SEISMOLOGY AND GEOLOGY ›› 2025, Vol. 47 ›› Issue (6): 1566-1585.DOI: 10.3969/j.issn.0253-4967.2025.06.20240052

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CHARACTERISTICS OF LATE QUATERNARY ACTIVITY AND TECTONIC IMPLICATIONS OF THE MAYAXUESHAN FAULT IN THE EASTERN QILIAN SHAN

CHEN Yan-wen1)(), YUAN Dao-yang1),*(), YAO Yun-sheng2), YU Jin-chao1), WEN Ya-meng1), SU Rui-huan1), SUN Hao1)   

  1. 1) School of Earth Sciences, Lanzhou University, Lanzhou 730000, China
    2) Lanzhou Institute of Geotechnique and Earthquake, China Earthquake Administration, Lanzhou 730000, China
  • Received:2024-04-16 Revised:2024-08-06 Online:2025-12-20 Published:2025-12-31
  • Contact: YUAN Dao-yang

祁连山东段玛雅雪山断裂晚第四纪活动特征及其构造意义

陈艳文1)(), 袁道阳1),*(), 姚赟胜2), 于锦超1), 文亚猛1), 苏瑞欢1), 孙浩1)   

  1. 1) 兰州大学, 地质科学与矿产资源学院, 兰州 730000
    2) 中国地震局兰州岩土地震研究所, 兰州 730000
  • 通讯作者: 袁道阳
  • 作者简介:

    陈艳文, 男, 1992年生, 现为兰州大学地质学专业在读博士研究生, 主要从事新构造与活动构造研究, E-mail:

  • 基金资助:
    第二次青藏高原综合科学考察研究(2019QZKK0901); 国家自然科学基金(42172227)

Abstract:

The Qilian Shan, Hexi Corridor, and Longzhong Basin, on the northeastern margin of the Tibetan plateau, form the leading edge of the plateau's outward advance into the mainland. They are young, critical components of the orogen, characterized by thrust faults, active folds, and strike-slip fault zones. The Mayaxueshan Fault(MYF), at the eastern end of the Qilian Shan, is a boundary thrust separating the northeastern Qilian margin from the Longzhong Basin. Constraining the late Quaternary activity and slip rate of the MYF is essential for elucidating regional deformation patterns and the mechanisms of Tibetan plateau uplift and outward growth, and it is also vital for seismic-hazard assessment.
Through remote-sensing interpretation, geological and geomorphic mapping, unmanned-aircraft photogrammetry, and optically stimulated luminescence dating, this paper examines the geometry, geomorphic expression, late Quaternary activity, and vertical slip rate of the MYF, and discusses its seismic risk and tectonic significance. Results show that the MYF is a SW-arching thrust-fault zone ~152km long, dipping SW-S at 32°~71°. The fault cuts a series of NE-SN-trending gullies, offsets landforms of multiple tiers, and forms scarps at 0.9~14.8m height. Variations in geometry and late Quaternary activity divide the MYF into three sections: Mayaxueshan(west), Baoquanshan(middle), and Hunanshan(east). Activity decreases from west to east, with respective activity epochs of late Holocene, end of late Pleistocene, and late Middle Pleistocene. From scarp heights and ages of corresponding geomorphic surfaces at Mayinggou and Shangbacigou, the vertical slip rate of the Mayaxueshan segment since the Holocene is(0.50±0.02)mm/a. This segment is thus capable of generating strong earthquakes of M6.7-7.0 in the future.
Comparative analysis suggests the western and middle-eastern sections of the MYF may belong to different fault systems. The Mayaxueshan segment shows a closer structural affinity with the Zhuanglanghe Fault; together they form arcuate thrust belts produced by regional compression. In contrast, the Baoquanshan segment appears to have evolved synergistically with the Baiyinbaiyangshugou Fault, constituting another arcuate belt in the north-central Longzhong Basin. As a whole, the MYF inherits an ancient arcuate architecture bulging toward the SW. Since the late Quaternary it has undergone progressive, west-to-east segmented reactivation, producing a mismatch between fracture geometry and the NE-oriented regional compressive stress and yielding along-strike differences in late Quaternary activity. On the northeastern Tibetan margin, NE-directed regional compression acting against stable blocks has generated foreland-propagating thrust-fold belts and curved extrusion structures, leading to crustal shortening and thickening and rapid mountain uplift. Consequently, the Tibetan plateau has risen and extended northeastward through the stepwise outward push of secondary blocks.

Key words: Mayaxueshan Fault, late Quaternary activity, slip rate, arc tectonic belt, plateau spreading

摘要: 玛雅雪山断裂是祁连山东段的一条挤压逆冲断裂带, 整体呈向SW拱曲的弧形, 全长约152km。文中基于卫星影像解译、 地质地貌填图、 无人机航测和断错地貌面年代测试等技术方法, 对玛雅雪山断裂的几何结构和晚第四纪活动性等进行研究。结果表明, 该断裂晚第四纪构造活动具有分段性, 可划分为玛雅雪山(西)段、 宝泉山(中)段和虎南山(东)段3段, 其活动时代分别为晚全新世、 晚更新世末期和中更新世晚期。其中, 玛雅雪山段全新世以来活动强烈, 断错T1-T2级冲洪积阶地, 形成明显的断层陡坎, 其全新世以来的垂直滑动速率为(0.50±0.02)mm/a, 未来有发生6.7~7.0级强震的潜能。通过对比分析发现, 在晚第四纪活动性方面, 玛雅雪山段与庄浪河断裂之间可能具有更为密切的构造组合关系, 两者是在区域挤压应力作用下形成的弧形逆冲构造带。同样地, 青藏高原东北缘在NE向区域应力挤压和稳定地块的阻挡作用下, 形成了一系列前展式逆冲褶皱带和弧形挤出构造, 导致地壳缩短增厚和山脉快速崛起, 以次级地块分阶段逐次向外推挤的方式实现了青藏高原NE向的隆升扩展。

关键词: 玛雅雪山断裂, 晚第四纪活动性, 滑动速率, 弧形构造带, 高原扩展