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    黔西北青山铅锌矿床构造控矿机理及其对深部找矿的启示

    Structural ore−controlling mechanism of the Qingshan lead−zinc deposit in northwestern Guizhou, China and its implications for deep prospecting

    • 摘要:
      研究目的 青山铅锌矿床地处扬子地块西南缘的黔西北矿集区威宁—水城成矿亚带中段,严格受构造控制,资源潜力巨大。基于前期资料综合分析及野外地质调研,发现矿区构造成生发展过程和构造控矿机理不清、深部找矿勘查方向不明等问题制约了找矿突破。
      研究方法 本文应用矿田地质力学理论和方法,通过大比例尺构造剖面精测、不同方向控矿构造力学性质鉴定与不同期次、序次构造筛分,结合区域构造应力场变化特征,揭示了构造控矿机理。
      研究结果 自印支期以来,该区的主压应力方向主要历经了北东−南西向→北西−南东向→北东−南西向→近东西向的转变过程,依次形成了早北西构造带、北东构造带、晚北西构造带、南北构造带(构造体系)。通过成矿构造解析及其与成矿关系讨论,厘定了北东构造带为该矿区的成矿构造体系,揭示了构造分级控矿规律:北西向威宁—水城断裂、威水背斜为矿区的一级控矿构造,控制了威宁—水城矿化带或矿田的展布;威宁—水城断裂扭动作用派生的北西向断裂F1、F2,控制了矿床(矿体群)的分布,为矿区的二级控矿构造;F1、F2断裂间的层间断裂破碎带,直接控制了矿体的形态和产状,为三级控矿构造;矿体旁侧的节理裂隙带控制矿脉,为四级控矿构造。
      结论 青山铅锌矿床构造分级控矿规律明显,主要受四个等级的控矿构造控制,并形成了与其相对应的4种矿化样式。

       

      Abstract:
      This paper is the result of mineral exploration engineering.
      Objective The Qingshan medium−size Pb−Zn deposit is located in the middle of the Weining−Shuicheng metallogenic sub−belt in the southwest margin of the Yangzi Block. The ore−body of the Qingshan deposit is strict controlled by structure and the resource potential is huge.
      Methods Based on the theory and method of orefield geomechanics, this research has revealed the mechanism of structural ore control by the fine survey of large−scale structural profile, the identification of mechanical properties of typical ore−controlling structures in different directions and the screening of structures in different periods and orders, combined with the characteristics of regional tectonic stress field.
      Results The results show that the principal compressive stress direction of the mining area since the Indosinian had changed from NE−SW−trending to NW−SE−trending to NE−SW−trending to near EW−trending, sequentially forming tectonic systems of the early NW tectonic belt, the NE tectonic belt, the late NW tectonic belt and the SN tectonic belt in turn. By the analysis of ore−controlling structure and the discussion of its relationship with mineralization, the metallogenic structural system of the north−east tectonic belt has been determined, and the hierarchical ore−controlling regularity of structure is revealed, it is, the northwest−trending Weining−Shuicheng fault and Weining−Shuicheng anticline are the first−grade ore−controlling structures, which control the distribution of the Weining−Shuicheng metallogenic sub−belt or orefield; The NW−trending faults (F1 and F2) derived from the Weining−Shuicheng fault, control the distribution of the deposit or orebody group, and are the second−grade ore−controlling structures in the mining area; The interlayer fracture zones between F1 and F2 faults directly control the feature and attitude of orebodies, which is the third−grade ore−controlling structure in the mining area; The joint fissures on the sides of orebodies control the ore−veins, which is the fourth−grade ore−controlling structure.
      Conclusions The regularities of structural classification control are obvious for the Qingshan Pb−Zn deposit, which is mainly controlled by the ore−controlling structures of four grades, and has formed the four types of mineralization styles.

       

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