地震地质 ›› 2019, Vol. 41 ›› Issue (3): 576-586.DOI: 10.3969/j.issn.0253-4967.2019.03.003

• 研究论文 • 上一篇    下一篇

郯庐断裂带安丘-莒县断裂江苏段全新世活动的新证据

张鹏1, 张媛媛1, 李丽梅2, 蒋新2, 孟科2   

  1. 1. 南京工业大学交通运输工程学院, 南京 210009;
    2. 江苏省地震局, 南京 210014
  • 收稿日期:2018-06-01 修回日期:2018-08-20 出版日期:2019-06-20 发布日期:2019-07-28
  • 作者简介:张鹏,男,1981年生,2007年于南京大学地球科学系获构造地质学专业博士学位,副研究员,研究方向为活动构造,E-mail:zhpnju@163.com。
  • 基金资助:
    国家自然科学基金(41202155)、宿迁市活动断层探测与地震危险性评价项目(SQZBTB20110162)和南京工业大学引进人才科研专项共同资助。

NEW EVIDENCES OF HOLOCENE ACTIVITY IN THE JIANGSU SEGMENT OF ANQIU-JUXIAN FAULT OF THE TANLU FAULT ZONE

ZHANG Peng1, ZHANG Yuan-yuan1, LI Li-mei2, JIANG Xin2, MENG Ke2   

  1. 1. College of Transportation Science & Engineering, Nanjing Tech University, Nanjing 210009, China;
    2. Jiangsu Earthquake Agency, Nanjing 210014, China
  • Received:2018-06-01 Revised:2018-08-20 Online:2019-06-20 Published:2019-07-28

摘要: 安丘-莒县断裂是郯庐断裂带内活动时代最新、地表形迹最明显、地震危险性最大的断裂,也是1668年郯城M8 1/2地震的发震断层。前人对郯城地震的地表破裂向S终止的位置存在多种观点,对该断裂江苏段的全新世活动情况也存在较大争议。文中通过在重岗山西侧和宿迁合欢路北侧开展的探槽开挖工作,发现了该断裂全新世活动的新证据,并对其最新活动时间进行了探讨。重岗山西侧后陈村探槽和宿迁合欢路北侧探槽都表明安丘-莒县断裂江苏段在全新世有过明显活动,推测最新一次古地震事件的发生时间为(4.853±0.012)~(2.92±0.3) ka BP。最新活动性质以走滑逆冲为主,剖面上获得的最大断错量为1m。未发现1668年郯城M8 1/2地震的地表破裂带到达江苏段的明确证据。

关键词: 郯庐断裂带, 安丘-莒县断裂, 江苏段, 郯城地震, 地表破裂

Abstract: Anqiu-Juxian Fault is an important fault in the Tanlu fault zone, with the largest seismic risk, the most recent activity date and the most obvious surface traces. It is also the seismogenic fault of the Tancheng M8 1/2 earthquake in 1668. There are many different views about the southern termination location of surface rupture of the Tancheng earthquake and the Holocene activity in Jiangsu segment of this fault. Research on the latest activity time of the Jiangsu segment of Anqiu-Juxian Fault, particularly the termination location of surface rupture of the Tancheng earthquake, is of great significance to the assessment of its earthquake potential and seismic risk.
Based on trench excavation on the Jiangsu segment of Anqiu-Juxian Fault, we discuss the time and characteristics of its latest activity. Multiple geological sections from southern Maling Mountain to Chonggang Mountain indicate that there was an ancient seismic event occurring in Holocene on the Jiangsu segment of Anqiu-Juxian Fault. We suggest the time of the latest seismic event is about(4.853±0.012)~(2.92±0.3)ka BP by dating results. The latest activity is characterized by thrust strike-slip faulting, with the maximum displacement of 1m. Combined with the fault rupture characteristics of each section, it is inferred that only one large-scale paleo-earthquake event occurred on the Jiangsu segment of Anqiu-Juxian Fault since the Holocene.
The upper parts of the fault are covered by horizontal sand layers, not only on the trench in the west of Chonggang mountain but also on the trench in Hehuan Road in Suqian city, which indicates that the main part of the Jiangsu segment of Anqiu-Juxian Fault was probably not the surface rupture zone of the 1668 Tancheng M8 1/2 earthquake.
In short, the Jiangsu segment of Anqiu-Juxian Fault has experienced many paleo-earthquake events since the late Pleistocene, with obvious activity during the Holocene. The seismic activities of the Jiangsu segment of Anqiu-Juxian Fault have the characteristics of large magnitude and low frequency. The Jiangsu segment of Anqiu-Juxian Fault has the deep tectonic and seismic-geological backgrounds of big earthquakes generation and should be highly valued by scientists.

Key words: the Tanlu fault zone, Anqiu-Juxian Fault, the Jiangsu segment, Tancheng earthquake, surface rupture

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