东昆仑断裂带西大滩段全新世古地震研究
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摘要
对东昆仑断裂带西大滩段进行了断错地貌填图和古地震探槽揭露,共揭露出6次古地震事件,它们的年龄分别为10302±651 aB.P.,8650±500 aB.P.,7160±506 aB.P.,2830±170 aB.P.,1985±121 aB.P.和1540±92 aB.P.;古地震重复间隔分别为1652±820 a,1490±711 a,4330±534 a,845±209 a和445±152 a。研究发现,西大滩段全新世古地震活动具有丛集现象和重复间隔时间的分段性,第1丛集期在10300~7100 aB.P.期间,平均重复间隔1571±543 a,第2丛集期在2800~1500 aB.P.期间,重复间隔400~800 a左右,平均重复间隔645±129 a,两个丛集期间隔4300 a。西大滩段全新世地震活动规律对昆仑山地区未来地震危险性评估具有重要意义。
The East Kunlun Fault zone in Northern Tibetan Plateau is a typical active fault zone,characterized by sinistral strike-slip faults.The field investigation has reveals a lot of relics along the fault traces of the Xidatan-Dongdatan segment of the Kunlun Fault,including push-up and pull-apart basins,sag pond,and earthquake fault scarps.They imply that the Xidatan-Dongdatan segment of the Kunlun Fault is a seismogenic fault in which surface-rupturing earthquakes often occured in regular or irregular intervals.To determine the chronology of Holocene surface ruptures of this part of the Kunlun Fault,four trenches were excavated across the Xidatan-Dongdatan segment at Xiaonanchuan near Xidatan Town and Jingxian Valley near Kunlun Pass,respectively.All sediment samples collected from the trenches were dated by using thermoluminescence(TL) and optically stimulated luminescence(OSL) methods.Paleoseismic evidence,combined with the optically stimulated luminescence(OSL) and thermoluminescence(TL) dating of sediments and collapse units from the trenches,shows that the Xidatan segment of the Kunlun Fault zone has generated at least 6 earthquakes during the Holocene,whose ages are 10302±651aB.P.,8650±500aB.P.,7160±506aB.P.,2830±170aB.P.,1985±121aB.P.,and 1540±92aB.P.respectively.The recurrence interval between two adjacent events is 1652±820a,1490±711a,4330±534a,845±209a,and 445±152a respectively.It shows that the recurrence is not uniform with time,that is,the distribution of paleoearthquakes on the Xidatan segment of the Kunlun Fault is characterized by clustering.The Holocene is divided into two subperiods in terms of paleoseismic evidence,the Early Holocene characterized by a recurrence interval of 1571±543a,and the Late Holocene characterized by a higher frequency of tectonic events and a recurrence interval of 645±129a. This result suggests that the Xidatan segment of the fault had displayed a time-dependent seismic behavior.The current research has significant implications for seismic hazard assessment in the Xidatan-Dongdatan segment of the fault,which stretches for 250km.The last large event occurred before 1540±92a,combined with the eastward motion of the Tibetan Plateau along the fault,underscore the possibility that the Xidatan segment of the Kunlun Fault may be a site of major faulting in the near future.
The East Kunlun Fault zone in Northern Tibetan Plateau is a typical active fault zone,characterized by sinistral strike-slip faults.The field investigation has reveals a lot of relics along the fault traces of the Xidatan-Dongdatan segment of the Kunlun Fault,including push-up and pull-apart basins,sag pond,and earthquake fault scarps.They imply that the Xidatan-Dongdatan segment of the Kunlun Fault is a seismogenic fault in which surface-rupturing earthquakes often occured in regular or irregular intervals.To determine the chronology of Holocene surface ruptures of this part of the Kunlun Fault,four trenches were excavated across the Xidatan-Dongdatan segment at Xiaonanchuan near Xidatan Town and Jingxian Valley near Kunlun Pass,respectively.All sediment samples collected from the trenches were dated by using thermoluminescence(TL) and optically stimulated luminescence(OSL) methods.Paleoseismic evidence,combined with the optically stimulated luminescence(OSL) and thermoluminescence(TL) dating of sediments and collapse units from the trenches,shows that the Xidatan segment of the Kunlun Fault zone has generated at least 6 earthquakes during the Holocene,whose ages are 10302±651aB.P.,8650±500aB.P.,7160±506aB.P.,2830±170aB.P.,1985±121aB.P.,and 1540±92aB.P.respectively.The recurrence interval between two adjacent events is 1652±820a,1490±711a,4330±534a,845±209a,and 445±152a respectively.It shows that the recurrence is not uniform with time,that is,the distribution of paleoearthquakes on the Xidatan segment of the Kunlun Fault is characterized by clustering.The Holocene is divided into two subperiods in terms of paleoseismic evidence,the Early Holocene characterized by a recurrence interval of 1571±543a,and the Late Holocene characterized by a higher frequency of tectonic events and a recurrence interval of 645±129a. This result suggests that the Xidatan segment of the fault had displayed a time-dependent seismic behavior.The current research has significant implications for seismic hazard assessment in the Xidatan-Dongdatan segment of the fault,which stretches for 250km.The last large event occurred before 1540±92a,combined with the eastward motion of the Tibetan Plateau along the fault,underscore the possibility that the Xidatan segment of the Kunlun Fault may be a site of major faulting in the near future.
