阳高-天镇断裂晚第四纪活动特征及滑动速率

doi:10.3969/j.issn.0253-4967.2020.02.010

摘要/Abstract

摘要： 山西地堑系北部的晋冀蒙盆岭构造区历史上无7级以上强震记录, 但该区地处多个Ⅱ级活动地块的接合部位, 具有孕育强震的构造条件, 对其开展活动构造研究对区内的地震危险性评价工作具有重要意义。文中以晋冀蒙盆岭构造区内研究相对薄弱的阳高-天镇断裂为对象, 基于遥感影像解译、野外地质、构造地貌调查对其晚第四纪活动特征进行了研究, 发现阳高-天镇断裂多沿基岩山体与盆地内沉积物之间的接触带展布, 在局部断裂几何结构不规则处向盆地内部生长; 第四纪以来断裂以正断运动为主, 但其运动性质沿走向存在差异。 NEE和NE向为纯正断性质, 而NWW向以正断为主, 兼具左旋走滑运动分量; 对沿断裂断错的地质体、地貌面进行了位移测量和光释光定年工作, 得到断裂晚更新世以来的滑动速率为0.12~0.20mm/a, 对应的拉张速率约占山西地堑系北部地壳伸展速率的10%。

关键词: 阳高-天镇断裂, 山西地堑系, 晋冀蒙盆岭构造区, 正断层, 滑动速率

Abstract: The Shanxi Graben System is one of the intracontinental graben systems developed around the Ordos Block in North China since the Cenozoic, and it provides a unique natural laboratory for studying the long-term tectonic history of active intracontinental normal faults in an extensional environment. Comparing with the dense strong earthquakes in its central part, no strong earthquakes with magnitudes over 7 have been recorded historically in the Jin-Ji-Meng Basin-and-Range Province of the northern Shanxi Graben System. However, this area is located at the conjunction area of several active-tectonic blocks(e.g. the Ordos, Yan Shan and North China Plain blocks), thus it has the tectonic conditions for strong earthquakes. Studying the active tectonics in the northern Shanxi Graben System will thus be of great significance to the seismic hazard assessment. Based on high-resolution remote sensing image interpretations and field investigations, combined with the UAV photogrammetry and OSL dating, we studied the late Quaternary activity and slip rate of the relatively poorly-researched Yanggao-Tianzhen Fault(YTF)in the Jin-Ji-Meng Basin-and-Range Province and got the followings: 1)The YTF extends for more than 75km from Dashagou, Fengzhen, Inner Mongolia in the west to Yiqingpo, Tianzhen, Shanxi Province in the east. In most cases, the YTF lies in the contact zone between the bedrock mountain and the sediments in the basin, but the fault grows into the basin where the fault geometry is irregular. At the vicinity of the Erdun Village, Shijiudun Village, and Yulinkou Village, the faults are not only distributed at the basin-mountain boundary, we have also found evidence of late Quaternary fault activity in the alluvial fans that is far away from the basin-mountain boundary. The overall strike of the fault is N78°E, but the strike gradually changes from ENE to NE, then to NWW from the west to the east, with dips ranging from 30° to 80°. 2)Based on field surveys of tectonic landforms and analysis of fault kinematics in outcrops, we have found that the sense of motion of the YTF changes along its strikes: the NEE and NE-striking segments are mainly normal dip-slip faults, while the left-laterally displaced gullies on the NWW segment and the occurrence characteristics of striations in the fault outcrop indicate that the NWW-striking segment is normal fault with minor sinistral strike-slip component. The sense of motion of the YTF determined by geologic and geomorphic evidences is consistent with the relationship between the regional NNW-SSE extension regime and the fault geometry. 3)By measuring and dating the displaced geologic markers and geomorphic surfaces, such as terraces and alluvial fans at three sites along the western segment of the YTF, we estimated that the fault slip rates are 0.12~0.20mm/a over the late Pleistocene. In order to compare the slip rate determined by geological method with extension rate constrained by geodetic measurement, the vertical slip rates were converted into horizontal slip rate using the dip angles of the fault planes measured in the field. At Zhuanlou Village, the T₂ terrace was vertically displaced for(2.5±0.4)m, the abandonment age of the T₂ was constrained to be(12.5±1.6)ka, so we determined a vertical slip rate of(0.2±0.04)mm/a using the deformed T₂ terrace and its OSL age. For a 50°dipping fault, it corresponds to extension rate of(0.17±0.03)mm/a. At Pingshan Village, the vertical displacement of the late Pleistocene alluvial fan is measured to be(5.38±0.83)m, the abandonment age of the alluvial fan is(29.7±2.5)ka, thus we estimated the vertical slip rate of the YTF to(0.18±0.02)mm/a. For a 65° dipping fault, it corresponds to an extension rate of(0.09±0.01)mm/a. Ultimately, the corresponding extensional rates were determined to be between 0.09mm/a and 0.17mm/a. Geological and geodetic researches have shown that the northern Shanxi Graben System are extending in NNW-SSE direction with slip rates of 1~2mm/a. Our data suggests that the YTF accounts for about 10% of the crustal extension rate in the northern Shanxi Graben System.

