滇西南地区孟连断裂晚第四纪走滑速率的厘定
|
摘要
通过卫星影像解译和野外实地调查,获得滇西南地区孟连断裂的几何特征和活动性参数。孟连断裂总体走向NE-NEE向,不具有明显的分段性,连续性较好。断裂从单侧控制着沿线的勐滨、孟连和勐马三个新生代盆地的发育。断裂沿线地貌以线性较好的断层谷、断层崖和断层陡坎为主,并发育多级左旋位错的河流、冲沟和阶(台)地等,观测到的最小左旋位错约为7 m。采用高精度Li-DAR测量方法,对4处典型水平位错地貌进行精细测量,根据获得的相应地貌面年代,得到孟连断裂晚第四纪以来平均左旋走滑速率为2.2±0.4 mm/a。其结果与滇西南地区其他NE向左旋走滑断裂滑动速率相当,反映了区域构造活动的整体协调性。根据跨断层地质体最大左旋位错量9.5±1.8 km,估算断裂开始左旋走滑的时代为距今4.7±1.6 Ma左右,即中新世中晚期。
Because of the limited extrusion of the Tibet Plateau from the northwest to southeast, the Sichuan-Yunnan block has one of the highest concentrations and frequencies of earthquakes in China. It is very critical to assess the seismic hazard and explore the geodynamics of this region by quantifying the slip rates of active faults as well as the earthquake occurrence. The Menglian fault, one of the active left-lateral strike-slip faults in Sichuan-Yunnan block, stretches from China to Myanmar. There are no records of earthquakes on the Menglian fault; however, many earthquakes occurred in its vicinity, which may be related to the activity of the fault, such as the Myanna M_S7.3 earthquake of 1995. In China, the Menglian fault has a length of 90 km and a trend of NE-ENE. The fault shows clear geomorphologic characteristic with linear fault scarps(mainly), fault valleys, and fault trenches. Additionally, various offset streams, gullies, and terraces have been formed along the fault, and the observed minimum left-lateral dislocation is about 7 m. Using high-precision Li-DAR measurement, four typical horizontal dislocation geomorphologies were finely measured. According to the obtained age of the geomorphic surface, the average left-lateral strike-slip rate of the fault since the late Quaternary was(2.2±0.4) mm/a. The results were equivalent to the sliding rate of other NE-trending left-lateral strike-slip faults in southwestern Yunnan, reflecting the overall coordination of regional tectonic activities. According to the maximum left-lateral dislocation of(9.5±1.8) km, the initial time of the left-lateral strike-slip of the fault was estimated to be about(4.7±1.6) Ma, in the middle and late Miocene.
Because of the limited extrusion of the Tibet Plateau from the northwest to southeast, the Sichuan-Yunnan block has one of the highest concentrations and frequencies of earthquakes in China. It is very critical to assess the seismic hazard and explore the geodynamics of this region by quantifying the slip rates of active faults as well as the earthquake occurrence. The Menglian fault, one of the active left-lateral strike-slip faults in Sichuan-Yunnan block, stretches from China to Myanmar. There are no records of earthquakes on the Menglian fault; however, many earthquakes occurred in its vicinity, which may be related to the activity of the fault, such as the Myanna M_S7.3 earthquake of 1995. In China, the Menglian fault has a length of 90 km and a trend of NE-ENE. The fault shows clear geomorphologic characteristic with linear fault scarps(mainly), fault valleys, and fault trenches. Additionally, various offset streams, gullies, and terraces have been formed along the fault, and the observed minimum left-lateral dislocation is about 7 m. Using high-precision Li-DAR measurement, four typical horizontal dislocation geomorphologies were finely measured. According to the obtained age of the geomorphic surface, the average left-lateral strike-slip rate of the fault since the late Quaternary was(2.2±0.4) mm/a. The results were equivalent to the sliding rate of other NE-trending left-lateral strike-slip faults in southwestern Yunnan, reflecting the overall coordination of regional tectonic activities. According to the maximum left-lateral dislocation of(9.5±1.8) km, the initial time of the left-lateral strike-slip of the fault was estimated to be about(4.7±1.6) Ma, in the middle and late Miocene.
