Abstract: The Wanyaogou Fault dislocates the Jurassic sandstone.The tilted bedrock becomes a natural barrier to the groundwater,and a water-rich stratum formed in the footwall which caused obvious resistance difference between the two walls of the fault.The electrical imaging is an effective way to detect the fault on this condition.The experimental electrical resistivity tomography survey was conducted to detect the Wanyaogao Fault.The results of 2-D resistivity inversion indicate that the electrical structures on both sides of the fault present obvious difference,the resistivity of the hanging wall is high,while that of the foot wall is low.And the interface of the high and low resistance regions inclines to the low resistance region.The electrical resistivity tomography survey was also conducted to detect other faults in Urmuqi which have similar tectonic characteristics with Wanyaogou Fault.And the electrical structures appear the similar abnormality.So the abnormal characteristic is an important indicator and basis for identification of fault in the Urumqi region.The faults in Urmuqi are almost all high-obliquity reverse faults.After comparing the electrical imaging with the trench section,we find the fault is not coincident with the borderline between the high and low resistance,but lies in the high resistance region.The fault inclination is reverse to the gradient direction of isolines.The fault location is near to the inflexion of the upper isolines.

Key words: Wanyaogou Fault, electrical imaging, trench, Urmuqi

摘要： 利用电阻率二维层析成像方法对碗窑沟断层进行了试验探测,获得了该断层典型的电阻率成像异常特征:地层电性结构存在强间断面,呈现明显的"二分"现象,高、低阻间的梯度界线倾向低阻区。在对乌鲁木齐地区其它具有类似构造特征的断层进行探测时,电阻率成像剖面呈现出相似的异常特征,说明这一异常特征可以作为乌鲁木齐地区判定断层的重要标志和依据。乌鲁木齐地区多为高角度的逆冲断层,此类构造电阻率成像剖面中高、低阻之间的界线与断层并不重合,断层处于高阻区域,倾向与视电阻率衰减梯度线倾向相反,断层的真实位置与图像最上部高、低电阻转折的拐点部位最接近。

关键词: 碗窑沟断层, 电阻率成像, 探槽, 乌鲁木齐