【摘要】 呼和浩特东北地区沿哈乐-盘羊山-乌兰合雅一带,发育有近东西走向、上盘向南推覆的盘羊山逆冲推覆体系。该体系自北往南分别为:新太古代变质侵入岩组合、新太古界色尔腾山岩群、新元古界震旦系什那干组与上石炭统拴马桩组构成的推覆体,下二叠统大红山组和中二叠统脑包沟组构成的准原地岩系,其中拴马桩可能为滑脱层。在该体系北部,247~244Ma未变形花岗岩岩基侵位到推覆体之中,具有类似"钉合岩体"的性质,限定了逆冲推覆时间的上限;锆石U-Pb定年得出的原地系沉积岩中最年轻地层的最大沉积年龄约为272Ma,限定了推覆作用时间的下限,从而厘定了具有争议的盘羊山逆冲断层活动时限的问题。即该逆冲体系可能是中晚二叠世古亚洲洋闭合、蒙古微陆块与华北克拉通碰撞引起的华北克拉通北缘地壳增厚的响应。更多还原

【Abstract】 In the northeast of Hohhot, the Panyangshan thrust-nappe system extends along Hale-Panyangshan-Wulanheya with roughly E-W strike and top-to-south kinematics. To the south, this system is composed of following structural units:the Nappe of Neoarchean metamorphic intrusive rock association and the Seertengshan Formation, the sheet of Neoproterozoic Sinian Shinagan Formation and the Late Carboniferous Shuanmazhuang Formation, and the quasi-autochthon composed of the Early Permian Dahongshan Formation and the Middle Permian Naobaogou Formation, whereas the Shuanmazhuang Formation is possibly a decollement. The undeformed monzogranite batholith of about 247–244 Ma, which intruded the deformed Neo-Archean nappe in the north, exhibits features of “stitching pluton” and places the upper limit for the thrusting. In addition, U-Pb dating results of detrital zircon from the youngest strata of the quasi-autochthon indicate that the strata were likely deposited after ca. 272 Ma. Therefore, the controversial issue about the activity time of the Panyangshan thrust system is solved finally. This thrust-nappe system was likely formed in response to the curst thickening of the north margin of the North China Craton subsequent to the closure of the Paleo Asian Ocean and the collision between the North China Craton and Mongolia microblocks.更多还原