北京平原西北部地壳浅部结构和隐伏活动断裂——由地震反射剖面揭示  

The crustal shallow structures and buried active faults revealed by seismic reflection profiles in northwestern area of Beijing plain

作　　者：刘保金[1] 胡平[2] 陈颙[3] 张先康[1] 酆少英[1] 杨晓平[4] 于慎鄂[5] 孟勇奇[2] 石金虎[1] 寇昆朋[1] 

机构地区：[1]中国地震局地球物理勘探中心,郑州450002 [2]北京市地震局,北京100080 [3]中国地震局地球物理研究所,北京100081 [4]中国地震局地质研究所,北京100029 [5]中国地震局地壳应力研究所,北京100085

出　　处：《地球物理学报》2009年第8期2015-2025,共11页Chinese Journal of Geophysics

基　　金：地震行业科研专项(200808041);国家与发展改革委员会发改投资"城市活断层试验探测"项目(20041138);北京市人民政府"十五"重点项目联合资助.中国地震局地球物理勘探中心科技论著编号:0907

摘　　要：已有地质和地球物理研究结果表明,北京平原区存在有多条第四纪隐伏活动断裂和隐伏盆地.为了研究该区的地壳浅部结构、断裂的空间展布、断裂活动性以及深浅构造关系,2006年,在北京平原的西北部地区完成了1条60次覆盖的中深层地震反射剖面和跨断裂的浅层地震反射剖面.结果表明,沿剖面结晶基底埋深约为3～6 km;在结晶基底以上,地震反射剖面揭示了一套连续性较好的强反射震相,应是新生代、中生代和古生代的沉积岩系;在结晶基底之下,为一系列横向连续性较差、能量较弱的短小反射事件,可能代表了变质程度较高的结晶变质岩系或不成层的其他岩体.中深层和浅层地震剖面揭示的断裂具有上下一致的对应关系和明显的第四纪活动,对本区地堑-地垒状盆岭构造和新生代地层厚度具有重要的控制作用.本项研究不仅可进一步提高对北京地区新构造活动的认识,而且研究中所采用的方法技术对其他地区的深浅构造探测研究也有借鉴意义.The results obtained from geological and geophysical studies suggested that there are multiple buried active faults and Quaternary buried basin in Beijing plain. In order to investigate crustal shallow structures, geometry of buried faults, fault activity and the relationship of deep-shallow tectonics in Beijing area, an mid-deep seismic reflection profile with 60-fold and multiple shallow reflection profiles crossing the buried faults was completed in northwestern region of Beijing plain in 2006. The results show that the depth of crystalline basement is about 3～6 km along the profile. The seismic reflection section shows a set of strong reflected phases with good lateral continuity above the crystalline basement, which should be the sedimentary rock systems of Cenozoic,Mesozoic, Paleozoic era. Beneath the crystalline basement, there is a series of weak reflected events with poor continuity possibly representing the crystallized rock system with comparatively strong metamorphism or other non-layered rock systems. The faults revealed by mid-deep and shallow seismic reflection profile present consistent upper-lower relationship and have been significantly active since Quaternary, which play an important role in controlling the rift valley-horst like basin and ridge tectonics as well as the thicknesses of Cenozoic stratum in this region. The study results not only may further improve the understanding of the neotectonics activity in Beijing area, but also the used exploration method and technology could be used as references for surveying deep-shallow structures in other areas.

关 键 词：北京平原区 地震反射剖面 地壳结构和构造 结晶基底 活动断层 

分 类 号：P315[天文地球—地震学]