新疆库车新生代前陆褶皱冲断带的变形特征、时代和机制

库车前陆褶皱冲断带自北向南可分为基底冲断带、箱状背斜带、梳状背斜带和挠曲褶皱带,东西方向上可分为西段、中段和东段。本文分段叙述了各变形带的变形特征,指出东段箱状背斜带不发育,秋里塔格山脉(构造带)东延未进入东段,因而总体看自西向东变形强度减弱,地形上趋于夷平。该冲断带的形成经历了两次重大的冲断活动,分别发生在中新世和早(-中)更新世;相应地,该带可分为南、北两个"盆""山"亚系统,两者在地层记录、变形期次和变形机制上尚有若干差异。库车前陆褶皱冲断带的发育,除了受南天山的冲断和向南扩展引起的近南北向挤压应力场控制外,还受到基底断裂在新生代的活化和膏盐层底辟的制约,前者以近北西向的构造变换带及其共轭发育的近北东向断层最为重要,后者既控制了秋里塔格山脉的形成(主要受垂直的挤压应力场作用),也在库车前陆褶皱冲断带东西方向的变形分段中起了重要作用。文章还讨论了变形与地貌发育的关系和在油气勘探中的指导意义。

Deformational features, ages and mechanism of the Cenozoic Kuqa foreland fold-and-thrust belt in Xinjiang

The Cenozoic Kuqa foreland fold-and-thrust belt in Xinjiang could be divided,in southward order,into the basement thrusting belt,box anticline belt,comb anticline belt and bended folding belt.And along the W-E orientation,it could be divided into the western,middle and eastern segments.The paper described deformation features of each segment,and thought that the deformation became weakened and the topographic relief tended to planation eastwards since the box anticline belt being not developed in the eastern segment and the Qiultag mountains(the southmost anticlinal row of the comb anticline belt)did not stretched into the eastern segment.There were two main periods of thrusting for creation of the fold-and-thrust belt,occurred in Miocene and Early(-Middle)Pleistocene respectively.Correspondingly,the Kuqa area attached separatedly to the northern and southern basin-orogen sub-systems,and some diversities in stratigraphic record,deformation generations and deformation mechanism between the both sub-systems were summarized.In addition to the S-N compressive stress field resulted from thrusting and expanding of the Chinese South Tianshan,the deformation of the fold-and-thrust belt was constrained by the basemental fractures and diapir structuring of the gypsum-salt layers.The NW-striking,as well as the conjugate NE-striking fractures played a role of transfer zone in the Cenozoic S-N compressional stress field.The diapir of the gypsum-salt layers controlled the creation of the Qiultag mountains(a compressive structural belt by vertical stress field),and also,it played an important role in the segmentation of the Kuqa fold-and-thrust belt.Furthermore,the paper discussed the relation between the deformation and morphogenesis,as well as the guidance to the oil-gas exploration.