Scholarlink

<p>The uplift of the Qilian Shan, which is located at the northeastern margin of the Tibetan Plateau, is a significant event in the plateau’s formation. There is an ongoing debate regarding the mechanism of the Qilian Shan: whether it involves gradual extension or uniform uplift. A key factor in resolving the debate is determining whether the North Qilian Shan fault (NQF), the north boundary thrust fault of the Qilian Shan, accounts for the majority of the crustal shortening across the range. In this study, we focused on the eastern section of the NQF to assess its deformation rate. The Zamu River flows almost perpendicularly through two branch faults of the NQF, and a flight of well-preserved terraces along the river provides an excellent opportunity to constrain a reliable deformation rate. We measured the elevation of these river terraces and dated them by Optically Stimulated Luminescence (OSL) and cosmogenic <sup>10</sup>Be exposure dating methods. The result shows that each terrace surface is offset at the Kangningqiao fault and is significantly folded in the hanging wall to the Shanggucheng-Shuangta fault. The abandonment ages of the four levels of terraces are determined as ~48 ka (T2), ~73 ka (T2a), 80–85 ka (T3), ~122 ka (T4), respectively. Based on the deformation characteristics of the terraces and geometric models of trishear folding and listric faulting, the relationship between these two branch faults and deforming kinematics is established. From this kinematic model, a total slip rate of 1.24±0.12 mm a<sup>−1</sup> is derived. The rate is consistent with the previously determined rate of 1.3±0.6 mm a<sup>−1</sup> in the western and central sections of the NQF. The similar shortening rate along the whole NQF indicates that the northern boundary fault accounts for 15%–20% of the total crustal shortening rate across the Qilian Shan. This shortening distribution is not in line with the tectonic wedge model which posits that the boundary fault absorbs the majority of the shortening rate, but rather supports the model of uniform uplift across the Qilian Shan.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Kinematics and deformation rates of the fault-fold system along the eastern section of the North Qilian Shan Fault

  • 期刊论文

  • 发表日期：

    2025年3月10日

查看全文
  • Xiaofei Hu,
  • Zihao Yi,
  • Jiuying Chen,
  • Yanan Zhang

摘要

The uplift of the Qilian Shan, which is located at the northeastern margin of the Tibetan Plateau, is a significant event in the plateau’s formation. There is an ongoing debate regarding the mechanism of the Qilian Shan: whether it involves gradual extension or uniform uplift. A key factor in resolving the debate is determining whether the North Qilian Shan fault (NQF), the north boundary thrust fault of the Qilian Shan, accounts for the majority of the crustal shortening across the range. In this study, we focused on the eastern section of the NQF to assess its deformation rate. The Zamu River flows almost perpendicularly through two branch faults of the NQF, and a flight of well-preserved terraces along the river provides an excellent opportunity to constrain a reliable deformation rate. We measured the elevation of these river terraces and dated them by Optically Stimulated Luminescence (OSL) and cosmogenic 10Be exposure dating methods. The result shows that each terrace surface is offset at the Kangningqiao fault and is significantly folded in the hanging wall to the Shanggucheng-Shuangta fault. The abandonment ages of the four levels of terraces are determined as ~48 ka (T2), ~73 ka (T2a), 80–85 ka (T3), ~122 ka (T4), respectively. Based on the deformation characteristics of the terraces and geometric models of trishear folding and listric faulting, the relationship between these two branch faults and deforming kinematics is established. From this kinematic model, a total slip rate of 1.24±0.12 mm a−1 is derived. The rate is consistent with the previously determined rate of 1.3±0.6 mm a−1 in the western and central sections of the NQF. The similar shortening rate along the whole NQF indicates that the northern boundary fault accounts for 15%–20% of the total crustal shortening rate across the Qilian Shan. This shortening distribution is not in line with the tectonic wedge model which posits that the boundary fault absorbs the majority of the shortening rate, but rather supports the model of uniform uplift across the Qilian Shan.