Development pattern of salt rocks in the Puwei subdepression of the Dongpu depression and their genesis

Abstract：Very thick salt rocks are developed in the Puwei subdepression of the Dongpu depression. To ascertain their development pattern and genesis is of great significance for the study of the regional geology and oil and gas exploration. Using the basic theory and method of high-resolution sequence stratigraphy, on the basis of an integrated analysis of the cores, logs and seismic data, combined with an analysis of the basin structure and stratigraphy, seven salt rhythmic successions are recognized in the Paleogene Shahejie Formation in the study area, of which 3 are of the first order and 4 are of the second order. The development and distribution pattern of each salt rhythmic succession is analyzed. Geochemical and paleontological analyses indicate that the Eocene climate in the area had high-frequency dry-moist change, that the source of salt rocks was mainly seawater in the marine flooding period, and that salt rocks in the high-frequency sequences formed by evaporation of water at depths during the dry lowstand phase.