摘要
太行山山前中—新生代伸展滑脱的主拆离构造出现在早前寒武纪变质结晶基底和中元古代以后的沉积盖层之间。卷入拆离带中的变形岩石以断层碎裂岩为主,局部形成大规模由基底和盖层岩石碎片组成的构造混杂岩带,结晶基底顶部未见典型的糜棱岩,拆离过程表现为准塑性—脆性变形机制,形成深度应小于10km。太行山山前拆离滑脱带沿走向分为阜平、赞皇两个独立的区段。拆离带中变形岩石的锆石、磷灰石裂变径迹年龄主要集中在68～52Ma和23～18Ma。结合太行山区夷平面年代和相邻盆地构造分析结果,华北大陆地壳的加厚作用可能发生在白垩纪中期(134±9Ma～92±4Ma),主要的伸展滑脱开始于白垩纪末(68Ma前)。
The Meso-Cenozoic detachment zones in the front of the Taihang Mountains occur between the early Precambrian metamorphic crystalline basement and post-Mesoproterozoic sedimentary cover.The deformed rocks involved into the detachment zones consist dominantly of fault cataclasite and locally there occur extensive tectonic mélange zones composed of basement and cover rock fragments,no typical my-lonite being seen at the top of the crystalline basement.The detachment process proceeded through a quasi-plastic to brittle deformation mechanism.The detachment structure formed at depths of <10km.The detachment zones in the front of the Taihang Mountains may be grouped into the Fuping and Zhanhuang sections along the strike.The zircon and apatite fission-track ages of deformed rocks in the detachment zones are mainly concentrated at68～52Ma and23～18Ma.According to these ages,combined with the age of the planation surfaces in the area and the tectonic analysis of the adjacent basin,the continental crustal thickening of North China may have occurred in the Middle Cretaceous (134Ma±9Ma ～92Ma±4Ma )and major extensional detachments were initiated at the end of the Cretaceous (before68Ma ).
出处
《地质通报》
CAS
CSCD
北大核心
2002年第4期207-210,共4页
Geological Bulletin of China
基金
国家自然科学基金项目(49772153)资助
