新疆哈巴河地区托库孜巴依金矿区两类含矿脉岩LA-ICP-MS 锆石U-Pb年龄及其地质意义

    LA-ICP-MS zircon U-Pb ages of two types of ore-bearing dykes in the Tuokuzibayi gold ore district in Habahe area of Xinjiang and their geological significance

    • 摘要: 新疆阿勒泰南缘托库孜巴依金矿属造山带型金矿,经历了沟弧盆体系、碰撞造山和后碰撞伸展多个演化阶段。矿区内辉长闪长岩脉和花岗斑岩脉较常见,且与金矿化关系密切。采用原位激光剥蚀同位素质谱(LA-ICP-MS)法对2期脉岩进行锆石U-Pb定年,获得花岗斑岩脉侵位年龄384.1Ma±1.5Ma和384.7Ma±1.2Ma,属中泥盆世弧前盆地演化阶段的产物;获得辉长闪长岩脉年龄295.3Ma±3.0Ma,应代表后碰撞伸展期辉长闪长岩脉的结晶年龄。2期脉岩的侵位往往继承了早期的构造部位和后期强韧性剪切的部位,均代表一期金矿化作用。

       

      Abstract: The Tuokuzibayi orogenic-type gold ore belt was formed by multi-stage evolution, which included complete forearc-arc-backarc system, collisional orogeny and post-collisional extensional tectonic activities. The Tuokuzibayi dykes include two intrusive phases, i.e., the granite-porphyry dyke phase and the diorite dyke phase, both of which are associated with Au mineralization. LA-ICP-MS U-Pb zircon analyses suggest that the granite-porphyry dykes were formed at 384.1±1.5 Ma and 384.7±1.2 Ma, suggesting their generation in a Middle Devonian fore-arc basin setting, whereas the diorite dyke was formed at 295.3±3.0 Ma, implying its generation in a post-collisional extensional setting. The emplacement of these two types of dykes that respectively represented a gold mineralization stage commonly inherited the previous tectonic position and later strong ductile shearing position.

       

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