豫西熊耳群分布区燕山期构造演化初探

THE PRELIMINARY STUDY OF THE TECTONIC EVOLUTIONAT YANSHAN STAGE ON THE DISTRIBUTIVE PROVINCEOF THE XIONG’ER GROUP IN WEST HENAN

运用现实主义原则，依据构造动力作用方式及其效应的不同，系统探讨了本区燕山期演化历程，将其划分为四个演化阶段（Ｊ，Ｋ１早期，Ｋ１晚期，Ｋ２）。概括为“两次重要转折，两次陆内层流造山，两期伸展作用”。Ｊ，第一次陆内层流造山，以挤压机制为主，盆地面积进一步缩小，马超营断裂带叠加脆性改造，新断裂形成；Ｋ１早期，花岗岩浆突变式侵入，产生热隆作用，引起重力滑脱，盆地面积扩大，数量增多，以引张应力为主，是本区大地构造发展的第一次重大转折；Ｋ１晚期，产生具压剪性质呈平行等间距排列的原始北北东向断裂；Ｋ２，第二次陆内层流造山，深部物质调整方向改变，为本区大地构造发展的又一次重大转折，在北北东向断裂基础上，马超营断裂带东西向左行平移作用的参与，形成本区断陷盆地，以引张应力为主。

n the principle of the realism and according to the modes of tectonodynamic action and its different effets,this paper has systematically studied the process of tectonic evolution at Yanshan stage in this area,and divided the process into four stages(Jurassic,early Early Cretaceous,late Early Cretaceous and Late Cretaceous)which have been summarized as“two important transforms,two intracontinental laminar flow orogenies and two extensional strains”.The first intracontinental laminar flow orogeny represented by the compressive mechanism which led to the basins to narrow and its number to reduce,overlaying the brittle reformation on Machaoying faulted zone,and forming new fractures in Jurassic period.The first important transform in the geotectonic development of this area occurred in the early Early Cretaceous,in which the extensional stress played the leading role,accompanied by the abrupt intrusion of granitic magma,at the same time led to the generation of thermal upwarping,the gravitation detachment and increasing in number,enlarging in area for the basins.In the late Early Cretaceous,the original NNE-direction faults bearing compressionshear feature generated in this area.The second intracontinental laminar flow orogeny represented by the adjusting change of direction of the deep material generated in the Late Cretaceous,led to another great transform in the geotectonic development of this area;based on the tension stress and NEE-direction fault,with Machaoying lefthanded strikeslip fault attending,the faulted basins formed in this area.