引文
[1] TAPPONNIER P,ZHIQIN X,ROGER F,et al.Oblique Stepwise Rise and Growth of the Tibet Plateau[J].Science,2001,294(5547):1671-1677.
[2] 邓起东,张培震,冉勇康,等.中国活动构造与地震活动[J].地学前缘,2003,10(增刊1):66-73.DENG Qidong,ZHANG Peizhen,RAN Yongkang,et al.Active Tectonics and Earthquake Activities in China[J].Earth Science Frontiers,2003,10(Supp1):66-73.
[3] 徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学(D辑):地球科学,2003,33(增刊1):151-162.XU Xiwei,WEN Xueze,ZHENG Rongzhang,et al.Latest Tectonic Deformation Style and Its Dynamic Sources of Active Blocks in Sichuan—Yunnan Region[J].Science in China(Series D),2003,33(Supp1):151-162.
[4] 邓起东,程绍平,马冀,等.青藏高原地震活动特征及当前地震活动形势[J].地球物理学报,2014,57(7):2025-2042.DENG Qidong,CHENG Shaoping,MA Ji,et al.Seismic Activities and Earthquake Potential in the Tibet Plateau[J].Chinese Journal of Geophysics,2014,57(7):2025-2042.
[5] 张培震.青藏高原东缘川西地区的现今构造变形、应变分配与深部动力过程[J].中国科学D 辑,2008,38(9):1041-1056.ZHANG Peizhen.The Present-day Tectonic Deformation,Strain Partitioning and Deep Dynamic Process of the Western Sichuan Region along Eastern Margin of Qinghai—Tibet Plateau[J].Science in China(Series D),2008,38(9):1041-1056.
[6] 李永华,张风雪,高家乙,等.云南地区地壳速度结构和地震活动性研究[J].地球物理学进展,2016,31(2):508-516.LI Yonghua,ZHANG Fengxue,GAO Jiayi,et al.P-wave Crustal Velocity Structure and Seismicity in Yunnan Area[J].Progress in Geophysics,2016,31(2):508-516.
[7] 王阎昭,王恩宁,沈正康,等.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学D辑,2008,38(5):582-597.WANG Yanzhao,WANG Enning,SHEN Zhenkang,et al.GPS-constrained Inversion of Present-day Slip Rates along Major Faults in Sichuan-Yunnan Province[J].Science in China:Series D,2008,38(5):582-597.
[8] 周瑞琦,虢顺民,何蔚.龙陵—澜沧断裂带双震型强震活动破裂模型讨论[J].地震地质,1998,20(3):261-268.ZHOU Ruiqi,GUO Shunmin,HE Wei.A Study on the Rupturing Model of the Double-main Shock in the Longling—Lancang Fault Zone[J].Seismology and Geology,1998,20(3):261-268.
[9] 虢顺民,向宏发,周瑞琦,等.滇西南龙陵—澜沧断裂带_大陆地壳上一条新生的破裂带.科学通报,1999,44(19):2118-2121.GUO Shunmin,XIANG Hongfa,ZHOU Ruiqi,et al.Longling—Lancang Fault Zone in Southwest Yunnan,China:A Newly-generated Rupture Zone in Continental Crust[J].Chinese Science Buletin,1999,44(19):2118-2121.
[10] 虢顺民,向宏发,徐锡伟,等.滇西南龙陵—澜沧第四纪新生断裂带特征和形成机制研究[J].地震地质,2000,22(3):277-284.GUO Shunmin,XIANG Hongfa,XU Xiwei,et al.Characteristics and Formation Mechanism of the Longling—Lancang Newly Emerging Fault Zone in Quaternary in the Southwest Yunnan[J].Seismology and Geology,2000,22(3):277-284.
