Origin of Salt-Rock in Paleogene Shahejie Formation and Its Significance for Sequence Stratigraph in Dongpu Depression

Three sets of salt beds exist in the Sha3 member of the Paleogene Shahejie Formation in the central uplift and its vicinity in the northern Dongpu Depression.Each set of salt bed has a number of salt rhythm sof salt rock andmudstone.There is close relationship between depositof salt beds andmigration and accumulation of oil-gas.Different explanations have been presented about the origin of the salt rock.Based on previous studies, through geochemical, structural, palaeoclinatic analysis and core observation as well as stratigraphical correlation of salt beds and their distribution, the paper suggests that the salt rock of the Shahejie Formtion was formed by deep,ater evaporation salification, and the salt beds represent the MFS.According to sequence stratigraphy, we argue that the Shahejie Formtion can be divided into 2 second class sequences and 10 third class sequences in the established models of salification and sequence stratigraphy.All these p rovide som a evidence for further study of sedin entary fades and it is significant for finding oil-gas reservoirs relating to salt rock.