Sedimentary facies and palaeogeography of the North China region during the Ordovician

The North China plate was situated in different tectonic settings during the Early Ordovician to the Middle and Late Ordovician,and different plate boundaries and basement topography of the original tectonic units tend to determine the distribution of the sedimentary facies and palaeogeography of the North China region. Seven sedimentary facies types have been distinguished in this study,including tidal flat,restricted platform,open platform,evaporate platform,shoal (reef bank),platform-margin slope and deep-water slope-basin facies. Five stages of the palaeogeographic maps have been reconstructed for the North China region,include the Tremadocian (Early Ordovician),Floian (Early Ordovician),Dapingian-Darriwilian (Middle Ordovician),Sandbian-Katian (Late Ordovician)and late Katian-Hirnantian (Late Ordovician).