摘要:
华北北部位于古亚洲和太平洋两大全球性构造域的交叠部位,其中新生代断裂演化、区域性不整合界面和盆地演化的地质事实显示华北北部中新生代存在5个挤压作用时期。自老至新为:①中三叠世末挤压期(老虎沟组或杏石口组前挤压期,峰值年龄 ≥ 215Ma);②早侏罗世末挤压期(海房沟组或九龙山组前挤压期,峰值年龄 ≥ 178Ma);③晚侏罗世末挤压期(义县组或东岭台组前挤压期,峰值年龄 ≥ 135Ma);④晚白垩世末挤压期(古近系前挤压期,峰值年龄65Ma);⑤古近纪末挤压期(新近纪前挤压期,峰值年龄25Ma).5个挤压期在时间上相对较短,并为6个时间较长,构造运动相对和缓或伸展的成盆沉积期一一隔开。6个成盆沉积期包括:早中三叠世、晚三叠世-早侏罗世、中晚侏罗世、白垩纪、古近纪、新近纪-第四纪。其中,中晚侏罗世、白垩纪、古近纪、新近纪-第四纪具有明显的伸展作用特征。也就是说,华北北部中新生代的构造演化过程是在前中生代华北克拉通岩石圈基础上发育起来的克拉通内(陆内或板内)成盆沉积与挤压变形的交替演化过程,在这一构造演化过程中,挤压作用和伸展作用均占有重要位置,总体来讲,挤压作用由强变弱,伸展作用由弱变强。伸展作用持续的时间长,挤压作用持续时间则相对较短。挤压作用和伸展作用交替出现,挤压构造和伸展构造间互发育。华北北部中新生代这种构造体制的转换过程,记录了从古亚洲洋构造域汇聚构造体制向太平洋构造域俯冲构造体制转换的大陆动力学过程。
Abstract:
The north of North China is situated in the overlapping area of Paleo-asian ocean tectonic system and Pacific ocean tectonic system.The geological facts of the regional unconformity,the evolution of Mesozoic-Cenozoic fault and basin in the area show that there are five compression deformations in Mesozoic-Cenozoic period.They are the compressions in the end of Middle Triassic (the compression deformation before Laohugou Formation or Xingshikou Formation, ≥ 215Ma),Early Jurassic (that before Haifanggou Formation or Jiulongshan Formation ≥ 178Ma),Late Jurassic (that before Yixian Formation or Donglingtai Formation, ≥ 135Ma),Cretaceous (that before Paleogene,65Ma) and Paleogene(that before Neogene,25Ma).The five compressions are short in time.There are six periods of sedimentary basin formation occurring among the five time compressions,that is longer in time,more gently and extensional in tectonic activity.The six periods of sedimentary basin formation are Early and Middle Triassic,Late Triassic and Early Jurassic,Middle and Late Jurassic,Cretaceous,Paleogene,Neogene and Quaternary.There are obvious extensional characteristics in Middle and Late Jurassic,Cretaceous,Paleogene,Neogene and Quaternary.That is,the Mesozoic-Cenozoic tectonic evolution process in the north of North China is an alternatively developing process of intracontinental (or intraplate) basin sedimentation and compression deformation in the basement of North China Craton.Both of compression and extension are all important,the compression from strong to weak,the extension from weak to strong in the process,and extension stays longer than the compression in time.The compression and extension occurred alternatively,compression structures and extension structures developed alternatively in the structrure evoltion. The tectonic regime transformation process in the north of North China records the continental dynamic process of tectonic regime transformation from the convergent tectonic regime of Paleo-asian ocean tectonic system to the subducting tectonic regime of Pacific ocean tectonic system.
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