| The Ganzi-Yushu fault zone is located in the northeastern part of the Qinghai-Tibet Plateau,which is strong in uplift and erosion.It is the middle of the Mani-Yushu-Xishuihe fault system,which is faulted with the Xianshui River in the fault system.Anning River fault,Xiaojiang fault and Daliangshan fault together constitute the clockwise rotation of the northern boundary of the Qinghai-Tibet Plateau south east plots.Based on the interpretation and analysis of remote sensing data of Ganzi-Yushu fault zone,this paper carried out field geological survey,micro-topographic survey and paleo-seismic trench exploration,etc.,combined with previous research results,the Ganzi Yushu fault zone in the ancient earthquake Event,repeat interval,sliding rate and other aspects of the analysis,access to the following points:(1)In the study of tectonic geomorphology,through the field geological survey,remote sensing image interpretation and micro-topographic survey,it is found that there are a lot of fault landscapes on the fault zone,such as the cut of the river gully,the fault of the terrace,Cut off and so on,these broken fault geomorphology along the fault distribution,the formation of nearly 300 km deformation zone.(2)In the study of paleo-seismic events,based on the 10 trench profiles excavated along the fault area,combined with the sedimentary characteristics of the strata and the dating results of the14 C samples,the regional depositional environment and the epicenter of the ancient earthquakes were analyzed.It is found that there are three ancient earthquakes in the southern section of Ganzi-Yushu fault zone since5000 a,the time is(1000±30)a BP,(3750±30)a BP,(1050±30)a BP.The last paleo-earthquake occurred close to(1000 ± 30)a BP.In the middle of the fault zone,the paleoclimatic events can be determined according to the historical records,and the most recent paleo-seismic time is AD(1320 ± 65).The data in the north west section of the exploration channel are abundant.A total of 7 ancient events were revealed in the combined trough of the Xiala village trench,The last time of the ancient earthquake in this section was AD1896.A total of 5 ancient events were revealed in the combined trough of the Chalai village trench,The latest period of an ancient earthquake in this section is elapsed(1765±30)aBP.A total of 9 ancientevents were revealed in the combined trough of the Cha wukou village trench,The latest period of an ancient earthquake in this section is elapsed(1045±415)aBP.(3)In the estimation of the sliding rate,the slip rate of 13 sites is calculated by selecting the dislocation deformation data and age data of the Ganzi-Yushu fault.The removal rate of left-lateral slip of Ganzi-Yushu fault was 6.5 ± 2.5,7.2 ± 0.7,8.8 ±1.2,10.9 ± 2.0,11.3 ± 1.8,12.8 ± 1.7 and 13.9 ± 1,1.4mm/a and so on,of which 12 ~14mm/a slip rate is the use of the ground floor of the ground acquisition point to obtain the age of data to replace the terrestrial dislocation of the era,therefore,the measured rate will be too large.The GPS velocity profile across the fracture indicates that the fracture slip rate is 6.6 ± 1.5 mm/a.According to the comprehensive analysis,it is considered that the overall slip rate of 8.9mm / a since the late Quaternary is closer to the whole slip of the fault zone.(4)In the ancient earthquake recurrence interval,combined with the trench data and slip rate analysis were obtained from the ancient earthquake recurrence interval data,Analysis that since 5000 a,the average recurrence interval of the large earthquake in Ganzi segment was(2725±30)a,the average recurrence interval of Dengke-Cuoa was 4968 a,the average recurrence interval of Dengke-Batang was(1282±220)a,the average recurrence interval of Batang basin was(3550 ± 460)a. |
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