SEISMOLOGY AND GEOLOGY ›› 2026, Vol. 48 ›› Issue (2): 386-402.DOI: 10.3969/j.issn.0253-4967.20240092

• Research paper • Previous Articles     Next Articles

LATE QUATERNARY ACTIVITY CHARACTERISTICS IN THE SHIBAN RIVER TO NANNIWAN SEGMENT OF THE SOUTHERN MAOMAOSHAN MARGINAL FAULT

XU Wei1,2)(), LI Guang-tao2), CHENG Li2), ZOU Zi-nan3)   

  1. 1) State Key Laboratory of Earthquake Dynamics and Forecasting, Institute of Geology, China Earthquake Administration, Beijing, 100029, China
    2) China Earthquake Disaster Prevention Center, Beijing, 100029, China
    3) POWERCHINA Chengdu Engineering Corporation Limited, Chengdu, 610072, China
  • Received:2025-01-16 Revised:2025-04-24 Online:2026-04-20 Published:2026-05-14

毛毛山南缘断裂石板沟至南泥湾一带晚第四纪活动特征

徐伟1,2)(), 李光涛2), 程理2), 邹子南3)   

  1. 1) 中国地震局地质研究所, 地震动力学与强震预测全国重点实验室, 北京 100029
    2) 中国地震灾害防御中心, 北京 100029
    3) 中国电建集团成都勘测设计研究院有限公司, 成都 610072
  • 作者简介:

    徐伟, 男, 1986年生, 2011年于中国地震局地壳应力研究所获固体地球物理学专业硕士学位, 现为中国地震局地质研究所构造地质学专业在读博士研究生, 主要从事活动构造、 第四纪年代、 构造地貌等研究, E-mail:

  • 基金资助:
    达坂山断裂1︰5万活动断层填图(DZ5WTT202305); 西藏自治区科技重大专项课题(XZ202201ZD0003G); 国家自然科学基金(42102267)

Abstract:

The Southern Maomaoshan Marginal Fault is a key structural constituent of the Qilian-Haiyuan fault zone, situated along the northeastern margin of the Qinghai-Xizang Plateau. Historically, research efforts have been predominantly concentrated on the Maomaoshan Fault along the northern flank, while the Southern Maomaoshan Marginal Fault on the southern flank has received comparatively less attention. This study seeks to investigate this understudied fault segment from the Shibangou River to Nanniwan, with three core objectives: 1) to reveal its Late Quaternary activity characteristics, 2) to assess its seismic hazard potential, and 3) to offer novel perspectives on regional tectonic evolution.
This study employed various methods, including high-precision topographic and geomorphic surveys, geomorphic surface dating, and trench excavation. Using high-precision airborne LiDAR technology, detailed 3D topographic data along the fault were obtained, and the heights of fault scarps were determined. Combined with optically stimulated luminescence(OSL)dating, the ages of geomorphic surfaces were measured. Additionally, trench excavations were conducted to reveal the near-surface structural characteristics of the fault, providing direct evidence of paleo-earthquake events.
The results indicate that the Southern Maomaoshan Marginal Fault has been significantly active during the Late Quaternary from Shibangou to Nanniwan segment, with left-lateral strike-slip movement accompanied by north-to-south thrusting. Airborne LiDAR revealed two distinct clusters of vertical displacement along the fault, indicating that the fault has experienced at least two strong paleo-earthquake events during the Late Quaternary. Based on fault scarps, trench profiles, and OSL dating, the recent strong earthquake activity has been constrained to 5.11~6.28kaBP, with vertical slip rates of 0.42~0.75mm/a since the Late Pleistocene. Trench excavations revealed that the near-surface structure of the fault displays typical flower structures characteristic of strike-slip faults.
The Southern Maomaoshan Marginal Fault is a Holocene active fault, which, together with the Maomaoshan Fault, accommodates tectonic deformation in the Maomaoshan region of the Qilian-Haiyuan fault zone. Its left-lateral strike-slip and thrust kinematics play an important role in shaping regional tectonic evolution. Given its proximity to several villages and the fact that its western segment constitutes a critical economic and transportation corridor, this fault underscores the urgency of seismic hazard assessment. Future studies ought to prioritize exploration of its slip rate and strong-motion earthquake recurrence patterns, integrating these results into regional hazard frameworks—a step that will enhance our comprehensive understanding of the northeastern Tibetan plateau’s tectonic evolution.

Key words: Southern Maomaoshan Marginal Fault, Late Quaternary, faulted landform, slip rate

摘要:

毛毛山南缘断裂是青藏高原东北缘祁连-海原断裂带的重要组成部分, 长期以来, 研究多集中于北麓的毛毛山断裂, 而对南麓的毛毛山南缘断裂研究较少。文中旨在通过对毛毛山南缘断裂石板沟至南泥湾一带的研究, 揭示其晚第四纪活动特征, 为区域构造演化提供新的认识。采用高精度地形地貌测量、 地貌面定年及探槽开挖等多种方法, 对断裂最近强震活动时代、 晚第四纪滑动速率进行了分析。通过机载激光LiDAR测量, 获取了断裂沿线三维精细地形数据, 并结合光释光测年, 对地貌面年代进行了厘定。此外, 通过探槽开挖, 揭示了断裂近地表结构特征。研究结果表明, 毛毛山南缘断裂石板沟至南泥湾一带晚第四纪活动显著, 断裂以左旋走滑为主, 兼具北向南逆冲。断裂最近一次强震活动发生在5.11~6.28kaBP以来, 晚更新世晚期以来的垂直滑动速率为0.42~0.75mm/a。毛毛山南缘断裂与毛毛山断裂共同调节着祁连-海原断裂带在毛毛山一带的构造变形, 其地震危险性需予以关注。

关键词: 毛毛山南缘断裂, 晚第四纪, 断错地貌, 滑动速率