地震地质 ›› 2002, Vol. 24 ›› Issue (3): 289-302.

• 研究论文 •    下一篇

山西中条山断裂带的晚第四纪分段模型

程绍平, 杨桂枝   

  1. 中国地震局地质研究所, 北京, 100029
  • 收稿日期:2001-09-04 修回日期:2002-03-03 出版日期:2002-09-04 发布日期:2009-10-26
  • 作者简介:程绍平,男,1943年生,1966年毕业于华东师范大学地貌学与第四纪地质学专业,研究员,主要研究方向为构造地貌学、新构造学和长期景观演化以及活动构造学,电话:010-62009127,E-mail:chengshaop@yahoo.com.
  • 基金资助:
    国家基础研究发展规划项目(G1998040701)资助

LATE QUATERNARY SEGMENTATION MODEL OF THE ZHONGTIAOSHAN FAULT, SHANXI PROVINCE

CHENG Shao-ping, YANG Gui-zhi   

  1. Institute of Geology, China Seismological Bureau, Beijing 100029, China
  • Received:2001-09-04 Revised:2002-03-03 Online:2002-09-04 Published:2009-10-26

摘要: 山西南部的中条山断裂是鄂尔多斯断块周边活动断裂系东南部分的1条断裂.有关断层活动性的最新研究结果表明,中条山断裂的活动性水平较低且重复间隔较长.在这个认识的基础上,根据构造不连续性、构造地貌学、探槽古地震学和断层运动学证据,进一步提出了晚第四纪中条山断裂的分段模型及其定量参数.

关键词: 分段模型, 晚第四纪, 中条山断裂, 山西

Abstract: The Zhongtiaoshan Fault, southern Shanxi is an active fault in the southeastern part of the active fault system around Ordos Massif, being the boundary between the Yuncheng Faulted basin and the Zhongtiaoshan Faulted Mountain. The recent study about fault activity indicates that it has a lower level of activity and a relatively long recurrence interval of faulting. On the basis of this understanding, a further study is carried out on the segmentation of the Zhongtiaoshan Fault, while the late Quaternary segmentation model and its quantitative parameters are provided in the light of evidence from tectonic discontinuity, tectonic geomorphology, trench paleoseismology, and fault kinematics. The Zhongtiaoshan Fault runs from the northern piedmont to the western piedmont of the Zhongtiaoshan Mountains, with a length of 137km, a general strike of NE-NEE, and a dip angle of 58°~75°, being a high angle normal fault. On one hand, the northern piedmont part of the fault exhibits a big curve convex southeast; and on the other hand, the western piedmont part of the fault intersects with its northern piedmont part at an angle of 120°. By these two major tectonic discontinuities, the Zhongtiaoshan Fault can be divided into three geometric segments from northeast to southwest: the Xiaxian segment, the Xiezhou segment, and the Hanyang segment. The major tectonic discontinuities persistently control the Cenozoic sedimentation in the Yuncheng Faulted Basin. The Xiezhou segment of the Yuncheng Faulted Basin was the depocenter not only of Tertiary system but also of Quaternary system. Morphometric analysis has indicated that the elevation profile of divides and geomorphic characteristics of drainage system in the Zhongtiaoshan Mountains, such as length and gradient index of stream, as well as evolution of its mountain front, have apparent segmented variations, showing an along strike tectonic inhomogeneity caused by long term faulting. The quantitative parameters, such as long term slip rate, displacement per event, age of the last event, and average recurrence interval obtained from the studies of trench paleoseismology and fault kinematics are indicative of segmented differences in late Quaternary fault behavior of the Zhongtiaoshan Fault. In summary, the Zhongtiaoshan Fault is a typical fault exhibiting relatively long recurrence intervals. The surface rupturing events revealed in the trenches correspond to strong earthquakes of magnitude 7.7~8.1, which were separated by a quiescence period of 12,000 years for the Xiezhou segment, and 50,000~85,000 years for the Xiaxian and Hanyang segments. For the Zhongtiaoshan Fault, the only segment that was active during the Holocene epoch is the Xiezhou segment, which has the fastest long term slip rate, the biggest displacement per event, and the shortest average recurrence interval among the three segments. The Holocene activity of this segment might be attributed to the growth and strong activity of the secondary faults of the Zhongtiaoshan Fault since at latest the middle Pleistocene, inducing the frequent rupturing on the main fault. The occurrence of such a type of fault as the Zhongtiaoshan Fault with a relatively long recurrence interval(104 years)in the active fault system around the Ordos Massif implies the inhomogeneity of the movement of the Ordos Massif as a whole. The segmentation model and its quantitative parameters proposed in this paper may provide basic materials for seismic risk evaluation.

Key words: segmentation model, late Quaternary, Zhongtiaoshan Fault, Shanxi Province

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