胶东北部大柳行金矿田成矿构造的广域电磁法勘查及对深部找矿的指示

    Wide field electromagnetic exploration and prospecting of metallogenic structures in Daliuhang gold field, the north of Jiaodong

    • 摘要: 大柳行金矿田位于胶东金矿集区三大成矿带之一的栖霞-蓬莱金矿带内,成矿构造研究一直是找矿工作的基础和前提。通过实施8条广域电磁测深剖面,进行一维反演和水平方向导数的求取,推断解释了大柳行金矿田的深部地质结构和断裂空间分布,并以此为基础分析了断裂控矿规律和找矿方向。在视电阻率剖面上,浅部出现大面积的低阻异常区,深部高阻异常较明显,水平方向一阶导数图显示NE—NNE向的带状视电阻率异常出现错断或扭折现象。推断解译表明,研究区浅表部主要为晚白垩世花岗岩,深部主要为早前寒武纪变质基底岩系,区内断裂构造非常发育。推断解译的虎路线断裂倾角较陡,断裂南段和北段延深约在-2000 m标高以上,中段延深至少可达-3000 m标高;NNE走向的4条主要控矿断裂倾角均较陡,并在标高-600 m左右和-1600 m左右均有明显变缓表现,断裂延深均超过-2000 m标高,最深处超过-3000 m;推断了5条NW向成矿后断裂,其中2条是新发现的断裂。综合分析认为,区内控矿断裂为虎路线断裂的次级断裂,而且前者可能是金成矿的导矿断裂;研究区南部4条主要控矿断裂2000~3000 m深度范围、虎路线断裂深部倾角波状变化部位和主要控矿断裂旁侧与其平行、等间距分布的小规模断裂、裂隙是今后找矿的重点方向。

       

      Abstract: Daliuhang gold field is located in Qixia-Penglai gold belt, one of the three major metallogenic belts in Jiaodong gold concentration area.The study of metallogenic structure has always been the basis and premise of prospecting.Through the implementation of 8 wide area electromagnetic sounding profiles, one-dimensional inversion and horizontal derivative calculation, the deep geological structure and fault spatial distribution of Daliuhang gold field are inferred and explained, and the fault ore control law and prospecting direction are analyzed on this basis.On the apparent resistivity profile, there is a large area of low resistivity anomaly in the shallow, and the deep high resistivity anomaly is more obvious.The horizontal first-order derivative diagram shows that the NE-NNE zonal apparent resistivity anomaly is broken or twisted.The inferred interpretation shows that the shallow part of the study area is mainly Late Cretaceous granite, and the deep part is mainly Early Precambrian metamorphic basement rock series.The fault structures in the area are very developed.It is inferred that the slope angle of the tiger line fault interpreted is relatively steep, the extension depth of the South and North segments of the fault is about more than -2000 m, and the extension depth of the middle segment is at least -3000 m; The dip angles of the four main ore controlling faults in NNE trend are steep, and they are obviously slowed down at the elevation of about -600 m and -1600 m.the extension depth of the faults exceeds the elevation of -2000 m, and the deepest is more than -3000 m; Five NW trending post metallogenic faults are inferred, of which two are newly discovered faults.The comprehensive analysis shows that the ore controlling fault in the area is a secondary fault of the tiger line fault, and the former may be the ore guiding fault of gold mineralization; The depth range of 2000 ~ 3000 m of the four main ore controlling faults in the south of the study area, the deep dip wavy change position of the tiger line fault, and the small-scale faults and fissures parallel to and equidistant from the main ore controlling faults are the key directions for ore prospecting in the future.

       

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