深地震反射剖面揭示的华北地块南缘地壳的精细结构  

THE FINE CRUSTAL STRUCTURE OF THE SOUTHERN MARGIN OF NORTH CHINA BLOCK REVEALED BY DEEP SEISMIC REFLECTION PROFILE

作　　者：酆少英[1] 刘保金[1] 李倩 袁洪克[1] 朱国军[1] 田一鸣 王宏伟[1] 侯黎华 邓小娟[1] 谭雅丽[1] FENG Shao-ying;LIU Bao-jin;LI Qian;YUAN Hong-ke;ZHU Guo-jun;TIAN Yi-ming;WANG Hong-wei;HOU Li-hua;DENG Xiao-juan;TAN Ya-li(Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China)

机构地区：[1]中国地震局地球物理勘探中心,郑州450002

出　　处：《地震地质》2020年第3期581-594,共14页Seismology and Geology

基　　金：国家自然科学基金(41674140);驻马店市活断层探测与地震危险性评价项目共同资助。

摘　　要：文中基于长100km的深地震反射剖面,揭示了秦岭造山带北缘和华北地块南缘交接部位的地壳精细结构和断裂的深、浅构造特征。结果显示,研究区地壳具有双层反射结构特征,莫霍面由一系列叠层状的弧形强反射构成,地壳厚约32~35km。上地壳内一系列方向不同、形态各异的反射波组分别对应秦岭北缘的逆冲推覆体及伸展构造环境下形成的沉积盆地。下地壳以错断莫霍面的地壳深断裂为界,具有南、北2段明显不同的反射结构。剖面南段以弧状强反射为主,北段由产状近水平或S倾的叠层状反射构成,暗示该区曾经历强烈、复杂的构造运动。剖面揭示的上地壳断裂控制了该区盆山构造的形成和地层沉积,错断莫霍面的地壳深断裂为深部物质的上涌和能量交换创造了条件,从而调节了地壳内部的物质构成和能量分配。The study area is located at the junction of the northern margin of the Qinling orogenic belt and the southern margin of the North China Block.In order to study the fine crustal structure and the deep-shallow structural features of faults in this area,we conducted deep seismic reflection profiling with the seismic profile of 100 km long,directing NE-SW in Zhumadian City,Henan Province,and got clear lithospheric structure images along the profile.As regards the data acquisition,we applied the geometry of 25 m group interval,1000 recording channels and more than 60 folds.Seismic wave exploding applies the 30 kg shots of dynamite source with the borehole depth of 25 m.The shot interval is 200 m.In data processing,we focused on improving the signal-to-noise ratio.Data processing methods mainly include first break removal,tomographic static correction,abnormal amplitude elimination,amplitude compensation,pre-stack denoising,surface consistent deconvolution,velocity analysis,several iterations of the residual static correction,dip moveout,post-stack time migration and post-stack denoising,etc.The profile with high signal-to-noise ratio was obtained.The reflection wave group characteristics is obvious in the crust,which reflects abundant information about geological structure.Along the profile,the crust is characterized by double-layer reflection structure,and the Moho surface is composed of a series of laminated arc-shaped strong reflections.The thickness of the upper crust is about 14.8~20.7 km,and the total thickness of the crust is about 32.0~35.1 km.The upper crust is dominated by the inclined,densely stratified or arc-shaped reflections.The lower crust is dominated by arc-shaped and inclined reflection,and there is a reflective transparent zone under the Moho surface.The reflection sequences with different directions and shapes in the upper crust constitute the nappe structure in southwest segment and the structural model of two concaves with one uplift in NE segment,which correspond to the north Qinling nappe,Zhu

关 键 词：深地震反射剖面 秦岭造山带 华北地块南缘 莫霍面 

分 类 号：P315.2[天文地球—地震学]