银川平原断裂体系划分与研究

Division and study of fracture system in Yinchuan Plain

银川平原位于宁夏北部,夹持于贺兰山与灵盐台地之间。大地构造隶属于鄂尔多斯西缘冲断带,为一新生代断陷盆地(五级构造单元)。区域上,受阿拉善微陆块NE向的挤压及鄂尔多斯西缘EW向的拉张作用,银川盆地构造活动性较强烈,地震灾害威胁严重。针对第四系厚覆盖区断层难以定位及划分的难题,本研究在地质研究的基础上,综合运用多种边界识别技术,分析处理1∶20万区域重力数据,相互比对、印证,共划定断裂43条,确立了银川平原断裂体系,并针对黄河断裂、贺兰山东麓断裂等6条主要断裂进行了深入的分析,为银川平原断裂活动性研究奠定了坚实的基础。

The Yinchuan Plain is located in the northern of Ningxia,sandwiched between Helan Mountain and the Lingwu-Yanchi platform.Its tectonics is a Cenozoic rift basin(fifth-order tectonic unit),belonging to the western Ordos thrust belt.Regionally,the tectonic activity of Yinchuan Basin is strong and the threat of earthquake disaster is serious because of the NE-trending compression of Alxa micro-continent block and the EW-trending stretching of the western margin of Ordos.It is difficult to locate and divide faults in the thick overburden area of Quaternary.On the basis of geological research,by means of comprehensive application of several boundary recognition technology,deal with 1∶200,000 regional gravity data,compared and verified each other,delimited 43 faults and establishes Yinchuan Plain fault system in this study.Six major faults,such as the Yellow River fault and the Helan fault,were studied in depth,which layed a solid foundation for the study of fault activity in Yinchuan Plain.