乌鲁木齐王家沟断层组地表变形特征及强变形带宽度

SURFACE DEFORMATION OF THE WANGJIAGOU FAULT SET IN URUMQI AND THE SAFETY DISTANCE FROM IT

王家沟断层组断错了中更新世砾石台地及王家沟东岸的Ⅲ级阶地,地貌形迹非常清晰,地表变形现象主要表现为地震断层、断层陡坎和挤压鼓包等。根据不同地貌面上跨断层测量获得的一系列实测数据,得到王家沟Ⅲ级阶地上的地表陡坎高度为0.4～1.6m,最大变形带宽度为50m左右;中更新世台地上的陡坎高度多为1.5～5.0m,最大变形带宽度为90m左右。利用探槽开挖揭露出的断层位置与地表强变形带测量剖面的叠加对比,初步确定王家沟断层组上、下盘之间变形宽度的比例为2:1左右,并由此讨论了王家沟断层组上、下盘的"避让带"宽度问题。

The Wangjiagou Fault set,a set of Holocene active faults,is located at western suburbs of Urumqi City.The faults dislocated the gravel platform of the mid Pleistocene and the third level terrace of the Wangjiagou east bank,generating apparent fault scarps of opposite-slope direction on the surface with clear geomorphic traces.There are a series of deformation indications on landform,such as seismic fault,scarp and upheaval.In the field,thirty-nine groups of data were measured by using line tape along the fault.Among them,six were measured on the third level terrace of the Wangjiagou,and the others on the mid Pleistocene platform.Based on the data measured across the fault,we obtain that the height of the scarps is 0.4～1.6m and the width of the fault deformation is about 50m on the third level terrace.And on the mid Pleistocene platform,the height of scarps is 1.5～5.0m and the width of the deformation is about 90m.After comparing the profile of strong topographic deformation zone with the trench section,we primarily recognize that the ratio of hanging wall to foot wall deformation width is 2： 1approximately.The widths of strong surface deformation belt on the mid Pleistocene platform and the third level terrace on the two walls are 60m,30m and 33m,17m,respectively.