周口坳陷的逆冲推覆构造特征

周口坳陷位于华北盆地南部，是在华北地块、华北地块南缘构造带这两个构造单元基础上发育的大型中、新生代断拗型坳陷。该坳陷有６条主要逆冲断裂，走向均为北西西向，剖面上有叠瓦式和对冲式两种构造组合样式，逆冲方向指向北北东方向，太古界至新生界不同程度地被卷入逆冲推覆系统，逆冲推覆构造是坳陷内最重要且独具特色的构造形迹。该坳陷推覆活动具有多期性、继承性和差异性等特点，早白垩世末期的逆冲推覆活动是印支晚期至燕山早期华北板块与扬子板块之间陆陆叠覆造山运动的结果，早第三纪末期以来的逆冲推覆活动则与秦岭—大别造山带晚近时期的差异块断和走滑作用有关。图４参６（王孝陵摘

Structural features of nappes in Zhoukou depression.

Zhoukou depression is located between Huainan coal field in Anhui province on the south and Qinling mountains in West Henan province on the north. It is a largescale MesoCenozoic depression developed on the basis of Huabei massif and the southern marginal tectonic belt of the Huabei massiftwo tectonic units. There are 6 main overthrust belts striked NWW. There are imprecated and ramped two types of structural assemblies in the profile. Overthrust is directed toward NEE. All Archean to Cenozoic formations have been involved in the overthrust systems in various degrees. Overthrust nappes are the most important and unique structural features. Overthrust activity has characteristics of multistage, succession and differentiability. Overthrust in Early Cretaceous is the result of landland superimposed orogenic movement between Huabei plate Author and Yantze plate in Late Indosinian to Early Yanshan orogenic stage. Overthrust since the last stage of Tertiary is related to the differential blockfaulting and the late strikeslip action of QinlingDabieshan orogenic movement.