PALEOSEISMOLOGY ON THE YEMAHE SEGMENT OF THE YEMAHE-DAXUESHAN FAULT REVEALED BY TRENCH STUDY

doi:10.3969/j.issn.0253-4967.2018.01.018

Abstract

Abstract: A series of NWW striking faults are obliquely intersected by the NEE striking Altyn Tagh fault zone in the western Qilian Mountains. These faults were mostly active in late Quaternary and play an important role in accommodating regional lateral extrusion by both reverse and sinistral slip. Detailed studies on late Quaternary activity, tectonic transformation, paleoseismology, and strain partitioning not only significantly affect our recognition on seismogenic mechanism and zones of potential large earthquakes, but also provide useful information for exploring tectonic deformation mechanism in the northern Tibetan plateau. The Danghenanshan Fault, Yemahe-Daxueshan fault, and Altyn Tagh Fault form a triplet junction point at southwest of Subei county. The Yemahe-Daxueshan fault is one important branch fault in the western Qilian Mountains that accommodated eastward decreasing slip of the Altyn Tagh Fault, which was active in late Holocene, with a length up to 170km. Based on geometry and late Quaternary activity, the Yemahe-Daxueshan fault was subdivided into 3 segments, i.e. the Subei fault, Yemahe fault and Daxueshan Fault. The Yemahe Fault has the most prominent appearance among them, and is dominated by left-lateral slip with a little normal component. The heights of fresh scarps on this fault are only several tens of centimeters. We dug 2 trenches at the Zhazhihu site, and cleaned and reinterpreted one trench of previous studies. Then we interpreted trench profiles and paleoseismic events, and collected ¹⁴C and Optical Stimulated Luminescence samples to constrain event ages. Finally, we determined 3 events on the Yemahe fault with ages(6 830±30) a BP-(6 280±40) a BP, (5 220±30) a BP, (2 010±30) a BP, respectively. The elapsed time of most recent earthquake is(2 010±30) years before present, which is very close to the recurrence interval, so the possibility of major earthquakes on the Yemahe fault is relatively large.

Key words: Yemahe-Daxueshan fault, paleoseismology, recurrence interval, Qilianshan fault

摘要： 野马河-大雪山断裂位于青藏高原东北缘祁连山西端，处于NEE向的阿尔金断裂向NW向的祁连山断裂转换的部位，是1条全新世活动断裂，全长170km。依据断裂几何学和活动特征可把该断裂分为3段，即肃北段、野马河段和大雪山段。野马河段是野马河-大雪山断裂带上活动性最强的段，断裂活动性质以左旋走滑为主，兼具正断层性质，至今保存了新鲜的断层陡坎，高度只有几十cm。通过野外地质调查，在扎子湖一带开挖了2个大探槽，清理了1个前人探槽。对这3个探槽进行了古地震事件分析和年代学样品的采集，最终确定有3次古地震事件发生，野马河断裂最后1次古地震事件的离逝时间为（2 010±30）a。

关键词: 野马河-大雪山断裂, 古地震, 复发间隔, 祁连山断裂

CLC Number:

P315.2

HE Wen-gui, ZHANG Bo, WU Ming, WANG Peng-tao, ZOU Xiao-bo, GAO Xiao-dong. PALEOSEISMOLOGY ON THE YEMAHE SEGMENT OF THE YEMAHE-DAXUESHAN FAULT REVEALED BY TRENCH STUDY[J]. SEISMOLOGY AND GEOLOGY, 2018, 40(1): 261-275.

何文贵, 张波, 吴明, 王朋涛, 邹小波, 高效东. 野马河-大雪山断裂野马河段探槽古地震特征[J]. 地震地质, 2018, 40(1): 261-275.

