华山山前断裂断错地貌及晚第四纪活动性
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摘要
基于华山山前断裂1︰5万活动断层填图成果,对断裂沿线地层地貌、断层三角面、河流阶地、陡坎地貌以及典型断错剖面等进行了详细的研究。研究表明:1)华山山前断裂按几何结构、断错地貌表现分西段(蓝田—华县段)、中段(华县—华阴段)及东段(华阴—灵宝段)3段;2)西段及东段断裂错断了T_2阶地及马兰黄土,T_1阶地跨断裂连续,测年结果表明,T_2阶地形成于晚更新世中期,T_1阶地形成于全新世早期,由此得出西段及东段断裂在晚更新世有过活动,全新世以来活动弱或不活动;3)中段断错地貌显著,河谷两侧发育Ⅲ级阶地,跨断裂阶地均被错断,测年结果表明:T_1阶地形成于2~3kaBP,T_2阶地形成于6~7kaBP,T_3阶地形成于60~70kaBP,结合阶地陡坎高度,得出不同时段的平均垂直滑动速率:T_3—T_2时期0.4mm/a;T_2—T_1时期1.1mm/a;T_1以来1.6mm/a;4)中段在晚更新世晚期以来发生过多次活动,在石堤峪、沟峪等地见漫滩陡坎,结合文化层及炭样年龄,可知漫滩形成于距今400~600a,对比历史地震资料,漫滩陡坎应为华县1556年地震的遗迹;5)结合前人研究认为,公元1556年华县81/2级地震的发震构造为华山山前断裂及渭南塬前断裂,其它断裂是否参与有待进一步研究。
Based on the 1︰50000 active fault geological mapping,combining with high-precision remote imaging,field geological investigation and dating technique,the paper investigates the stratum,topography and faulted landforms of the Huashan Piedmont Fault. Research shows that the Huashan Piedmont Fault can be divided into Lantian to Huaxian section(the west section),Huaxian to Huayin section(the middle section) and Huayin to Lingbao section(the east section) according to the respective different fault activity.The fault in Lantian to Huaxian section is mainly contacted by loess and bedrock.Bedrock fault plane has already become unsmooth and mirror surfaces or striations can not be seen due to the erosion of running water and wind.10~20m high fault scarps can be seen ahead of mountain in the north section near Mayu gully and Qiaoyu gully,and we can see Malan loess faulted profiles in some gully walls.In this section terraces are mainly composed of T_1and T_2which formed in the early stage of Holocene and late Pleistocene respectively.Field investigation shows that T_1is continuous and T_2is dislocated across the fault.These indicate that in this section the fault has been active in the late Pleistocene and its activity becomes weaker or no longer active after that.In the section between Huaxian and Huayin,neotectonics is very obvious,fault triangular facets are clearly visible and fault scarps are in linear distribution.Terrace T_1,T_2and T_3develop well on both sides of most gullies.Dating data shows that T_1 forms in 2~3kaBP,T_2forms in 6~7kaBP,and T_3forms in 60~70kaBP.All terraces are faulted in this section,combing with average ages and scarp heights of terraces,we calculate the average vertical slip rates during the period of T_3to T_2,T_2to T_1and since the formation of T_1,which are 0.4mm/a,1.1mm/a and 1.6mm/a,and among them,1.1mm/a can roughly represent as the average vertical slip rate since the middle stage of Holocene.Fault has been active several times since the late period of late Pleistocene according to fault profiles,in addition,Tanyu west trench also reveals the dislocation of the culture layer of(0.31~0.27)aBP.1~2m high scarps of floodplains which formed in(400~600)aBP can be seen at Shidiyu gully and Gouyu gully.In contrast with historical earthquake data,we consider that the faulted culture layer exposed by Tanyu west trench and the scarps of floodplains are the remains of Huanxian M_S81/2 earthquake.The fault in Huayin to Lingbao section is also mainly contacted by loess and mountain bedrock.Malan loess faulted profiles can be seen at many river outlets of mountains.Terrace geomorphic feature is similar with that in the west section,T_1is covered by thin incompact Holocene sand loam,and T_2is covered by Malan loess.OSL dating shows that T_2formed in the early to middle stage of late Pleistocene.Field investigation shows that T_1is continuous and T_2is dislocated across the fault.These also indicate that in this section fault was active in the late Pleistocene and its activity becomes weaker or no longer active since Holocene.According to this study combined with former researches,we incline to the view that the seismogenic structure of Huanxian M_S81/2 earthquake is the Huashan Piedmont Fault and the Northern Margin Fault of Weinan Loess,as for whether there are other faults or not awaits further study.
