Sedimentary facies and palaeogeography of NE Guizhou and its adjacent areas during the Doushantuoan(Neoproterozoic)

Sedimentary environments in northeastern Guizhou and its adjacent areas may be divided into the intraplatform supertidal flat-periplatform shoal and shallow-sea shelf basin facies during the early Doushantuoan,and deep-water shelf-bathyal facies also from northwest to southeast during the late Doushantuoan.The Miaohe-type biotas occur in the black shale and siliceous shale in the transitional areas from the late open platform facies to deep-water shelf-bathyal facies.The preceding sedimentary environments are interpreted as the quiet and dysaerobic environments below the maximum wave base,and suspension deposition acts as a main kind of depositional styles.