Abstract: The eroded strata recovery technologies such as sonic logging, fission track and strata correlation are used to recover the erosion thickness of the 2nd episode of Himalayan movement in Jiyang depression of Bohai Bay basin, and the result reveals that the denudation thickness becomes smaller from uplifts to slopes and to subsidence centers of sags. The erosion phenomena are more serious in DONGying sag and Huimin sag of southern Jiyang depression than in Chezhen sag and Zhanhua sag of northern Jiyang depression. The horizontal differences of denudation thickness suggest that the structural features at the Late Paleogene were characterized by the swellsag alternating and the high in the southwest and low in the northeast within Jiyang depression.

Key words: stratigraphic erosion, unconformity, strata correlation, Jiyang depression