山西罗云山山前断裂带中段龙祠-峪口全新世活动证据
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摘要
通过断错地貌调查和探槽开挖,获得了临汾盆地西界罗云山山前断裂带龙祠-峪口段的最新活动信息:该段山前洪积扇后缘断断续续存在高2.5m、5.2m、8m左右的地表地貌陡坎;附近冲沟的Ⅰ级阶地热释光测年为距今7500a左右;在NW向的席坊沟内存在拔沟3.5m、8m、18m左右的3级阶地,与地貌陡坎有对应关系;席坊沟探槽揭示罗云山山前断裂带断错了晚更新世晚期以来的地层,存在5次古地震事件,最新一次活动断错了14C测年为距今(7.52±0.1)ka的垆土层,这为临汾盆地的防震减灾决策提供了新的依据。
The 145-km-long,southeast-dipping and normal-faulting with dextral slip Luoyunshan frontal fault zone controls the western edge of NE-trending Linfen Basin which locates at the southwestern part of the Shanxi fault-depression system.Two historic strong earthquakes successively occurred in the Linfen Basin:the A.D.1695 Linfen M7W1/2 and the A.D.1303 Hongdong M8 earthquakes.In the previous work,based on distribution features of the fault that it is intersected by three NW-trending faults and its strike changes abruptly at Fanjiazhuang village,the fault is divided into five segments:Wanshengsi-Tumen,Tumen-Yuli,Yuli-Weicun,Weicun-Fanjiazhuang,and Fanjiazhuang-Xiweikou.And its Quternary activity history is divided into three phases:end of Middle Pleistocene to early of Late Pleistocene,end of Late Pleistocene to early of Holocene and Holocene.Quaternary deposition thickness and deposition rate of the Tumen-Yuli segment are prominent along the Luoyunshan frontal fault zone.Longci depression center is adjacent to the fault and extends along its direction.Cenozoic strata is 1800meters thick,including 1100meters thick of Pliocene strata and 700meters thick of Quaternary strata,indicating a gradually increased trend of depression's deposition and the most intensive activity.Many previous studies show that the segment is active in Holocene.However,few of these studies have provided authentic geologic evidence.Paleoseismic trenching and fault geomorphologic investigation provide effective methods to obtain the most recent activity parameters of active faults.Applying these methods,this paper makes some breakthroughs on the most recent activity of Longci-Yukou segment along the Luoyunshan frontal fault zone on the western boundary of Linfen Basin.Research indicates that tectonic geomorphologic scarps with heights of 2.5m±,5.2m± and 8m±,respectively,present continually on these alluvial fanheads;the terraces T1 of gully around Longci are dated to be about 7500aBP;terraces with heights of 3.5m±,8m±,18m± above the gully base,respectively,in the NW-trending Xifanggou are related to the scarps;the Xifanggou trench exposure records five surface-rupturing paleoearthquake events since late Pleistocene and the youngest event in the trench probably occurred in Holocene,sometime after(7.52±0.1)ka,which is significant for protecting against and mitigating earthquake disasters in the Linfen Basin.
The 145-km-long,southeast-dipping and normal-faulting with dextral slip Luoyunshan frontal fault zone controls the western edge of NE-trending Linfen Basin which locates at the southwestern part of the Shanxi fault-depression system.Two historic strong earthquakes successively occurred in the Linfen Basin:the A.D.1695 Linfen M7W1/2 and the A.D.1303 Hongdong M8 earthquakes.In the previous work,based on distribution features of the fault that it is intersected by three NW-trending faults and its strike changes abruptly at Fanjiazhuang village,the fault is divided into five segments:Wanshengsi-Tumen,Tumen-Yuli,Yuli-Weicun,Weicun-Fanjiazhuang,and Fanjiazhuang-Xiweikou.And its Quternary activity history is divided into three phases:end of Middle Pleistocene to early of Late Pleistocene,end of Late Pleistocene to early of Holocene and Holocene.Quaternary deposition thickness and deposition rate of the Tumen-Yuli segment are prominent along the Luoyunshan frontal fault zone.Longci depression center is adjacent to the fault and extends along its direction.Cenozoic strata is 1800meters thick,including 1100meters thick of Pliocene strata and 700meters thick of Quaternary strata,indicating a gradually increased trend of depression's deposition and the most intensive activity.Many previous studies show that the segment is active in Holocene.However,few of these studies have provided authentic geologic evidence.Paleoseismic trenching and fault geomorphologic investigation provide effective methods to obtain the most recent activity parameters of active faults.Applying these methods,this paper makes some breakthroughs on the most recent activity of Longci-Yukou segment along the Luoyunshan frontal fault zone on the western boundary of Linfen Basin.Research indicates that tectonic geomorphologic scarps with heights of 2.5m±,5.2m± and 8m±,respectively,present continually on these alluvial fanheads;the terraces T1 of gully around Longci are dated to be about 7500aBP;terraces with heights of 3.5m±,8m±,18m± above the gully base,respectively,in the NW-trending Xifanggou are related to the scarps;the Xifanggou trench exposure records five surface-rupturing paleoearthquake events since late Pleistocene and the youngest event in the trench probably occurred in Holocene,sometime after(7.52±0.1)ka,which is significant for protecting against and mitigating earthquake disasters in the Linfen Basin.