Based on the 1︰50000 active fault geological mapping,combining with high-precision remote imaging,field geological investigation and dating technique,the paper investigates the stratum,topography and faulted landforms of the Huashan Piedmont Fault. Research shows that the Huashan Piedmont Fault can be divided into Lantian to Huaxian section(the west section),Huaxian to Huayin section(the middle section) and Huayin to Lingbao section(the east section) according to the respective different fault activity.The fault in Lantian to Huaxian section is mainly contacted by loess and bedrock.Bedrock fault plane has already become unsmooth and mirror surfaces or striations can not be seen due to the erosion of running water and wind.10~20m high fault scarps can be seen ahead of mountain in the north section near Mayu gully and Qiaoyu gully,and we can see Malan loess faulted profiles in some gully walls.In this section terraces are mainly composed of T_1and T_2which formed in the early stage of Holocene and late Pleistocene respectively.Field investigation shows that T_1is continuous and T_2is dislocated across the fault.These indicate that in this section the fault has been active in the late Pleistocene and its activity becomes weaker or no longer active after that.In the section between Huaxian and Huayin,neotectonics is very obvious,fault triangular facets are clearly visible and fault scarps are in linear distribution.Terrace T_1,T_2and T_3develop well on both sides of most gullies.Dating data shows that T_1 forms in 2~3kaBP,T_2forms in 6~7kaBP,and T_3forms in 60~70kaBP.All terraces are faulted in this section,combing with average ages and scarp heights of terraces,we calculate the average vertical slip rates during the period of T_3to T_2,T_2to T_1and since the formation of T_1,which are 0.4mm/a,1.1mm/a and 1.6mm/a,and among them,1.1mm/a can roughly represent as the average vertical slip rate since the middle stage of Holocene.Fault has been active several times since the late period of late Pleistocene according to fault profiles,in addition,Tanyu west trench also reveals the dislocation of the culture layer of(0.31~0.27)aBP.1~2m high scarps of floodplains which formed in(400~600)aBP can be seen at Shidiyu gully and Gouyu gully.In contrast with historical earthquake data,we consider that the faulted culture layer exposed by Tanyu west trench and the scarps of floodplains are the remains of Huanxian M_S81/2 earthquake.The fault in Huayin to Lingbao section is also mainly contacted by loess and mountain bedrock.Malan loess faulted profiles can be seen at many river outlets of mountains.Terrace geomorphic feature is similar with that in the west section,T_1is covered by thin incompact Holocene sand loam,and T_2is covered by Malan loess.OSL dating shows that T_2formed in the early to middle stage of late Pleistocene.Field investigation shows that T_1is continuous and T_2is dislocated across the fault.These also indicate that in this section fault was active in the late Pleistocene and its activity becomes weaker or no longer active since Holocene.According to this study combined with former researches,we incline to the view that the seismogenic structure of Huanxian M_S81/2 earthquake is the Huashan Piedmont Fault and the Northern Margin Fault of Weinan Loess,as for whether there are other faults or not awaits further study.
引文
程谦恭.1988.华山北麓断层崖与大地震重复周期分析[J].西安地质学院报,10(4):53-64.CHENG Qian-gong.1988.An analysis of fault scarps on north Huashan mountain front and the recurrence intervals oflarger earthquakes[J].Journal of Xi'an College of Geology,10(4):53-64(in Chinese).
