THE TRIASSIC OF THE YINING BASIN, XINJIANG

The Yining basin, situated in the central Tianshan orogenic belt, hosts a thickness of more than 700 m of Triassic continental strata. According to the sequence, lithology, sedimentary facies and sporo pollen assemblages of the Triassic section, the Triassic may be divided in ascending order into: （1）the Lower Triassic upper Cangfanggou Group, which consists of fluvial purplish red and grayish purple sandy conglomerate and mudstone with sandstone, 340～474 m thick; （2）the Middle Triassic Karamay Formation, which is composed of fluvial lacustrine silty mudstone and sandstone, 58～121 m thick; （3）the Upper Triassic Huangshanjie Formation and Haojiagou Formation, which are made up of lacustrine dark gray black mudstone and siltstone and fine sandstone, 140～263 m thick.