库车前陆褶皱冲断带前缘滑脱层内部变形特征

古近系库姆格列木组和新近系吉迪克组膏盐层构成了库车前陆褶皱冲断带的区域滑脱层。在褶皱冲断带前缘,膏盐层发生塑性流动,其内部形成多种构造样式。根据野外考察、地震剖面解释和钻井资料识别出的膏盐层内部构造变形样式主要包括盐枕、盐墙、盐推覆、鱼尾构造、盐焊接(断层焊接)、盐缩颈、透镜状增厚和盐垛等盐构造。盐构造在形成时间上具有一定的演化序列,库车前陆褶皱冲断带总体表现为由北向南迁移,前缘秋里塔格构造带则是从西往东迁移,盐推覆、盐焊接、盐枕等构造形成时间较早,盐墙形成较晚,东秋地区的盐构造形成时间整体较西段和中段晚,规模也较小。

Internal deformation features of detachment layers in the front of the Kuqa foreland fold-thrust belt

The evaporite beds of the Paleogene Kumugeliemu Formation and Neogene Jidike Formation form regional detachment layers in the Kuqa foreland fold-thrust belt. In the front of the Kuqa foreland fold-thrust, the evaporite bed underwent plastic flow and various structural styles formed inside the detachment with plastic flow of evaporite beds. Based on the field observations, seismic and well data, the deformation structures recognized inside the evaporite bed in the Qiulitag structural belt include salt pillows, salt walls, salt nappes, fish-tail structure, salt welds (fault welds), salt neckening, lentoid thickening and salt stacks. The formation and evolution of various salt structures have a certain sequence. On the whole, the salt structures in the northern part of the Kuqa foreland fold-thrust belt formed earlier than those in the south, while the salt structures in the western Qiulitag structural belt also formed earlier and are of larger size, whereas in the eastern portion the salt structures developed later, with smaller size. The salt structures such as salt nappes, salt welds and salt pillows developed in the Qiulitag structural belt formed earlier than salt walls.