Quaternary pollen record and paleoenvironmental evolution of the Bohai Sea strait

Based on the sedimentary features and pollen found in borehole BHS01, the Quaternary transgression and paleoenvironment of the Bohai Sea were reconstructed by divide the core into 13 spore-pollen assemblage zones that reflect environmental changes that have occurred since the late early Pleistocene. The results show paleovegetation zonation and paleogeographic changes, with paleoclimatic variations indicating significant fluctuations between cold and warm periods. Cold periods including Zones 1, 3, and 5 which correspond to terrestrial deposits, whereas warm periods in Zones 2, 4, and 6, and the paleoclimate warms between Zones 7 and 13 accompanied by an increase in the vegetation and number of plant species. In general, the Bohai Strait has stable sedimentary land development from 2.25 to 0.89 Ma when transgression began which may correspond to the development of the Bohai paleolake, and the strait began marine sedimentation later. The most recent transgression occurred during the Holocene (10.65 ka), the T-2 (MIS 3) transgression does not appear to have been recorded in the Bohai Strait, and the third marine phase was deposited no earlier than 0.24 Ma.