塔里木盆地西南缘山前带逆冲推覆构造特征  

Structural features of Cenozoic thrust-fault belts in the piedmont of southwestern Tarim basin

作　　者：胡建中[1] 谭应佳[1] 张平[1] 张艳秋[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地学前缘》2008年第2期222-231,共10页Earth Science Frontiers

基　　金：中石化西部新区勘探指挥部项目(XBKY04-44-04)

摘　　要：塔里木盆地西南缘山前带是西昆仑逆冲推覆构造在前陆形成的冲断带,主要由断层相关褶皱、双重构造、叠瓦状构造、三角带等构造组成。通过地表构造剖面、地震与非震资料的综合解释与研究,结合平衡剖面的正演方法,对该冲断带进行了几何学、运动学与动力学研究,对冲断带断层的扩展方式以及冲断时代进行了讨论。研究认为塔西南逆冲推覆构造具有"南北分带、东西分段以及垂向结构变异"的特点。自南向北分为逆冲推覆的根带、中带、锋带和反冲断裂带,由西向东可以划分为帕米尔弧形构造段、齐姆根弧形构造段、甫沙-克里阳三角带构造段与和田南逆冲推覆体构造段。冲断带在垂向结构上由三套区域性滑脱层划分为浅构造层次的外来系统断坡背斜、中构造层次的准原地系统双重构造、三角带构造以及深构造层次的原地系统弱变形带三层结构。冲断席内断层的扩展方式为前展式,而不同冲断席间则为后展式模式。冲断带自中新世中期开始形成,中新世末发生位移推覆,上新世—早更新世定型,中更新世—全新世隆升均衡调整。The piedmont in the southwestern Tarim basin is the foreland thrust-fault belts formed by the nappe structure in the western Kunlun mountains and it is mainly composed of fault-related folding, duplex, imbricated structures and triangular zones. Through the study of surface geological structure, seismic and non-seismic data, and combining with the method of balance profile, we carry on a research on the geometry, kinematics, and dynamics of foreland thrust-fault belts in the southwestern Tarim basin. The result shows that the nappe structures in the southwest of Tarim basin have characteristics of S-N zonation, E-W segmentation and vertical structural variation. The root zone, middle zone, frontal zone and passive back thrust zone of nappe structure can be distinguished from south to north, with deformation intensity weakened from the base-lnvolved thickskin structure to the foreland thin-skin structure. Four structural segmentations, i. e. , the Pamir arcuate structure, the Qimugen arcuate segment, the Fusha-Keliyang triangular zone segment and Hetian nappe segment, bounded by NE strike-slip faults, have also been identified from west to east and the structural deformation in the western region is stronger than that in the eastern region. The vertical structure of thrusting nappe consists of the superstructure fault-bend folding in allochthonous stratigraphic system, the middle-tectonic-layer duplex and triangular zone in para-in-situ stratigraphic system and the non-deformed or weak-deformed infrastructure in in-situ stratigraphic system. The mode of fault propagation is piggyback propagation within a thrust sheet, whereas the propagation mode is overstep propagation between different thrust sheets. The thrust-fault belts were primarily formed in the middle of the Miocene, with its displacement of thrusting at the end of the Miocene, its final setting during the Pliocene-early Pleistocene and its uplifted isostatic adjustment in the late Pleistocene-Holocene.

关 键 词：逆冲推覆构造 断坡背斜 双重构造 三角带 冲断带 山前带 塔西南 

分 类 号：P542[天文地球—构造地质学]