引文
1 Van D erW oerd J,Tapponn ier P,Ryerson F Jet a.l Un iformpostglacial slip-rate along the Kun lun fau lt(Tibet),from26A l,10Beand14C dating of riser offsets,and climatic origin of the regionalmorphology.Geophysical Journal Internationa,l 2002,148:356~388
2陈杰,陈宇坤,丁国瑜等.2001年昆仑山口西8.1级地震地表破裂带.第四纪研究,2003,23(6):629~639Chen Jie,Chen Yukun,D ing Guoyuet al.Surface rupture zones ofthe 2001 earthquakeMS8.1 west ofKun lun Pass,northern Q inghai-X izang P lateau.Quaternary Sciences,2003,23(6):629~639
3徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库赛湖地震(MS8.1)地表破裂带的基本特征.地震地质,2002,24(1):1~13Xu X iwei,Chen W enb in,Yu Gu ihuaet a.l Characteristic featuresof the surface ruptures of the Hoh SaiHu(Kun lunshan)earthquake(MS8.1)northern Tibetan P lateau,Ch ina.Seism ology andGeology,2002,24(1):1~13
4中国地震局编,宋瑞祥主编.中国昆仑山口西8.1级地震图集.北京:地震出版社,2003.1~105Ch ina Seismological Bureau,Song Ru ixiang eds.A lbum of theKun lun PassW.MS8.1 Earthquake,Ch ina.Beijing:SeismologicalPress,2003.1~105
5任金卫,汪一鹏,吴章明等.青藏高原北部库玛断裂东、西大滩全新世地震形变带及其位移特征和水平滑动率.地震地质,1993,15(3):285~288Ren Jinwei,W ang Y ipeng,W u Zhangm inget al.Holoceneearthquake deformation zones and their d isplacem ent and slip ratealong the X idatan-Dongdatan of Kusaihu-Maqu fau lt in NorthernQ inghai-X izang P lateau.Seism ology and Geology,1993,15(3):285~288
6任金卫,王敏.GPS观测的2001年昆仑山口西MS8.1级地震地壳变形.第四纪研究,2005,25(1):34~44Ren Jinwei,W ang M in.GPS m easured crustal deformation of theMS8.1 Kun lun earthquake on November 14 th 2001 in Q inghai-X izang P lateau.Quaternary Sciences,2005,25(1):34~44
7 Van D erW oerd J,Ryerson F J,Tapponn ier Pet al.Holocene leftslip-rate determ ined by cosmogen ic surface dating on the X idatansegm ent of the Kun lun fau lt(Q inghai,Ch ina).Geology,1998,26(8):695~698
8田勤俭,丁国瑜.青藏高原北部第四纪早期断裂活动的新生性变化初步研究.第四纪研究,2006,26(1):32~39Tian Q in jian,D ing Guoyu.Prelim inary analysis on an EarlyQuaternary new fau lt trace in North of Tibetan P lateau.QuaternarySciences,2006,26(1):32~39
9胡道功,赵希涛,尹功明等.昆仑山口羌塘组湖相层的ESR年龄测定.第四纪研究,2004,24(3):366~367Hu Daogong,Zhao X itao,Y in Gongm inget al.ESR dating of thelacustrine deposits of Q iangtang Formation from the Kun lunMountains Pass areas.Quaternary Sciences,2004,24(3):366~367
10青海省地震局,中国地震局地壳应力研究所编.东昆仑活动断裂带.北京:地震出版社,1999.1~186Seismological Bureau of Q inghai Province,Institute of C rustalDynam ics,Ch ina Seismological Bureau eds.Eastern Kun lun ActiveFau lt Zone.Beijing:Seismological Press,1999.1~186
11 Cu i Zh ijiu,W u Yongq iu,L iu Gengn ianet a.l On Kun lun-YellowR iver tecton ic movem ent.Scinece in China(Series D),1998,41(6):592~600