References

邓起东, 闻学泽. 2008. 活动构造研究:历史、进展与建议［J］. 地震地质, 30(1):1-30. doi:10.3969/j.issn.0253-4967.2008.01.002. DENG Qi-dong, WEN Xue-ze. 2008. A review on the research of active tectonics:History, progress and suggestions［J］. Seismology and Geology, 30(1):1-30(in Chinese).
国家地震局"阿尔金活动断裂带"课题组. 1992. 阿尔金活动断裂带［M］. 北京:地震出版社:1-319. Research Group of the Altyn Tagh Active Fault Zone, State Seismological Bureau. 1992. The Altyn Tagh Active Fault Zone［M］. Seismological Press, Beijing:1-319(in Chinese).
国家地震局地质研究所, 宁夏回族自治区地震局. 1990. 海原活动断裂带［M］. 北京:地震出版社:1-286. Institute of Geology of State Seismological Bureau and Seismological Bureau of Ningxia Hui Autonomous Region. 1990. The Haiyuan Active Fault Zone［M］. Seismological Press, Beijing:1-286(in Chinese).
毛凤英, 张培震. 1995. 古地震研究的逐次限定方法与新疆北部主要断裂带的古地震研究［G］//国家地震局地质研究所. 活动断裂研究(4). 北京:地震出版社:153-164. MAO Feng-ying, ZHANG Pei-zhen. 1995. Progressive constraining method in paleoseismologic study and paleoearthquakes along the major active faults in northern Xinjiang［G］//Institute of Geology, SSB. Research of Active Fault (4). Seismological Press, Beijing:153-164(in Chinese).
庞炜, 何文贵, 袁道阳, 等. 2015. 青海大柴旦断裂古地震特征［J］. 地球科学与环境学报, 37(3):87-103. PANG Wei, HE Wen-gui, YUAN Dao-yang, et al. 2015. Paleoseismic characteristics of Dachaidan Fault in Qinghai［J］. Journal of Earth Sciences and Environment, 37(3):87-103(in Chinese).
冉勇康, 王虎, 李彦宝, 等. 2012. 中国大陆古地震研究的关键技术与案例解析(1):走滑活动断裂的探槽地点、布设与事件识别标志［J］. 地震地质, 34(2):197-210. doi:10.3969/j.issn.0253-4967.2012.02.001. RAN Yong-kang, WANG Hu, LI Yan-bao, et al. 2012. Key techniques and several cases analysis in Paleoseismic studies in mainland China(1):Trenching sites, Layouts and Paleoseismic indicators on active strike-slip Faults［J］. Seismology and Geology, 34(2):197-210(in Chinese).
邵延秀. 2010. 祁连山西段野马河-党河南山断裂晚第四纪活动特征 F. 兰州:中国地震局兰州地震研究所:19-22. SHAO Yan-xiu. 2010. The activity features during late Quaternary of Yema River:Danghe Nan Shan faults in western Qilian Shan F. Lanzhou Institute of Seismology, Lanzhou:19-22(in Chinese).
王根厚, 李明, 冉书明, 等. 2001. 转换断层及其地质意义:以阿尔金转换断层为例［J］. 成都理工学院学报, 28(2):183-186. WANG Gen-hou, LI Min, RAN Shu-ming, et al. 2001. Transform Fault and its geological significance:A study on the Altyn Tagh transform fault［J］. Journal of Chengdu University of Technology, 28(2):183-186(in Chinese).