[11] 虢顺民,徐锡伟,向宏发,等.龙陵—澜沧新生断裂带地震破裂分段与地震预测研究[J].地震地质,2002,24(2):133-144.GUO Shunmin,XU Xiwei,XIANG Hongfa,et al.Segmentation of Earthquake Rupture and Earthqueke Prediction along the Longling—Lancang Fault Zone in the Southwestwen Yunnan Procince[J].Seismology and Geology,2002,24(2):133-144.
[12] 俞维贤,安晓文,李世成,等.澜沧江流域主要断裂断层泥中石英碎砾表面SEM特征及其断裂活动研究[J].地震研究,2002,25(3):275-280.YU Weixian,AN Xiaowen,LI Shicheng,et al.Study on SEM Characteristics of Quartz Grains in the Lancang River Valley[J].Journal of Seismological Research,2002,25(3):275-280.
[13] 吴坤罡,吴中海,黄小龙,等.云南盈江2014年5·30 MS6.1地震的主要震害特征[J].地质力学学报,2015,21(1):87-96.WU Kungang,WU Zhonghai,HUANG Xiaolong,et al.Analysis on Main Characteristics of Earthquake Damage Caused by MS6.1 Earthquake on May 30,2014 in Yingjiang County,Yunnan Province[J].2015,21(1):87-96.
[14] 何文贵,刘兴旺,袁道阳,等.滇西南地区孟连断裂晚第四纪新活动特征初步研究[J].地震工程学报,2015(4):986-995.HE Wengui,LIU Xingwang,YUAN Daoyang,et al.Preliminary Study on the Late Quaternary Activity Characteristics of the Menglian Fault in Southwest Yunnan[J].China Earthquake Engineering Journal,2015,37(4):986-995.
[15] 庄儒新,陈宇军,陈刚,等.孟连断裂晚第四纪活动特征[J].震灾防御技术,2018,13(3):619-626.ZHUANG Ruxin,CHEN Yujun,CHEN Gang,et al.Characteristics of the Quaternary Activity of Menglian Fault[J].Technology for Earthquake Disaster Prevention,2018,13(3):619-626.
[16] 刘兴旺,袁道阳,张波,等.滇西南地区澜沧断裂全新世滑动速率与走滑起始时间探讨[J].地震工程学报,2016,38(3):413-422.LIU Xingwang,YUAN Daoyang,ZHANG Bo,et al.Study of Holocene Slip Rate and Strike-Slip Initial Time along theLancang Fault,Southwestern Yunnan[J].China Earthquake Engineering Journal,2016,38(3):413-422.
[17] 邓起东,陈立春,冉勇康.活动构造定量研究与应用[J].地学前缘,2004,11(4):383-392.DENG Qidong,CHEN Lichun,RAN Yongkang.Quantitative Studies and Applications of Active Tectonics[J].Earth Science Frontiers,2004,11(4):383-392.
[18] 张培震,李传友,毛凤英.河流阶地演化与走滑断裂滑动速率[J].地震地质,2008,30(1):44-57.ZHANG Peizhen,LI Chuanyou,MAO Fengying.Strath Terrace Formation and Strike-slip Faulting[J].Seismology and Geology,2008,30(1):44-57.
[19] 邵延秀,张波,邹小波,等.采用无人机载LiDAR进行快速地质调查实践[J].地震地质,2017,39(6):1185-1197.SHAO Yanxiu,ZHANG Bo,ZOU Xiaobo,et al.Application of UAVLS to Rapid Geological Surveys[J].Seismology and Geology,2017,39(6):1185-1197.
[20] OSKIN M E,ARROWSMITH J R,CORONA A H,et al.Near-field Deformation from the El Mayor-Cucapah Earthquake Revealed by Differential LIDAR.[J].Science,2012,335(6069):702-705.
