综合物探方法在冈底斯东段帮浦矿区深部找矿中的应用

    Application of integrated geophysical prospecting to deep mineral exploration in the Bangpu mining area, eastern Gangdese metallogenic belt

    • 摘要: 帮浦矿区是冈底斯成矿带东段典型斑岩—矽卡岩型矿床,斑岩体外围浅部的矽卡岩型矿体已基本采空,急需寻找深部接替资源。为进一步查明研究区深部隐伏岩体及周边矿体的空间分布,实现找矿突破,本文对帮浦矿区东部区域开展了1∶1万重力、高精度磁法测量以及大地音频电磁测量,并对物探异常原因进行分析总结。综合物探测量显示,研究区中部高重力异常区和低重力异常区分别对应着中基性和中酸性隐伏岩体,南西侧两处磁异常可能为矽卡岩周边的磁铁矿、磁黄铁矿引起的矿致异常。结合AMT测量结果,在高重力异常边部的低电阻区和强磁、中重力、低电阻异常区布设了钻孔以探索深部岩体和周边矽卡岩型矿体,并成功探获铜矿带(体)两条、铅锌矿体两条。勘查成果表明:高精度重力、磁法测量结合大地音频电磁测量的物探方法在西藏帮浦矿区寻找深部隐伏矿体具有良好的效果,是本区域同类型矿床深部找矿的有效物探勘查技术组合。

       

      Abstract: The Bangpu mining area, located in the eastern Gangdese metallogenic belt, represents a typical porphyry-skarn deposit. Since skarn ore bodies occurring in shallow skarns at the periphery of porphyries have been largely exhausted, there is an urgent need to explore deep replacement resources. This study aims to further determine the spatial distribution of deep-seated concealed rock masses and their surrounding ore bodies in the study area. This effort will help achieve breakthroughs in mineral exploration. To this end, this study conducted 1:10000 gravity surveys, high-precision magnetic surveys, and audio-frequency magnetotelluric (AMT) surveys in the eastern part of the Bangpu mining area, followed by an analysis and summary of the causes of geophysical anomalies. The comprehensive geophysical prospecting results indicate that the high- and low-amplitude gravity anomaly zones in the central part of the study area correspond to intermediate-mafic and intermediate-acid concealed rock masses, respectively. Two magnetic anomalies identified in the southwest might be ore-induced anomalies caused by magnetite and pyrrhotite surrounding skarns. In combination with the AMT data, boreholes were drilled in low-resistivity zones at the edge of high-amplitude gravity anomalies, as well as zones with strong magnetism, moderate gravity, and low-amplitude resistivity anomalies, to explore the deep rock masses and their surrounding skarn-type ore bodies. Consequently, two copper belts (ore bodies) and two lead-zinc ore bodies were identified. The exploration results of this study demonstrate that high-precision gravity surveys, magnetic surveys, and AMT surveys perform well in exploring deep concealed ore bodies in the Bangpu mining area, Tibet. These methods constitute an effective technical combination for deep mineral exploration of similar deposits in the Gangdese metallogenic belt.

       

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