北京地区地壳精细结构的深地震反射剖面探测研究  

Research on fine crustal structure using deep seismic reflection profile in Beijing region

作　　者：刘保金[1,2] 胡平[1,3] 孟勇奇[3] 酆少英[2] 石金虎[2] 姬计法[2] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国地震局地球物理勘探中心,郑州450002 [3]北京市地震局,北京100080

出　　处：《地球物理学报》2009年第9期2264-2272,共9页Chinese Journal of Geophysics

基　　金：国家与发展改革委员会发改投资"城市活断层试验探测"(20041138);地震行业科研专项(200808041)共同资助;中国地震局地球物理勘探中心科技论著(200808)

摘　　要：长度100 km、NW向穿过三河-平谷8.0级地震区和北京地区主要断裂构造的深地震反射剖面,揭示了该区地壳精细结构图像和断裂的深浅构造特征.结果表明,该区地壳以TWT6-7 s左右的强反射带为界分为上地壳和下地壳,上地壳厚约18-21 km,下地壳厚约13-1 5 km.剖面TWT3-4s以上,反射层位丰富,构造形态清晰,且在剖面上具有明显不同的构造特征;在三河平谷地震区以西,剖面揭示了2-3组反射能量较强的反射震相和一系列错断基底面的断裂,在三河-平谷地震区以东,为一套自东向西倾伏的密集强反射层,这套反射具有典型的沉积盆地特征,盆地最深处约为8-9 km.剖面揭示的地壳深断裂倾角陡直,该断裂切割、扰动了下地壳物质和壳幔过渡带,向上延伸至上地壳,将地壳深部构造与浅部断裂联系在一起,构成了该区最主要的深浅构造特征.The fine crustal structure and deep-shallow tectonic features of Beijing region are explored by using a 100 km long,NW-trending deep seismic reflection profile. This profile passed through the Sanhe-Pinggu earthquake （M8.0） area and main faults in Beijing region. The results show that the crust beneath the investigated area is divided into upper and lower crust by a strong reflective zone at about 6～7 s TWT. The thickness of the upper and lower crust is about 18～21 km and 13～15 km, respectively. There are rich reflective layers and clear structural patterns above 3～4 s TWT as well as obviously different structural features along the profile. In the western region of Sanhe-Pinggu earthquake area, the stacked deep seismic reflection section shows 2～3 groups of strong reflective layers and a series of basement faults. In the eastern region of Sanhe-Pinggu earthquake area, there is a set of dense, westward-dipping, reflective strata with relatively strong energy, which have the typical characteristics of sedimentary basin. The largest depth of the sedimentary basin is about 8～9 km. The crustal deep fault revealed by deep seismic reflection profile has a steep fault plane, and it cuts and disturbs the lower crust and crust-mantle transitional zone. This deep fault extends upwards into the upper crust, and joins the crustal deep structure to the shallow fault. The profile reveals that the deep-shallow fault system represents the major deep-shallow tectonic feature in the study region.

关 键 词：北京地区 深地震反射剖面 地壳细结构 三河-平谷地震区 深浅构造特征 

分 类 号：P631[天文地球—地质矿产勘探]