大别造山带东段扬子陆块和华北陆块间缝合带的位置

第30卷第3期

地球科学———中国地质大学学报

Vol.30　No.32005年5月

Earth Science —Journal of China University of G eosciences

May 2005

基金项目:国家重点基础研究发展规划项目(No.T G1999075506);国家自然科学基金项目(Nos.40472177,40072070).作者简介:江来利(1957-),男,博士,教授级高工,主要从事构造地质和岩石大地构造研究.E 2mail :lailij @

大别造山带东段扬子陆块和华北陆块间缝合带的位置

江来利,吴维平,储东如

安徽省地质调查院,安徽合肥230001

摘要:大别山为扬子陆块和华北陆块之间的碰撞造山带.构造-岩石单元的岩石组成、同位素年代学资料和构造关系表明,大别山东段主要由扬子陆块北缘不同变质程度的变质基底和少量浅变质盖层组成,没有代表蛇绿混杂岩和华北陆块南缘古生代活动大陆边缘的火山-侵入岩建造.各主要构造-岩石单元间的界线为超高压变质岩折返过程中形成的伸展型剪切带,大别山北部的伸展-逆冲推覆构造也是超高压变质岩折返过程中伸展构造的一部分,其中不存在具有缝合带意义的重要构造界线.因此,在大别山东段,华北陆块和扬子陆块间的缝合带既不是水吼-五河剪切带,也不是磨子潭-晓天断裂.根据地球物理资料推测,南北陆块间的缝合带应分布在信阳-舒城断裂的前缘,但现在覆于合肥盆地中新生代沉积之下.关键词:大别造山带东段;缝合带;北淮阳带;信阳-舒城断裂.中图分类号:P542 文章编号:1000-2383(2005)03-0264-11 收稿日期:2005-01-18

Location of the Suture Zone bet w een Yangtze and North

China Blocks in E astern Dabie Orogen

J IAN G Lai 2li ,WU Wei 2ping ,C HU Dong 2ru

Geological S urvey of A nhui Province ,Hef ei 230001,China

Abstract :Dabie mountains are a collision orogen between the Yangtze and the North China blocks.The rock components ,isotopic dating and tectonic relation of the tectonic 2petrological units in the eastern Dabie orogen indicate that the Dabie oro 2gen is composed mainly of the metamorphic basement suffered different 2grade metamorphism and low 2grade metamorphic cover of the north margin of the Yangtze block ,without ophiolitic m élange and Paleozoic vocanic 2intrusive rock association in the south margin of the North China block.The boundary between the tectonic 2petrological units is extensional shear zone developed in the exhumation process of the ultra 2high pressure metamorphic rocks ,and the extensional 2thrust and nappe structure in the northern part of the Dabie Mountains is also one part of the extensional structures in the exhumation process of the ultra 2high pressure metamorphic rocks.There is no key tectonic boundary indicating the occurrence of the suture zone.Therefore ,not the Shuihou 2Wuhe shear zone ,nor the Mozitan 2Xiaotian fault are the suture zone between the Y angtze and the North China bining the geophysical data ,the Xinyang 2Shucheng fault is the Indo 2Chinese suture between the Y an 2gtze and the North China blocks ,but now is covered under the Mesozoic and Cenozoic deposits of the Hefei basin.K ey w ords :eastern Dabie orogen ;suture zone ;North Huaiyang belt ;Xinyang 2Shucheng fault.

大别山为扬子陆块和华北陆块之间的碰撞造山带.根据超高压变质作用年龄(Ames et al .,1993;Li et al .,1993;Rowley et al .,1997;Hacker et al .,1998)及卷入前陆褶冲带变形的最新地层(徐

树桐等,1992a ,1994),扬子陆块和华北陆块最终碰撞发生在二叠纪末—三叠纪初.超高压变质岩是扬子陆块陆壳沿着缝合带向北俯冲到大于90km 的地幔深处经受超高压变质作用然后快速折返至地壳浅