12吴珍汉,胡道功,吴中海等.青藏高原中段活动断层及诱发地质灾害.北京:地质出版社,2005.188~250W u Zhenhan,Hu Daogong,W u Zhonghaiet a.l Active Fau lts andGeological Hazards along the Golmud-Lhasa Railway across theTibetan P lateau.Beijing:Geological Pub lish ing House,2005.188~250
13崔之久,伍永秋,刘耕年等.昆仑山垭口地区晚新生代以来的气候构造事件.见:青藏项目专家委员会编.青藏高原形成演化、环境变迁与生态系统研究.北京:科学出版社,1996.74~84Cu i Zh ijiu,W u Yongq iu,L iu Gengn ianet al.The climatic andtecton ic events in the Kun lun Mountains Pass areas,Q inghaiProvince,since the Late Cenozoic.In:The Expert Comm ittee on theQ ingzang Program ed.Study on the Formation and Evolution of theQ inghai-X izang P lateau,Environm ent Change and EcologicalSystem.Beijing:Science Press,1996.74~8414伍永秋,崔之久,刘耕年等.昆仑山垭口地区的冰期系列.冰川冻土,1999,21(1):71~76W u Yongq iu,Cu i Zh ijiu,L iu Gengn ianet a.l G laciation sequencesin the Kun lunshan Pass area.Journal ofGeology and Geocryology,1999,21(1):71~76
15李虎侯.热释光断代.香港:国际科学出版有限公司.1999.1~55L iHuhou.Thermolum inesecene Dating.Hong Kong:Scientist PressInternational,Inc.1999.1~55
16王峰,王驹,范洪海等.甘肃北山旧井地区晚第四纪活动断裂分布及其构造意义.地质论评,2005,51(3):250~255W ang Feng,W ang Ju,Fan Honghaiet a.l D istrbution of LateQuaternary active fau lts and its tecton ic sign ificance in the Beishanregion,Gansu Province,Ch ina.Geological Review,2005,51(3):250~255
17邓起东,汪一鹏,廖玉华等.断层崖崩积楔及贺兰山山前断裂全新世活动历史.科学通报,1984,29(9):557~560D eng Q idong,W ang Y ipeng,L iao Yuhuaet al.Colluvial wedge offau lt scarp and Holocene active h istory along the Helanshan M t.P iedmont fau lt.Chinese Science Bulletin,1984,29(9):557~560
18冉勇康,段瑞涛,邓起东等.海原断裂高湾子地点三维探槽的开挖与古地震研究.地震地质,1997,19(2):97~106Ran Yongkang,Duan Ru itao,D eng Q idonget al.3D trenchexcavation and paleoseismology at Gaowanzi of the Haiyuan fau lt.Seism ology and Geology,1997,19(2):97~106
19闻学泽.时间相依的活动断裂分段地震危险性评估及其问题.科学通报,1998,43(14):1457~1466W en Xueze.Assessm ent of tim e-dependent seism ic hazards onsegm ents of active fau lt,and its prob lem.Chinese Science Bulletin,1998,43(14):1457~1466
20聂高众,高建国,邓砚.地震诱发的堰塞湖初步研究.第四纪研究,2004,24(3):293~301N ie Gaozhong,Gao Jianguo,D eng Yan.Prelim inary study onearthquake-induced damm ed lake.Quaternary Sciences,2004,24(3):293~301
21毛凤英,张培震.古地震研究中的逐次限定法与新疆北部主要断裂带的古地震研究.活动断裂研究(4).北京:地震出版社,1995.153~164Mao Fengying,Zhang Peizhen.M ethod for progressive constraint ofpaleoseism ic events and paleoseismological study ofmajor fau lt zonein northern X in jiang.Research on Active Fau lt(4).Beijing:Seismologial Press,1995.153~164
22 Van D erW oerd J,Ryerson F J,Tapponn ier Pet al.Un iform slip-rate along the Kun lun fau lt:Implications for seism ic behaviour andlarge-scale tecton ics.Geophysical Research Letters,2000,27(16):2353~2356*1993年根据国办发(1990)32号文件和社会团体登记的有关规定,中国第四纪研究委员会,以“中国第四纪科学研究会”为名在民政部登记,中国第四纪研究委员会和中国第四纪科学研究会两个名称,一套班子。