杜建军,黎敦朋,马寅生,等.2013.18.7万年前的高速远程古滑坡:来自陕西华县莲花寺滑坡体上覆黄土光释光(OSL)测年的证据[J].第四纪研究,33(5):1005-1015.DU Jian-jun,LI Dun-peng,MA Yin-sheng,et al.2013.The high-speed and long-distance ancient landslides before187ka:The evidence from the OSL dating of the loess overlying the landslide body of Lianhuasi landslides in Huaxian,Shaanxi Province,China[J].Quaternary Sciences,33(5):1005-1015(in Chinese).
郭增建.1957.1556年1月23日关中大地震[J].地球物理学报,6(1):59-68.GUO Zeng-jian.1957.On the Shensi earthquake of January 23,1556[J].Acta Geophysica Sinica,6(1):59-68(in Chinese).
韩恒悦,贺明静,李永善.1987.渭河盆地东部地区的活断层[J].地震地质,9(2):85-90.HAN Heng-yue,HE Ming-jing,LI Yong-shan.1987.The active faults in the eastern of the Weihe Basin[J].Seismology and Geology,9(2):85-90(in Chinese).
环文林,时振梁,李世勋.2003.对1556年8级大地震震中位置和发震构造的新认识[J].中国地震,19(1):20-32.HUAN Wen-lin,SHI Zhen-liang,LI Shi-xun.2003.The new recognizes for epicenter location and seismogenic structure of 1556 M 8large earthquake[J].Earthquake Research in China,19(1):20-32(in Chinese).
雷祥义,屈红军,岳乐平.1992.灞河阶地黄土-古土壤系列及其年代意义[J].西北大学学报,22(2):219-226.LEI Xiang-yi,QU Hong-jun,YUE Le-ping.1992.Loess-paleosol sequence at terrace of Bahe River and its significance of age[J].Journal of Northwest University,22(2):219-226(in Chinese).
李祥根,冉勇康.1983.华山北坡及渭南塬前活断层[J].华北地震科学,1(2):10-18,9.LI Xiang-gen,RAN Yong-kang.1983.Active faults in the north slope of Huashan Mountain and the front of the Weinan tableland[J].North China Earthquake Sciences,1(2):10-18,9(in Chinese).
李永善,耿大玉,韩许恒,等.1992.西安地裂及渭河盆地活断层研究[M].北京:地震出版社.LI Yong-shan,GENG Da-yu,HAN Xu-heng,et al.1992.Research on Ground Fissures in Xi'an Region and Active Faults in Weihe Basin[M].Seismological Press,Beijing(in Chinese).
李昭淑,崔鹏.2007.1556年华县大地震的次生灾害[J].山地学报,25(4):425-430.LI Zhao-shu,CUI Peng.2007.The secondary disasters of great Huaxian earthquake in 1556[J].Journal of Mountain Science,25(4):425-430(in Chinese).
单修政.1988.1556年华县地震人口死亡原因浅析[J].灾害学,3(4):94-96.SHAN Xiu-zheng.1988.Analysis on the cause of death of the Huaxian earthquake in 1556[J].Journal of Catastrophology,3(4):94-96.
宋立胜.1989.1556年华县8级大震死亡人数初探[J].灾害学,4(4):68-72.SONG Li-sheng.1989.Preliminary study on the number of the deaths of the great Huaxian earthquake in 1556[J].Journal of Catastrophology,4(4):68-72(in Chinese).
万景林,李齐,王瑜.2000.华山岩体中、新生代抬升的裂变径迹证据[J].地震地质,22(1):53-58.doi:10.3969/j.issn.0253-4967.2000.01.007.WAN Jing-lin,LI Qi,WANG Yu.2000.The fission track evidence of Huashan batholith uplifting in MesozoicCenozoic[J].Seismology and Geology,22(1):53-58(in Chinese).
