华北地块怀涿盆地北缘断裂晚第四纪滑动速率及其地震地质意义

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摘要活动断层的滑动速率代表了某一时间段内断层平均滑动的速度，反映了断层应变能量积累的速率，同时也代表了断层的活动方式和强度，与断层的地震危险性评估密切相关。怀涿盆地北缘断裂既属于华北地块西部鄂尔多斯高原和东部华北平原的重要过渡与转换地带，又处于鄂尔多斯东北缘与北西向张渤带的交汇区，地理位置独特，构造变形强烈，其晚第四纪滑动速率研究是我们分析该断裂活动习性并评判其强震危险性的重要定量依据，也是我们认识华北地块活动构造变形和应变分配过程的不可或缺性参数。受年代测试方法和精度所限，前人对怀涿盆地北缘断裂滑动速率的研究多依靠热释光和地貌面结合的方法开展，时代久远，存在较大的不确定性。此次研究借助于高精度的遥感影像解译、大比例尺的地表地质地貌调查、探槽古地震分析和第四纪年代学测试等方法，首次通过多个探槽剖面中的地层垂直位错、碳十四和光释光等多种年代学数据，联合约束了怀涿盆地北缘断裂的晚第四纪滑动速率。研究结果显示，怀涿盆地北缘断裂晚第四纪以来以伸展变形为主，其垂直滑动速率约为0.04~0.11 mm/a。综合前人成果及本研究得到的11组有效数据进行拟合得到垂直滑动速率~0.06 mm/a，R2为0.91。这一认识远低于前人研究得到的约0.5 mm/a的结果。分析推测认为，这种较大的认识偏差形成的原因要么是~30年前的测年技术手段和位移测量设备带来的系统误差所致，要么是怀涿盆地北缘断裂目前可能处于闭锁状态，其长时间的地震平静期和极低的滑动速率暗示该断层的强震危险性需要高度重视，亟需地震学、形变测量和地震前兆观测等相关研究手段开展进一步的深入研究。这一结果同时有助于深入地认识京华北地块的现今构造变形特征，和分析该地块的应变分配与应力转换等特征等。

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关键词：华北地块怀涿盆地北缘断裂晚第四纪滑动速率地震地质

Abstract： Although the late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin (NFHB) was studied approximately 30 years ago using thermoluminescence and geomorphic methods, the underlying uncertainty cannot be neglected, considering the limitations resulting from age and displacement measurements. Accordingly, we attempted to re-estimate the late Quaternary slip rate of the NFHB using high-precision remote sensing image interpretation, large-scale geological and geomorphic mapping, paleoseismic analysis, and Quaternary geochronology testing. The results, based on stratigraphic dislocation and age constraint in the trenches, show that the present deformation of the NFHB has been dominated by the extension, with a vertical slip rate ~0.04-0.11 mm/a. We estimate a vertical slip rate of ~0.06 mm/a, with an R2 value of ~0.91, which is much lower than the ~0.5 mm/a result estimated previously. There are three possible reasons for this discrepancy. The fi rst is the limitation resulting from dating and displacement measurements in earlier studies; the second is the slip decomposition caused by multiple branches of the NFHB, which leads to the low slip rate observed at a single fault; and third possible explanation is that the fault may be locked at present with a low slip rate, which means that the earthquake hazard of the NFHB cannot be ignored, and more in-depth research, such as geodetic and intensive observations of earthquake precursors, is urgently needed. This discovery poses a new challenge for the active study of the NFHB and the northeast corner of the Ordos Plateau in the North China Block.

Key words： North China Block The Northern Margin Fault of the Huaizhuo Basin Late Quaternary slip rate Seismological Implications

收稿日期: 2024-09-20;

基金资助:北京防灾科技有限公司研发专项（FZKJYF202201）资助

通讯作者: 余中元（1982—），男，博士，教授，主要从事地震地质与地震工程方面的研究郑荣荧（1995—），男，工程师，主要从事地球物理与地震地质方面的研究 E-mail: Yuyangzi9811@126.com；zry19950315@163.com

作者简介: 作者简介：李路伟（1997—），男，硕士研究生，主要从事活动构造方面的研究通讯作者：余中元（1982—），男，博士，教授，主要从事地震地质与地震工程方面的研究郑荣荧（1995—），男，工程师，主要从事地球物理与地震地质方面的研究

引用本文:

. 华北地块怀涿盆地北缘断裂晚第四纪滑动速率及其地震地质意义[J]. 应用地球物理, 2025, 22(1): 53-70.

. Late Quaternary slip rate of the Northern Margin Fault of the Huaizhuo Basin in the North China Block and its seismological implications[J]. APPLIED GEOPHYSICS, 2025, 22(1): 53-70.