Sedimentary Facies Characteristics and Palaeoenvironment of Jurassic Yangye Formation in the Southeastern Depression of the Tarim Basin

Depositional environment is directly related to the development of source rock, and hence the study of the depositional environment has important significance for optimizing the favorable exploration blocks. The authors studied sedimentary facies characteristics and palaeoenvironment of Jurassic Yangye Formation on the basis of core observation, lithologic-electric logging features, test data, outcrop and palaeontological features. It is pointed out that the study area has developed two types of sedimentary facies: braided delta river facies and lake facies. The palaeoenvironment was a terrestrial freshwater environment characterized by strong reducibility. The paleoclimate was in a warm-humid climate background. A viewpoint confirmed by the field investigation is given, arguing that the optimum sedimentary facies were the shallow to half-deep lakes. Based on investigating the source rock sedimentary facies and palaeoenvironment, the authors have summarized the flat facies characteristics and the four main controlling factors.