王斌,郑洪波,王平,等.2013.渭河盆地新生代地层与沉积演化研究:现状和问题[J].地球科学进展,28(10):1126-1135.WANG Bin,ZHENG Hong-bo,WANG Ping,et al.2013.The Cenozoic strata and depositional evolution of Weihe Basin:Progresses and problems[J].Advances in Earth Science,28(10):1126-1135(in Chinese).
王景明.1983.渭河盆地活动构造与地震[J].地壳形变与地震,(4):59-66.WANG Jing-ming.1983.Active tectonics and earthquakes in Weihe Basin[J].Crustal Deformation and Earthquake,(4):59-66(in Chinese).
杨源源,高战武,徐伟.2012.华山山前断裂中段晚第四纪活动的地貌表现及响应[J].震灾防御技术,7(4):335-347.YANG Yuan-yuan,GAO Zhan-wu,XU Wei.2012.Geomorphic expression and response of the activity along the middle section of Huashan front fault in the late Quaternary period[J].Technology for Earthquake Disaster Prevention,7(4):335-347(in Chinese).
尹功明,卢演俦,赵华,等.2001.华山新生代构造抬升[J].科学通报,46(13):1121-1123.YIN Gong-ming,LU Yan-chou,ZHAO Hua,et al.2001.The tectonic uplift of the Hua Shan in the Cenozoic[J].Chinese Science Bulletin,46(19):1665-1668.
袁宝印,汤国安,周力平,等.2012.新生代构造运动对黄土高原地貌分异与黄河形成的控制作用[J].第四纪研究,32(5):829-838.YUAN Bao-yin,TANG Guo-an,ZHOU Li-ping,et al.2012.Control action on the geomorphic differentiation in Loess Plateau and the formation of Yellow River by Cenozoic tectogenesis[J].Quaternary Sciences,32(5):829-838(in Chinese).
原廷宏,冯希杰.2010.一五五六年华县特大地震[M].北京:地震出版社.YUAN Ting-hong,FENG Xi-jie.2010.The 1556 Great Huaxian Earthquake[M].Seismological Press,Beijing(in Chinese).
张安良,米丰收,种瑾.1989.1556年陕西华县大地震形变遗迹及华山山前断裂古地震研究[J].地震地质,11(3):73-81.ZHANG An-liang,MI Feng-shou,CHONG Jin.1989.Deformation relics of the 1556 Huaxian(Shaanxi,China)great earthquake and the study of palaeoseismicity on the frontal fault zone of the Huashan Mts[J].Seismology and Geology,11(3):73-81(in Chinese).
周可兴,王志莲.1998.1556年华县大地震前的大旱灾分析[J].灾害学,13(3):72-75.ZHOU Ke-xing,WANG Zhi-lian.1998.Analysis on the severe drought before 1556 Huaxian great earthquake[J].Journal of Catastrophology,13(3):72-75(in Chinese).
Li D P,Du J J,Ma Y S,et al.2015.Active faults and dip slip rates along the northern margins of the Huashan Mountain and Weinan loess tableland in the southeastern Weihe Graben,central China[J].Journal of Asian Earth Sciences,114:266-278.
Liu J H,Zhang P Z,Lease R O,et al.2013.Eocene onset and late Miocene acceleration of Cenozoic intracontinental extension in the North Qinling Range-Weihe Graben:Insights from apatite fission track thermochronology[J].Tectonophysics,584:281-296.
Rao G,Lin A M,Yan B,et al.2014.Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben,central China[J].Tectonophysics,636:270-285.
Rao G,Lin A M,Yan B.2015.Paleoseismic study on active normal faults in the southeastern Weihe Graben,Central China[J].Journal of Asian Earth Sciences,114:212-225.
Wang J M.1987.The Fenwei rift and its recent periodic activity[J].Tectonophysics,133(3-4):257-275.
Zhang Y Q,Ma Y S,Yang N,et al.2003.Cenozoic extensional stress evolution in North China[J].Journal of Geodynamics,36(5):591-613.
