Development and Genetic Mechanism of Chepaizi-Mosuowan Uplift in Junggar Basin, China

Abstract

The Junggar continental block is a ‘neo-cratonic block’ that developed on the basis of the pre-Cambrian micro- continental block and its surrounding Early Paleozoic continental marginal accretion fold belts, and experienced the tectonic transitional development in the Carboniferous–Permian period. The Junggar Basin is a superimposed depositional basin developed on the ‘neo-craton’, which resulted from the superposition of the intracratonic depression of the Triassic to the Paleogene (T–E) and the foreland basin of the Neogene to the Quaternary (N–Q). The multi-stage activities of surrounding fault belts and the heterogeneity of basement had led to strong activities of the ‘neo-cratonic block’ in the later stages, resulting in the development of a large-scale SWW-NEE trending Chepaizi-Mosuowan Uplift in the interior of the Junggar Basin in the Middle and Late Jurassic. This uplift has experienced a complete process—the initial development in the Early Yanshanian period (J 1 s), rapid growing and shaping in the middle Yanshanian period (J 2 x, J 2 t), buried in the Late Yanshanian period, and tilting and destructed in the Himalayan period. Controlled by the activities of the surrounding fault belts under the regional transpression of the Middle and Late Jurassic, it has been an image-like rotated transpressional structural belt, a composite uplift with an irregular shape, owing to the decoupling of the overlying Jurassic–Cretaceous structural layer and the underlying Carboniferous–Triassic structural layer. The Chepaizi-Mosuowan Uplift had a marked influence upon the deposition and oil and gas accumulations. A series of lithologic and stratigraphic traps have developed on the two slopes of the uplift. Currently, a number of large and medium-sized oil and gas fields have been found in the area, such as Shinan-21, Shinan-31, Mobei, Moxizhuang, and Yongfeng. The Chepaizi-Mosuowan Uplift will be an important area for oil and gas exploration of the lithologic and stratigraphic plays in the interior of the Junggar Basin at the next stage.