Although nearly thirty years of research on internal- wave and internal- tide deposits in stratigraphic record are available, there is a lack of studies on the origin of internal- waves and internal- tides. This has seriously limited further research on fluid interactions between different flows in deep- water complex hydrodynamic conditions, and understanding the relationship between internal- wave and internal- tide deposits and hydrocarbon generation and migration, further aggravated by the lack of biological and trace fossils.Here we focus on the deep- water deposits of the Upper Ordovician Lashenzhong Formation in the Zhuozishan area of western Ordos basin, and comprehensively investigatetheir internal- wave and internal- tide deposits by combining sedimentary geochemistry and sedimentology based on the detailed field work. The results show that the bi- directional cross- laminations and wave- ripple laminations could exist have together and were mainly developed in the Tc division of complete or nearly complete Bouma succession, wherethe host lithologies are grayish green thin- to medium- bedded fine- grained sandstones, siltstones, argillaceous siltstones and silty claystones. The characteristics of depositional aqueous media include fewer seawater properties in general, oxidation- reduction stratification, salinity inversion, no effects of hydrothermal fluids and relatively strong hydrodynamic force. Combined with the existing fact of turbidity current reflections, these results perhaps suggest that the Lashenzhong Formation was deposited in the slope to basin plain environments of confined sea, and their internal- wave and internal- tide deposits have obvious characteristics of event action which could have co- existed with large biological (graptolite) and trace fossils because of the pycnoclines in which the internal- waves and internal- tides were formed and related to the reflection of turbidity currents rather than thermocline. The new type of internal- wave and internal- tide deposits discovered in this study have an important significance for oil- gas prospecting of deep- water tractive current deposits.