[21] SHI X,WANG Y,SIEH K,et al.Fault Slip and GPS Velocities Across the Shan Plateau Define a Curved Southwestward Crustal Motion Around the Eastern Himalayan Syntaxis[J].Journal of Geophysical Research:Solid Earth,2018.
[2] 邓起东,张培震,冉勇康,等.中国活动构造与地震活动[J].地学前缘,2003,10(增刊1):66-73.DENG Qidong,ZHANG Peizhen,RAN Yongkang,et al.Active Tectonics and Earthquake Activities in China[J].Earth Science Frontiers,2003,10(Supp1):66-73.
[3] 徐锡伟,闻学泽,郑荣章,等.川滇地区活动块体最新构造变动样式及其动力来源[J].中国科学(D辑):地球科学,2003,33(增刊1):151-162.XU Xiwei,WEN Xueze,ZHENG Rongzhang,et al.Latest Tectonic Deformation Style and Its Dynamic Sources of Active Blocks in Sichuan—Yunnan Region[J].Science in China(Series D),2003,33(Supp1):151-162.
[4] 邓起东,程绍平,马冀,等.青藏高原地震活动特征及当前地震活动形势[J].地球物理学报,2014,57(7):2025-2042.DENG Qidong,CHENG Shaoping,MA Ji,et al.Seismic Activities and Earthquake Potential in the Tibet Plateau[J].Chinese Journal of Geophysics,2014,57(7):2025-2042.
[5] 张培震.青藏高原东缘川西地区的现今构造变形、应变分配与深部动力过程[J].中国科学D 辑,2008,38(9):1041-1056.ZHANG Peizhen.The Present-day Tectonic Deformation,Strain Partitioning and Deep Dynamic Process of the Western Sichuan Region along Eastern Margin of Qinghai—Tibet Plateau[J].Science in China(Series D),2008,38(9):1041-1056.
[6] 李永华,张风雪,高家乙,等.云南地区地壳速度结构和地震活动性研究[J].地球物理学进展,2016,31(2):508-516.LI Yonghua,ZHANG Fengxue,GAO Jiayi,et al.P-wave Crustal Velocity Structure and Seismicity in Yunnan Area[J].Progress in Geophysics,2016,31(2):508-516.
[7] 王阎昭,王恩宁,沈正康,等.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学D辑,2008,38(5):582-597.WANG Yanzhao,WANG Enning,SHEN Zhenkang,et al.GPS-constrained Inversion of Present-day Slip Rates along Major Faults in Sichuan-Yunnan Province[J].Science in China:Series D,2008,38(5):582-597.
[8] 周瑞琦,虢顺民,何蔚.龙陵—澜沧断裂带双震型强震活动破裂模型讨论[J].地震地质,1998,20(3):261-268.ZHOU Ruiqi,GUO Shunmin,HE Wei.A Study on the Rupturing Model of the Double-main Shock in the Longling—Lancang Fault Zone[J].Seismology and Geology,1998,20(3):261-268.
[9] 虢顺民,向宏发,周瑞琦,等.滇西南龙陵—澜沧断裂带_大陆地壳上一条新生的破裂带.科学通报,1999,44(19):2118-2121.GUO Shunmin,XIANG Hongfa,ZHOU Ruiqi,et al.Longling—Lancang Fault Zone in Southwest Yunnan,China:A Newly-generated Rupture Zone in Continental Crust[J].Chinese Science Buletin,1999,44(19):2118-2121.
[10] 虢顺民,向宏发,徐锡伟,等.滇西南龙陵—澜沧第四纪新生断裂带特征和形成机制研究[J].地震地质,2000,22(3):277-284.GUO Shunmin,XIANG Hongfa,XU Xiwei,et al.Characteristics and Formation Mechanism of the Longling—Lancang Newly Emerging Fault Zone in Quaternary in the Southwest Yunnan[J].Seismology and Geology,2000,22(3):277-284.
