长江三角洲(江南)地区新近纪地层划分及时代讨论

THE DIVISION AND AGE OF THE NEOGENE STRATA IN THE YANGTZE DELTA AREA

根据对长江三角洲 (江南 )地区多年来积累的古地磁、孢子花粉、微体生物化石、同位素测年等资料的重新研究 ,并结合岩性特征、地层层序进行区域地层对比 ,发现区内新近纪地层较齐全 ,自下而上将新近系层序厘定为中新统洞玄观组 (N1 d) /白龙港组 (N1 b)、六合组 (N1 l) ,上新统新建干窑镇组 (N2 g) ,并将第四纪 /新近系界线划在磁性地层极性柱的 M/ G之间 (距今大约 2 .6 Ma)。

On the basis of analysing the accumulated information on the paleomagnetism, sporo-pollen, micropalaeontology, and isotope assaying and combined with the lithological characters and regional stratigraphical correlation, it is found that the Neogene strata are developed completely in the Yangtze delta area. These strata may be divided from bottom to top into the Miocene Dongxuanguan Formation (N 1d), Bailonggang Formation (N 1b), Liuhe Formation (N 1l) and Pliocene Ganyaozhen Formation (N 2g). The Quaternary/Neogene boundary is placed between the M/G of polarity column of the magnetostratigraphy, being about 2.6 MaB.P.