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    西藏冈底斯成矿带与俯冲-碰撞作用相关的斑岩铜矿的找矿方向

    The exploration potential of the subduction-collision associated porphyry copper deposits in the Gangdise metallogenic belt, southern Xizang

    • 摘要: 本文从构造-岩浆演化、典型矿床特征、构造-岩浆产物空间分布特征等方面,对冈底斯成矿带形成于195~80Ma的与俯冲-碰撞作用相关的斑岩(-矽卡岩)型铜矿的找矿方向进行了探讨。认为研究区与俯冲-碰撞作用相关的斑岩型铜矿大致可分为早-中侏罗世、晚侏罗-早白垩世、晚白垩世3个成矿时期,分别对应于雅鲁藏布江洋向北、班公湖怒江洋向南相向俯冲、班公湖怒江洋碰撞关闭、雅鲁藏布江洋向北持续俯冲、雅鲁藏布江洋向北晚期俯冲等构造-岩浆事件。与早期相向俯冲相关的雄村式矿床,在拉萨东部达孜-工布江达一带具有良好找矿前景;与中期俯冲-碰撞相关的多龙式矿床,在昂龙岗日、东恰错、桑日等火山岩浆弧区成矿条件较佳;与晚期俯冲相关的尕尔穷式矿床,在冈底斯东段和西段具有较大的找矿潜力。

       

      Abstract: The exploration potential of the subduction-collision associated porphyry (skarn-type) copper deposits dated at 195 to 80 Ma in the Gangdise metallogenic belt, southern Xizang are approached in the light of tectonic-magmatic evolution and characteristics of the representative copper deposits. Three metallogenic periods are separated, including the Early to Middle Jurassic, Late Jurassic to Early Cretaceous and Late Cretaceous corresponding to the tectonic-magmatic events such as the northward subduction of the Yarlung Zangbo Ocean and southward subduction of the Bangong Lake-Nujiang Ocean, collision-closure of the Bangong Lake-Nujiang Ocean and steadily northward subduction of the Yarlung Zangbo Ocean, and finally northward subduction of the Yarlung Zangbo Ocean. The Xiongcun-type copper deposits associated with the early opposite subduction of the Yarlung Zangbo Ocean and Bangong Lake-Nujiang Ocean occur in the Dagze-Gongbo'gyamda zone east of Lhasa as more promising areas. The Duolong-type copper deposits associated with the subduction-collision of the Bangong Lake-Nujiang Ocean and steadily northward subduction of the Yarlung Zangbo Ocean in the middle stages are hosted in the volcanic-magmatic arc areas as the favourable metallogenic areas in Nganglong Kangri, Dongqiaco and Sangri. The Gar'erqiong-type copper deposits associated with the finally northward subduction of the Yarlung Zangbo Ocean in the Late Cretaceous are considered highly prospective in the eastern and western parts of the Gangdise metallogenic belt.

       

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