Abstract: Based on seismic profile and well-tie profile, the paper discusses the paleo-water depth of the lake through the study of the delta sedimentation during the Paleogene middle Es3 period in Dongying Depression, NE China, by means of combining core and well logging data and restoring the height of delta foresets. Results show that constructive deltas develop well, and the delta foresets develop extremely well especially in Niuzhuang sag. The statistical results of five seismic profiles reveal the average height of delta foresets is 485 m and the inversion overlying water depth after correction is 681 m. Therefore, the lake ′ s paleo water depth in Dongying delta can reach up to 485-681 m at the middle Es3 period. The delta foreset is mainly a set of fine-grain sediments, grey siltstone and dark mudstone as the major. The siltstone often contains floating boulder clay. These features reveal that it is a kind of sandy debris flow and turbidity deposition along the delta front slope, further reflecting a deep-water sedimentary environment

Key words: paleo-water depth, paleo-lake, delta, Shahejie Formation, foreset, Dongying Depression, Paleogene