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内蒙古乌拉特中旗的华北板块北缘中段发育了大量的花岗岩类,主要由石英闪长岩和花岗闪长岩组成。岩石具有钙碱性I型花岗岩类特征:暗色矿物以黑云母为主,A/CNK为0.77～1.04。多数岩体地球化学特征类似于埃达克岩:SiO2含量为55.70%～68.65%,Al2O3含量为15.32%～22.87%,Y和Yb含量分别为2.82～20.89μg/g和0.25～2.24μg/g;大离子亲石元素(LILE)和轻稀土元素(LREE)富集,如Ba含量为627～2124μg/g,Sr含量为327～968μg/g,Sr/Y为32.2～211,(La/Yb)N为5.83～81.1;Eu多为正异常(δEu=0.63～2.25)。它们形成于后碰撞抬升的背景,主要由增厚的下地壳部分熔融形成,可能与来自EM1型富集地幔的玄武质岩浆底侵作用有关。北七哥陶岩体、塔拉布基岩体、阿格如岩体和保尔汗图庙岩体中黑云母的40Ar/39Ar年龄分别为260±3,258±1,260±3和258±2Ma,表明它们的侵位时代均为晚二叠世。
A large number of granitoids are developed in the middle part of the northern margin of North China Plate in the Wulatezhong Banner, Inner Mongolia, and are mainly composed of quartz diorite and granodiorite. The rocks are characterized by calc-alkaline type I granites: the dark-colored minerals are dominated by biotite, with A / CNK ranging from 0.77 to 1.04. The geochemical characteristics of most of the rock mass are similar to that of adakite: the content of SiO2 is 55.70% -68.65%, the content of Al2O3 is 15.32% -22.87%, the content of Y and Yb are 2.82-20.89μg / g and 0.25-2.24μg / g respectively LILE and LREE, such as Ba content 627 ~ 2124μg / g, Sr content 327 ~ 968μg / g, Sr / Y 32.2 ~ 211, (La / Yb ) N is 5.83 ~ 81.1; Eu is mostly positive anomaly (δEu = 0.63 ~ 2.25). They formed in the context of post-collision uplift and are mainly formed by the partial melting of the thickening lower crust, which may be related to the basaltic magma underplating from the EM1 enriched mantle. The 40Ar / 39Ar age of the biotite in the Beiqigetao body, the Talabuji body, the Agageru body and the Pa’erhan Tumiao body are 260 ± 3,258 ± 1,260 ± 3 and 258 ± 2Ma, respectively, indicating that Their emplacement times are Late Permian.