安宁河断裂紫马跨一带晚第四纪地貌变形与断层位移速率
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摘要
紫马跨一带是安宁河断裂北段晚第四纪断错地层地貌序列保存最好的地区,通过数字影像分析、全站仪实测和探槽开挖,对该地点断错现象进行细致研究,获得了晚全新世以来的左旋位移速率为6·2mm/a,垂直位移速率1·4mm/a;距今约10ka以来的平均左旋位移速率3·6~4·0mm/a,垂直位移速率约为1·1mm/a;距今约20ka以来的左旋位移速率为3·8~4·2mm/a,垂直位移速率最小为0·9mm/a。断层水平和垂直位移速率的比例约为4∶1。断层位移速率在时间分布上的变化与古地震研究的丛集复发特征有较好的一致性,反映断裂的活动强度存在强弱活动的交替现象。
The Anninghe Fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block,and the study of its distribution feature of displacement rates in the late Quaternary is of fundamental importance for understanding the dynamic theory on Chinese continent,boundary dynamic process of the active block and the recurrence interval of large earthquakes. The active Anninghe Fault in late Quaternary has the length of 160km and consists of two segments. Zimakua is an area where the latest neotectonic rupture trajectories are relatively simple and the offset geomorphologic sequences are well developed. Using the methods of detailed geomorphic and geological survey,digital image analysis,total station instrument survey,excavation of trench and dating,the paper makes an analysis on the geomorphologic sequences of the strata and obtains some new results as follows: The terrace(step)T3 consisting of moraine deposits was formed at about 20kaBP and offset by the Anninghe Fault with a left-lateral displacement of (84±3)m and a vertical displacement of 18m. On the base of the moraine deposits overlies terrace(step)T2 of mainly alluvial deposits formed at 10～7kaBP with the maximum left-lateral displacement of about 40m,an average of (36±4)m,and a vertical displacement of about 11m. Terrace T1 is composed mainly of the alluvium and partial dammed-pond deposits which were formed during 3～2.2kaBP. The earliest event that offset the T1 happened at 1.7kaBP.Three events have been discovered since 1.7kaBP and the cumulative left-lateral displacement is 10.5m and the vertical displacement 2.3m. So,the left-lateral displacement rates are 6.2mm/a,3.6～4mm/a,3.8～4.2mm/a and the vertical rates are 1.4mm/a,1.1mm/a,0.9mm/a(at least)on average in about 2.6ka,10ka and 20ka,respectively. The proportion of horizontal to vertical displacements is about 4 ∶1. That means the vertical rate on Anninghe Fault is about 25% of horizontal slip rate. The left-lateral slip rate in late Holocene is well consistent with GPS measurement. The change of the left-lateral rates in different stage is also consistent with recurrence interval of paleoearthquakes. It means that there is alternation between strong and weak activities of the Anninghe Fault.
The Anninghe Fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block,and the study of its distribution feature of displacement rates in the late Quaternary is of fundamental importance for understanding the dynamic theory on Chinese continent,boundary dynamic process of the active block and the recurrence interval of large earthquakes. The active Anninghe Fault in late Quaternary has the length of 160km and consists of two segments. Zimakua is an area where the latest neotectonic rupture trajectories are relatively simple and the offset geomorphologic sequences are well developed. Using the methods of detailed geomorphic and geological survey,digital image analysis,total station instrument survey,excavation of trench and dating,the paper makes an analysis on the geomorphologic sequences of the strata and obtains some new results as follows: The terrace(step)T3 consisting of moraine deposits was formed at about 20kaBP and offset by the Anninghe Fault with a left-lateral displacement of (84±3)m and a vertical displacement of 18m. On the base of the moraine deposits overlies terrace(step)T2 of mainly alluvial deposits formed at 10～7kaBP with the maximum left-lateral displacement of about 40m,an average of (36±4)m,and a vertical displacement of about 11m. Terrace T1 is composed mainly of the alluvium and partial dammed-pond deposits which were formed during 3～2.2kaBP. The earliest event that offset the T1 happened at 1.7kaBP.Three events have been discovered since 1.7kaBP and the cumulative left-lateral displacement is 10.5m and the vertical displacement 2.3m. So,the left-lateral displacement rates are 6.2mm/a,3.6～4mm/a,3.8～4.2mm/a and the vertical rates are 1.4mm/a,1.1mm/a,0.9mm/a(at least)on average in about 2.6ka,10ka and 20ka,respectively. The proportion of horizontal to vertical displacements is about 4 ∶1. That means the vertical rate on Anninghe Fault is about 25% of horizontal slip rate. The left-lateral slip rate in late Holocene is well consistent with GPS measurement. The change of the left-lateral rates in different stage is also consistent with recurrence interval of paleoearthquakes. It means that there is alternation between strong and weak activities of the Anninghe Fault.
