Tectonics Analysis Of BaiYinXiLe, Inner Mongolia Autonomous Region

The study area is in the northern margin of the North China plate, where the geotectonic location spanned two completely different subordinate tectonic units. The northern margin of the North China plate is to the south of the DaMiao-Xiao WuLanHua-HuShaoShan mountain Fault, and the Paleozoic Aggradational belt of the northern margin of the North China plate is to the north of that.Based on the features of the sedimentary facies and the relation of the unconformity, there are six tectonic zones in the area. The first one is formed by the stratum of Baiyunebo Formation, which is faulted with the third one. The second tectonic zone is formed by the stratum of Bainaimiao Formation, which presents angular unconformity with the third one. The third tectonic zone formed by the stratum of Xuniwusu Formation, which presents angular unconformity with the forth one. The forth one is formed by the stratum of Xibiehe Formation. The fifth one is formed by Sanmianjing Formation, which is faulted with both the second and the third one. The sixth one is formed by the Hannuoba Formation and the Baogedawula Formation.Comprehensively analyzing the stratum provinces, the features of the tectonic deformation and features of the tectonic stress field, there are three stages of folding. The folds in the stratum of Baiyunebo Group probably formed late in PCLP LATE PROTEROZOIC is the earliest of all the three, which are in the direction of E—W. And the folds of second stage which are also in the direction of E—W, are distributed in the stratum provinces of the Baiyunebo Formation, Bainaimiao Formation, Xuniwusu Formation, and the Xibiehe Formation. The folds of second stage are formed in Hercynian, when the collision and compression process of plates happened. The third stage folds, N—S folds, which were formed after Early Permian, are the result of the regional stress field.The main fault structure in this area is the Xuniwusu Thrust System, which is made up of the allochthonous systems and the autochthonous systems. The leading thrust belt includes a series of imbricated reverse fault. The middle belt includes a series of reverse fault and fold. And the root belt of the thrust system includes tectonic mélange, fold belt and cleavage belt. The thrust system was formed in the Permian, when the Sino-Korean Plate and the Siberian plate collided. The thrust stretches for a distance of more than 8 km.By analyzing the sedimentary formation, magmatism, metamorphism and the features of the tectonic deformation in the area, we divide the tectonic evolution into five stage: stage of continental rift, stage of volcanic island arc, stage of the Aggradation of the North China plate, stage of the collision of the North China plate and the Siberian plate, and stage of new tectonic movement.