阳关断裂带变形样式及其对阿尔金断裂扩展的指示意义

阳关断裂位于青藏高原北部阿尔金断裂系向北扩展的前缘位置，对其几何学和运动学的深入研究，有助于理解青藏高原向大陆内部扩展的机制。文章通过卫星影像解译、探槽开挖、差分GPS及无人机测量等对阳关断裂开展了详细研究。结果显示：阳关断裂东段发育多条正反向断层陡坎，断层陡坎高度在0.4～8 m之间，平均约2.2 m,探槽揭示断裂倾角约60°,形成高角度逆断层，局部发育正断层；西段断裂向北西前缘扩展，形成一组弧形分布的断层陡坎，陡坎高度多在0.9～2.4 m,平均约1.9 m。同时自南向北，逆冲断层陡坎形态由多级陡坎转为单一陡坎。对探槽剖面分析，显示断裂断错晚更新世冲洪积砾石层，发育的断层倾角较缓，以低角度逆冲为主要特征，约26°,有的甚至沿地层向前推覆。结合前人的研究成果，阳关断裂可能为本区阿尔金向北扩展的北边界，与三危山断裂共同协调吸收了阿尔金断裂东段的部分应变量。

Deformation pattern along the Yangguan fault and its implications in the propagation of the Altyn Tagh fault

The Yangguan fault is located in the northern part of the Tibet Plateau, where the Altyn Tagh fault system extends northward. Further studies on its geometry and kinematics are needed to understand the extension mechanism of the Tibet Plateau to the interior of the continent. We investigate the Yangguan fault in detail using satellite image interpretation, trench excavation, differential GPS, and UAV survey. The results show the existence of multiple positive and negative fault scarps in the eastern part of the Yangguan fault; the height of fault scarps ranges from 0.4 to 8 m with an average of 2.2 m. The dip angle of the fault revealed by the trench is approximately 60°, forming high-angle reverse faults and locally developing normal faults. The western part of the fault extends to the NW front, forming a group of arc-shaped fault scarps; their height ranges of 0.9-2.4 m with an average of 1.9 m. From south to north, the pattern of the thrust fault scarps changes from multistage scarps to single scarps. The trench profile analysis results show that the fault dates to the alluvial-diluvial gravel layer of the Late Pleistocene age. The dip angle of the developed faults is relatively even, mainly characterized by a low angle thrust of approximately 26°; some faults even push forward along the formation. Combined with previous research results, the Yangguan Fault may be the northern boundary of the Altyn Fault''s northward expansion, and it absorbs part of the strain in the eastern Altyn Fault in coordination with the Sanweishan fault.