“长江深断裂带”的构造性质：深地震反射证据  

The nature of Yangtze River deep fault zone:Evidence from deep seismic data

作　　者：吕庆田[1,2] 刘振东[3] 董树文[2] 严加永[3] 张永谦[3] 

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [2]中国地质科学院地球深部探测中心,北京100037 [3]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《地球物理学报》2015年第12期4344-4359,共16页Chinese Journal of Geophysics

基　　金：国家地质调查项目(1212011220243;1212011220244);国家“深部探测技术与实验研究”专项第3项目(SinoProbe-03);国家自然科学基金重点项目(40930418)联合资助

摘　　要：长江深断裂带自20世纪50年代提出以来,因其在区域控岩、控矿、工程地质和灾害地质研究中的重要意义,一直受到广泛关注和研究,但由于缺乏深部资料,对长江深断裂带的构造性质、空间展布众说纷纭.本文通过分析穿过长江河床及两岸的六条深地震反射剖面,讨论了长江中下游成矿带及长江深断裂带的构造性质及演化,获得如下认识:(1)长江中下游成矿带是燕山期的陆内俯冲带,上地壳发生强烈挤压变形,以大型逆冲、叠瓦、褶皱和推覆构造为特征;下地壳及岩石圈地幔俯冲或叠置到相邻块体之下,在宁芜火山岩盆地和沿江凹陷下形成了"鳄鱼嘴"构造.(2)白垩纪以来,长江深断裂带(CJF)由一系列拆离断层组成,大致沿长江河床分布.该断裂带在燕山期陆内造山阶段为一组逆冲断裂,伸展垮塌阶段反转为正断层或拆离断层,同时控制了沿江凹陷的形成和演化.(3)陆内俯冲或叠置导致地壳加厚、拆沉,引发大规模岩浆活动."鳄鱼嘴"构造或是沟通深部岩浆向上迁移的主要通道,控制了沿江成矿岩浆岩的分布.正是这种特殊的深部过程和构造特征,导致了燕山期长江中下游地区的大规模成岩、成矿作用.Due to its significance both in petro-genesis,metallogenesis,and engineer and environmental geology,the Yangtze River Deep Fault Zone has been the focus of studies since it was first proposed in the fifties of last century.For lacking of deep geophysical data,however,there is little consensus regarding the nature and spatial extension of the fault zone.Using the data from six deep seismic reflection profiles that stride over Yangtze River bed,the authors analysed the crustal structure,deformation and evolution of the middle and lower Yangtze River area and the Yangtze deep fault zone.Results based on the interpretation of deep seismic data include：（1）the middle and lower metallogenic belt is an intro-continental subduction zone formed during Yanshanianperiod,the middle and upper crust were strongly deformed,and characterized by a series of mega-thrust,nappe and thrust-related folds;the lower crust and lithosphere mantle was subducted or stacked beneath the adjacent block,forming a crustal＂crocodile＂structure beneath the Ningwu volcanic area and along-River depression;（2）since the Cretaceous,the Yangtze River fault zone consist of series of detachments,which extends approximately along the Yangtze River bed.In the compressional regime,the fault zone might be a group of thrust fault,and inversed to normal faults or detachments while the tectonic regime shifted from compression to extension,and thus control the formation and evolution of along-River depression;（3）the introcontinental subduction or crustal stacking lead to the thickening and thus delamination of the crustal root,which induce a large scale magmatism.The＂crocodile＂structure might have played a major role in channeling deep magma to the upper crust,controlling the distribution of alongRiver igneous rock.Just because of this special deep process and structure,a large scale magmatism and related metallogenesis occurred in the middle and lower Yangtze River region during the Yanshanian period.

关 键 词：长江深断裂带 长江中下游成矿带 深地震反射 偏移剖面 陆内俯冲带 

分 类 号：P541[天文地球—构造地质学] P315[天文地球—地质学]