The types of sequences developed in the Upper Triassic and Lower-Middle Jurassic in Ordos basin include fluvial sequence

lacustrine sequence

and lake delta sequence

and they constitute two serial sequences namely the fluvial-lacustrine-lake-delta sequences in the Upper Triassic and the fluvial-lake-delta-fluvial-lacustrine sequences in the Lower-Middle Jurassic.The episodes and cyclicity of tectonic subsidence controlled the cyclicity of the sequence and the stage of sequence development;paleoclimate controlled the formation and preservation of the source rocks and coalbeds;sediment supply influenced the accommodation space of the basin;and the change of lake level was caused by the combined forces of tectonics

source and paleoclimate.These are the main factors leading to the formation of sequences in continental basins.The accumulation of various energy resources maight be related with the sequence stratigraphic framework.The well-developed reservoirs in lowstand system tract formed stratigraphic-lithological traps in the delta sand bodies in the Yanchang Formation and the channel sand bodies in the Yanan Formation.The condensed intervals of transgressive system tract are good source rocks and caps.The Yanan Formation coalbed was developed on the abandoned delta plain in the late transgressive system tract. In addition to the highstand system tract

the incised valley and braided channel sand bodies developed in the lowstand system tract of the Zhiluo Formation are also important potential target horizons for uranium deposits of interlayer oxidation zone and of sandstone-type.