孟银生, 张瑞忠, 汤磊, 李瑞红, 王偲瑞, 华北, 王刚. 2022: 胶东半壁店隐伏金矿床综合地球物理探测. 地质通报, 41(6): 1095-1106. DOI: 10.12097/j.issn.1671-2552.2022.06.015
    引用本文: 孟银生, 张瑞忠, 汤磊, 李瑞红, 王偲瑞, 华北, 王刚. 2022: 胶东半壁店隐伏金矿床综合地球物理探测. 地质通报, 41(6): 1095-1106. DOI: 10.12097/j.issn.1671-2552.2022.06.015
    MENG Yinsheng, ZHANG Ruizhong, TANG Lei, LI Ruihong, WANG Sirui, HUA Bei, WANG Gang. 2022: Integrated geophysical exploration of the hidden gold deposit in Banbidian, Jiaodong Peninsula. Geological Bulletin of China, 41(6): 1095-1106. DOI: 10.12097/j.issn.1671-2552.2022.06.015
    Citation: MENG Yinsheng, ZHANG Ruizhong, TANG Lei, LI Ruihong, WANG Sirui, HUA Bei, WANG Gang. 2022: Integrated geophysical exploration of the hidden gold deposit in Banbidian, Jiaodong Peninsula. Geological Bulletin of China, 41(6): 1095-1106. DOI: 10.12097/j.issn.1671-2552.2022.06.015

    胶东半壁店隐伏金矿床综合地球物理探测

    Integrated geophysical exploration of the hidden gold deposit in Banbidian, Jiaodong Peninsula

    • 摘要: 胶东半岛是中国重要的金矿集区,金矿床的分布严格受NE—NNE向断裂带控制,招平断裂带是其中规模最大的控矿断裂带。然而,在断裂带中段的招远—道头镇区段(半壁店地区),新生代盖层下尚未发现成规模的金矿床。在总结招平断裂带内金矿床成矿模式和控矿地质体物性差异的基础上,从区域和断裂带尺度对比分析了1:60万和1:20万2种比例尺的布格重力异常特征,厘清了区域构造和岩体分布情况;进而在招平断裂带中段的半壁店地区利用1:1万高精度磁测和代表性剖面1:1万可控源音频大地电磁测量,揭示隐伏控矿地质体的分布情况。区域布格重力异常揭示出近EW向相对低密度正值((0~6)×10-5 m/s2)表征的构造带、团状正密度值(大于2×10-5m/s2)表征的玲珑黑云母花岗岩体和NE—NNE向密度值梯级带表征的招平断裂带;3组赋矿相关地质体的空间相对展布特征显示,玲珑黑云母花岗岩体南边界被近EW向构造带围限,招平断裂带切穿了早期生成的玲珑黑云母花岗岩体。高精度磁测结果反映:①招平断裂带穿切玲珑黑云母花岗岩体;②近EW向低密度、高磁性(相对磁性场值超过100 nT)花岗闪长岩体在深部受控于EW向深大构造带;③NE向串珠状低密度、高磁异常(相对磁性场值超过40 nT)表征了矿床尺度招平次级断裂内的系列花岗岩体(主成矿期之后生成)。可控源音频大地电磁测深和测区中部钻孔均证实,这些花岗岩脉从北向南(指向主断裂方向)埋深逐渐变浅。因此,NE向招平断裂带和近EW向构造带共同控制岩体分布,其交会部位是金矿体产出的有利空间,但上侵花岗岩体本身贫矿。半壁店地区隐伏金矿床形成时间晚于招平断裂主成矿期。研究结果表明,近EW向低密度带内的金矿找矿前景不乐观。

       

      Abstract: The distribution of gold deposits in Jiaodong peninsula, the most important gold concentration area of China, is strictly controlled by NE-NNE-trending faults.However, no large-scale gold deposits have been found under the Cenozoic rocks in Zhaoyuan-Daotouzhen section in the middle part of the fault zone.On the basis of summarizing the difference of metallogenic model and ore-controlling geological body in Zhaoping fault zone, the Bouguer gravity anomaly characteristics of 1:600 and 1:200 thousand scale are compared from regional and fault scale, and the distribution of regional structure and rock mass are clarified.Furthermore, the distribution of concealed ore-controlled geological bodies is revealed by 1:10000 high-precision magnetic survey and 1:10000 controlled-source audio magnetotelluric survey of representative section in the Banbidian area.The regional Bouguer gravity anomaly reveals the tectonic zone characterized by the relatively low density positive value((0~6)×10-5 m/s2)near EW direction, the Linglong biotite granite characterized by the positive agglomerate density value(>2×10-5 m/s2)and the Zhaoping fault characterized by the NE-NNE density step zone.The spatial distribution characteristics of the three groups of ore-bearing geological bodies show that the southern boundary of Linglong biotite granite is bounded by the EW-trending tectonic belt, and Zhaoping fault belt cuts through the early Linglong biotite granite.High precision magnetic measurements show that, ①Linglong biotite granite is cut by Zhaoping fault zone; ②The granodiorite with low density and high magnetism near EW-trending(relative magnetic field value is more than 100 nT)is controlled by the EW direction deep structural belt in depth; ③The series of granites within Zhaoping secondary fault(formed after the main mineralization period)of the ore deposit scale are characterized by NE-trending bead-like low density and high magnetic anomaly(relative magnetic field value over 40 nT).Both CSAMT sounding and boreholes in the middle of the survey area confirm that the buried depth of the granite dyke decreases gradually from south to north(towards the direction of the main fault).Therefore, the NE-trending Zhaoping fault belt and the nearly EW-trending tectonic zone jointly control the distribution of the rock mass, and the intersection of them is a favorable space for the production of gold orebodies, while the intruding granitic body itself is depleted in gold.The concealed gold deposits in Banbidian area were formed later than the main metallogenic period of Zhaoping fault.The result shows that the prospecting prospect of gold ore in the low-density zone near EW-trending is not optimistic.

       

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