秦岭-大别造山带北缘新生代的构造特征及动力学探讨
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摘要
秦岭-大别造山带北缘新生代的推覆构造带位于宜阳、鲁山、确山、六安一线,由SW→NE依次逆冲叠置。滑脱面主要发育在上古生界软弱岩层或差异岩性的接触面上。在推覆构造的南侧,发育有东西向串珠状分布的变质核杂岩、NE向延伸的垒-堑构造组合、北宽南窄的楔形新生代盆地和正断层等。地球物理资料表明,宜阳、鲁山、确山、六安一线为向南倾斜的地球物理异常带。北部的华北地壳与南部的秦岭-大别地壳在视电阻率、地震反射波组、地震波速、流变学分层、地壳类型和岩石圈结构等方面,均有明显的差别。秦岭-大别造山带北缘新生代不同性质、有规律展布的构造,是中生代末期以来,华北板块相对于秦岭-大别造山带作巨型陆内俯冲的结果。
The Cenozoic nappe structure zone on the northern margin of the Qinling-Dabie Mountains lies along the Yiyang-Lushan-Queshan-Liu'an line.The nappes were thrust and stacked each other succes-sively from SW to NE.The shortening rate is52%.The detachment surface is developed mainly on the upper Paleozoic beds of weakness or on the contact surface between differential lithologies.The E-W-trending bead-like metamorphic core complex,horst-graben tectonic combination stretching in a NE di-rection,wedge-shaped Cenozoic basins narrowing southward and normal faults are developed on the southern side of the nappe structure.Geophysical data indicate that the Yiyang-Lushan-Queshan-Liu'an line is a south-dipping geophysical anomaly zone.There are appreciable differences in apparent resistivity,seis mic reflection series,seismic wave velocity,rheo logical stratification,type of crust and lithosphere structure between the crust of North China in the north and the crust of the Qinling-Dabie orogenic belt in the south.The structures of different natures and regular distribution on the northern margin of the Qinling-Dabie orogenic belt in Cenozoic are the result of large-scale intracontinental subduction of the North China plate relative to the Qinling-Dabie orogenic belt since the end of the Mesozoic.
The Cenozoic nappe structure zone on the northern margin of the Qinling-Dabie Mountains lies along the Yiyang-Lushan-Queshan-Liu'an line.The nappes were thrust and stacked each other succes-sively from SW to NE.The shortening rate is52%.The detachment surface is developed mainly on the upper Paleozoic beds of weakness or on the contact surface between differential lithologies.The E-W-trending bead-like metamorphic core complex,horst-graben tectonic combination stretching in a NE di-rection,wedge-shaped Cenozoic basins narrowing southward and normal faults are developed on the southern side of the nappe structure.Geophysical data indicate that the Yiyang-Lushan-Queshan-Liu'an line is a south-dipping geophysical anomaly zone.There are appreciable differences in apparent resistivity,seis mic reflection series,seismic wave velocity,rheo logical stratification,type of crust and lithosphere structure between the crust of North China in the north and the crust of the Qinling-Dabie orogenic belt in the south.The structures of different natures and regular distribution on the northern margin of the Qinling-Dabie orogenic belt in Cenozoic are the result of large-scale intracontinental subduction of the North China plate relative to the Qinling-Dabie orogenic belt since the end of the Mesozoic.
引文
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[2]吴正文,柴育成,黄万夫,等.秦岭造山带的推覆构造格架[A].见:秦岭造山带学术讨论会论文集.[C]西安:西北大学出版社,1991.111～120.
[3]许志琴,卢一伦,汤耀庆,等.东秦岭复合山链的形成—变形、演化及板块动力学[M].北京:中国环境科学出版社,1988.38～87.
[4]张国伟,孟庆任,于在平,等.秦岭造山带的造山过程及其动力学特征[J].中国科学(D辑),1996,26(增刊):193～208.
[5]宋传中.东秦岭造山带地学断面的结构、流变学分层及动力学分析[M].合肥:中国科技大学出版社,2000.9～108.
[6]索书田,游振东,钟增球.秦岭造山带根部地壳结构及流变学演化[J].地球科学,1994,19(5):632～646.
[7]钟增球,索书田,游振东.大别山高压、超高压变质期后伸展构造格架[J].地球科学,1998,23(3):225～229.
[8]吴利仁,徐贵忠.东秦岭—大别碰撞造山带的地质演化[M].北京:科学出版社,1998.
[9]徐树桐,江来利.大别山构造格局和演化[M].北京:科学出版社,1994.
[10]杨巍然,王国灿,简平.大别造山带构造年代学[M].武汉:中国地质大学出版社,2000.
[11]索书田.大别地块超高压变质省的构造变形研究[J].地学前缘,1999,6(4):255～262.
[12]张进江,郑亚东,石铨曾.小秦岭变质核杂岩、拆离断层及其运动学特征的研究[A].见:岩石圈地质科学[C].北京:地震出版社,1996.42～52.
[13]周国藩,罗孝宽,管志宁,等.秦巴地区地球物理场特征与地壳构造格架关系的研究[M].武汉:中国地质大学出版社,1992.
[14]袁学诚,徐明才,唐文榜,等.东秦岭陆壳反射地震剖面[J].地球物理学报,1994,37(6):749～758.
[15]袁学诚.秦岭造山带地壳结构与楔入成山[J].地质学报,1997,71(3):227～235.
[16]宋传中,张国伟.东秦岭造山带的流变学及动力学分析[J].地球物理学报,1998,41(增刊):55～63.
[17]RanalliG,MurphyDC.Rheologicalstratificationofthelithosphere[J].Tectonophysics,1987,132:281～295.
[18]KirbySH,KronenbersAK.Rheologyofthelithosphere[J].Rev.Geophys.,1987,25:1219～1244.
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