长江三角洲地区全新世蕨类孢子与藻类——以奉贤DY03钻孔的产出类型为例

HOLOCENE SPORES AND MICROSCOPIC ALGAE FROM THE YANGTZE DELTA,EAST CHINA

长江三角洲奉贤DY03钻孔的全新统沉积物中蕨类孢子和藻类的种类丰富,如何正确鉴别,并解释它们的来源、传播与沉积过程等问题,成为讨论过去生物多样性变化、古生态环境与气候事件的重要基础。本文收录奉贤DY03钻孔沉积物中出现频率较高的蕨类孢子和藻类,蕨类孢子可能鉴定到种或属的水平,但也有部分种类只能鉴定到科的水平,有的类型难以确定,则以形态种来归类。凤尾蕨科的种类具有突出的多样性(约8种类型),其次是水龙骨科、卷柏科、里白科、石松科,再次是紫萁科、水蕨科、桫椤科等。藻类根据生态型分为淡水域和咸水域或半咸水域的种类,前者以环纹藻和盘星藻为代表,后者则以沟鞭藻为典型。本研究包含的41种孢子和5种藻类可作为亚热带地区类似沉积环境的孢粉鉴定参考。文中还简要讨论了DY03钻孔的蕨类孢子来源和藻类的古生态学价值。

Abundant fern spores and microscopic algae have been recovered from Core DY03 drilled into Holocene sediments of the Yangtze Delta,East China,in the Fengxian district of Shanghai.Chronological context are based on AMS 14C dates.Accurate identifications of these palynomorphs as well as their frequencies of occurrence provide a basis for tracing their source areas and modes of dispersal and deposition.This enables identification of important aspects of former biodiversity and of the palaeoecological landscape associated with historic and prehistoric environmental situations and changes,including climatic events.Most of the palynomorphs,especially fern spores,could be identified at generic level,with some at family level only or unidentified,in which cases we treat them as palynomorphological categories.41 fern spore forms are recognized in all,mainly from Pteris（Pteridaceae）,Polypodiaceae,Selaginella-ceae,Gleicheniaceae,Lycopodiaceae,Osmunda-ceae,Parkeriaceae,and Cyatheaceae.According to their habitats today,the microscopic algae could be separated into two groups：fresh-water vs salt-tolerant forms.The freshwater forms are cha-racterised by Concentricystes and Pediastrum,the salt-water forms being mainly Dinoflagellates such as Spiniferites,Lingulodinium,and Operculodinium.All the slides/samples examined in this study are kept at NIGPAS.Beside fern spores and microscopic algae,diverse pollen taxa are also presented in the same core,which will be presented elsewhere.It should be pointed out that,what those genera are not presented in this paper doesn＇t mean there are no fossil records in the study areas,such as Lygodium.Further examinations are still needed to establish keys of spores and microscopic algae to Holocene deposits of the Yangtze Delta.