吴明. 2017. 野马河-大雪山断裂分段活动性研究F. 兰州:中国地震局兰州地震研究所:1-97. WU Ming. 2017. Study on the segmental activities of the Yema He-Daxue Shan Fault F. Lanzhou Institute of Seismology, Lanzhou:1-97(in Chinese).
徐锡伟, 计凤桔, 于贵华, 等. 2000. 用钻孔地层剖面记录恢复古地震序列:河北夏垫断裂古地震研究［J］. 地震地质, 22(1):9-19. doi:10.3969/j.issn.0253-4967.2000.01.002. XU Xi-wei, JI Feng-ju, YU Gui-hua, et al. 2000. Reconstruction of paleoearthquake sequence using stratigraphic records from drill logs:A study at the Xiadian Fault, Beijing［J］. Seismology and Geology, 22(1):9-19(in Chinese).
徐锡伟, Tapponnier P, Van Der Woerd J, 等. 2003. 阿尔金断裂带晚第四纪左旋走滑速率及其构造运动转换模式讨论［J］. 中国科学(D辑), 33(10):967-974. XU Xi-wei, Tapponnier P, Van Der Woerd J, et al. 2003. Late Quaternary sinistral slip rate along the Altyn Tagh Fault and its structural transformation mode［J］. Science in China(Ser D), 48(3):384-397.
赵朋. 2009. 肃北地区主要断裂晚第四纪活动特征研究 F. 北京:中国地震局地质研究所:1-88. ZHAO Peng. 2009. Active characteristics study of major faults in the Subei region in the late Quaternary F. Institute of Geology of China Earthquake Administration. 1-88(in Chinese).
赵朋, 闵伟, 焦德成, 等. 2009. 肃北野马河北侧断裂地貌特征及其晚第四纪活动性［J］. 地震地质, 31(3):459-469. doi:10.3969/j.issn.0253-4967.2009.03.008. ZHAO Peng, MIN Wei, JIAO De-cheng, et al. 2009. Geomorphologic character and Quaternary activity of the north of Yemahe Fault in Subei［J］. Seismology and Geology, 31(3):459-469(in Chinese).
Luo H, He W G, Yuan D Y, et al. 2015. Slip rate of Yema River-Daxue Mountain Fault since the Late Pleistocene and its implications on the deformation of the northeastern margin of the Tibetan plateau［J］. Acta Geologica Sinica(English Edition), 89(2):56-574.
Meyer B, Tapponnier P, Bourjot L, et al. 1998. Crustal thickening in Gansu-Qinghai, lithospheric mantle subduction, and oblique, strike-slip controlled growth of the Tibet Plateau［J］. Geophysical Journal International, 135(1):1-47.
Peltzer G, Tapponnier P, Armijo R. 1989. Magnitude of late Quaternary left-lateral displacements along the north edge of Tibet［J］. Science, 246(4935):1285-1289.
Tapponnier P, Molnar P. 1977. Active faulting and tectonics in China［J］. Journal of Geophysical Research, 82(20):2905-2930.
Van der Woerd J, Xu X W, Li H B, et al. 2001. Rapid active thrusting along the northwestern range front of Tanghe Nan Shan(Western Gansu, China). Journal of Geophysical Research, 106(B12):30475-30504.

