Keywords: 
• Junggar Basin /
• Jurassic Sangonghe Formation /
• base-level cycle /
• sedimentary microfacies /
• sedimentary evolution

Abstract: Based on the high-resolution stratigraphic principles, the Jurassic Sangonghe Formation is divided into 10 short-term base-level cycles and 2 middle-term base-level cycles. The analysis of sedimentary evolution was carried out based on the short-term base-level cycles. In the period of Sangonghe Formation sedimentation, the 3 kinds of sedimentary conditions (braded-river delta front, meandering-river delta front and shore shallow lacustrine) occurred alternately. In the different sub-periods, there are different microfacies. The microfacies of braded-river delta front mainly include braded sub-water channels and interchannels, debouch bars and mat-shape sands scarcely occur. Meandering-river delta front mainly consists of sub-water meandering branch channels, interchannels, debouch bars, far bars and mat-shape sands; While shore shallow lacustrine consists of mudflats and bank bars. The study result shows in braided-river delta front sub-water channels that superimpose and distribute widely in succession, are favorable reservoirs for structural oil pools and exist in change place of middle base-level from descending to ascending. In center of middle base-level ascending and descending, sub-water channels and debouch bars that distribute isolatedly, are the main microfacies in meandering-river delta fronts. They are advantageous reservoirs for lithologic oil pools.