库车坳陷中段盐相关构造形成控制因素

Control Factors of the Structure Formation Related to Salt Layer in the Central Segment of Kuqa Depression

库车坳陷中段盐层广泛分布,可细分为盐岩层、膏泥岩层、膏盐层等不同沉积端元。在沉积载荷、浮力及区域构造挤压应力作用下,盐层发生塑性流动,盐上构造层、盐下构造层也发生变形,形成了盐下构造层、盐层、盐上构造层三位一体的复合盐相关构造样式。本文从构造变形差异分析入手,结合盐层沉积特征、基底古地貌特征、盐上构造层沉积差异,运用生长地层和不整合分析方法认为库车坳陷中段盐相关构造样式的形成主要受控于盐层性质、基底特征、构造应力和沉积差异负载。

The Paleogene salt bed of Kumugeliemu Formation distributes widely in the central segment of Kuqa depression. It is composed of rock salt, creaming mudstone, creaming rock salt. The salt bed began to flow because of the sedimentary loading, buoyance and compressive stress, and then the structural layers both the top of and underside of the evaporite bed commence to deform. Thus, the triune compound structure styles related to salt of the supersah layer, salt layer and subsalt layer came into being. By analyzing the difference of tectonic deformation, together with the characters of salt bed sediment and palaeo-geomorphology, and the difference of overlying formation sedimentation, it is concluded that the styles of salt-related structures in the central segment of Kuqa depression were under the control of the salt bed characteristics, palaeo-geomorphology feature, tectonic stress and the differential loading of the upper sedimentary. Plastic deformation and density character of the salt bed was the internal cause of the salt-related structure formation. The Palaeo-geomorphology feature dominated the sedimentary distribution and plastic flow of the salt bed. The differential loading of the upper sedimentary was the main reason of salt bed flowing by different pressure at the early stage. Tectonic stress was the main external dynamic force of the saltrelated structure formation during the late stage. Both of them were the external cause of the salt-related structure formation. It was just the action and counteraction between the internal and external cause, so that the complicated and multiple styles of salt-related structures were being. Tubei 4 salt-related Piercement structure and Dawanqi anticline, west of the central segment of Kuqa depression were the typical examples.