Abstract:
The Wuwei Basin in the northeast margin of Qilianshan structural belt is one of the oil/gas-bearing basins for Carboniferous shale gas exploration in the west China. However, much disagreement is going on the structures and tectonics in the Wuwei Basin due to the Quaternary covering of the basin. Here we conducted the 2D seismic surveying and drill exploration, and defined three sets of structural layers from the seismic profile, e.g., lower structural layer composed of Lower Cambrian strata (Dahuangshan Formation) and Early Cretaceous strata, middle structural layer consisting of Neogene strata, and upper structural layer formed of Quaternary strata. In the lower structural layer, some faulted basins developed, which were filled by the Lower Cambrian or Late Cretaceous; and the Lower Cambrian was also thrusted and folded.Together with regional structure analysis, we suggest three stages of deformation process, including NE-SW extension in the Early Cambrian, NE-SW shortening in the Late Jurassic-Early Cretaceous, and NE-SW extension in the Early Cretaceous.In addition, it also shows the differences on the regional structure and sedimentary sequences in the west and east parts of the Wuwei Basin, which indicates the Wuwei Basin, limited by the Wuwei-Caiqi structural belt, can be divided into west and east sub-basins.