Through the core observations, storm deposits are found in Chang 8 of Yanchang Formation, Ordos Basin, with features including the etching structure, the hummocky cross stratification, the ailochthonous coal, the storm lag deposit, and the Fugichnia. The deposits are developed by the tempestuous currents retransporting and redepositing the delta sediment near the lacustrine shoreline. Their vertical sedimentary sequence consists of seven lithofacies units from A to G. Toward the lacustrine centre, the storm lag deposits and the massive sandstones gradually decrease and correspondingly, the hummocky cross stratification and ripples increase. It is shown that the distinctive storm deposits are developed in the wide and shallow lacustrine environment. The multi-stage deposits are overlain in the vertical section and the fully reconstructed shallow delta sediment is in the horizontal section, with rich sandstones being raised in the whole basin to provide a new reservoir. This study is conducive to the formation of the large lithologic reservoirs and to a new field for the petroleum exploration in Ordos Basin.

storm deposits  /  rich sandstones in the whole basin  /  wide and shallow lacustrine environment  /  Yanchang Formation  /  Ordos Basin