引文
陈桂华.2006.川滇块体东边界活动构造带的构造转换与变形分解作用[D]:[学位论文].北京:中国地震局地质研究所.CHEN Gui-hua.2006.Structure transformation and strain partitioning along the northeast boundary belt of the Sichuan-Yunnan block[D].Ph D thesis.Institute of Geology,CEA,Beijing(in Chinese).
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冉勇康,程建武,宫会玲,等.2008.安宁河断裂冕宁以北晚第四纪地表变形与强震破裂行为[J].中国科学(D辑)(出版中).RAN Yong-kang,CHENG Jian-wu,GONG Hui-ling,et al.2008.Late Quaternary surface deformation and rupturebehavior of strong earthquake on the segment north of Mianning of the Anninghe Fault[J].Science in China(SerD),(in press).
申重阳,王琪.2002.川滇菱形块体主要边界运动模型的GPS数据反演分析[J].地球物理学报,45(3):352—361.SHEN Chong-yang,WANG Qi.2002.GPS inversion of kinematic model of the main boundaries of the rhombus blockin Sichuan and Yunnan[J].Chinese J Geophys,45(3):352—361(in Chinese).
宋方敏,汪一鹏,俞维贤.1998.小江活动断裂带[M].北京:地震出版社.237.SONG Fang-min,WANG Yi-peng,YU Wei-xian,et al.1998.The Active Xiaojiang Fault Zone[M].SeismologicalPress,Beijing.237(in Chinese).
唐荣昌,钱洪,黄祖智,等.1992.安宁河断裂北段晚更新世以来的分段活动特征[J].中国地震,8(3):60—67.TANG Rong-chang,QIAN Hong,HUANG Zu-zhi,et al.1992.The segmentation characteristics of late Pleistocenemovement of the northern segment of Anninghe Fault[J].Earthquake Research in China,8(3):60—67(inChinese).
闻学泽,杜平山,龙德雄.2000.安宁河断裂带小相岭段古地震的新证据及最晚事件的年代[J].地震地质,22(1):1—8.WEN Xue-ze,DU Ping-shan,LONG De-xiong.2000.Newevidence of paleoearthquakes and date of the latest event onthe Xiaoxiangling mountain segment of the Anninghe Fault zone[J].Seismology and Geology,22(1):1—8(inChinese).
闻学泽.2000.四川西部鲜水河-安宁河-则木河断裂带的地震破裂分段特征[J].地震地质,22(3):239—249.WEN Xue-ze.2000.Character of rupture segmentation of the Xianshuihe-Anninghe-Zemuhe Fault zone,westernSichuan[J].Seismology and Geology,22:(3)239—249(in Chinese).
王新民,张成贵,裴锡瑜.1998.安宁河活动断裂带的新活动性[J].四川地震,(4):13—33.WANG Xin-min,ZHANG Cheng-gui,PEI Xi-yu.1998.The neo-activity of the Anninghe active fault zone[J].Earthquake Research in Sichuan,(4):13—33(in Chinese).
徐锡伟,闻学泽,郑荣章,等.2003.川滇地区活动块体最新构造变形样式及其动力来源[J].中国科学,33(4):151—162.XUXi-wei,WEN Xue-ze,ZHENG Rong-zhang,et al.2003.Recent tectonic deformation pattern and dynamics of theactive crustal block in the Sichuan-Yunnan region[J].Science in China(Ser D),33(4):151—162(in Chinese).
徐锡伟,张培震,闻学泽.2005.川西及其邻近地区活动构造基本特征与强震复发模型[J].地震地质,27(3):446—461.XU Xi-wei,ZHANG Pei-zhen,WEN Xue-ze.2005.Features of active tectonics and recurrence behaviors of strongearthquakes in the western Sichuan Province and its adjacent regions[J].Seismology and Geology,27(3):446—461(in Chinese).
