【作者】 吕晔；

【导师】 王张华；

【作者基本信息】 华东师范大学 ， 自然地理学， 2022， 博士

【摘要】 淤泥质海岸是现代人口众多、经济发达的重要区域,同时也是早期人类社会定居聚集区之一。淤泥质海岸对气候、海平面变化及海洋灾害十分敏感,研究新石器时代人类社会与其环境变化的关系,对于应对当前的气候变化挑战有重要意义。姚江-宁波平原不仅有中外闻名的河姆渡文化,近年也发现埋在地表下5-10 m的贝丘遗址—井头山遗址,以姚江-宁波平原为例,在该区获取了CC、ZF、XY、DJQ四个钻孔,进行岩性、AMS¹⁴C测年、粒度、有孔虫、生物遗迹等多指标分析,同时收集该区域前人已发表的钻孔地层,重建古宁波湾全新世沉积环境演变过程,分析水文和地貌环境对海平面波动的响应,并探讨新石器文化与环境变化的关系。研究主要取得以下认识:（1）姚江-宁波平原全新世沉积环境演变主要受海平面波动控制,依次经历滨海沼泽,泥质海湾、潮滩和滨海平原。全新世早期海平面快速上升,使研究区成为半封闭的古宁波湾;7.6 ka海平面上升事件使姚江古河谷东西两侧均与杭州湾连通,古宁波湾成为开放的海湾;7.2 ka以后,海平面接近现代海面,沉积物可容空间减少,古宁波湾被快速充填成陆,只有少数区域、如宁奉平原东南部直到6 ka左右才向滨海沼泽环境演变。（2）多个钻孔的岩性、粒度、有孔虫分析结果显示,8.8 ka古宁波湾内沉积动力和海水入侵增强,可能与海平面快速上升及极端事件增多有关;7.6 ka左右各孔粒度再次变粗,壳体大、壳壁厚的陆架有孔虫同现卷转虫和压扁卷转虫比例增多,应是对7.6 ka海平面再次加速上升事件的响应。（3）研究区钻孔的沉积速率早中全新世表现为高值,自大约7 ka以来显著减小,与海平面的变化速率基本一致。推测该现象反映了邻近大河入海口的古海湾,有充足的泥沙供应,沉积速率主要取决于受海平面变化控制的沉积物可容空间,而且半封闭的古海湾地形有利于捕集潮汐和沿岸流带来的细颗粒泥沙。（4）井头山遗址的贝丘堆积时间8.2-7.8 ka与海平面较为稳定,古海湾淤泥质潮滩发育、水生资源丰富易采集的有利环境一致,其贝丘堆积终止时期与地层记录中生物遗迹数量及尺寸显著减少、减小一致,推测7.8ka之前可能由于古海湾面积较小,发生了资源承载力过载现象,导致井头山文化结束;7.6 ka海平面加速上升即MWP-1D事件可能造成了跨湖桥文化和河姆渡文化之间的文化“空白”;7.2 ka研究区内滨海平原的快速建造为河姆渡文化的兴起提供了有利的资源与环境。更多还原

【Abstract】 The muddy coast is an important area with large population and developed economy in modern society.It was also the important area for the Neolithic settlements.The muddy coast is very sensitive to climate and sea level changes and associated marine hazards.Investigation of the relationship between Neolithic cultures and environmental change is useful for the preparation of climate challenge in present day.Yaojiang-Ningbo Plain not only has the famous Hemudu Culture at home and abroad,but also has recently found the Jingtoushan site buried 5-10 m below the surface as a shell-mound site.This study takes Yaojiang-Ningbo Plain as an example and collected four sediment cores（CC,ZF,XY,and DJQ）there.Lithology observation,AMS ¹⁴C dating,grain size analysis,and identifications of foraminifers and bioturbation were carried out.Together with collected core data,this study tends to reconstruct the Holocene sedimentary environmental evolution and to discuss the response of hydrological and morphological environments to the sea level change and their linkage to the evolution of Neolithic culture.Main conclusions are obtained as follows:（1）The Holocene evolution of sedimentary environment in the Yaojiang-Ningbo Plain was mainly controlled by the sea level change and has evolved from coastal marsh to muddy embayment and coastal plain.The semi-closed Ningbo embayment was formed as a result of rapid sea-level rise in the early Holocene.The embayment was open to Hangzhou Bay due to the sea-level rise at ca.7.6 ka.It was then rapidly infilled after 7.2 ka when the sea level tended to be stable and a large reduction in the accommodation space occurred.Only local areas such as the southeast Ningfeng Plain evolved into coastal marsh until after ca.6 ka.（2）The analyses of lithology,grain size,and foraminifer indicate that marine invasion and hydrological condition strengthened in the paleo-embayment at ca.8.8ka as a response to the accelerated sea-level rise and increased extreme events.The sediments coarsened again,along with the increase in the percentage of thick-and-big-shelled shelf foraminiferal species Cavarotalia annectens and Ammonia compressiuscula at ca.7.6 ka,indicating the acceleration of sea-level rise at that time.（3）The sedimentation rates recorded in numerous cores were high in the paleo-embayment during the early to mid-Holocene and reduced largely after ca.7 ka,which is consistent with the sea level change.Such consistent change indicates that the sediment supply was rich as being close to the large river mouth which can keep up with the accommodation space created by the sea-level rise,and the semi-enclosed embayment is beneficial for trapping of the fine-grained sediments supplied by tides and longshore currents.（4）The shell mound at Jingtoushan site was formed during the period of slowed sea-level rise at ca.8.2-7.8 ka.Such sea level change is beneficial for the aggradation of tidal flat and collection of aquatic resources.The termination of cultural deposition at ca.7.8 ka agrees with the obvious reduction in both intensity and size of the bioturbation,indicating that the resource carrying capacity may have been overloading before 7.8 ka in the small paleo-embayment.Furthermore,the acceleration of sea-level rise at ca.7.6 ka possibly explains the interruption between Kuahuqiao and Hemudu Cultures.The rapid formation of coastal plain at ca.7.2 ka as a response to the stable sea level provided beneficial resources and environment for the development of Hemudu Culture.更多还原