2陈杰,陈宇坤,丁国瑜等.2001年昆仑山口西8.1级地震地表破裂带.第四纪研究,2003,23(6):629~639Chen Jie,Chen Yukun,D ing Guoyuet al.Surface rupture zones ofthe 2001 earthquakeMS8.1 west ofKun lun Pass,northern Q inghai-X izang P lateau.Quaternary Sciences,2003,23(6):629~639
3徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库赛湖地震(MS8.1)地表破裂带的基本特征.地震地质,2002,24(1):1~13Xu X iwei,Chen W enb in,Yu Gu ihuaet a.l Characteristic featuresof the surface ruptures of the Hoh SaiHu(Kun lunshan)earthquake(MS8.1)northern Tibetan P lateau,Ch ina.Seism ology andGeology,2002,24(1):1~13
4中国地震局编,宋瑞祥主编.中国昆仑山口西8.1级地震图集.北京:地震出版社,2003.1~105Ch ina Seismological Bureau,Song Ru ixiang eds.A lbum of theKun lun PassW.MS8.1 Earthquake,Ch ina.Beijing:SeismologicalPress,2003.1~105
5任金卫,汪一鹏,吴章明等.青藏高原北部库玛断裂东、西大滩全新世地震形变带及其位移特征和水平滑动率.地震地质,1993,15(3):285~288Ren Jinwei,W ang Y ipeng,W u Zhangm inget al.Holoceneearthquake deformation zones and their d isplacem ent and slip ratealong the X idatan-Dongdatan of Kusaihu-Maqu fau lt in NorthernQ inghai-X izang P lateau.Seism ology and Geology,1993,15(3):285~288
6任金卫,王敏.GPS观测的2001年昆仑山口西MS8.1级地震地壳变形.第四纪研究,2005,25(1):34~44Ren Jinwei,W ang M in.GPS m easured crustal deformation of theMS8.1 Kun lun earthquake on November 14 th 2001 in Q inghai-X izang P lateau.Quaternary Sciences,2005,25(1):34~44
7 Van D erW oerd J,Ryerson F J,Tapponn ier Pet al.Holocene leftslip-rate determ ined by cosmogen ic surface dating on the X idatansegm ent of the Kun lun fau lt(Q inghai,Ch ina).Geology,1998,26(8):695~698
8田勤俭,丁国瑜.青藏高原北部第四纪早期断裂活动的新生性变化初步研究.第四纪研究,2006,26(1):32~39Tian Q in jian,D ing Guoyu.Prelim inary analysis on an EarlyQuaternary new fau lt trace in North of Tibetan P lateau.QuaternarySciences,2006,26(1):32~39
9胡道功,赵希涛,尹功明等.昆仑山口羌塘组湖相层的ESR年龄测定.第四纪研究,2004,24(3):366~367Hu Daogong,Zhao X itao,Y in Gongm inget al.ESR dating of thelacustrine deposits of Q iangtang Formation from the Kun lunMountains Pass areas.Quaternary Sciences,2004,24(3):366~367
10青海省地震局,中国地震局地壳应力研究所编.东昆仑活动断裂带.北京:地震出版社,1999.1~186Seismological Bureau of Q inghai Province,Institute of C rustalDynam ics,Ch ina Seismological Bureau eds.Eastern Kun lun ActiveFau lt Zone.Beijing:Seismological Press,1999.1~186
11 Cu i Zh ijiu,W u Yongq iu,L iu Gengn ianet a.l On Kun lun-YellowR iver tecton ic movem ent.Scinece in China(Series D),1998,41(6):592~600
12吴珍汉,胡道功,吴中海等.青藏高原中段活动断层及诱发地质灾害.北京:地质出版社,2005.188~250W u Zhenhan,Hu Daogong,W u Zhonghaiet a.l Active Fau lts andGeological Hazards along the Golmud-Lhasa Railway across theTibetan P lateau.Beijing:Geological Pub lish ing House,2005.188~250