杜建军,黎敦朋,马寅生,等.2013.18.7万年前的高速远程古滑坡:来自陕西华县莲花寺滑坡体上覆黄土光释光(OSL)测年的证据[J].第四纪研究,33(5):1005-1015.DU Jian-jun,LI Dun-peng,MA Yin-sheng,et al.2013.The high-speed and long-distance ancient landslides before187ka:The evidence from the OSL dating of the loess overlying the landslide body of Lianhuasi landslides in Huaxian,Shaanxi Province,China[J].Quaternary Sciences,33(5):1005-1015(in Chinese).
郭增建.1957.1556年1月23日关中大地震[J].地球物理学报,6(1):59-68.GUO Zeng-jian.1957.On the Shensi earthquake of January 23,1556[J].Acta Geophysica Sinica,6(1):59-68(in Chinese).
韩恒悦,贺明静,李永善.1987.渭河盆地东部地区的活断层[J].地震地质,9(2):85-90.HAN Heng-yue,HE Ming-jing,LI Yong-shan.1987.The active faults in the eastern of the Weihe Basin[J].Seismology and Geology,9(2):85-90(in Chinese).
环文林,时振梁,李世勋.2003.对1556年8级大地震震中位置和发震构造的新认识[J].中国地震,19(1):20-32.HUAN Wen-lin,SHI Zhen-liang,LI Shi-xun.2003.The new recognizes for epicenter location and seismogenic structure of 1556 M 8large earthquake[J].Earthquake Research in China,19(1):20-32(in Chinese).
雷祥义,屈红军,岳乐平.1992.灞河阶地黄土-古土壤系列及其年代意义[J].西北大学学报,22(2):219-226.LEI Xiang-yi,QU Hong-jun,YUE Le-ping.1992.Loess-paleosol sequence at terrace of Bahe River and its significance of age[J].Journal of Northwest University,22(2):219-226(in Chinese).
李祥根,冉勇康.1983.华山北坡及渭南塬前活断层[J].华北地震科学,1(2):10-18,9.LI Xiang-gen,RAN Yong-kang.1983.Active faults in the north slope of Huashan Mountain and the front of the Weinan tableland[J].North China Earthquake Sciences,1(2):10-18,9(in Chinese).
李永善,耿大玉,韩许恒,等.1992.西安地裂及渭河盆地活断层研究[M].北京:地震出版社.LI Yong-shan,GENG Da-yu,HAN Xu-heng,et al.1992.Research on Ground Fissures in Xi'an Region and Active Faults in Weihe Basin[M].Seismological Press,Beijing(in Chinese).
李昭淑,崔鹏.2007.1556年华县大地震的次生灾害[J].山地学报,25(4):425-430.LI Zhao-shu,CUI Peng.2007.The secondary disasters of great Huaxian earthquake in 1556[J].Journal of Mountain Science,25(4):425-430(in Chinese).
单修政.1988.1556年华县地震人口死亡原因浅析[J].灾害学,3(4):94-96.SHAN Xiu-zheng.1988.Analysis on the cause of death of the Huaxian earthquake in 1556[J].Journal of Catastrophology,3(4):94-96.
宋立胜.1989.1556年华县8级大震死亡人数初探[J].灾害学,4(4):68-72.SONG Li-sheng.1989.Preliminary study on the number of the deaths of the great Huaxian earthquake in 1556[J].Journal of Catastrophology,4(4):68-72(in Chinese).
万景林,李齐,王瑜.2000.华山岩体中、新生代抬升的裂变径迹证据[J].地震地质,22(1):53-58.doi:10.3969/j.issn.0253-4967.2000.01.007.WAN Jing-lin,LI Qi,WANG Yu.2000.The fission track evidence of Huashan batholith uplifting in MesozoicCenozoic[J].Seismology and Geology,22(1):53-58(in Chinese).