Key words: Yanggao-Tianzhen Fault, Shanxi Graben System, Jin-Ji-Meng Basin-and-Range Province, normal fault, slip rate

中图分类号:

P315.2

罗全星, 李传友, 任光雪, 李新男, 马字发, 董金元. 阳高-天镇断裂晚第四纪活动特征及滑动速率[J]. 地震地质, 2020, 42(2): 399-413.

LUO Quan-xing, LI Chuan-you, REN Guang-xue, LI Xin-nan, MA Zi-fa, DONG Jin-yuan. THE LATE QUATERNARY ACTIVITY FEATURES AND SLIP RATE OF THE YANGGAO-TIANZHEN FAULT[J]. SEISMOLOGY AND GEOLOGY, 2020, 42(2): 399-413.

参考文献

[1] 邓起东, 米仓伸之, 徐锡伟, 等. 1994. 山西高原六棱山北麓断裂晚第四纪运动学特征初步研究[J]. 地震地质, 16(4): 339—343.
DENG Qi-dong, Yonekura N, XU Xi-wei, et al.1994. Study on the late Quaternary kinematics of the northern piedmont fault of the Liuleng Mountain[J]. Seismology and Geology, 16(4): 339—343(in Chinese).
[2] 段瑞涛. 1994. 阳原盆地及邻近地区活动断裂及地震危险性研究 [D]. 北京: 国家地震局地质研究所.
DUAN Rui-tao.1994. Research on active faults and seismic hazard in Yangyuan Basin and its neighbouring area [D]. Institute of Geology, China Earthquake Administration, Beijing(in Chinese).
[3] 方仲景, 段瑞涛, 郑炳华, 等. 1994. 河北省怀安盆地北缘断裂活动性研究[J]. 华北地震科学, 12(4): 25—33.
FANG Zhong-jing, DUAN Rui-tao, ZHENG Bing-hua, et al.1994. Research on activity of the northern margin fault of the Huai'an Basin in Hebei Province[J]. North China Earthquake Sciences, 12(4): 25—33(in Chinese).
[4] 国家地震局“鄂尔多斯周缘活动断裂系”课题组. 1988. 鄂尔多斯周缘活动断裂系 [M]. 北京: 地震出版社.
The Research Group on “Active Fault System around Ordos Massif”, State Seismological Bureau. 1988. Research on Active Faults System around the Ordos Block [M]. Seismological Press, Beijing(in Chinese).
[5] 李铁明, 沈正康, 徐杰, 等. 2007. 华北地区M_S≥6.5地震震源断层参数的研究[J]. 地球物理学进展, 22(1): 95—103.
LI Tie-ming, SHEN Zheng-kang, XU Jie, et al.2007. Analysis on the parameters of seismogenic fault of the earthquake more than 6.5 in North China[J]. Progress in Geophysics, 22(1): 95—103(in Chinese).
[6] 孙稳. 2018. 六棱山北麓断裂晚第四纪活动性 [D]. 北京: 中国地震局地质研究所.
SUN Wen.2018. Late Quaternary activity of the northern Liuleng Mountain piedmont fault [D]. Institute of Geology, China Earthquake Administration, Beijing(in Chinese).
[7] 王林. 2012. 盆地边界活动正断层多尺度构造地貌研究: 以京西北蔚广盆地南缘断裂带为例 [D]. 北京: 中国地震局地质研究所.
WANG Lin.2012. Research of basin marginal active normal faults through multi-scale tectonic geomorphology: A case study on the Yuguang Basin south margin fault [D]. Institute of Geology, China Earthquake Administration, Beijing(in Chinese).
[8] 徐锡伟. 1990. 剪切带尾端张性区构造扩展的模拟实验及其地震危险性分析[J]. 华北地震科学, 8(3): 40—46.
XU Xi-wei.1990. The soil simulated experiments of the structural development in tensile areas at the terminations of a shear zone and its earthquake risks analysis[J]. North China Earthquake Sciences, 8(3): 40—46(in Chinese).
[9] 徐锡伟, 邓起东. 1988. 晋北张性区盆岭构造及其形成的力学机制[J]. 中国地震, 4(2): 19—27.
XU Xi-wei, DENG Qi-dong.1988. The basin-range structure in the tensile area at the northern part of Shanxi Province and its mechanism of formation[J]. Earthquake Research in China, 4(2): 19—27(in Chinese).
[10] 徐锡伟, 韩竹军, 杨晓平, 等. 2016. 中国及邻区地震构造图[CM]. 北京: 地震出版社.
XU Xi-wei, HAN Zhu-jun, YANG Xiao-ping, et al. 2016. Seismotectonic Map of China and Its Adjacent Regions [CM]. Seismological Press, Beijing(in Chinese).
[11] 徐锡伟, 吴卫民, 张先康, 等. 2002. 首都圈地区地壳最新构造变动与地震 [M]. 北京: 科学出版社.
XU Xi-wei, WU Wei-min, ZHANG Xian-kang, et al. 2002. Latest Tectonic Deformation and Earthquakes in the Capital Circle Area [M]. Science Press, Beijing(in Chinese).
