乌兰乌拉湖-玉树断裂东段晚第四纪滑动速率
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摘要
乌兰乌拉湖-玉树断裂是巴颜喀拉地块与羌塘地块分界地带的一条重要活动断裂。该断裂东段晚第四纪以来活动强烈,断错地貌特征明显,为全新世活动的左旋逆冲断裂。利用后差分GPS对阶地与洪积扇断错地貌进行了精细测量,并结合碳十四(14C)和光释光(OSL)测年结果对地貌面年代进行限定,获得该断裂东段晚更新世晚期以来的垂直位错量为5.5～6.3m,平均垂直滑动速率为0.23～0.28mm/a;全新世以来的垂直位错量为2.2～4.3m,平均垂直滑动速率为0.40～0.63mm/a;晚第四纪以来的平均左旋滑动速率为4～6mm/a。为该断裂的地震危险性分析和相邻活动地块的运动学特征探讨提供了基础资料。
Wulanwulahu-Yushu Fault is an important active fault at the boundary area between Bayankala block and Qiangtang block.The slip rate of this fault in the late Quaternary is of fundamental importance for analyzing the seismic hazards and kinematic characteristics of neighboring active blocks.Due to the limited field conditions,the study of the late Quaternary fault activity on the eastern segment of this fault is rare.On the basis of interpretations of remote sensing images and field investigation,the eastern segment of this fault is active since late Quaternary and the offset geomorphic features are prominent,displaying left-lateral and high-angle thrust faulting.Using the methods of detailed geomorphic mapping,geological survey,differential GPS survey,optically stimulated luminescence(OSL)dating and radiocarbon(\{14C\})dating,this paper makes an analysis of the late Quaternary geomorphic features and slip rate of the eastern segment of this fault.Four typical sites on the fault,including Xiabatang,Zhada,Shangbatang and southwest corner of Batang Basin,were selected for the field investigation.At Xiabatang,the vertical slip rate of the fault is 0.23～0.28mm/a since around 22～27kaBP,0.40～0.51mm/a since 4～5kaBP,and left lateral slip rate is 6.0mm/a since 27kaBP.At Zhada,the vertical slip rate is 0.23mm/a since around 24kaBP.At Shangbatang,the vertical slip rate is 0.45～0.63mm/a since around 6～9kaBP.At southwest corner of Batang Basin,the left lateral slip rate is 4.0mm/a since 150kaBP.The average vertical slip rate of the eastern segment of Wulanwulahu-Yushu Fault is 0.23～0.28mm/a since late Pleistocene,the average vertical slip rate is 0.40～0.63mm/a since early-mid Holocene,and the left lateral slip rate is about 4～6mm/a since late Quaternary.
Wulanwulahu-Yushu Fault is an important active fault at the boundary area between Bayankala block and Qiangtang block.The slip rate of this fault in the late Quaternary is of fundamental importance for analyzing the seismic hazards and kinematic characteristics of neighboring active blocks.Due to the limited field conditions,the study of the late Quaternary fault activity on the eastern segment of this fault is rare.On the basis of interpretations of remote sensing images and field investigation,the eastern segment of this fault is active since late Quaternary and the offset geomorphic features are prominent,displaying left-lateral and high-angle thrust faulting.Using the methods of detailed geomorphic mapping,geological survey,differential GPS survey,optically stimulated luminescence(OSL)dating and radiocarbon(\{14C\})dating,this paper makes an analysis of the late Quaternary geomorphic features and slip rate of the eastern segment of this fault.Four typical sites on the fault,including Xiabatang,Zhada,Shangbatang and southwest corner of Batang Basin,were selected for the field investigation.At Xiabatang,the vertical slip rate of the fault is 0.23～0.28mm/a since around 22～27kaBP,0.40～0.51mm/a since 4～5kaBP,and left lateral slip rate is 6.0mm/a since 27kaBP.At Zhada,the vertical slip rate is 0.23mm/a since around 24kaBP.At Shangbatang,the vertical slip rate is 0.45～0.63mm/a since around 6～9kaBP.At southwest corner of Batang Basin,the left lateral slip rate is 4.0mm/a since 150kaBP.The average vertical slip rate of the eastern segment of Wulanwulahu-Yushu Fault is 0.23～0.28mm/a since late Pleistocene,the average vertical slip rate is 0.40～0.63mm/a since early-mid Holocene,and the left lateral slip rate is about 4～6mm/a since late Quaternary.