王斌,郑洪波,王平,等.2013.渭河盆地新生代地层与沉积演化研究:现状和问题[J].地球科学进展,28(10):1126-1135.WANG Bin,ZHENG Hong-bo,WANG Ping,et al.2013.The Cenozoic strata and depositional evolution of Weihe Basin:Progresses and problems[J].Advances in Earth Science,28(10):1126-1135(in Chinese).
王景明.1983.渭河盆地活动构造与地震[J].地壳形变与地震,(4):59-66.WANG Jing-ming.1983.Active tectonics and earthquakes in Weihe Basin[J].Crustal Deformation and Earthquake,(4):59-66(in Chinese).
杨源源,高战武,徐伟.2012.华山山前断裂中段晚第四纪活动的地貌表现及响应[J].震灾防御技术,7(4):335-347.YANG Yuan-yuan,GAO Zhan-wu,XU Wei.2012.Geomorphic expression and response of the activity along the middle section of Huashan front fault in the late Quaternary period[J].Technology for Earthquake Disaster Prevention,7(4):335-347(in Chinese).
尹功明,卢演俦,赵华,等.2001.华山新生代构造抬升[J].科学通报,46(13):1121-1123.YIN Gong-ming,LU Yan-chou,ZHAO Hua,et al.2001.The tectonic uplift of the Hua Shan in the Cenozoic[J].Chinese Science Bulletin,46(19):1665-1668.
袁宝印,汤国安,周力平,等.2012.新生代构造运动对黄土高原地貌分异与黄河形成的控制作用[J].第四纪研究,32(5):829-838.YUAN Bao-yin,TANG Guo-an,ZHOU Li-ping,et al.2012.Control action on the geomorphic differentiation in Loess Plateau and the formation of Yellow River by Cenozoic tectogenesis[J].Quaternary Sciences,32(5):829-838(in Chinese).
原廷宏,冯希杰.2010.一五五六年华县特大地震[M].北京:地震出版社.YUAN Ting-hong,FENG Xi-jie.2010.The 1556 Great Huaxian Earthquake[M].Seismological Press,Beijing(in Chinese).
张安良,米丰收,种瑾.1989.1556年陕西华县大地震形变遗迹及华山山前断裂古地震研究[J].地震地质,11(3):73-81.ZHANG An-liang,MI Feng-shou,CHONG Jin.1989.Deformation relics of the 1556 Huaxian(Shaanxi,China)great earthquake and the study of palaeoseismicity on the frontal fault zone of the Huashan Mts[J].Seismology and Geology,11(3):73-81(in Chinese).
周可兴,王志莲.1998.1556年华县大地震前的大旱灾分析[J].灾害学,13(3):72-75.ZHOU Ke-xing,WANG Zhi-lian.1998.Analysis on the severe drought before 1556 Huaxian great earthquake[J].Journal of Catastrophology,13(3):72-75(in Chinese).
Li D P,Du J J,Ma Y S,et al.2015.Active faults and dip slip rates along the northern margins of the Huashan Mountain and Weinan loess tableland in the southeastern Weihe Graben,central China[J].Journal of Asian Earth Sciences,114:266-278.
Liu J H,Zhang P Z,Lease R O,et al.2013.Eocene onset and late Miocene acceleration of Cenozoic intracontinental extension in the North Qinling Range-Weihe Graben:Insights from apatite fission track thermochronology[J].Tectonophysics,584:281-296.
Rao G,Lin A M,Yan B,et al.2014.Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben,central China[J].Tectonophysics,636:270-285.
Rao G,Lin A M,Yan B.2015.Paleoseismic study on active normal faults in the southeastern Weihe Graben,Central China[J].Journal of Asian Earth Sciences,114:212-225.
Wang J M.1987.The Fenwei rift and its recent periodic activity[J].Tectonophysics,133(3-4):257-275.
Zhang Y Q,Ma Y S,Yang N,et al.2003.Cenozoic extensional stress evolution in North China[J].Journal of Geodynamics,36(5):591-613.