Scholarlink

<p>The northeasternmost active deformation front of the Tibetan Plateau is defined by the North Qilian Shan and the Jiuquan Basin, located ∼1,500 km away from the India-Asia collision zone. Understanding the lithospheric-scale convergence between these units is critical for deciphering the mechanisms driving the northeastward plateau expansion. In this study, we conduct systematic geometric and kinematic analysis of upper-crustal deformation across the northern margin of the North Qilian Shan and the Jiuquan Basin, by integrating multiple datasets including high-resolution seismic reflection data, borehole loggings, surface geology and deformed fluvial terraces. Our results indicated that this region is dominated by NE-directed, thick-skinned, basement-involved reverse faults that root into a gently south-dipping (∼10°) décollement at ∼13–15 km depth, likely within the brittle-ductile transition zone. Wedge-shaped foreland basin deposits in the Middle-Late Miocene Shulehe Formation indicate that uplift of the North Qilian Shan initiated during this time. Palinspastic reconstruction reveals that the upper-crustal shortening is limited to 7.6–11.7 km, with up to 54%–95% accommodated by the frontal thrusts of the North Qilian Shan. These observations indicate that North Qilian Shan has acted as a stable plateau margin since the Middle Miocene, with limited northeastward propagation of deformation into the Jiuquan Basin. Reinterpretation of previously published deep geophysical data identifies a north-dipping lithospheric-scale fault offsetting the Moho by ∼7.8 km. Collectively, our results support a lithospheric-scale tectonic wedge model along the northeastern margin of the Tibetan Plateau, in which the rigid Jiuquan Basin indents into the weakened North Qilian lower crust under horizontal compression, accommodating limited convergence without large-scale subduction. Our findings suggest that northeastward plateau growth occurs through lithospheric wedging of mechanically distinct tectonic units characterized by distributed deformation, rather than by intracontinental subduction localized along a discrete subduction zone.</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

Limited intracontinental convergence accommodated by lithospheric-scale wedge tectonics along the northeastern margin of the Tibetan Plateau

  • 期刊论文

  • 发表日期：

    2025年10月14日

查看全文
  • Kun Li,
  • Lei Wu,
  • Bo Guo,
  • Guoli Liu,
  • Xiubin Lin,
  • Ancheng Xiao,
  • Shufeng Yang,
  • Hanlin Chen

摘要

The northeasternmost active deformation front of the Tibetan Plateau is defined by the North Qilian Shan and the Jiuquan Basin, located ∼1,500 km away from the India-Asia collision zone. Understanding the lithospheric-scale convergence between these units is critical for deciphering the mechanisms driving the northeastward plateau expansion. In this study, we conduct systematic geometric and kinematic analysis of upper-crustal deformation across the northern margin of the North Qilian Shan and the Jiuquan Basin, by integrating multiple datasets including high-resolution seismic reflection data, borehole loggings, surface geology and deformed fluvial terraces. Our results indicated that this region is dominated by NE-directed, thick-skinned, basement-involved reverse faults that root into a gently south-dipping (∼10°) décollement at ∼13–15 km depth, likely within the brittle-ductile transition zone. Wedge-shaped foreland basin deposits in the Middle-Late Miocene Shulehe Formation indicate that uplift of the North Qilian Shan initiated during this time. Palinspastic reconstruction reveals that the upper-crustal shortening is limited to 7.6–11.7 km, with up to 54%–95% accommodated by the frontal thrusts of the North Qilian Shan. These observations indicate that North Qilian Shan has acted as a stable plateau margin since the Middle Miocene, with limited northeastward propagation of deformation into the Jiuquan Basin. Reinterpretation of previously published deep geophysical data identifies a north-dipping lithospheric-scale fault offsetting the Moho by ∼7.8 km. Collectively, our results support a lithospheric-scale tectonic wedge model along the northeastern margin of the Tibetan Plateau, in which the rigid Jiuquan Basin indents into the weakened North Qilian lower crust under horizontal compression, accommodating limited convergence without large-scale subduction. Our findings suggest that northeastward plateau growth occurs through lithospheric wedging of mechanically distinct tectonic units characterized by distributed deformation, rather than by intracontinental subduction localized along a discrete subduction zone.