【摘要】 地震反射勘探法是当前城市地震活断层探测的主要方法,它在厚覆盖区探测断层及其上断点的效果取决于所采用的工作方法和技术参数。桥北镇—宿迁断裂是郯庐断裂带在江苏境内一条重要的隐伏断裂。以宿迁市活动断层探测项目中针对该断裂敷设于厚覆盖层地区的QL14测线为例,为了查明测线控制地段内断裂的空间展布形态、性质以及活动性,针对不同目标、目的层深度和精度要求,作者按照组合、分步探测的工作思路,采用了不同的地震勘探方法技术和采集参数对其进行了高分辨率地震反射成像,解决了地质任务要求与野外资料采集方法之间的矛盾,从而获得了埋深约16~450 m范围内高分辨率的地层结构和非常清晰的断裂构造图像,为钻孔联合剖面位置的布设、钻孔深度的设计以及断裂活动性的评价提供了地震学依据。最后经高精度钻孔联合地质剖面证实,地震勘探方法反演得到的主要地层界面和构造特征都与钻孔联合地质剖面吻合较好。试验结果表明:采用组合探测的方法能够获得断层在不同深度的产状、展布以及由深至浅完整的分布图像;地震勘探法在厚覆盖区确定隐伏断层具体位置和判定断层活动性具有可行性以及地震勘探与钻孔联合地质剖面相结合的工作方法具有有效性。更多还原

【Abstract】 Seismic reflection exploration is the main technique in present urban active faults detecting. The effect of investigating fault and its up-breakpoint in thick Quaternary sediments depends on the working methods and technical parameters. Qiaobei-Suqian fault is an important buried fault along Tan-Lu fault zone in Jiangsu. In this paper,based on QL14 line laid on the fault in thick sediments during the active fault survey in Suqian City and aimed at investigating the spatial distribution,characteristics and activities of the fault controlled by the line,the authors used different seismic exploration methods and acquisition parameters to perform a high-resolution seismic reflection experiment and obtain the imaging of buried fault in the light of the work thinking of combination and fractional steps and according to different targets,the depth of the target layer and the accuracy requirement. The technique solved the contradiction between the field data acquisition and the geological task. The authors obtained high-resolution images of structures in the depths of 16 ~ 450 m after data processing,and the prospecting results provide seismological evidence for the position layout of composite drilling sections,the depth designing of drilling and the evaluation of fault activity. The high-precision composite drilling geological sections show that the main stratigraphic boundaries and tectonic features obtained from the seismic exploration methods are quite consistent with the results from the composite drilling geological section. The experimental result shows that the combined detection methods can receive the attitude and distribution of the fault in different depths and the complete distribution image from the depth to the shallow part of the fault. The feasibility of the seismic exploration methods for locating the buried fault and determining its activity in thick Quaternary sediments and the efficiency of the combination of seismic exploration and composite drilling geological profiles are also demonstrated in this study.更多还原