引文
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蒋金平.1998.水在地裂缝形成过程中的作用[J].矿业世界,2:38—40.JIANG Jin-ping.1998.Role of water in ground fissures developing[J].Mining World,2:38—40(in Chinese).蒋臻蔚,彭建兵,王启耀.2010.抽水作用下先期断裂对地裂缝的影响研究[J].工程地质学报,18(5):651—656.JIANG Zhen-wei,PENG Jian-bing,WANG Qi-yao.2010.Influence of pre-existing fault on ground fissures during pumping action[J].Journal of Engineering Geology,18(5):651—656(in Chinese).
刘光勋.1985.汾渭地堑系边缘挤压构造带及其地质意义[A].见:构造地质论丛(4).北京:地震出版社.LIU Guang-xun.1985.Compressional tectonic zones on the Linfen-Weihe graben margin and its geological significance[A].In:Collected Papers and Notes on Tectonics,No.4.Seismological Press,Beijing(in Chinese).
刘光勋,肖振敏.1982.山西地堑系及其地震构造特征[A].见:中国地质学会构造地质专业委员会编.第二届全国构造地质学术会议论文选集,第三卷.北京:科学出版社.66—74.LIU Gong-xun,XIAO Zhen-min.1982.Shanxi graben system and its seismotectonics[A].In:Commission on Tectonicsof the Geological Society of China(ed).Selected Proceedings of the Second National Conference on Tectonics,VolumeⅢ.Science Press,Beijing.66—74(in Chinese).
马宗晋主编.1993.山西临汾地震研究与系统减灾[M].北京:地震出版社.MA Zong-jin(ed).1993.Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi[M].SeismologicalPress,Beijing(in Chinese).
苏宗正,程新原,安卫平.1993.山西临汾盆地的断陷沉降[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.102—110.SU Zong-zheng,CHENG Xin-yuan,AN Wei-ping.1993.Down-faulting of the Linfen Basin,Shanxi[A].In:MA Zongjin(ed).Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi.Seismological Press,Beijing.102—110(in Chinese).
苏宗正,阎凤忠.1985.罗云山断裂全新世活动的新发现[J].山西地震,4:6.SU Zong-zheng,YAN Feng-zhong.1985.New discovery on the Holocene activity of Luoyunshan Fault[J].EarthquakeResearch in Shanxi,4:6(in Chinese).
王景明.2000.地裂缝及其灾害的理论与应用[M].西安:陕西科学技术出版社.WANG Jing-ming.2000.Theory of Ground Fissures Hazards and Its Application[M].Science and Technology Press ofShaanxi,Xi'an(in Chinese).
王挺梅,郑炳华,李新元,等.1993.罗云山山前断裂带第四纪活动特征[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.159—171.WANG Ting-Mei,ZHENG Bing-hua,LI Xin-yuan,et al.1993.Quaternary activity characteristics of the Luoyunshanfrontal fault zone[A].In:MA Zong-jin et al.(ed).Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi.Seismological Press,Beijing.159—171(in Chinese).
阎凤忠,苏宗正,贺明华.1988.1695年临汾八级地震形变遗迹[J].山西地震,(4):25—28.YAN Feng-zhong,SU Zong-zheng,HE Ming-hua.1988.Deformation remains of the1695Linfen(M8)earthquake[J].Earthquake Research in Shanxi,(4):25—28(in Chinese).
邓起东,苏宗正,王挺梅,等.1993.临汾盆地晚第四纪沉积与新构造运动[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.111—129.DENG Qi-dong,SU Zong-zheng,WANG Ting-mei,et al.1993.Late Quaternary deposition and neotectonic movement ofLinfen Basin[A].In:MA Zong-jin et al.(eds).Linfen Earthquake Research and Systematic Disaster Reductionin Shanxi.Seismological Press,Beijing.111—129(in Chinese).
邓起东,王克鲁,汪一鹏,等.1973.山西隆起区断陷地震带地质条件及地震发展趋势概述[J].地质科学,(1):37—47.DENG Qi-dong,WANG Ke-lu,WANG Yi-Peng,et al.1973.A review of seismo-geological conditions and seismic activity tendency in Shanxi faulted depression of Shanxi uplift zone[J].Scientia Geologica Sinica,(1):37—47(inChinese).