[1]	LI Xi, RAN Yong-kang, WU Fu-yao, MA Xing-quan, ZHANG Yan-qi, CAO Jun. RUPTURE CHARACTERISTICS OF LATE QUATERNARY STRONG EARTHQUAKES ON THE WESTERN BRANCH OF THE XIAOJIANG FAULT ZONE [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(6): 1179-1203.
[2]	DONG Shao-peng, ZHANG Pei-zhen, ZHENG Wen-jun, YU Zhong-yuan, LEI Qi-yun, YANG Hui-li, LIU Jin-feng, GONG Hui-ling. PALEOSEISMOLOGICAL RESEARCH ON THE LANGSHAN RANGE-FRONT FAULT, HETAO AREA, CHINA: INSIGHTS FOR STUDIES ON TECTONICS AND SEISMIC RISK [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(6): 1216-1239.
[3]	WANG Ming-ming, HE Yu-lin, LIU Shao, WANG Shi-yuan, MA Chao, ZHANG Wei, JIA Zhao-liang. LATE QUATERNARY ACTIVITY AND PALEOSEISMIC RUPTURE BEHAVIOR FOR THE SOUTHEAST SECTION OF THE GANZI-YUSHU FAULT [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(4): 738-752.
[4]	DING Rui, REN Jun-jie, ZHANG Shi-min, LÜ Yan-wu, LIU Han-yong. LATE QUATERNARY PALEOEARTHQUAKES ON THE MIDDLE SEGMENT OF THE LIJIANG-XIAOJINHE FAULT, SOUTHEASTERN TIBET [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(3): 622-640.
[5]	XU Jian-hong, HUI Xu-hui, CHENG Hong-bin, ZHANG Xiao-liang, SHANG Si-qi. PALEOSEIMOLOGY AND LATE QUATERNARY SLIP RATE OF THE YOUSHASHAN FAULT AT SOUTHWESTERN MARGIN OF QAIDAM BASIN [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(2): 465-479.
[6]	YU Zhong-yuan, ZHANG Pei-zhen, MIN Wei, WEI Qing-hai, LIU Yu-gang, LIU Shuang. LATE HOLOCENE AVERAGE RECURRENCE INTERVAL OF GREAT EARTHQUAKES OF SHANGZHI PART OF THE YILAN-YITONG FAULT ZONE, NE CHINA: CONSTRAINTS FROM PALEO-EARTHQUAKES AND HISTORICAL WRITTEN RECORDS [J]. SEISMOLOGY AND GEOLOGY, 2016, 38(4): 844-861.
[7]	WEI Lei-hua, HE Hong-lin, JIANG Han-chao, XU Yue-ren, WEI Zhan-yu, GAO Wei, ZOU Jun-jie. significance of high-resolution loess stratification based on grain size and magnetic susceptibility analysis to paleo-earthquake study: a case study of dongyugou loess section, at hongtong, shanxi province [J]. SEISMOLOGY AND GEOLOGY, 2015, 37(4): 1096-1114.
[8]	LI Yan-hao, JIANG Han-chao, XU Hong-yan, LIANG Lian-ji. analyses on the triggering facrors of large quantities of landslides in the upper reaches of the minjiang river, sichuan province [J]. SEISMOLOGY AND GEOLOGY, 2015, 37(4): 1147-1161.
[9]	ZHU Ai-yu, ZHANG Dong-ning, JIANG Chang-sheng, LI Ming. THE NUMERICAL SIMULATION OF THE STRAIN ENERGY DENSITY CHANGING RATE AND STRONG EARTHQUAKE RECURRENCE INTERVAL OF THE SICHUAN-YUNNAN BLOCK [J]. SEISMOLOGY AND GEOLOGY, 2015, 37(3): 906-927.
[10]	RAN Yong-kang, WANG Hu, YANG Hui-li, XU Liang-xin. KEY TECHNIQUES AND SEVERAL CASES ANALYSIS IN PALEOSEISMIC STUDIES IN MAINLAND CHINA(4) —SAMPLING AND EVENT ANALYSIS OF PALEOSEISMIC DATING METHODS [J]. SEISMOLOGY AND GEOLOGY, 2014, 36(4): 939-955.
[11]	WANG Hu, RAN Yong-kang, LI Yan-bao, CHEN Li-chun. PALEOSEISMIC BEHAVIOR OF THE ANNINGHE FAULT AND ITS COMPARISON WITH THE ZEMUHE FAULT IN WESTERN SICHUAN [J]. SEISMOLOGY AND GEOLOGY, 2014, 36(3): 706-717.
[12]	HUANG Xiu-ming. THE METHOD OF LATENT DEVELOPMENT LEVEL OF EARTHQUAKE-PREGNANT STRUCTURES AND THE ANALYSIS OF RELEVANT SEISMOGEOLOGICAL INFORMATION [J]. SEISMOLOGY AND GEOLOGY, 2012, (3): 500-515.
[13]	BAI Yu-zhu, XU Jie, ZHOU Qing, ZHOU Ben-gang. THE PRELIMINARY RESEARCH ON RUPTURE AND FACTORS AFFECTING RUPTRUING OF HOH SAI HU SEGMENT IN EASTERN KUNLUNSHAN [J]. SEISMOLOGY AND GEOLOGY, 2012, (2): 269-281.
[14]	HUANG Xiu-ming. PRELIMINARY RESEARCH ON PALAEOSEISMIC TRACES IN KARST CAVES [J]. SEISMOLOGY AND GEOLOGY, 2004, 26(2): 281-292.
[15]	Min Wei, Zhang Peizhen, Deng Qidong. THE STUDY OF HOLOCENE PALEOEARTHQUAKES ON ZHONGWEI TONGXIN FAULT ZONE [J]. SEISMOLOGY AND EGOLOGY, 2001, 23(3): 357-366.