江苏江都市大桥镇晚更新世晚期—全新世有孔虫动物群的发现及其地质意义

Discovery and Geological Significance of Late Pleistocene-Holocene Marine Facies Foraminifer Assemblage in Daqiao Town,Jiangdu,Jiangsu Province

在江苏省江都市ZKA4钻孔孔深4.0～42.6 m岩心段中发现有孔虫化石,鉴定识别出有孔虫38属56种,其中9个未定种,根据有孔虫动物群在钻孔剖面上的分布规律,建立了3个有孔虫化石组合,自上而下为:Ammonia beccarii(Linne)vars.-Orbulina universa组合,Ammonia beccarii(Linne)vars.-Cibicidoides bellus组合和Ammonia beccarii(Linne)vars.-Lagena sreiata组合,并将钻孔的有孔虫化石组合与国内其他地区相同层位的有孔虫化石组合对比,将滆湖组的时代厘定为晚更新世晚期,将如东组的时代厘定为全新世。据光释光测年结果,ZKA4钻孔有孔虫动物群始现年龄(孔深42.6～42.8 m)约为(14.2±0.6)ka,该有孔虫动物群是末次冰期冰后期大海侵的产物,此次海侵可细分为两个次一级旋回,影响区域达江苏省西部。

Diverse and abundant foraminifer fossils were found in the bore ZKA4 in Jiangdu,Jiangsu Province.This research was made based on 56 species of foraminifer that belong to 38 generas,including 9 undefined species.According to their distributions,the foraminifer assemblages have been observed： Ammonia beccarii（Linne） vars.-Orbulina universa assemblage,Ammonia beccarii（Linne） vars.-Cibicidoides bellus assemblage and Ammonia beccarii（Linne） vars.-Lagena sreiata assemblage.The correlation of the foraminifer assemblages in the bore with the foraminifer fauna worldwide in the same stratum indicates that the age of Gehu Formation is Late Pleistocene,and the age of Rudong Formation is Holocene.According to the result of the optically stimulated luminescence dating,the beginning age of the foraminifer fauna of the bore ZKA4（depth 42.6-42.8 m） is about（14.2±0.6）ka,which is the result of the great transgression of the late last glacier.The transgression can be subdivided into two second cycles,the influence of which reaches the western Jiangsu Province.