Late Cenozoic diagnostic pollen-spore distribution in southern Yangtze Delta Plain: Depositional geomorphological implications
Zhou Yuanjun1, Wang Zhanghua2, Li Xiao3, Xie Jianlei3, He Zhongfa3, Zhao Baocheng3
1 Department of Geography，East China Normal University，Shanghai 200062 2 State Key Laboratory for Estuarine and Coastal Research，East China Normal University，Shanghai 200062 3 Institute of Shanghai Geological Survey，Shanghai 200072
Abstract：The present study examined the stratigraphy，lithology，and pollen-spore，especially the diagnostic pollen-spores of the wetland plant,aquatic plant and Cyathea from 5 Late Cenozoic boreholes drilled in the southern Yangtze delta plain，aiming to reveal the sedimentary geomorphological evolution since the Neogene and give insight to the studies of the Yangtze catchment evolution.The results demonstrate that the very poorly-sorted，wetland pollen-lacked sediments were formed as alluvial fan in the Neogene，when topography change was prominent and rapid accumulation of adjacent materials occurred.In the Early Pleistocene，significant reduction in palaeo-topography difference occurred and depositional center shifted westward.However，the sediments are still characterized by the mixture of gravel，sand and mud，and the shortage of wetland plant pollen.Hilly basin of regional small catchment is inferred.The sediments of the Middle Pleistocene are characterized by finer grain size，increasing content of spore fossil，and the appearance of wetland plant pollen and fossil spore of Cyathea，indicating an environment of open alluvial plain.Wetland pollen，fossil spore of Cyathea， and content of total spore increase clearly in the Late Pleistocene-Holocene sediments，suggesting a further decline of altitude of the study area，i.e.，a coastal-estuarine depositional environment.The environmental evolution of the study area further suggests that local sediment source prevailed during the Neogene and Early Pleistocene age when hilly geomorphology dominated.Lowland that could receive large amount of Yangtze sediments did not formed until the Middle Pleistocene，which is very important for the studies of provenance and evolution of the Yangtze River by using the Late Cenozoic sediments from the study area.
陈静，王哲，王张华，等.2007.长江三角洲东西部晚新生代地层中的重矿物差异及其物源意义［J］.第四纪研究，27(5):700-708. 陈中原.2001.长江三角洲之沉降［J］.火山地质与矿产，22(2):95-101. 范代读，李从先，Yokoyama K.2004.长江三角洲晚新生代地层独居石年龄谱与长江贯通时间研究［J］.中国科学（D辑），34(11):1015-1022. 贾军涛，郑洪波，黄湘通.2010.长江三角洲晚新生代沉积物碎屑锆石U-Pb年龄及其对长江贯通的指示［J］.科学通报，55(4-5):350-358. 金翔龙.1992.东海海洋地质［M］.北京：海洋出版社. 秦蕴珊.1989.黄海地质［M］.北京：海洋出版社. 王开发，韩信斌.1983.我国东部新生界环纹藻化石研究［J］.古生物学报，22(4):468-472. 王张华，张丹，李晓，等.2008a.长江三角洲晚新生代沉积物磁性特征和磁性矿物及其指示意义［J］.中国地质，35(4):670-682. 王张华，赵宝成，陈静，等.2008b.长江三角洲地区晚第四纪年代地层框架及两次海侵问题的初步探讨［J］.古地理学报，10(1):99-110. 王张峤，陈中原，魏子新，等.2005.长江口第四纪沉积物中构造与古气候耦合作用的探讨［J］.科学通报，50(14):1503-1511. 严钦尚，许世远.1987.长江三角洲现代沉积研究［M］.上海：华东师范大学出版社. 杨守业，韦刚健，夏小平，等.2007.长江口晚新生代沉积物的物源研究：REE和Nd同位素制约［J］.第四纪研究，27(3):339-346. 战庆，王张华，王昕.2009.长江口区晚新生代沉积物粒度特征和沉积地貌环境演变［J］.沉积学报，27(4):674-683. 张丹，王张华，魏巍，等.2009.长江三角洲地区晚新生代沉积物岩石磁学特征极其物源指示意义［J］.第四纪研究，29(2):308-317. 张丹，王张华，李卫康，等.2010.现代长江口的形成及末次冰消期以来沉积环境演变［J］.海洋地质与第四纪地质，30(2):17-25. Brookfield M E.1998.The evolution of the great river systems of southern Asia during Cenozoic India-Asia collision: River draining southwards［J］.Geomorphology，22:285-312. Burbank D W.1992.Cause of recent Himalayan uplift deduced from depositied patterns in the Ganges Basin［J］.Nature，357:680-683. Chen Z，Stanley D J.1995.Quaternary subsidence and river channel migration in the Yangtze Delta Plain，Eastern China［J］.Journal of Coastal Research，11: 927-945. Clift P D，Lee J Ⅰ，Hildebrand P， et al.2002.Nd and Pb isotope variability in the Indus River System: Implications for sediment provenance and crustal heterogeneity in the Western Himalaya［J］.Earth and Planetary Science Letters，200: 91-106. Clift P D，Layne G D，Blusztajn J.2004.Marine sedimentary evidence for monsoon strengthening，Tibetan uplift and drainage evolution in east Asia［C］.In: Clift P D，Wang P，Kuhnt W， et al.(eds).Continent-Ocean Interactions within East Asian Marginal Seas.Geophysical Monograph Series, 149: 255-282. Lin J，Zhang S，Qiu J， et al.1989.Quaternary marine transgressions and paleoclimate in the Yangtze River delta region［J］.Quaternary Research，32(3):296-306. Wageman J M，Hilde T W C，Emery K O.1970.Structural framework of East China Sea and Yellow Sea［J］.AAPG Bulletin，54: 1611-1643. Wang P X.2004.Cenozoic deformation and the history of sea-land interactions in Asia［C］.In: Clift P D，Wang P，Kuhnt W， et al.(eds).Continent-Ocean Interactions within East Asian Marginal Seas，Geophysical Monograph Series 149: 1-22. Wang S，Wu X，Zhang Z， et al.2002.Sedimentary records of environmental evolution in the Sanmen Lake Basin and the Yellow River running through the Sanmenxia Gorge eastward into the sea［J］.Science in China，45(7):595-608. Yang S，Li C，Yokoyama K.2006.Elemental compositions and monazite age patterns of core sediments in the Changjiang Delta: Implications for sediment provenance and development history of the Changjiang River［J］.Earth and Planetary Science Letters，245: 762-776. Zhang Y，Xue Y Q，Wu J C， et al. 2008.Land subsidence and earth fissures due to groundwater withdrawal in the Southern Yangtze Delta，China［J］.Environmental Geology，55: 751-762. Zheng H，Huang X，Ji J， et al.2007.Ultra-high rates of loess sedimentation at Zhengzhou since Stage 7: Implication for the Yellow River erosion of the Sanmen Gorge［J］.Geomorphology，85: 131-142.
