库车坳陷东部构造变形样式及演化特征

通过分析地面地质图、地震剖面和钻井资料,对库车坳陷东部构造变形样式进行解析,结果表明,库车坳陷东部构造呈现南北分带、东西分段、上下分层的几何学特点。以古近系上部吉迪克组膏泥岩分隔,分为膏泥岩上构造层、膏泥岩层、膏泥岩下构造层和基底4层模式。研究区以发育收缩变形及膏泥岩塑性变形为主,膏泥岩上构造层、膏泥岩层及膏泥岩下构造层的构造几何样式及分布具显著差异。膏泥岩上构造层以逆冲断层及收缩褶皱为主,膏泥岩层发育膏泥岩塑性变形构造,膏泥岩下构造层以逆冲断层主导的推覆叠瓦构造为主。库车坳陷东部构造具有显著的分段变形特点,细划分为依西—东秋里塔格构造段、依奇克里克—迪那构造段、吐孜洛克—迪那构造段和吐格尔明—阳北构造段,差异特征主要表现在膏泥岩上构造层的地面线性褶皱带展布、膏泥岩层的塑性变形样式、膏泥岩下构造层变形差异。构造演化剖面分析表明,库车坳陷东部地区大致经历中生代伸展断陷—拗陷盆地、古近纪挠曲过渡型盆地和新近纪—第四纪再生前陆盆地3个演化历程。现今构造定型于库车组沉积时期。

Structural Deformation Styles and Tectonic Evolution Characteristics in Eastern Kuqa Depression

Through analyzing geological maps,seismic section and drilling data,the tectonic deformation styles of the eastern Kuqa depres?sion are studied.The study results show that the structures in the eastern Kuqa depression have some geometric features:banding along N?S orientation,segmentation along W?E orientation and zonation vertically.Taking the gypsum?mudstone layer of the Paleogene Jidike forma?tion as a barrier,4 layers such as structural layer above gypsum?mudstone,gypsum?mudstone layer,structural layer under gypsum?mud?stone and basement are classified.The shrinkage distortion and the plastic deformation of the gypsum?mudstone are dominant in the study area,and the tectonic styles and distributions of the upper structural layer,gypsum?mudstone layer and lower structural layer are signifi?cantly different.The upper structural layer is dominated by thrust faults and constricted folds,the gypsum?mudstone layer by plastic defor?mation structures and the lower structural layer by nappe imbricate structures dominated by thrust faults.The structures in the eastern Kuqa depression display an obvious characteristic of segmented deformation,which can be divided into 4 structural segments,i.e.,Yixi-Eastern Qilitage,Yiqikelike-Dina,Tuziluoke-Dina and Tugerming-Yangbei,whose differences are manifested in the distribution of the linear fold belt on the surface of the upper structural layer,the plastic deformation style of the gypsum?mudstone layer and the deformation differences of the lower structural layer.The sections of structural evolution indicate that the eastern Kuqa depression experienced 3 evolu?tion processes including extensional faulted?depression-depression basin in Mesozoic,bending transitional basin in Paleogene and regener?ated foreland basin from Neogene to Quaternary.The present structures in the depression were mainly formed in the depositional period of Kuqa formation.