| 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 |
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| 引用本文： | 刘兴旺,袁道阳,张波,何文贵,方良好.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].西北地震学报,2016,38(3):413-422. |
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| 作者姓名： | 刘兴旺 袁道阳 张波 何文贵 方良好 |
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| 作者单位： | 中国地震局兰州地震研究所, 甘肃 兰州 730000;兰州地球物理国家野外科学观测研究站, 甘肃 兰州 730000,中国地震局兰州地震研究所, 甘肃 兰州 730000,中国地震局兰州地震研究所, 甘肃 兰州 730000;兰州地球物理国家野外科学观测研究站, 甘肃 兰州 730000,中国地震局兰州地震研究所, 甘肃 兰州 730000;兰州地球物理国家野外科学观测研究站, 甘肃 兰州 730000,安徽省地震局, 安徽 合肥 230031 |
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| 基金项目： | 公益性行业科研专项《中国地震活断层探察-南北地震带中南段》(201108001);国家自然基金项目(41572197) |
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| 摘 要： | 通过卫星影像解译、野外实地调查和地质填图,获得滇西南地区澜沧断裂的基本特征和活动性参数,澜沧断裂属于龙陵—澜沧新生地震断裂带的东南段,北起耿马县联合村,向南东经澜沧县哈卜吗、战马坡、大塘子至澜沧县城东南,总体走向NNW,长度约85km。该断裂为一条全新世活动的右旋走滑断裂,兼具倾滑分量,沿断裂形成了丰富的断错地貌现象,主要表现为断层陡崖、冲沟右旋、断层陡坎、断层沟槽、断层垭口和断陷凹坑等。通过详细的野外考察,选择典型断错地貌进行差分GPS测量,结合所获相应地貌面的年代数据,得到该断裂全新世以来平均右旋走滑速率为(4.2±2.3)mm/a,其结果与现今GPS观测所得速率相当,反映了该断裂长期以来滑动速率的稳定性。同时根据岩体的最大位错量4.6~4.8km,估算断裂开始右旋走滑的时代为距今约1.1 Ma,即早更新世晚期。
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| 关 键 词： | 澜沧断裂 河流阶地 滑动速率 |
| 收稿时间： | 2015/5/18 0:00:00 |
Study of Holocene Slip Rate and Strike-slip Initial Time alongthe Lancang Fault,Southwestern Yunnan |
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| LIU Xing-wang,YUAN Dao-yang,ZHANG Bo,HE Wen-gui and FANG Liang-hao.Study of Holocene Slip Rate and Strike-slip Initial Time alongthe Lancang Fault,Southwestern Yunnan[J].Northwestern Seismological Journal,2016,38(3):413-422. |
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| Authors: | LIU Xing-wang YUAN Dao-yang ZHANG Bo HE Wen-gui and FANG Liang-hao |
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| Institution: | Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China;Lanzhou National Observatory of Geophysics, Lanzhou 730000, Gansu, China,Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China,Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China;Lanzhou National Observatory of Geophysics, Lanzhou 730000, Gansu, China,Lanzhou Institute of Seismology, CEA, Lanzhou 730000, Gansu, China;Lanzhou National Observatory of Geophysics, Lanzhou 730000, Gansu, China and Earthquake Administration of Anhui Province, Hefei 230031, Anhui, China |
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| Abstract: | Two earthquakes with magnitudes of 7.6 and 7.3 occurred in the Lancang and Gengma areas,respectively,in southwestern Yunnan on November 6,1988.The M7.6 earthquake showed complicated earthquake-generating tectonic characteristics; the seismogenic structure was the Heihe and Lancang faults and an obvious seismic deformation belt was formed separately along the two faults.The Longling-Lancang fault is located in southwestern Yunnan and was an active fault zone in the late Quaternary.It has a length of 500 km,a trend of 320°~340°,and is mainly right-lateral strike slip with dip slip.It starts north of Tengchong,stretches through Longling,Gengma,Lancang,and terminates in Menghun in the south.The fault is composed of a plurality of discontinuous secondary fault components with a diagonal or clustered distribution.A number of fault basins and offset drainage systems have been formed along the fault.According to differences in fault geometric distribution,mechanism,fault scale,boundaries,and seismicity,the Longling-Lancang fault can be divided into four secondary fault segments: the Gudong-Tengchong,Longling-Yongde,Hanmuba-Lancang,and Jiufang-Mengzhe.The focus of this paper is the Lancang fault in the Hanmuba-Lancang segment.The Lancang fault starts to the north of Lianhe,transverses south of Yanshuai in Cangyuan county,across Nanliu,Habuma,Zhanmapo,Datangzi,Datangzi,Laodazhai,and Makadi,and terminates in the southeast of Lancang county.It has a length of 85 km and a NNW trend.The Lancang fault was a Holocene-active right-lateral strike slip fault with a dip slip component.A variety of dislocation landforms have been formed along the fault,such as fault steep cliffs,fault scarps,dextral dislocation of gullies and ridges,fault trenches,fault passes,and pits.The fault intersects the Heihe fault with a NWW trend at Zhanmapo where the M7.6 Langcang earthquake occurred.In this paper,the geological and geomorphological characteristics of activity along the Lancang fault are studied in accordance with the use of satellite image interpretation and field geological investigations.The research focuses on the slip rate of the fault during the Holocene.Two level terraces appeared with synchronized displacement at Nanjingwa; the displacement of the T2 terrace is about (40±2) m.No dating samples are available from this area,and therefore regional dating data is used to determine the slip rate.At a location near Makadi,five gullies have synchronous right-lateral displacement because of fault movement; according to differential GPS measurements in one of these gullies the displacement is about (19±3) m.Using age data for the corresponding landform surface,we thus determine that the right-lateral strike slip rate at this location is approximately (4.2±0.6) mm/a.Analysis of the slip rate and bedrock displacement leads us to infer that the fault was initiated in the late-early Pleistocene. |
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| Keywords: | Lancang fault river terrace slip rate |
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