Biota and Palaeoenvironment In Northern Jiangsu, China Since 10000a Bp

The purpose of this book is to present the results of our studies on the alteration of the Holocene biota in time and space and the sedimentary and geochemical indicators in Jianhu and the adjacent areas, northern Jiangsu, and to discuss the palaeoenvironmental changes, essentially to study future environmental changes in these regions. The authors carried out field investigations in the study area and collected fossil specimens and sediment samples at the Qingfeng section of Jianhu, Jianhu brick-field and Sanchakou brick-field of Jianhu, the Liujun section of Huai' an and the Xiyuan section of Funing. Systematic sampling was madde in the Qingfeng section, where eight kinds of fossils including sporo-pollen, charophytes, foraminifers, ostracods, gastropods, bivalves, microinsects and acarids were forund and identified. The 8 palynological zones were estabilished and 3 foraminiferal assemblages, 4 ostracod assemblages and 3 bivalve communities were recobgnized in the section. Gastropods, micro-insects and acarids are restricted to several layers in the section and charophytes are only distribted in its top part. The palaeoecology of these faunas is discussed. The biotic alternation is clearly showed in the Qingfeng section. On the basis of the biotic variance, it is suggested that the Holocene transgression started at about 6900a BP and the highest sea level appeared in the time from 6400a BP to 5400a BP in the study area. After 5400a BP the sea level was gradually declined and the sea water rapidly retreated from this area at about 4500a BP. From 2200a BP to 1000a BP happened another transgression, which was much smaller in intensity than the preceding one. The Holocene palaeoenvironment can be reconstructed in Qingfeng region as follows: coastal muddy marsh - coastal salted mud flat - inner bay - neritic bay - salted nearshore lowland-freshened lagoon. According to the palynological data, the Hypsithermal interval is deted at 8500-3700a BP in Jianhu and the climatic corresponded well to the Holocene global climatic changes.