Abstract:The northwestern shore of the Bohai Bay is part of the sand bar-lagoon sedimentary system along the Bohai Bay.Its sediments contain rich information on the evolution of the geological environment, which is the key to understanding the climate environment and new tectonic activities in the area. Based on the shallow stratigraphic sedimentary environment, sporopollen analysis and micropaleontological studies of the 80m above QEJ01 hole in the northwestern coast of the Bohai Bay, combined with dating data and quantitative paleoclimate reconstruction data, the vegetation evolution in the characteristic period since the middle-Pleistocene in this area was discussed. To replace the environmental evolution, the regional comparisons of the climate and environmental changes in the northwestern coast of the Bohai Bay at each stage of MIS6～MIS1 were carried out. QEJ01 hole 450.4～377.14ka, the vegetation type is mainly coniferous and broad-leaved mixed forest, the climate is warm and dry, and the sedimentary environment gradually evolves from a river bed to a coastal lake; 377.14～113.96ka, the climate is relatively cold and humid, and the vegetation type is coniferous and broad-leaved mixed forest -The grassland is the main, the sedimentary environment is mainly lake, and the later is the flood plain; 113.96～98.84ka, the climate fluctuates frequently during this period, mainly the sparse tree desert grassland, the climate is cool and humid, the river bed is developed; 98.84～74.33ka, The climate is warm and humid, the vegetation landscape is coniferous and broad-leaved mixed forest-grassland, precipitation increases, the sedimentary environment is mainly floodplain lake and riverbed facies; 74.33～48.09ka, the climate is unusually cold and dry, and the sparse-desert forest is mainly coniferous forest Grasslands are more developed; 48.09～25.72ka, the vegetation type is coniferous and broad-leaved mixed forest-grassland, the climate is warm and humid; 25.72～22.52ka, the climate is cold and dry, the vegetation is sparse tree-desert grassland; 22.52～3.87ka, the vegetation type is Evergreen deciduous broad-leaved forest evolves into coniferous-broad mixed forest-grassland, with a warm and humid climate, and the sedimentary environment is mainly delta plain; 3.87-0.0 ka, the climate is cool and dry, and the vegetation type is mainly coniferous-broad mixed forest. The plain on the northwestern coast of the Bohai Bay is an active zone of tectonic activity. Since the MIS5 stage, the subsidence center has migrated from northwest to southeast, and the degree of development of the transgressive layer is controlled by regional tectonic movements and changes in climate and environment.
