ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    甘肃武都塘坝金矿床地质特征及矿床成因

    Geological Characteristics and Genesis of the Tangba Gold Deposit in Wudu, Gansu Province

    • 摘要: 甘肃武都塘坝金矿床位于西秦岭南部阳山-石鸡坝金矿带的东段。矿体赋存于古生界下泥盆统桥头组中,在空间上与花岗斑岩脉关系密切,矿体及岩脉受褶皱轴部断层的控制,矿体呈脉状、透镜状,矿石矿物主要为黄铁矿和毒砂,围岩蚀变主要为硅化、绢云母化、碳酸盐化。主成矿流体δ18OH2O(V-SMOW)变化范围为7.89‰~9.97‰,δD(V-SMOW)变化范围为-81.3‰~-77.0‰,黄铁矿δ34S(‰)变化范围为-1.3‰~0.8‰,平均为-0.23‰,显示深源硫的特征。花岗斑岩中锆石U-Pb测年年龄为(212.8±2.7)Ma。矿区流体包裹体测试分析显示出成矿热液具有中-低温、中-低盐度特征,主成矿期石英中CO2相完全均一温度范围为252.6~342.8℃,平均值为279.72℃;水液两相型包裹体均一温度范围为156.9℃~307.6℃,平均值为256.7℃。综合研究认为,该矿床为与岩浆活动有关的中-低温岩浆热液型金矿床。

       

      Abstract: The Tangba gold deposit is located at the eastern section of the Yangshan-Shijiba gold mineralization belt in the southern part of the Western Qinling. The ore body is occurred in the strata of Paleozoic Lower Devonian Qiaotou Formation, which is closely related to the granite porphyry vein in space. The ore body and the vein are controlled by the fault in the fold's axial part. The ore body is occurred as veined and lens texture. The ore minerals are mainly pyrite and arsenopyrite, and the surrounding rock alterations are mainly silicification, sericitization and carbonation. The δ18OH2O(V-SMOW) values of main ore-forming fluid vary from 7.89‰ to 9.97‰, δD(V-SMOW) values range from -81.3‰ to -77.0‰, and the pyrite δ34S(‰) change from -1.3‰ to 0.8‰, with an average of -0.23‰, showing the characteristics of deep source sulfur. The zircon U-Pb dating age is (212.8±2.7)Ma for granite porphyry. The test analysis of fluid inclusions in this mining area shows that the ore-forming hydrothermal fluid has the characteristics of medium-low temperature and low salinity. The complete uniform temperature range of CO2 phase in the main ore-forming period is 252.6℃~342.8℃, with an average of 279.72℃. The volume uniform temperature range is 156.9℃~307.6℃, and their average value is 256.7℃. The comprehensive study considers that this deposit belongs to a medium-low temperature magmatic hydrothermal gold deposit associated with magmatic activity.

       

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