库车坳陷中部构造分层差异变形特征和构造演化

基于地表露头调查、地震资料解释、钻井及与盐相关的构造样式分析,对库车坳陷中部构造变形特征进行研究。结果表明:库车坳陷中部具有南北分带、东西分段、垂向分层的变形特征。以库姆格列木群膏盐岩为界可以分为盐上构造层、盐构造层、盐下构造层及基底构造层4层结构。该区域主要发育收缩构造样式及盐构造样式,盐上构造层、盐构造层及盐下构造层的构造样式及分布具有明显差异。盐上层主要发育逆冲断层及褶皱,盐岩层则以盐流动构造样式为主,盐下层则发育逆冲叠瓦断层等大规模推覆构造。研究区具有明显的分段变形特征,可划分为博孜—却勒构造段、大北—西秋构造段、克深—西秋构造段、克拉3—东秋构造段,其差异性主要表现为地表线性褶皱带分布、盐构造样式、盐下构造变形的差异。区域构造演化剖面研究表明库车坳陷主要经历了中生代伸展坳陷盆地(三叠纪—白垩纪)、新生代早期"挠曲"盆地(古近纪—中新世)及新生代晚期前陆盆地(上新世—第四纪)的演化过程。现今构造主要形成于库车组沉积的中晚期。

Differential Structural Deformation and Tectonic Evolution in the Middle Part of Kuqa Depression, Tarim Basin

Based on the field observation,interpretation of seismic,well data,and analysis of salt-related structure styles,the research on the structural deformation characters in the middle of Kuqa depression was done.The result shows that:(1)The middle part of Kuqa depression can be separated into segments in west-east direction,belts in south-north direction and layers in vertical.Four layers,overburden salt layer,salt layer,subsalt layer and basement layer,are divided in vertical.(2)The main structural styles in this area are contraction styles and salt tectonics.The distribution of structural styles are various in different segments.Different types of thrust and fold can be found in overburden layer.Salt-related structural styles are mainly in salt layer and imbricate thrust fault and fold are in subsalt layer.(3)Distribution of fold belt in surface,salt tectonics and deformation in sub-salt layer are three important factors which decide the differential deformation of Kuqa depression.It can be divided into four segmentations: Bozi-Quele segmentation,Dabei-Xiqiu segmentation,Keshen-Xiqiu segmentation and KL3-Dongqiu segmentation.(4) The research on the balanced section and tectonic evolution history indicate that Kuqa depression experienced extensional depression stage in Mesozoic,bending depression stage from Paleogene to Miocene and intracontinental foreland basin from Pliocene to Quaternary.The present structures of the basins are mainly formed in the middle-late deposition period of Kuqa Formation.