Abstract: In Tazhong area, the carbonate platform may be deformed into independent platform, resulting from the Galidonian event during the end of Early Ordovician to early period of Middle Ordovician. The steep slope occurs between the east end of the platform and deep-sea basin within Kuman aucolgon, above which gravity-low carbonate is deposited. based on the drilling data, three different sedimentary types are identified on the slope, namely, colluvial limestone, slip sedimentary rock, and debris flow brecciated limestone.

Key words: Tarim Basin, Ordovician, Carbonate deposit, Gravity flow deposit, Platform, Slope zone