. The gold deposit mainly includes Shizhaigou and Lingdong mining areas that comprise of three to four gold-bearing quartz veins, respectively. The ore-forming process includes three stages, i.e. the early, middle and late stages, characterized by mineral assemblages of quartz-pyrite, quartz-polymetallic sulfides and quartz-carbonate, respectively. The most intensive gold mineralization is developed in the middle stage, secondarily in the early stage. Fluid inclusions in quartz of three stages are mainly H2O-rich. Some inclusions contain a little of CO2 in gas and liquid phases. Pure H2O inclusions can be also observed. Homogeneous temperatures of the early-, middle- and late-stage fluid inclusions are 240.9~315.9 °C, 188.7~304.5 °C, and 137.3~259.3°C respectively in the Shizhaigou; while in the Lingdong mining area are 303.7~343.1°C, 251.8~325.4°C, and 305.7~355.0℃, respectively. In the Shizhaigou the salinities are (6.74~12.85)wt% NaCl.eq, (2.41~8.68) wt% NaCl.eq and (2.24~7.86) wt% NaCl.eq, respectively; and in the Lingdong mining area are (5.11~11.70) wt% NaCl.eq, (2.74~10.11) wt% NaCl.eq and (0.53~6.74) wt% NaCl.eq, respectively. The ore-fluids of these two mining areas were characterized by moderate-temperature and low-salinity at the main metallogenic stage. The early-stage ore-fluids were mixed hydrothermal solutions of reworking and metamorphic fluids, containing a small amount of CO2. From early to late stage, the CO2 content and salinities of fluids gradually decreased. From early to late, homogeneous temperatures of fluid inclusions in Shizhaigou mining area decrease gradually, whereas increase after a firstly decrease in Lingdong mining area. This, together with that the temperatures of each stage of the Lingdong area are generally higher those of the Shizhaigou area, suggests that the ore-forming fluid-system were driven by magmatic heat, and that the Lingdong area is more close to and was reheated by the blinded pulsing magmatic intrusion which was possibly seated beneath the south of the Duanhe deposit.

       

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