摘要
The last stage of Late Triassic and Middle Jurassic in northwest Guizhou Province and the nearby area is a land facies sedimentary period after the sea facies sediment caused by indosinian movement. Its sedimentary characteristic is that the lake sediment is predominant, and the next is the river sediment.In the vertical dimension, it shows that the river sediment appears in the lower Er’qiao Formation and upper Xiashaximiao Formation and Shangshaximiao Formation of the stratum succession in this period, the lake sediment crosses the stratum in the whole study period, especially develops well in the Bailiujing Formation. The river sediment is dualistic structure, the lower part is flat sediment and the upper part is embankment sediment. The lake sediment is divided into three sub-facies sediments: lakeside, low lake and deep lake, it shows two procession features from shallow to deep in the stratum succession.