[12] 徐锡伟, 吴熙彦, 于贵华, 等. 2017. 中国大陆高震级地震危险区判定的地震地质学标志及其应用[J]. 地震地质, 39(2): 219—275. doi: 10.3969/j.issn.0253-4967.2017.02.001.
XU Xi-wei, WU Xi-yan, YU Gui-hua, et al.2017. Seismo-geological signatures for identifying M≥7.0 earthquake risk areas and their preliminary application in mainland China[J]. Seismology and Geology, 39(2): 219—275(in Chinese).
[13] 闫小兵, 周永胜, 李自红, 等. 2018. 1695年临汾7<inline-graphic xlink:href="0253-4967-42-2-399/img_12.jpg"/>级地震发震构造研究[J]. 地震地质, 40(4): 883—902. doi: 10.3969 /j.issn.0253-4967.2018.04.012.
YAN Xiao-bing, ZHOU Yong-sheng, LI Zi-hong, et al.2018. A study on the seismogenic structure of Linfen M7<inline-graphic xlink:href="0253-4967-42-2-399/img_13.jpg"/> earthquake in 1695[J]. Seismology and Geology, 40(4): 883—902(in Chinese).
[14] 张红艳, 谢富仁, 荆振杰. 2009. 京西北盆岭构造区现代构造应力场的非均匀特征[J]. 地球物理学报, 52(12): 3061—3071.
ZHANG Hong-yan, XIE Fu-ren, JING Zhen-jie.2009. Research on heterogeneity of the present tectonic stress field in the basin-and-range province northwest of Beijing[J]. Chinese Journal of Geophysics, 52(12): 3061—3071(in Chinese).
[15] 张培震, 邓起东, 张国民, 等. 2003. 中国大陆的强震活动与活动地块[J]. 中国科学(D辑), 33(S1): 12—20.
ZHANG Pei-zhen, DENG Qi-dong, ZHANG Guo-min, et al.2003. Active crustal blocks and strong earthquakes in continental China[J]. Science in China(Ser D), 33(S1): 12—20(in Chinese).
[16] Liang K, Ma B Q, Li D W, et al.2019. Quaternary activity of the Zhuozishan west piedmont fault provides insight into the structural development of the Wuhai Basin and northwestern Ordos Block, China[J]. Tectonophysics, 754:56—72.
[17] Middleton T A, Elliott J R, Rhodes E J, et al.2017. Extension rates across the northern Shanxi Grabens, China, from Quaternary geology, seismicity and geodesy[J]. Geophysical Journal International, 209(2): 535—558.
[18] Wan Y G, Shen Z K, Shang D, et al.2006. Crustal stress evolution over the past 700 years in North China and earthquake occurrence[J]. Earthquake Research in China, 20(3): 244—261.
[19] Xu X W, Ma X Y.1992. Geodynamics of the Shanxi rift system, China[J]. Tectonophysics, 208(1-3): 325—340.
[20] Xu X W, Ma X Y, Deng Q D.1993. Neotectonic activity along the Shanxi rift system, China[J]. Tectonophysics, 219(4): 305—325.
[21] Xu Y R, He H L, Deng Q D, et al.2018. The CE 1303 Hongdong earthquake and the Huoshan piedmont fault, Shanxi Graben: Implications for magnitude limits of normal fault earthquakes[J]. Journal of Geophysical Research: Solid Earth, 123(4): 3098—3121. doi: 10.1002/2017JB014928.
[22] Zhang H, He Z T, Ma B Q, et al.2017. The vertical slip rate of the Sertengshan piedmont fault, Inner Mongolia, China[J]. Journal of Asian Earth Sciences, 143:95—108.
[23] Zhang Y Q, Ma Y S, Yang N, et al.2003. Cenozoic extensional stress evolution in North China[J]. Journal of Geodynamics, 36(5): 591—613.
[24] Zhang Y Q, Mercier J L, Vergely P.1998. Extension in the graben systems around the Ordos(China), and its contribution to the extrusion tectonics of South China with respect to Gobi-Mongolia[J]. Tectonophysics, 285(1-2): 41—75.
[25] Zhao B, Zhang C H, Wang D Z, et al.2017. Contemporary kinematics of the Ordos block, North China and its adjacent rift systems constrained by dense GPS observations[J]. Journal of Asian Earth Sciences, 135:257—267.