太湖平原更新世的古植被与古环境——以ZKW4孔为例

PALEOVEGETATION AND PALEOENVIRONMENT OF THE TAIHU PLAIN DURING THE PLEISTOCENE——A CASE STUDY OF CORE ZKW4

提要太湖平原位于长江中下游地区,该区域气候受季风环境支配,属北亚热带南部向中亚热带北部过渡的季风气候。因此,该地区第四纪气候环境变化研究对于揭示东亚季风时空变化乃至海平面变化都具有重要意义。本文通过综合分析太湖平原北部ZKW4钻孔深度25.05 m至112.68 m地层孢粉记录以及地球化学元素记录,初步恢复该地区更新世的植被变化情况和受到海水影响的历史。研究揭示,研究区更新世主要植被演化过程为早更新世早期(2 113-1 800 ka)落叶阔叶林、早更新世中期(1 800-1 070 ka)落叶阔叶林-草地、早更新世晚期至中更新世(1 070-126 ka)常绿落叶阔叶混交林、晚更新世(126-72 ka)含常绿成分的落叶阔叶林-混交林,可能在中更新世期间(约470.3-408.7 ka)、晚更新世期间(约111.6-95.8 ka)经历了两次海侵事件。

Situated in the middle and lower reaches of the Yangtze River,the Taihu plain is controlled by the East Asian Monsoon,with the transitional climate of the southern north subtropical and the northern middle subtropical.The study on the Quaternary climate and environmental change in this region is of great significance for the investigation of spatio-temporal variation of East Asian Monsoon and sea level changes.Based on an integrative analysis of palynology and geochemical elements of Core ZKW4 through 25.05 m to 112.68 m in depth in the northern Taihu plain,Wuxi City,vegetation changes and seawater influences at the research site during the Pleistocene period were preliminarily restored.The vegetation has evolved from deciduous broad-leaf forest in the early Early Pleistocene(2113−1800 ka)through deciduous broad-leaved forest and grassland in the middle Early Pleistocene(1800−1070 ka),evergreen and deciduous broad-leaf mixed forest in the late Early to Middle Pleistocene(1070−126 ka),and deciduous broadleaf forest with evergreen component-mixed in the Late Pleistocene(126−72 ka).Two transgressions might have occurred during the Middle Pleistocene(about 408.7−470.3 ka)and Late Pleistocene(about 95.8−111.6 ka).