东秦岭陆壳反射地震剖面
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摘要
河南省叶县一邓州的反射地震剖面给出了秦岭地壳构造模型．东秦岭深部构造可分为３个区域：华北克拉通、扬子克拉通和秦岭碰撞缝合带．华北克拉通是稳定的地壳；扬子地壳要比稳定的华北地壳更具流变性质，有多层滑脱，至少可分辨出４个滑脱面：陡岭滑脱面、武当滑脱面、扬子滑脱面和地壳底部滑脱面；秦岭碰撞缝合带宽约１００ｋｍ，向南倾，倾角约１５°，地壳结构呈菱形块体样式．秦岭地区的上部地壳为巨型推覆构造，可分为北秦岭和南秦岭两个推覆体，各由主推覆体和前缘叠瓦扇组成．前印支期，秦岭地壳向南俯冲，秦岭古生代海盆闭合．在碰撞的后期，秦岭下部地壳向扬子作Ａ型俯冲，而上部地壳则发生大规模由北向南的推覆。
The seismic reflection profiling from Yexian to Dengxian,Henan province,gives a crustal structural model of Qinling orogenic belt.The deep structure of eastern Qinling can be divided into three regions:the North China craton,the Yangtze craton and the Qinling collision-suture zone.The crust of North China craton is stable,the crust of the Yangtze is much more fluid than the North China craton,where at least four detachment surfaces can be detected,that is,Donling detachment surface,Wudang detachment surface,Yangtze detachment surface,and the detachment surface at the bottom of Crust.The Qinling collision-suture zone is 100km in width,dipping 15°to the south,and has a rhombic structural pattern.The upper part of crust consists of two huge nappes:the North Qinling nappe and the South Qinling mappe,both composed of main nappe and front imbricate fan.In Pre-Indosinian period,the crust of Qinling subducted to the south,led to the closing of Paleozoic sea basin in Qinling.To the later stage of collision,the lower crust of Qinling subducted under the crust of Yangtze craton and its upper crust napped to the south.
The seismic reflection profiling from Yexian to Dengxian,Henan province,gives a crustal structural model of Qinling orogenic belt.The deep structure of eastern Qinling can be divided into three regions:the North China craton,the Yangtze craton and the Qinling collision-suture zone.The crust of North China craton is stable,the crust of the Yangtze is much more fluid than the North China craton,where at least four detachment surfaces can be detected,that is,Donling detachment surface,Wudang detachment surface,Yangtze detachment surface,and the detachment surface at the bottom of Crust.The Qinling collision-suture zone is 100km in width,dipping 15°to the south,and has a rhombic structural pattern.The upper part of crust consists of two huge nappes:the North Qinling nappe and the South Qinling mappe,both composed of main nappe and front imbricate fan.In Pre-Indosinian period,the crust of Qinling subducted to the south,led to the closing of Paleozoic sea basin in Qinling.To the later stage of collision,the lower crust of Qinling subducted under the crust of Yangtze craton and its upper crust napped to the south.
引文
［1］张二朋，中华人民共和国秦岭—大巴山及邻区地质图（1：1000000），北京：地质出版社，1992．［2］张二朋、朱道韫、霍有光、李益桂、张兰芳，秦岭地区主要地质—构造特征梗概，西北地质科学，13（2），31—44，1992。［3］游振东、索书田、韩郁菁、陈能松，秦岭造山带核部变质杂岩的基本特征与东秦岭大地陆壳的构造，秦岭造山带学术讨论会论文选集，1—4，西安：西北大学出版社，1991．［4］刘国惠、张寿广、游振东、索书田、张国伟等，秦岭造山带主要变质岩群及变质作用，北京：地质出版社，1993．
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