摘要
系统总结了区内逆冲推覆构造的形成时代、空间展布格局、构造形迹组合等特征,认为区内推覆构造至少有3期:晚二叠世—中三叠世推覆构造切割的最新地质体为脑包沟组(P2n),推覆界面被231Ma的花岗岩侵入,局部被五当沟组及大青山组不整合;中侏罗世末-晚侏罗世推覆构造使太古宙地质体推覆于五当沟组(J1-2w)以及大青山组(J2d)之上,推覆断层被李三沟组(K1l)不整合覆盖,且被早白垩世花岗岩(119Ma)侵入;早白垩世晚期推覆构造,太古宙及古元古代地质体推覆于李三沟组之上,推覆断层被上新世(N2)红层覆盖。第二期逆冲推覆事件在区内表现最为强烈,时间发育上西早东晚,强度、规模西弱东强,以东经111°为界,西部基本以营盘湾—庙沟中下侏罗统煤系地层为中心南北对冲;东部则表现为由南向北单向逆冲。
This paper systematically sums up the age,spatial distribution pattern and association of structural features of the thrust nappe structures in the Baotou-northern Hohhot area,Inner Mongolia.The thrust nappe structure occurred in three phases.The youngest geologic body cut by the Late Permian-Middle Triassic nappe structure is the Late Permian Naobaogou Formation.The nappe boundary is intruded by the231Ma granite and locally overlain unconformably by the Early-Mid Wudanggou Formation and Middle Jurassic Daqingshan Formation.The terminal Middle Jurassic -Late Jurassic nappe structure thrust the Archean geologic body over the Wudanggou and Daqingshan Formations and the overthrust is uncon-formably by the Early Cretaceous Lisangou Formation and intruded by the Early Cretaceous (119Ma )granite.The late Early Cretaceous nappe structure thrust the Archean and Proterozoic geologic bodies over the Lisangou Formation and the overthrust is covered by the Pliocene red bed.The overthrusting of the second phase was the strongest in the area.In terms of time it occurred earlier in the west than in the east,and in terms of the intensity and scale it was weaker in the west and stronger in the east.With lon-gitude111°E as the boundary,the west was mainly marked by ramping toward the north and south with the Mid-Lower Jurassic Yingpanwan-Miaogou coal measures as the center,while the east part by north-vergent unidirectional thrusting.
出处
《地质通报》
CAS
CSCD
北大核心
2002年第4期251-258,共8页
Geological Bulletin of China
基金
内蒙古中部地区小佘太幅等42幅1:5万区域地质调查成果之一。