[11] 虢顺民,徐锡伟,向宏发,等.龙陵—澜沧新生断裂带地震破裂分段与地震预测研究[J].地震地质,2002,24(2):133-144.GUO Shunmin,XU Xiwei,XIANG Hongfa,et al.Segmentation of Earthquake Rupture and Earthqueke Prediction along the Longling—Lancang Fault Zone in the Southwestwen Yunnan Procince[J].Seismology and Geology,2002,24(2):133-144.
[12] 俞维贤,安晓文,李世成,等.澜沧江流域主要断裂断层泥中石英碎砾表面SEM特征及其断裂活动研究[J].地震研究,2002,25(3):275-280.YU Weixian,AN Xiaowen,LI Shicheng,et al.Study on SEM Characteristics of Quartz Grains in the Lancang River Valley[J].Journal of Seismological Research,2002,25(3):275-280.
[13] 吴坤罡,吴中海,黄小龙,等.云南盈江2014年5·30 MS6.1地震的主要震害特征[J].地质力学学报,2015,21(1):87-96.WU Kungang,WU Zhonghai,HUANG Xiaolong,et al.Analysis on Main Characteristics of Earthquake Damage Caused by MS6.1 Earthquake on May 30,2014 in Yingjiang County,Yunnan Province[J].2015,21(1):87-96.
[14] 何文贵,刘兴旺,袁道阳,等.滇西南地区孟连断裂晚第四纪新活动特征初步研究[J].地震工程学报,2015(4):986-995.HE Wengui,LIU Xingwang,YUAN Daoyang,et al.Preliminary Study on the Late Quaternary Activity Characteristics of the Menglian Fault in Southwest Yunnan[J].China Earthquake Engineering Journal,2015,37(4):986-995.
[15] 庄儒新,陈宇军,陈刚,等.孟连断裂晚第四纪活动特征[J].震灾防御技术,2018,13(3):619-626.ZHUANG Ruxin,CHEN Yujun,CHEN Gang,et al.Characteristics of the Quaternary Activity of Menglian Fault[J].Technology for Earthquake Disaster Prevention,2018,13(3):619-626.
[16] 刘兴旺,袁道阳,张波,等.滇西南地区澜沧断裂全新世滑动速率与走滑起始时间探讨[J].地震工程学报,2016,38(3):413-422.LIU Xingwang,YUAN Daoyang,ZHANG Bo,et al.Study of Holocene Slip Rate and Strike-Slip Initial Time along theLancang Fault,Southwestern Yunnan[J].China Earthquake Engineering Journal,2016,38(3):413-422.
[17] 邓起东,陈立春,冉勇康.活动构造定量研究与应用[J].地学前缘,2004,11(4):383-392.DENG Qidong,CHEN Lichun,RAN Yongkang.Quantitative Studies and Applications of Active Tectonics[J].Earth Science Frontiers,2004,11(4):383-392.
[18] 张培震,李传友,毛凤英.河流阶地演化与走滑断裂滑动速率[J].地震地质,2008,30(1):44-57.ZHANG Peizhen,LI Chuanyou,MAO Fengying.Strath Terrace Formation and Strike-slip Faulting[J].Seismology and Geology,2008,30(1):44-57.
[19] 邵延秀,张波,邹小波,等.采用无人机载LiDAR进行快速地质调查实践[J].地震地质,2017,39(6):1185-1197.SHAO Yanxiu,ZHANG Bo,ZOU Xiaobo,et al.Application of UAVLS to Rapid Geological Surveys[J].Seismology and Geology,2017,39(6):1185-1197.
[20] OSKIN M E,ARROWSMITH J R,CORONA A H,et al.Near-field Deformation from the El Mayor-Cucapah Earthquake Revealed by Differential LIDAR.[J].Science,2012,335(6069):702-705.
[21] SHI X,WANG Y,SIEH K,et al.Fault Slip and GPS Velocities Across the Shan Plateau Define a Curved Southwestward Crustal Motion Around the Eastern Himalayan Syntaxis[J].Journal of Geophysical Research:Solid Earth,2018.