贺兰山黄旗口花岗岩锆石SHRIMP U-Pb定年和岩石地球化学特征

通过锆石SHRIMP U-Pb测年,获得了(2 003±10)Ma和(1 976±17)Ma两组同位素年龄,表明贺兰山黄旗口花岗岩形成时代为古元古代.黄旗口花岗岩岩石化学类型属钙性-钙碱性岩系,属过铝的岩石类型;稀土元素总量中等,轻、重稀土分异显著,轻稀土相对富集,重稀土相对亏损,具铕负异常.岩石化学特征表明,黄旗口花岗岩具有壳源型花岗岩的一些特征,属S型花岗岩,是上地壳深熔岩浆侵入而形成的花岗岩类,岩石化学图解表明,应形成于大陆碰撞造山环境.

Zircon SHRIMP U-Pb dating technique for Huangqikou granite in Helanshan area and its lithogeochemical characteristics

By using dating technique of zircon SHRIMP U-Pb, the isotopic ages of （2 003±10）Ma and （1 976±17）Ma from Huangqikou granite were obtained, it shows that Huangqikou granite of Helanshan were formed in paleoproterozoic. The geochemical types of Huangqikou granite belongs to calcium and calc-alkali series, which is peraluminous type. The total volume of rare earth elements is moderate; and content of light and heavy rare earth elements is different significantly, content of light rare earth elements is richer and content of heavy rare earth elements is shorter relatively, Eu is negative anomalies. Geochemcial characteristics indicate that Huangqikou granite has some characteristics of the crustal type granite and belong to the S-type granite, were formed by the intrusion of upper crust anatcctic magma. Rock chemical diagrams show that the Huangqikou granite were formed in a continental collision orogenic environment.