【作者】 石丰登；

【导师】 程振波； 石学法；

【作者基本信息】 国家海洋局第一海洋研究所 ， 海洋地质， 2008， 硕士

【摘要】 本文通过对长江口地区及其邻近的南黄海海域4个沉积物柱样(CJ08-3、CJ08-185、CJ08-322和CJ08-630)的孢粉分析、粒度分析数据和AMS14C测年资料,结合历史气候资料和前人研究资料,对全新世以来研究区所在的陆缘区域进行了气候地层划分,探讨了古环境、古气候演变历史。Ⅰ长江口地区全新世以来的古植被和古气候大致经过如下4个阶段的变化:(1)北方期:含有常绿阔叶树的针叶、落叶阔叶混交林,气候温和略干;(2)大西洋期:以常绿栎类、栲属、杨梅等为主的常绿阔叶林,气候热暖潮湿,气温比现在高约2℃;(3)亚北方期:以栎、松、禾本科为主的针叶、阔叶混交林,之后气候温暖略干;(4)亚大西洋期:以落叶栎类、常绿栎类、松为主的落叶阔叶、常绿阔叶、针叶混交林-草地。在这一时期内,气候出现连续波动,早期为温和干燥,中期温暖略干,到了晚期变为温暖湿润。Ⅱ南黄海地区全新世以来的古植被和古气候也大致经过如下4个阶段的变化:(1)北方期:以阔叶为主的针、阔叶混交林-草原,这一时期气候比较温暖干燥。很可能是冬季较冷并且干燥,夏季较温暖,季节性明显;(2)大西洋期:含常绿阔叶树的落叶混交林-草地,气候达到全新世最为热暖、湿润的时期,海平面到达全新世最高位置;(3)亚北方期:阔叶为主的针阔叶混交林-草原,气候温暖略干,海平面比前一时期有所回落;(4)亚大西洋期:含常绿阔叶树的针、阔叶混交林,气候温和干燥,海平面高度跟现代相近。将上述两地区全新世以来各个阶段的孢粉组合进行比较,可以发现其古气候、古植被演变呈纬度地带性,即在同一时期,纬度越低,气候越温暖潮湿。江淮地区处于北亚热带与南暖温带的过渡带上,对气候变化敏感密切,气候的波动变化在某种程度上体现在研究区内常绿栎与落叶栎之间的演替。更多还原

【Abstract】 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.更多还原