关于兰州市“刘家堡断裂”的地震勘探研究

Study on the seismic exploration of Liujiabu fault in Lanzhou

摘要:

各种地质调查方法的综合研究证明,兰州市所谓的"刘家堡断裂"实际上应该是兰州七里河向斜盆地的北部边界。采用适合于百米以内地震勘探的观测系统,主要探测"刘家堡断裂"沿线浅部岩层变化情况,通过分析4个场地的浅层地震剖面,阐述了勘探场地附近地震图像的特征及其所反映的七里河向斜盆地西北边缘的构造趋势。地震勘探认为,向斜构造界线两侧岩层物理性质差异明显,地震反射剖面对比反映出"刘家堡断裂"与"深沟桥断裂"交汇的部位褶皱变形非常剧烈。总之,兰州盆地内部地质构造复杂,地震勘探的正确解释是建立在对地质构造正确认识的基础上的。

Abstract:

The integration of the various techniques of geological survey has proved that Liujiabu fault is not a fault actually, but a northern boundary of the Qilihe syncline basin in Lanzhou city. In order to get the deformation of the shallow stratum along the Liujiabu fault, a set of observing system, which is suit for seismic reflection above one hundred meters, is used in the survey. There are four survey lines discussed in this paper, and we delineate the structure of the Qilihe syncline basin by analyzing the characteristics of the four seismic images. Comparison of the seismic images shows that the obvious physical differences are on two sides of the syncline structure, meanwhile, the intersection of Liujiabu fault and Shengouqiao fault is deformed greatly. This study suggests that the geological structure under the Lanzhou basin is quite complicated and the correct interpretation of seismic exploration is based on a correct understanding of the geological structure.