库车前陆褶皱-冲断带基底断裂对盐构造形成的影响

地震剖面解释和构造物理模拟实验表明,库车前陆褶皱—冲断带前古近系基底构造对上覆盐构造的形成演化有重要的控制作用。位于冲断带前缘的秋里塔格构造带西段前古近系基底表现为古隆起形态,并发育有丰富的基底断裂和盐构造。基底断裂大多表现为逆断裂,其走向与地表山系基本一致,倾向主要为NNW和SSE,具有较明显的分段特征。古近系库姆格列木组膏盐层塑性流动变形形成的盐构造主要有盐枕、盐推覆、盐焊接和鱼尾构造等。前古近系基底断裂通过影响古近系库姆格列木组膏盐层的塑性流动方式和平面展布特征,进而控制盐层及上覆层的构造变形过程,最终导致在盐层和上覆层形成了大量形态各异的盐相关构造。

Influence of Basement Faults on the Development of Salt Structures in the Kuqa Foreland Fold-and-Thrust Belt in the Northern Tarim Basin

Salt structures are predominant in the Kuqa foreland fold-and-thrust belt. Interpretation of seismic profiles and structural physical modeling demonstrate that the pre-Paleogene basement tectonics has important influence on the development of salt structures in the Kuqa foreland fold-and-thrust belt in the northern Tarim basin. The pre-Paleogene basement in the western sector of the Qiulitag structural belt in the frontal ranges of the Kuqa foreland fold-and-thrust belt appears as a paleo-uplift on which basement faults and salt structures have developed well. The basement faults are reverse faults dipping to NNW and SSE, and strike along the surface mountains. The structural segmentation of the basement faults is relatively obvious. The salt structures induced by the viscous flow of halite layers in the Paleogene Kumugeliemu Formation involve salt pillows, salt nappes, salt welds and fish-tails. The basement faults controlled the salt flowage and spatial variations of salt thickness in the Paleogene Kumugeliemu Formation, and then influenced the structural evolution of halite layers and overburden.