兰坪金顶超大型铅锌矿田深部地质结构与成矿潜力来自综合地球物理探测的约束

    Deep geological architecture and prospecting potential of the giant Jinding lead-zinc ore field, Lanping: Constraints from integrated geophysical data

    • 摘要:
      研究目的 滇西北金顶超大型铅锌矿田位于青藏高原东南缘中—新生代兰坪盆地的中部,受印度–欧亚大陆斜向碰撞造山有关构造转换的影响,深浅部地壳物质经历多期次的构造变形而相互叠加。本文旨在解析矿田深部地质结构,明确找矿潜力和深部勘探方向。
      研究方法 利用同时穿越金顶矿田内北厂和跑马坪矿床的2条音频大地电磁法(AMT)和重力勘探剖面测量,借助地表构造填图数据和已有勘查钻孔约束的地层岩性界面,综合解译矿田地层格架及其与断层的配置关系,厘定其深部地质结构。
      研究结果 受到新生代以来EW向地壳缩短变形的影响,区内大量基底岩系和盆地充填地层沿近SN向逆断层和(或)近EW向走滑–掀斜断层发生变形和相互叠加,导致上三叠统三合洞组(T3s)和麦初箐组(T3m)、白垩系景星组(K1j)和南新组(K2n)及古近系始新统云龙–果朗组(E1y+g)沿断层面逆冲到新近系中新统金顶群(N1J)之上,从而形成了控矿地质结构。
      结论 圈定了11处深部找矿靶区,认为金顶矿田深部具备较好的找矿潜力。

       

      Abstract:
      Objective The giant Jinding lead–zinc ore field in northwestern Yunnan is situated in the central part of Meso–Cenozoic Lanping Basin, SE Qinghai−Xizang Plateau. Influenced by tectonic transitions associated with the oblique Indo–Eurasian collision and orogeny, deep and shallow crustal materials have undergone multi−phase structural deformation and mutual superposition. This study aims to analyze the deep geological structure of the ore field, clarify its mineral exploration potential, and identify directions for deep prospecting.
      Methods Based on two audio−frequency magnetotellurics (AMT) and gravity survey profiles simultaneously traversing the Beichang and Paomaping ore deposits within the Jinding ore field, and supported by surface structural mapping data and lithological interfaces constrained by existing exploration drillholes, we conducted an intergrated interpretation of the ore field’s stratigraphic framework and its structural relationships with faults, thereby delineating the deep geological architecture.
      Results Due to E–W directed crustal shortening and deformation since the Cenozoic, extensive basement rock series and basin−fill strata in the region have undergone deformation and mutual superposition along the approximately N–S−trending thrust faults and/or E–W oriented strike–slip tilting faults. This resulted in the thrusting of the Upper Triassic Sanhedong (T3s) and Maichuqing (T3m) formations, the Cretaceous Jingxing (K1j) and Nanxin (K2n) formations, and the Paleogene−Eocene Yunlong–Guolang Formation (E1y+g) over the Neogene Miocene Jinding Group(N1J), thereby forming the ore−controlling geological structure.
      Conclusions Eleven deep prospecting targets have been delineated, indicating substantial ore−forming potential in the deep regions of the Jinding orefield.

       

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