元谋断裂晚第四纪活动性定量分析

ETM影像揭示了元谋断裂以左行剪切走滑为主, 局部张剪或压剪的性质.利用1:5万地形图和影像图内冲沟、山脊等地貌位错估测了元谋断裂一平浪-江边段晚第四纪活动性, 详细调查实测并分析了研究区断错地貌和构造剖面, 获取的该断裂晚第四纪活动性、活动强度, 与估测结果一致.结果显示, 元谋断裂一平浪-江边(金沙江边) 段最新活动时间为晚更新世末期-全新世; 其中一平浪-大龙潭一带, 水平滑动速率约2.0mm/a, 垂直滑动速率为0.07mm/a; 木莲旧-秧田井一带, 水平滑动速率接近0.53mm/a, 垂直滑动速率为0.06mm/a; 乐胜古-江边一带, 水平滑动速率接近1.32mm/a, 垂直滑动速率为0.03mm/a.综合分析表明, 该段断裂晚第四纪平均水平滑动速率为1~2.0mm/a, 以走滑运动为主. 

Quantitative Analysis on Activity of the Yuanmou Fault in Late Quaternary

ETM data reveal that the Yuanmou fault is mainly characterized by horizontal left-lateral and shear strike-slip, including ringent shear and pressed shear in part.Taking the advantage of the level moving and offset of the gullies and ridges in 1∶50000 landform and ETM image, we estimated the activity of Yuanmou fault of Yipinglang-Jiangbian segment in the Late Quaternary, and later the results from field exploration, including the analysis of the profiles of landform offsets such as gullies and fluvial landforms, the sections of the active structures in the studied area and activity and active intensity in the Yuanmou fault is the same as what we presumed before.The result shows that the latest active time of the Yuanmou fault of Yipinglang-Jiangbian segment is from the mid-late of Late Pleistocene to Holocene.During these ages, the level moving velocity of left-lateral strike-slip of Yipinglang-Dalongtan segment is approximately 2.0 mm/a, the velocity of uprightness strike-slip approximately 0.07 mm/a.While the respective velocity of left-lateral strike-slip and uprightness strike-slip is approximately 0.53 mm/a and approximately 0.06 mm/a from Yangtianjing to Mulianjiu, the respective velocity of left-lateral strike-slip and uprightness strike-slip approximately 1.32 mm/a and 0.03 mm/a from Leshenggu to Jiangbian.Comprehensive analysis indicates that the level moving velocity since the Late Quaternary in the studied phase is 1~2.0 mm/a, with a major left-lateral shear strike-slip.