Abstract:

In southwestern Tarim basin in the piedmont of western Kunlun Mountain, there are several thrust belts where multiple oil and gas fields have been found. Based on the fault-related fold theory and drilling and 2D seismic data, the Yingjisha anticline in the piedmont of southwestern Tarim basin is finely interpreted, where shallow detachment layers are discovered in the mudstone and gypsum mudstone of the Miocene Anju’an formation, and several shallow simple fault-bended folds are developed as well. It is concluded that the Yingjisha anticline is composed of shallow, middle-deep and deep structural intervals that are superimposed vertically. A wedge structure which contains multiple imbricate structures of thrust faults are developed in the middle-deep interval. Simple imbricate structures are in the deep interval. The growth strata and structural deformation styles indicated that the shallow structures were formed the earliest, followed by the middle-deep structures, and finally the deep structures. In short, there are multiple stages of episodic thrusts starting from the west Kunlun Mountain toward the Tarim basin, so the thrust structures in southwestern Tarim basin have undergone multiple stages of episodic activities. The structures developed in different periods are superimposed vertically, resulting in the present structural pattern.

Key words: Tarim basin, southwestern Tarim, Yingjisha anticline, thrust belt, wedge structure, imbricate structure, fault-bended fold, multistage deformation