库车前陆褶皱-冲断带前缘盐构造分段差异变形特征

库车前陆褶皱-冲断带前缘秋里塔格构造带发育大量盐构造,其类型丰富多样。根据野外露头、钻井和地震资料识别出的盐构造样式主要有盐推覆、盐枕、盐墙、盐焊接、鱼尾构造、盐撤凹陷、突发构造、断层传播褶皱、断层转折褶皱和三角带构造等。秋里塔格构造带盐构造变形表现出明显的分段差异变形特征,其中西段却勒地区以古隆起(盐下)—盐枕(盐层)—逆冲推覆构造(盐上)为主;中段西秋地区以构造斜坡(盐下)—盐墙(盐层)—断层传播褶皱、向斜(盐上)为主;东段东秋地区则以断层转折褶皱(盐下)—盐推覆(盐层)—断层传播褶皱(盐上)为主。造成这种盐构造分段差异变形的主要控制因素包括基底断裂、含盐层系、构造转换带和变形空间等方面的差异性,其中基底构造和含盐层系的差异性起主导作用。

Structural Segmentation of Salt Structures in the Frontal Ranges of the Kuqa Foreland Fold and Thrust Belt,Northern Tarim Basin

Numerous salt structures have developed well in the Qiulitag structural belt which is located in the frontal ranges of the Kuqa foreland fold and thrust belt, northern Tarim Basin. Based on the field observation, well and seismic data, the types of salt structures can be divided into salt nappe, salt pillow, salt wall, salt wedding, fish-tail, salt-withdrawal minibasin, pop-up, fault propagation fold, fault bend fold and triangle zone. The geometric and kinematic features of salt structures vary along the strike of the belt, and structural segmentation is very obvious. The structural segmentation of salt structures is mainly referred to their perpendicular assemblages where there are paleo-uplift (subsalt)-salt pillow (salt layer)-thrust (overburden) in the Quele region, structural slope (subsalt)-salt wall (salt layer)-fault propagation fold, inversion anticline and syncline (overburden) in the Xiqiu region, and fault bend fold (subsalt) -salt nappe (salt layer)-fault propagation fold (overburden) in the Dongqiu region. The major factors influencing the segmentation of salt structures include the diversities of basement faults, salt layers, transfer zones and deformation space, of which the basement tectonics and salt layers had imposed the most important effects on the segmentation of salt structures.