The researchers studied the sedimentary facies and evolution of the Paleogene Dongying Formation in the Zhanhua-Chezhen area. They found 8 types of sedimentary facies, with lake facies being the most common. The third section of the formation experienced continuous depression, leading to the development of deep lake and shore-shallow lake facies. The second section uplifted, resulting in lake shrinkage and the dominance of shallow lacustrine shore facies. The first section continued to uplift, leading to the prevalence of alluvial fan-fluvial sedimentary facies.