徐孝彬,王建,朱捷,等.2004.利用宇宙核素测年技术对青藏高原东南部冰蚀面年代的研究[J].地理科学,24(1):101—104.XU Xiao-bin,WANG Jian,ZHU Jie,et al.2004.Study on glacial erosion surface of the Southeast of plateau usingcosmogenic isotopes dating[J].Scientia Geographica Sinica,24(1):101—104(in Chinese).
张培震,王敏,甘卫军.2003.GPS观测的活动断裂滑动速率及其对现今大陆动力作用的制约[J].地学前缘,10(特刊):81—92.ZHANG Pei-zhen,WANG Min,GAN Wei-jun,et al.2003.Slip rates along major active faults from GPS measurements andconstraints on contemporary continental tectonics[J].Earth Science Frontiers,10(suppl):81—92(in Chinese).
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,33(增刊):12—20.ZHANG Pei-zhen,DENG Qi-dong,ZHANG Guo-min,et al.2003.Strong seismicity and active blocks in continentalChina[J].Science in China(Ser D),33(suppl):12—20(in Chinese).
周荣军,何玉林,杨涛.2001.鲜水河-安宁河断裂带磨西-冕宁段的滑动速率与强震位错[J].中国地震,17(3):253—262.ZHOURong-jun,HE Yu-lin,YANG Tao.2001.Slip rate and strong earthquake displacement along the Moxi-Mianningsegment of the Xianshuihe-Anninghe Fault zone[J].Earthquake Research in China,17(3):253—262(in Chinese).
McCalpin J P.1996.Paleoseismology[M].Academic Press,San Diego.588.
Wallace R E.1970.Earthquake recurrence intervals on the San Andreas Fault[J].Geol Soc Am Bull,81:2875—2890.
邓起东,张培震,冉勇康,等.2002.中国活动构造基本特征[J].中国科学,32(12):1020—1030.DENG Qi-dong,ZHANG Pei-zhen,RAN Yong-kang,et al.2002.Basic characteristics of active tectonics of China[J].Science in China,32(12):1020—1030(in Chinese).
李天祒,杜其方,游泽李,等.1997.鲜水河活动断裂带及强震危险性评估[M].成都:成都地图出版社.LI Tian-shao,YU Qi-fang,YOU Ze-li,et al.1997.The active Xianshuihe Fault zone and seismic risk assessment[M].Cartographic Publishing House of Chengdu,Chengdu(in Chinese).
吕江宁,沈正康,王敏.2003.川滇地区现代地壳运动速度场和活动块体模型研究[J].地震地质,25(4):543—554.L Jiang-ning,SHEN Zheng-kang,WANG Min.2003.Contemporary crustal deformation and active tectonic blockmodel of the Sichuan-Yunnan region,China[J].Seismology and Geology,25(4):543—554(in Chinese).
裴锡瑜,王新民,张成贵.1997.晚第四纪安宁河断裂分段的基本特征[J].四川地震,(4):52—61.PEI Xi-yu,WANG Xin-min,ZHANG Cheng-gui.1997.Basic character of segmentation of late Quaternary movement onthe Anninghe Fault[J].Earthquake Research in Sichuan,(4):52—61(in Chinese).
钱洪,伍先国,马声浩,等.1990.安宁河断裂带北段的古地震事件及其在地震研究中的意义[J].中国地震,6(4):43—49.QIAN Hong,WU Xian-guo,MA Sheng-hao,et al.1990.The paleoseismic events on the northern segment of theAnninghe Fault zone and their significance in earthquake study[J].Earthquake Research in China,6(4):43—49(in Chinese).
冉勇康,程建武,宫会玲,等.2008.安宁河断裂冕宁以北晚第四纪地表变形与强震破裂行为[J].中国科学(D辑)(出版中).RAN Yong-kang,CHENG Jian-wu,GONG Hui-ling,et al.2008.Late Quaternary surface deformation and rupturebehavior of strong earthquake on the segment north of Mianning of the Anninghe Fault[J].Science in China(SerD),(in press).
申重阳,王琪.2002.川滇菱形块体主要边界运动模型的GPS数据反演分析[J].地球物理学报,45(3):352—361.SHEN Chong-yang,WANG Qi.2002.GPS inversion of kinematic model of the main boundaries of the rhombus blockin Sichuan and Yunnan[J].Chinese J Geophys,45(3):352—361(in Chinese).
