隐伏断裂的活动时代与影响带宽度分析——利用浅层地震和钻探资料
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摘要
在现场实验探测的基础上 ,获得了最佳浅层地震反射探测参数 .数据处理过程中采用了滤波、编辑切除、预测反褶积、初至时拟合静校正和速度分析等技术 ,得到了高质量的浅层地震反射探测剖面 .利用地震剖面中反射波组信息、测线附近多个钻孔的地层和新年代学资料 ,揭示出探测到的断层带上断点位于埋深 75～ 80m ,距今约 2 2万年的中更新世地层中 .从反射波组的连贯性、间断性、数量的增加或减少和形态变化等特点 ,结合钻探地质剖面等资料 ,认识到断层带上断点的宽度为 1 0 0m .从反射波组的数量在剖面中的变化推测 ,隐伏断层陡坎的宽度为 2 0 0m ,它在早更新世和中更新世早期是一条同沉积活动断层 ,中更新世晚期以来没有发生明显错断上覆地层的构造活动 .
Field experimental seismic sounding permitted us to obtain optimal shallow seismic reflection sounding parameters. In process of data processing, we used the techniques, such as filtering, edition surgical blanking, prediction deconvolution, fitting static correlation of first arrival time, and velocity analysis, and obtained a high-qualitative shallow seismic reflection sounding profile. Comprehensive analysis of the information of reflection wave groups along the seismic sounding profile and the stratigraphic and neogeochronological data obtained from many drills near the sounding line reveals that the upper termination of the detected fault zone is located at depth of 75～80 m, in the Middle Pleistocene deposits dated to be about 220 ka BP. The continuity, discontinuity, increasing and decreasing amount of reflection wave groups and change of their configurations, in combination with geological columns of drills, permitted us to know that the width of upper termination of the fault zone is 100 m. It can be inferred from the variation of number of reflection wave groups along the profile that the scarp of hidden fault is 200 m wide and the fault is a synsedimentary active fault in the Early Pleistocene and the early stage of Middle Pleistocene. No tectonic movement, that offset the covering deposits, had occurred since the late stage of Middle Pleistocene.
Field experimental seismic sounding permitted us to obtain optimal shallow seismic reflection sounding parameters. In process of data processing, we used the techniques, such as filtering, edition surgical blanking, prediction deconvolution, fitting static correlation of first arrival time, and velocity analysis, and obtained a high-qualitative shallow seismic reflection sounding profile. Comprehensive analysis of the information of reflection wave groups along the seismic sounding profile and the stratigraphic and neogeochronological data obtained from many drills near the sounding line reveals that the upper termination of the detected fault zone is located at depth of 75～80 m, in the Middle Pleistocene deposits dated to be about 220 ka BP. The continuity, discontinuity, increasing and decreasing amount of reflection wave groups and change of their configurations, in combination with geological columns of drills, permitted us to know that the width of upper termination of the fault zone is 100 m. It can be inferred from the variation of number of reflection wave groups along the profile that the scarp of hidden fault is 200 m wide and the fault is a synsedimentary active fault in the Early Pleistocene and the early stage of Middle Pleistocene. No tectonic movement, that offset the covering deposits, had occurred since the late stage of Middle Pleistocene.
引文
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刘嘉麒,刘强.2000.中国第四纪地层[J].第四纪研究,20(2):129～141
闵隆瑞,迟振卿.2000.对中国第四系中统划分方案的回顾与讨论[J].第四纪研究,20(2):101～107
向宏发,王学潮,虢顺民,等.2000.聊城—兰考隐伏断裂第四纪活动性的综合探测研究[J].地震地质,22(4):351～359
徐锡伟,吴卫民,张先康,等.2002.首都圈地区地壳最新构造变动与地震[M].北京:科学出版社,135～197
赵成斌,孙振国,顾梦林,等.2001.玛纳斯地震区地壳浅部构造特征探测研究[J].地球物理学报,44(1):54～63
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