Palynological Assemblage And Correlation Of Climate Stratigraphy Since Holocene In The Changjiang River Estuary And Its Approach Of The Southern Yellow Sea

Based on the analysis of palynological assemblage in cores CJ08-3,CJ08-185,CJ08-322and CJ08-630 , combined with other data such as carbon isotopic compositions of foraminifera ,AMS14C analysis results, grain size analysis and the paleoclimatic data , the history of vegetation and climate variation in the contiguous areas of the Changjiang River Estuary has been reconstructed since Holocene in this paper.We researched the spore-pollen data from the Changjiang River Estuary, and got the sequence of palynological assemblage of this region. According to the characters of those assemblages, the dominated genera and the whole rule of the palynological fossils, the paleovegetation, paleoclimate and paleoenvironment were rebuilt. All those changes went through four stages as follows: 1.The mixed forest of sparse conifers and broadleaves with some evergreen broadleaves, it was warm and a little dry. The age is Boreal.2.The evergreen forest of evergreen Quercus, Castanopsis, Myrica, and so on. It was hot and wet, and it was 2℃higher than that of now, the stage is Atlantic.3. The mixed forest mainly comprise Quercus, pinus, Gramineae.it was warm and a little dry. The stage is sub-Boreal.4.Grassland and the mixed forest of deciduous broadleaves and conifers being made up of deciduous broadleaves, evergreen broadleaves and conifers being made up of evergreen Quercus, deciduous Quercus and pinus, the climate was warm and damp. This stage is Sub-Atlantic.In the same way, four palynological assemblages have been distinguished in the southern Huanghai Sea. four stages of the evolution of paleovegetation and paleoclimate which are reconstructed in Holocene in this area are as follows:1. The mixed forest of conifers and broadleaves– grassland, reflecting a temperate and dry climate (Boreal period).2.The mixed forest of broad-leave trees with a few kinds of evergreen broad-leave trees-meadow, indicating a hot and moist climate(Atlantic period).3. The mixed forest of conifers and broadleaves– grassland, taking Quercus,Pinus as the main elements in palynological assemblages, reflecting a warm and little dry climate(Sub-Boreal period).4. The mixed forest of conifers and broadleaves with a few kinds of evergreen broad-leave trees, it was a warm and slightly dry (Sub-Atlantic period).To compare the Palynological assemblage between two sub-regions since Holocene, it is easily to find the paleoclimate and paleovegetation changes with Latitude. During the same period, at lower latitudes, the climate becomes warmer and humid.Jianghuai regions, which are sensitive to climate change, locate in the transition region of the warm-temperate zone and subtropical zone. To a certain extent, fluctuations in climate change reflected the succession between evergreen Quercus and deciduous Quercus in the study area.