宋方敏,汪一鹏,俞维贤.1998.小江活动断裂带[M].北京:地震出版社.237.SONG Fang-min,WANG Yi-peng,YU Wei-xian,et al.1998.The Active Xiaojiang Fault Zone[M].SeismologicalPress,Beijing.237(in Chinese).
唐荣昌,钱洪,黄祖智,等.1992.安宁河断裂北段晚更新世以来的分段活动特征[J].中国地震,8(3):60—67.TANG Rong-chang,QIAN Hong,HUANG Zu-zhi,et al.1992.The segmentation characteristics of late Pleistocenemovement of the northern segment of Anninghe Fault[J].Earthquake Research in China,8(3):60—67(inChinese).
闻学泽,杜平山,龙德雄.2000.安宁河断裂带小相岭段古地震的新证据及最晚事件的年代[J].地震地质,22(1):1—8.WEN Xue-ze,DU Ping-shan,LONG De-xiong.2000.Newevidence of paleoearthquakes and date of the latest event onthe Xiaoxiangling mountain segment of the Anninghe Fault zone[J].Seismology and Geology,22(1):1—8(inChinese).
闻学泽.2000.四川西部鲜水河-安宁河-则木河断裂带的地震破裂分段特征[J].地震地质,22(3):239—249.WEN Xue-ze.2000.Character of rupture segmentation of the Xianshuihe-Anninghe-Zemuhe Fault zone,westernSichuan[J].Seismology and Geology,22:(3)239—249(in Chinese).
王新民,张成贵,裴锡瑜.1998.安宁河活动断裂带的新活动性[J].四川地震,(4):13—33.WANG Xin-min,ZHANG Cheng-gui,PEI Xi-yu.1998.The neo-activity of the Anninghe active fault zone[J].Earthquake Research in Sichuan,(4):13—33(in Chinese).
徐锡伟,闻学泽,郑荣章,等.2003.川滇地区活动块体最新构造变形样式及其动力来源[J].中国科学,33(4):151—162.XUXi-wei,WEN Xue-ze,ZHENG Rong-zhang,et al.2003.Recent tectonic deformation pattern and dynamics of theactive crustal block in the Sichuan-Yunnan region[J].Science in China(Ser D),33(4):151—162(in Chinese).
徐锡伟,张培震,闻学泽.2005.川西及其邻近地区活动构造基本特征与强震复发模型[J].地震地质,27(3):446—461.XU Xi-wei,ZHANG Pei-zhen,WEN Xue-ze.2005.Features of active tectonics and recurrence behaviors of strongearthquakes in the western Sichuan Province and its adjacent regions[J].Seismology and Geology,27(3):446—461(in Chinese).
徐孝彬,王建,朱捷,等.2004.利用宇宙核素测年技术对青藏高原东南部冰蚀面年代的研究[J].地理科学,24(1):101—104.XU Xiao-bin,WANG Jian,ZHU Jie,et al.2004.Study on glacial erosion surface of the Southeast of plateau usingcosmogenic isotopes dating[J].Scientia Geographica Sinica,24(1):101—104(in Chinese).
张培震,王敏,甘卫军.2003.GPS观测的活动断裂滑动速率及其对现今大陆动力作用的制约[J].地学前缘,10(特刊):81—92.ZHANG Pei-zhen,WANG Min,GAN Wei-jun,et al.2003.Slip rates along major active faults from GPS measurements andconstraints on contemporary continental tectonics[J].Earth Science Frontiers,10(suppl):81—92(in Chinese).
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,33(增刊):12—20.ZHANG Pei-zhen,DENG Qi-dong,ZHANG Guo-min,et al.2003.Strong seismicity and active blocks in continentalChina[J].Science in China(Ser D),33(suppl):12—20(in Chinese).
周荣军,何玉林,杨涛.2001.鲜水河-安宁河断裂带磨西-冕宁段的滑动速率与强震位错[J].中国地震,17(3):253—262.ZHOURong-jun,HE Yu-lin,YANG Tao.2001.Slip rate and strong earthquake displacement along the Moxi-Mianningsegment of the Xianshuihe-Anninghe Fault zone[J].Earthquake Research in China,17(3):253—262(in Chinese).
McCalpin J P.1996.Paleoseismology[M].Academic Press,San Diego.588.
Wallace R E.1970.Earthquake recurrence intervals on the San Andreas Fault[J].Geol Soc Am Bull,81:2875—2890.
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