Sedimentary facies and controlling factors of the Lower Jurassic Badaowan Formation in the Junggar Basin

The integration of lithology,sedimentary textures and structures,palaeontology and well logs shows that the Lower Jurassic Badaowan Formation in the Junggar Basin is assigned to the braided stream deposits under the humid climates,and consist of channel subfacies including the main channel,distributary channel and channel bar microfacies,and flood-plain subfacies including the overbank,backswamp and washover microfacies.These sedimentary microfacies display five types of well logs including box-shaped,belled-shaped,hopper-shaped,finger-shaped and zigzag well logs.The sedimentary microfacies analysis has led to the construction of the plans of 12 sublayers of the Badaowan Formation and sedimentary facies model for the Badaowan Formation.The orogenesis around the foreland lake basin boundary and humid climates are believed to be the main controls on the base-level variations and the formation of the braided stream deposits,respectively.