苏州澄湖SC1孔晚更新世晚期以来的古环境演变研究

Evolution of Paleoenvironment since Late Pleistocene of SC1 Core in Chenghu Lake,Jiangsu Province

通过对苏州澄湖SC1孔沉积物的粒度、磁化率、孢粉和有孔虫等的实验分析,并结合沉积物的岩性构造特征以及AMS14C测年数据,探讨了晚更新世晚期以来苏州澄湖地区的气候波动特征以及海侵、海退沉积巡回序列。研究发现该区域气候与世界气候波动性一致,具有温暖湿润—冷而略干—温暖湿润—暖热潮湿—温凉略干—温暖湿润的波动变化特征;晚更新世晚期以来具有两个海相沉积地层,一为晚更新世晚期海侵(约为34 kaBP),另一为全新世中期海侵((6 955±50)aBP);整个剖面缺失硬粘土层,与之对应的则是两海相地层之间的泥砂互层;沉积环境经历了晚更新世晚期海侵期河床、河漫滩相—末次冰期干冷期河流湖沼相—全新世早期河口湾亚相—全新世中期滨浅海相—全新世晚期淡水湖沼相的演变过程。

Based on the analyses of grain size,magnetic susceptibility,sporopollen,foraminifera,lithology and AMS14C from SC1 core in Chenghu Lake,this paper discusses the evolutions of climate and paleoenvironment since Late Pleistocene.The records of sporopollen show that climate is accord with the world＇s： warm-wet during the Late Pleistocene,a cool and dry climate during the last glaciation,warm-wet in the Early Holocene,a hot-wet climate in the Middle Holocene,cool-dry to warm-moist during the Late Holocene;Two marine invasion events are discovered,one is Gehu during Late Pleistocene and the other is Zhenjiang in the Middle Holocene.This district has undergone great palaeogeographic changes since Late Pleistocene： rivers in the Late Pleistocene,rivers and marshlands during the last glaciation,flood plain-estuary during the Early Holocene,estuary-shallow marine in the Middle Holocene,lakes and marshlands during the Late Holocene.