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笔者主要对北祁连山中段的牛心山岩体、民乐窑沟岩体进行了锆石SHRIMP定年研究。结果表明:牛心山花岗岩的年龄为476 Ma,民乐窑沟花岗闪长岩的年龄为463 Ma。岩石地球化学显示,两岩体均具有大陆活动边缘的岩浆作用特征,结合岩体产出的区域构造位置及区域地质资料,笔者认为早古生代北祁连洋板块分别发生了向南、向北俯冲,其中向南俯冲形成牛心山花岗岩(476 Ma),向北俯冲,形成了民乐窑沟花岗岩侵入体(463 Ma)。
The author mainly conducted the SHRIMP zircon dating on the Niuxinshan and Minleyaogou bodies in the middle of the North Qilian Mountains. The results show that the age of Niuxinshan granite is 476 Ma, and the age of Minleyaogou granodiorite is 463 Ma. Rock geochemistry shows that the two rock mass have the magmatic characteristics of the active continental margin. Combined with the regional tectonic location and regional geological data, the authors believe that the Early Paleozoic north Qilian Ocean Plate respectively occurred southward and northward subduction, in which The Niushenshan granite (476 Ma) is subducted southward and subducted northward to form the Minleyaogou granite intrusive body (463 Ma).