苏北平原中部地区晚更新世海侵特征研究

Transgression have occurred many times in east coast of China since Quaternary. The research on the transgression in the late Pleistocene is able to provide a reference to predict the interaction between land and sea under the different magnitude of climate change in the future. Therefore, the studies on the transgression characteristics in the late Pleistocene are attracting more attentions. However, so far understanderings are not uniform on the transgression in the northern Jiangsu basin during late Pleistocene, such as times of occurrence, the relative strength, mechanism, etc. In this study we choose the central region of the norther Jiangsu plain as the study region, where sedimentary environment is relatively stable, deposition is continuous in late Pleistocene, and select 5 evenly distributed cores as the research object. In this project, we will use OSL dating and AMS14C to obtain accurate chronosequence of Late Pleistocene in the study area, and analyse the evolution of regional sedimentary environment by using foraminifera, pollen (including brackish water algae), particle size, sedimentary characteristics, sequence stratigraphy. Through these studies we can explore the impacts of transgression in the late Pleistocene and reveal the times and the relative strength of transgression by horizontal comparison and vertical comparison between cores , and determine the scope of transgression preliminary.

中国东部沿海地区第四纪以来发生了多次海侵，其中对晚更新世海侵特征的认识能够为预测未来不同气候变化幅度下海陆作用提供参照。因此，晚更新世时期的海侵特征研究备受关注。但到目前为止，研究者在晚更新世阶段我国东部沿海地区海侵发生期次、相对强度及发生机制等方面的认识上仍不统一。本研究选择自晚更新世以来沉积环境相对稳定，地层连续的苏北平原中部为研究区，选择区内均匀分布的5个钻孔作为研究对象。结合沉积物粒度特征，利用特征层位对比法，系统开展OSL测年和AMS14C测年研究，准确获得研究区晚更新世沉积物年代学序列；利用有孔虫、孢粉（包括咸淡水藻类）、粒度分析、沉积与层序地层特征等分析区域沉积环境演化过程，并通过钻孔横向和纵向的对比，探讨晚更新世海侵对该区的影响，揭示晚更新世海侵期次和相对强度，并初步确定海侵影响范围。

江苏沿海平原不仅受东亚季风气候影响显著，而且是连接海洋与内陆的关键地段，是研究海洋-陆地-大气耦合作用过程的理想场所。特别是对该区的晚更新世海侵特征的认识能够为预测未来海平面变化趋势提供参照。本次工作，我们选择长江三角洲、苏北平原及里下河地区多个钻孔，利用光释光、AMS14C及磁性地层等手段，重新厘定了研究区晚上新世以来年代地层框架，特别是建立了长江三角洲地区晚更新世以来的地层年代学标尺；在准确的年代学标尺基础上，开展了区域性沉积环境对比研究，揭示了晚更新世以来苏北平原地区海侵期次及强度，阐述了晚上新世以来区域海侵、海退发生机制等。