关键词: 柴达木盆地北缘, 构造应力场, 数值模拟, 构造演化

Abstract: In order to analyze tectonic evolution of the eastern section of North Qaidam from the Late Paleozoic to Mesozoic and explore the reasons for the lack of Carboniferous-Jurassic strata, this study uses the finite element method to simulate tectonic stress field of Indosinian (Triassic), Early Yanshanian (Jurassic), late Yanshanian (Cretaceous) in the eastern section of North Qaidam. The characteristics of principal stress and shear stress distribution of this area in different periods have been analyzed. According to the Coulumb and Griffith fracture principles, the ancient structures have been predicted and the reasons for the lack of strata have been identified. The results are as follows. The eastern section of North Qaidam formed two rows of nearly east-west trending anticline in Triassic, which was affected by the uneven distribution of the principal stress and dextral shear of Indosinian orogeny. It resulted in the erosion of strata in various regions from Carboniferous to Permian. Under the action of tensile stress field of early Yanshanian in Jurassic, the fault basin evolved into a depression basin from the Early-Middle Jurassic to the Late Jurassic. The Ounan area, which was an inherited uplift, had not deposited. The stress field gradually transformed from tensile into compression in late Yanshanian during the Cretaceous, leading to tectonic inversion and revival of thrust faults. As a result, the mountains such as Lvliang, Xitie, Amunike, Olongbluk uplifted under the control of reactivity of thrust faults and the Mesozoic basin evolution in the eastern section of North Qaidam ended.

Key words: North Qaidam, tectonic stress field, numerical simulation, tectonic evolution