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对新疆阿尔泰蒙库铁矿区斜长花岗岩体进行了锆石SHRIMP-U-Pb年龄测定,获得了400±6Ma(MSDW=1.3)的生成年龄,与1号矿体北部黑云母花岗岩年龄相似(锆石SHRIMP-U-Pb年龄404±8Ma),表明岩体侵位时代为早泥盆世早期。这些岩体侵入到康布铁堡组中,限定康布铁堡组时代大于404Ma。同时蒙库铁矿的形成与岩浆热液活动有关,也限定铁矿成矿时代略晚于404~400Ma。蒙库斜长花岗岩具有高硅,富钠,Th、La、Ce、Nd、LREE元素相对富集,贫钾,Nb、Ta、Sr、P、Ti具有明显负异常和中等负铕异常(δEu=0.38~0.50)的特点。Na2O/K2O=6.36~13.3,属低钾(拉斑玄武质)系列。铝过饱和指数为1.03~1.09,为微过铝质。ISr=0.70438~0.70986,εNd(t)=1.04~2.17,表明蒙库岩体物源以幔源物质为主,有少量壳源物质的混入。结合区域地质资料,认为蒙库岩体形成于活动大陆边缘的陆弧环境,处于拉张环境中。
Zircon SHRIMP-U-Pb zircon dating of the plagiogranite granites in the Altay Mengku iron ore district of Xinjiang was obtained with an age of 400 ± 6 Ma (MSDW = 1.3), similar in age to the northern biotite granites in No. 1 ore body Zircon SHRIMP-U-Pb age 404 ± 8Ma), indicating that the emplacement age of the rock mass was Early Devonian. These rocks intruded into the Cambon group, defining the Cambon group more than 404Ma. At the same time, the formation of Mengku iron ore is related to the magmatic hydrothermal activity and also limits the ore-forming age slightly later than 404-400Ma. The Mongolian plagioclase granite is characterized by high Si, Na, Th, La, Ce, Nd and LREE elements, with negative and normal negative Eu anomalies (δEu = 0.38 ~ 0.50) features. Na2O / K2O = 6.36 ~ 13.3, is a low-potassium (tholei basaltic) series. Aluminum supersaturation index 1.03 ~ 1.09, for the micro-aluminum. ISr = 0.70438 ~ 0.70986, εNd (t) = 1.04 ~ 2.17, indicating that the source rocks of the Mengku pluton are mainly mantle-derived materials with a small amount of crustacean matter being mixed in. Combined with the regional geological data, it is considered that the Mengku rock mass is formed in the arc environment of the active continental margin, and is in a tension environment.