13崔之久,伍永秋,刘耕年等.昆仑山垭口地区晚新生代以来的气候构造事件.见:青藏项目专家委员会编.青藏高原形成演化、环境变迁与生态系统研究.北京:科学出版社,1996.74~84Cu i Zh ijiu,W u Yongq iu,L iu Gengn ianet al.The climatic andtecton ic events in the Kun lun Mountains Pass areas,Q inghaiProvince,since the Late Cenozoic.In:The Expert Comm ittee on theQ ingzang Program ed.Study on the Formation and Evolution of theQ inghai-X izang P lateau,Environm ent Change and EcologicalSystem.Beijing:Science Press,1996.74~8414伍永秋,崔之久,刘耕年等.昆仑山垭口地区的冰期系列.冰川冻土,1999,21(1):71~76W u Yongq iu,Cu i Zh ijiu,L iu Gengn ianet a.l G laciation sequencesin the Kun lunshan Pass area.Journal ofGeology and Geocryology,1999,21(1):71~76
15李虎侯.热释光断代.香港:国际科学出版有限公司.1999.1~55L iHuhou.Thermolum inesecene Dating.Hong Kong:Scientist PressInternational,Inc.1999.1~55
16王峰,王驹,范洪海等.甘肃北山旧井地区晚第四纪活动断裂分布及其构造意义.地质论评,2005,51(3):250~255W ang Feng,W ang Ju,Fan Honghaiet a.l D istrbution of LateQuaternary active fau lts and its tecton ic sign ificance in the Beishanregion,Gansu Province,Ch ina.Geological Review,2005,51(3):250~255
17邓起东,汪一鹏,廖玉华等.断层崖崩积楔及贺兰山山前断裂全新世活动历史.科学通报,1984,29(9):557~560D eng Q idong,W ang Y ipeng,L iao Yuhuaet al.Colluvial wedge offau lt scarp and Holocene active h istory along the Helanshan M t.P iedmont fau lt.Chinese Science Bulletin,1984,29(9):557~560
18冉勇康,段瑞涛,邓起东等.海原断裂高湾子地点三维探槽的开挖与古地震研究.地震地质,1997,19(2):97~106Ran Yongkang,Duan Ru itao,D eng Q idonget al.3D trenchexcavation and paleoseismology at Gaowanzi of the Haiyuan fau lt.Seism ology and Geology,1997,19(2):97~106
19闻学泽.时间相依的活动断裂分段地震危险性评估及其问题.科学通报,1998,43(14):1457~1466W en Xueze.Assessm ent of tim e-dependent seism ic hazards onsegm ents of active fau lt,and its prob lem.Chinese Science Bulletin,1998,43(14):1457~1466
20聂高众,高建国,邓砚.地震诱发的堰塞湖初步研究.第四纪研究,2004,24(3):293~301N ie Gaozhong,Gao Jianguo,D eng Yan.Prelim inary study onearthquake-induced damm ed lake.Quaternary Sciences,2004,24(3):293~301
21毛凤英,张培震.古地震研究中的逐次限定法与新疆北部主要断裂带的古地震研究.活动断裂研究(4).北京:地震出版社,1995.153~164Mao Fengying,Zhang Peizhen.M ethod for progressive constraint ofpaleoseism ic events and paleoseismological study ofmajor fau lt zonein northern X in jiang.Research on Active Fau lt(4).Beijing:Seismologial Press,1995.153~164
22 Van D erW oerd J,Ryerson F J,Tapponn ier Pet al.Un iform slip-rate along the Kun lun fau lt:Implications for seism ic behaviour andlarge-scale tecton ics.Geophysical Research Letters,2000,27(16):2353~2356*1993年根据国办发(1990)32号文件和社会团体登记的有关规定,中国第四纪研究委员会,以“中国第四纪科学研究会”为名在民政部登记,中国第四纪研究委员会和中国第四纪科学研究会两个名称,一套班子。
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