引文
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吴章明,汪一鹏,任金卫,等.1994.青藏高原中部的活动断层[A].见:国家地震局地质研究所编.活动断裂研究(3).北京:地震出版社.56—73.WU Zhang-ming,WANG Yi-peng,REN Jin-wei,et al.1994.The active faults in the central Tibet Plateau[A].In:Institute of Geology,SSB(ed).Research on Active Fault(3).Seismological Press,Beijing.56—73(in Chinese).
张培震,李传友,毛凤英.2008.河流阶地演化与走滑断裂滑动速率[J].地震地质,30(1):44—57.ZHANG Pei-zhen,LI Chuan-you,MAO Feng-ying.2008.Strath terrace formation and strike-slip faulting[J].Seismology and Geology,30(1):44—57(in Chinese).
郑本兴,李世杰,王苏民,等.1995.若尔盖盆地周围高山第四纪冰川演变史[A].见:青藏高原形成演化、环境变迁与生态系统研究学术论文年刊(1994).北京:科学出版社.218—226.ZHENG Ben-xing,LI Shi-jie,WANG Su-min,et al.1995.The Quaternary glacial evolution of the mountains surroundingZoige Basin[A].In:Annals of Research on Formation,Evolution,Environmental Change,and Ecological Systemof the Qinghai-Xizang Plateau(1994).Science Press,Beijing.218—226(in Chinese).
周尚哲.1995.巴颜喀拉山地区的第四纪环境演变[M].见:青藏高原形成演化、环境变迁与生态系统研究学术论文年刊(1994).北京:科学出版社.6—72.ZHOU Shang-zhe.1995.Quaternary environment evolution of the Bayankala mountain area[A].In:Annals of Research on Formation,Evolution,Environmental Change,and Ecological System of the Qinghai-Xizang Plateau(1994).Science Press,Beijing.6—72(in Chinese).
周荣军,马声浩,蔡长星,1996.甘孜-玉树断裂带的晚第四纪活动特征[J].中国地震,12(3):250—260.ZHOU Rong-jun,MA Sheng-hao,CAI Chang-xing.1996.Late Quaternary active features of the Ganzi-Yushu Fault zone[J].Earthquake Research in China,12(3):250—260(in Chinese).
周荣军,闻学泽,蔡长星,等.1997.甘孜-玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,l9(2):115—124.ZHOU Rong-jun,WEN Xue-ze,CAI Chang-xing,et al.1997.Recent earthquakes and assessment of seismic tendency onthe Ganzi-Yushu Fault zone[J].Seismology and Geology,19(2):115—124(in Chinese).
Wang S F,Fan C,Wang G,et al.2008.Late Cenozoic deformation along the northwestern continuation of the XianshuiheFault system,Eastern Tibetan Plateau[J].Geological Society of America Bulletin,120(3-4):312—327.
Zhai X J,Dai Z Y,Ge L L,et al.2011.Fault geometry and slip distribution of the2010Yushu earthquakes inferred fromInSAR measurement[J].Bulletin of the Seismological Society of America,101(4):1951—1958.
彭华,马秀敏,白嘉启,等.2006.甘孜玉树断裂带第四纪活动特征[J].地质力学学报,12(3):295—304.PENG Hua,MA Xiu-min,BAI Jia-qi,et al.2006.Characteristics of Quaternary activities of the Ganzi-Yushu Fault zone[J].Journal of Geomechanics,12(3):295—304(in Chinese).
闻学泽.1995.活动断裂地震潜势的定量评估[M].北京:地震出版社.WEN Xue-ze.1995.Quantitative Estimates of Seismic Potential on Active Faults[M].Seismological Press,Beijing(inChinese).
