| 安宁河断裂带新生代构造变形与磁组构特征 |
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| 关键词:Anninghe fault zone cenozoic structural deformation magnetic fabric |
| 基金项目:中国科学院战略性先导科技专项(编号: XDA23090203);国家自然科学基金(编号: 41602153; 41472107) |
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| Cenozoic Structural Deformation and Magnetic Fabric Characteristics of Anninghe Fault Zone |
| The Anninghe fault zone located on the southeast margin of the Tibet Plateau is an important constituent of the Xianshuihe–Xiaojiang fault system. It is an ideal target to understand the uplift and lateral growth of the plateau. To further clarify the structural deformation of the Anninghe fault zone since the Cenozoic, in this study, a detailed field geological survey and magnetic fabric study on the middle section of the fault zone were conducted. The characteristics and sequence of the Cenozoic structural deformation of the Anninghe fault zone were determined. The following results were obtained: (1) Structural analysis showed that there are three stages of structural deformation in the Anninghe fault zone. According to the cutting relationship, the direction of the maximum principal stress of the first stage deformation is NE–SW, resulting in thrust and dextral strike slip movement of the local faults. In the second stage, the direction of the maximum principal stress is E–W, forming a cleavage zone oriented in the N–S direction. The direction of the maximum principal stress of the third stage deformation is NW–SE, which is dominated by thrust. (2) The rock magnetism study showed that the main magnetic bearing minerals of Baiguowan formation are paramagnetic silicate minerals. The Anninghe fault zone has more developed magnetic foliation than the magnetic lineation, and the susceptibility ellipsoid is mainly oblate, indicating that the Anninghe fault zone is dominated by compression and shear deformation. Moreover, the comparative study of tectonic deformation and magnetic fabric showed that the records of magnetic fabric on strain are different under multi-stage brittle deformation. Evaluation of the magnetic fabric in the brittle deformation area must be based on structural analysis. (3) Combined with regional tectonic evolution, stratigraphic unconformity, and geochronology, this study speculates that the NE–SW compression may be related to the initial collision of the Indo-Asian plate. Under the control of the NE–SW stress field, the Anninghe fault zone is reactivated. The E–W compression may mainly respond to the eastward growth of the Tibetan Plateau, which may have occurred from Oligocene to Early Miocene. Moreover, the NW–SE compression may mainly respond to the southeastward growth of the Tibetan Plateau—that is, the lateral extrusion of the Chuandian block. During this period, the Xianshuihe–Anninghe–Xiaojiang fault formed in the form of sinistral strike-slip from N–S. |
| HUA Tian,LI Jin-xi,LI Zhi-wu,YUAN Meng-yu,CAI Hong-yan,TONG Kui,WANG Zi-jian,LI Ke,LIU Shu-gen,ZENG Lu.2022.Cenozoic Structural Deformation and Magnetic Fabric Characteristics of Anninghe Fault Zone[J].Acta Geoscientica Sinica,43(2):144-156. |
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