摘要
嘉黎断裂带通常被认为是控制青藏高原东南缘物质向东南挤出的重要边界构造之一,但其第四纪是否仍在活动以及活动特征如何一直存在争议.在前人工作基础上,通过高分辨率遥感影像解译、DEM数据分析和详细的地表调查,并结合震源机制解和GPS观测等数据,分析研究了嘉黎断裂带易贡-察隅段的第四纪活动性及特征.结果表明,嘉黎断裂带易贡-察隅段在第四纪期间未显示出明显的右旋走滑活动特征,仅在局部段落发育小规模的北西或近东西向的正断层活动.GPS速率分析也显示,嘉黎断裂带易贡-察隅段的现今右旋走滑活动不明显,而表现出以伸展变形为主,这与震源机制解反映出的沿断裂带主要发生正断型地震的特征向吻合.综合分析认为,伴随青藏高原东南缘地区构造变形方式由早期向东横向挤出转变为围绕东构造结的顺时针旋转运动,嘉黎断裂带易贡-察隅段第四纪期间整体上已不活动,不再是调节物质向东挤出运动的边界走滑断裂,而局部的小规模正断层活动可能与东构造结强挤压背景下引起的局部张裂或者冰川融化引发地壳回弹作用相关.新的研究结果支持藏东-川西地区第四纪构造变形模式更符合深部通道流驱动下的围绕东构造结顺时针旋转-挤出模式,而非横向或侧向挤出模式.
The Jiali Fault Zone is one of the major active tectonic structures along the southeastern margin of the Tibetan Plateau,playing a crucial role in regional seismicity and geomorphic evolution.This study systematically analyzes the tectonic activity of the Yiong-Zayu segment of the Jiali Fault Zone by integrating high-resolution remote sensing imagery,DEM data,field investigations,and focal mechanism solutions.The results indicate that the Jiali Fault Zone has exhibited weak tectonic activity since the Quaternary,with no significant evidence of right-lateral strike-slip motion.Instead,localized NW-and nearly E-W-trending normal faulting has been observed along certain segments,and seismic activity is predominantly characterized by local normal-faulting earthquakes.GPS velocity analysis reveals that the fault exhibits low horizontal slip rates,with deformation primarily characterized by extension,suggesting that it does not function as a major boundary fault.By integrating previous studies,we further infer that the formation of local normal faults is primarily influenced by localized shear stress or post-glacial rebound.Moreover,the kinematic model of southeastern Xizang is more consistent with a clockwise rotational extrusion mechanism.
作者
陆诗铭
吴中海
韩帅
胡渊
凡福新
Lu Shiming;Wu Zhonghai;Han Shuai;Hu Yuan;Fan Fuxin(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Active Tectonics and Geological Safety,Ministry of Natural Resources,Beijing 100081,China;School of Earth and Resources,China University of Geosciences,Beijing 100083,China;Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China)
出处
《地球科学》
北大核心
2025年第8期3052-3069,共18页
Earth Science
基金
中国地质调查局项目(No.DD20230600601)
科技基础资源调查专项课题(No.2021YFB2301401)
国家自然科学基金项目(No.42472287)。
关键词
嘉黎断裂带
青藏高原
构造地貌
正断层
顺时针旋转-挤出模式
构造学
Jiali Fault Zone
Tibetan Plateau
tectonic geomorphology
normal fault
clockwise rotational extrusion model
tectonics