闻学泽,黄圣睦,江在雄.1985.甘孜-玉树断裂带的新构造特征及地震危险性估计[J].地震地质,7(3):23—32.WEN Xue-ze,HUANG Sheng-mu,JIANG Zai-xiong.1985.Neotectonic features of the Ganzi-Yushu Fault zone and assessment of its earthquake risk[J].Seismology and Geology,7(3):23—32(in Chinese).
闻学泽,徐锡伟,郑荣章,等.2003.甘孜-玉树断裂带平均滑动速率与近代大地震破裂[J].中国科学(D辑),33(增刊):199—208.WEN Xue-ze,XU Xi-wei,ZHENG Rong-zhang,et al.2003.Slip rate and recent earthquake ruptures of the Ganzi-YushuFault zone[J].Science in China(Ser D),33(Suppl):199—208(in Chinese).
吴章明,汪一鹏,任金卫,等.1993.青藏高原北部金沙江、澜沧江缝合线晚第四纪的活动性[J].地震地质,15(1):28—31WU Zhang-ming,WANG Yi-peng,REN Jin-wei,et al.1993.Activity of the Jinsha and Lancang sutures,northern Qinghai-Xizang plateau in late Quaternary[J].Seismology and Geology,15(1):28—31(in Chinese).
吴章明,汪一鹏,任金卫,等.1994.青藏高原中部的活动断层[A].见:国家地震局地质研究所编.活动断裂研究(3).北京:地震出版社.56—73.WU Zhang-ming,WANG Yi-peng,REN Jin-wei,et al.1994.The active faults in the central Tibet Plateau[A].In:Institute of Geology,SSB(ed).Research on Active Fault(3).Seismological Press,Beijing.56—73(in Chinese).
张培震,李传友,毛凤英.2008.河流阶地演化与走滑断裂滑动速率[J].地震地质,30(1):44—57.ZHANG Pei-zhen,LI Chuan-you,MAO Feng-ying.2008.Strath terrace formation and strike-slip faulting[J].Seismology and Geology,30(1):44—57(in Chinese).
郑本兴,李世杰,王苏民,等.1995.若尔盖盆地周围高山第四纪冰川演变史[A].见:青藏高原形成演化、环境变迁与生态系统研究学术论文年刊(1994).北京:科学出版社.218—226.ZHENG Ben-xing,LI Shi-jie,WANG Su-min,et al.1995.The Quaternary glacial evolution of the mountains surroundingZoige Basin[A].In:Annals of Research on Formation,Evolution,Environmental Change,and Ecological Systemof the Qinghai-Xizang Plateau(1994).Science Press,Beijing.218—226(in Chinese).
周尚哲.1995.巴颜喀拉山地区的第四纪环境演变[M].见:青藏高原形成演化、环境变迁与生态系统研究学术论文年刊(1994).北京:科学出版社.6—72.ZHOU Shang-zhe.1995.Quaternary environment evolution of the Bayankala mountain area[A].In:Annals of Research on Formation,Evolution,Environmental Change,and Ecological System of the Qinghai-Xizang Plateau(1994).Science Press,Beijing.6—72(in Chinese).
周荣军,马声浩,蔡长星,1996.甘孜-玉树断裂带的晚第四纪活动特征[J].中国地震,12(3):250—260.ZHOU Rong-jun,MA Sheng-hao,CAI Chang-xing.1996.Late Quaternary active features of the Ganzi-Yushu Fault zone[J].Earthquake Research in China,12(3):250—260(in Chinese).
周荣军,闻学泽,蔡长星,等.1997.甘孜-玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,l9(2):115—124.ZHOU Rong-jun,WEN Xue-ze,CAI Chang-xing,et al.1997.Recent earthquakes and assessment of seismic tendency onthe Ganzi-Yushu Fault zone[J].Seismology and Geology,19(2):115—124(in Chinese).
Wang S F,Fan C,Wang G,et al.2008.Late Cenozoic deformation along the northwestern continuation of the XianshuiheFault system,Eastern Tibetan Plateau[J].Geological Society of America Bulletin,120(3-4):312—327.
Zhai X J,Dai Z Y,Ge L L,et al.2011.Fault geometry and slip distribution of the2010Yushu earthquakes inferred fromInSAR measurement[J].Bulletin of the Seismological Society of America,101(4):1951—1958.
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