深地震反射剖面揭示沧县隆起和黄骅坳陷及邻区的地壳精细结构和构造特征  

THE DEEP SEISMIC REFLECTION PROFILE UNVEILS FINE STRUC-TURE AND TECTONIC CHARACTERISTICS OF THE CANGXIAN UPLIFT,HUANGHUA DEPRESSION,AND ADJACENT AREAS

作　　者：秦晶晶[1] 刘保金[1] 酆少英[1] 徐锡伟 田一鸣 朱国军[1] 左莹[1] QIN Jing-jing;LIU Bao-jin;FENG Shao-ying;XU Xi-wei;TIAN Yi-ming;ZHU Guo-jun;ZUO Ying(Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China;China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地震局地球物理勘探中心,郑州450002 [2]中国地质大学(北京),北京100083

出　　处：《地震地质》2024年第3期608-626,共19页Seismology and Geology

基　　金：山西太原大陆裂谷动力学国家野外科学观测研究站项目(NORSTY2021-07);河南省自然科学基金面上项目(242300421374);国家自然科学基金(91214205);中国大陆活动断层探察-华北构造区项目(200908001)共同资助。

摘　　要：为研究华北盆地的地壳精细结构和断裂的深、浅构造关系,跨冀中坳陷、沧县隆起、黄骅坳陷和埕宁隆起完成了1条长约200km的深地震反射剖面和1条长66km的中-浅层地震反射剖面。结果表明,沿剖面地壳厚30~35km,且具有东薄西厚的分布特征,在冀中坳陷下方,莫霍面出现明显上隆,其隆起幅度为2~3km。研究区上地壳反射结构具有凹隆相间的展布特征,多条规模较大的断裂隐伏于华北盆地之下,对该区隆起和坳陷的形成与发展具有重要的控制作用。剖面上一系列与主断裂同向或反向的次级断裂将研究区的上地壳切割为多个次级小型地堑或半地堑断陷,导致整个华北盆地的上地壳结构复杂化。下地壳反射结构由一系列反射能量变化较大、横向上不能稳定成层、产状复杂多变的反射事件构成,这与反射能量强、横向连续性好及产状近水平展布的上地壳反射明显不同,暗示研究区上、下地壳物质有着明显不同的形成环境、变形方式和温压条件。中-浅层地震剖面和深地震反射剖面共同揭示的太行山山前断裂表现为一条低角度的大型铲形正断层,向下可与太行山东缘向E缓倾的大型滑脱构造(拆离断层)相联系;沧西断裂、沧东断裂和埕西断裂作为沧县隆起、黄骅坳陷、埕宁隆起的边界断裂,控制了该区堑、垒构造的形成与发展,是第四纪以来的隐伏活动断裂,推测其深部终止于深约18km的壳内解耦面上。文中研究结果可为进一步理解华北盆地的深部动力学过程及分析研究区深、浅断裂构造关系提供地震学依据。A comprehensive seismic profiling study was conducted across the Jizhong depression,Cangxian uplift,Huanghua depression,and Chengning uplift in the North China Plain to investigate crustal fine structure and the relationship between deep and shallow faults.Two profiles were completed:a deep seismic reflection profile spanning approximately 200km and a middle-shallow seismic reflection profile covering about 66km.Our results indicate a crust thickness of approximately 30 to 35km along the section,with a thin distribution in the east and thick in the west.Notably,there is a significant uplift on the Moho surface beneath the Jizhong depression,with an uplift amplitude of about 2 to 3km.The deep seismic reflection profile reveals distinct upper and lower structural characteristics of the crust.The upper crust displays typical sedimentary layer reflection characteristics,marked by alternating depressions and uplifts.Numerous large-scale faults are concealed beneath the North China Plain,playing a pivotal role in uplift and sag formation.The lower crust s reflection structure comprises events with significant changes in reflection energy,unstable stratification,and complex occurrences,contrasting with the strong reflection energy and good horizontal continuity of the upper crust reflections.The piedmont fault of the Taihang Mountain,identified by the mid-shallow seismic profile and deep seismic reflection section,is a large shovel-shaped normal fault with a low angle,linked to the large detachment structure at the eastern margin of Taihang Mountain.The detachment structure is developed between the basement and the sedimentary cover layer,and is shown on the profile as a reflection zone consisting of 3 to 4 strong reflection phases,lasting 0.3~0.4 seconds.This detachment structure controls the formation of graben and horst structures.The Jizhong depression may have been an extensional tectonic system formed in the upper crust on the basis of the extensional detachment of the Taihang Mountain front fault.The deep seismic

关 键 词：沧县隆起 黄骅坳陷 冀中坳陷 深地震反射剖面 地壳结构和构造 

分 类 号：P315.2[天文地球—地震学]