丁国瑜.1998.关于公元649年临汾地震的讨论[J].中国地震,14(3):38—42.DING Guo-yu.1998.A discussion on the Linfen earthquake of649A.D.[J].Earthquake Research in China,14(3):38—42(in Chinese).
高名修.1995.1695年山西临汾大震构造探讨[J].山西地震,(3-4):24—27.GAO Ming-xiu.1995.Study on the seismogenic tectonics of1695Linfen macroquake[J].Earthquake Research inShanxi,(3-4):24—27(in Chinese).
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.Active Fault System around Ordos Massif[M].Seismological Press,Beijing(in Chinese).
国家地震局地震地质大队,北京大学地质地理系.1979.临汾盆地活动构造体系与地震[A].见:中国地质科学院地质力学研究所编.地质力学论丛(5).北京:科学出版社.140—150.Seismo-geological Brigade,State Seismological Bureau,Geology and Geography Department,Peking University.1979.Active tectonic system and earthquake in Linfen Basin[A].In:Institute of Geomechanics,Chinese Academy ofGeological Sciences(ed).Collected papers and notes on geomechanics,No.5.Science Press,Beijing.140—150(inChinese).
蒋金平.1998.水在地裂缝形成过程中的作用[J].矿业世界,2:38—40.JIANG Jin-ping.1998.Role of water in ground fissures developing[J].Mining World,2:38—40(in Chinese).蒋臻蔚,彭建兵,王启耀.2010.抽水作用下先期断裂对地裂缝的影响研究[J].工程地质学报,18(5):651—656.JIANG Zhen-wei,PENG Jian-bing,WANG Qi-yao.2010.Influence of pre-existing fault on ground fissures during pumping action[J].Journal of Engineering Geology,18(5):651—656(in Chinese).
刘光勋.1985.汾渭地堑系边缘挤压构造带及其地质意义[A].见:构造地质论丛(4).北京:地震出版社.LIU Guang-xun.1985.Compressional tectonic zones on the Linfen-Weihe graben margin and its geological significance[A].In:Collected Papers and Notes on Tectonics,No.4.Seismological Press,Beijing(in Chinese).
刘光勋,肖振敏.1982.山西地堑系及其地震构造特征[A].见:中国地质学会构造地质专业委员会编.第二届全国构造地质学术会议论文选集,第三卷.北京:科学出版社.66—74.LIU Gong-xun,XIAO Zhen-min.1982.Shanxi graben system and its seismotectonics[A].In:Commission on Tectonicsof the Geological Society of China(ed).Selected Proceedings of the Second National Conference on Tectonics,VolumeⅢ.Science Press,Beijing.66—74(in Chinese).
马宗晋主编.1993.山西临汾地震研究与系统减灾[M].北京:地震出版社.MA Zong-jin(ed).1993.Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi[M].SeismologicalPress,Beijing(in Chinese).
苏宗正,程新原,安卫平.1993.山西临汾盆地的断陷沉降[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.102—110.SU Zong-zheng,CHENG Xin-yuan,AN Wei-ping.1993.Down-faulting of the Linfen Basin,Shanxi[A].In:MA Zongjin(ed).Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi.Seismological Press,Beijing.102—110(in Chinese).
苏宗正,阎凤忠.1985.罗云山断裂全新世活动的新发现[J].山西地震,4:6.SU Zong-zheng,YAN Feng-zhong.1985.New discovery on the Holocene activity of Luoyunshan Fault[J].EarthquakeResearch in Shanxi,4:6(in Chinese).
王景明.2000.地裂缝及其灾害的理论与应用[M].西安:陕西科学技术出版社.WANG Jing-ming.2000.Theory of Ground Fissures Hazards and Its Application[M].Science and Technology Press ofShaanxi,Xi'an(in Chinese).
王挺梅,郑炳华,李新元,等.1993.罗云山山前断裂带第四纪活动特征[A].见:马宗晋主编.山西临汾地震研究与系统减灾.北京:地震出版社.159—171.WANG Ting-Mei,ZHENG Bing-hua,LI Xin-yuan,et al.1993.Quaternary activity characteristics of the Luoyunshanfrontal fault zone[A].In:MA Zong-jin et al.(ed).Linfen Earthquake Research and Systematic Disaster Reduction in Shanxi.Seismological Press,Beijing.159—171(in Chinese).
阎凤忠,苏宗正,贺明华.1988.1695年临汾八级地震形变遗迹[J].山西地震,(4):25—28.YAN Feng-zhong,SU Zong-zheng,HE Ming-hua.1988.Deformation remains of the1695Linfen(M8)earthquake[J].Earthquake Research in Shanxi,(4):25—28(in Chinese).
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