晚更新世古黄海暖流形成演化和环境效应的生物标志物记录

As the main provider of heat and salt of Yellow Sea, the Yellow Sea Warm Current is the only seawater carrying high temperature and high salinity water from open seas. Its formation and the strength variation have important influence on the marine environment and sedimentary system of Yellow Sea. This study intends to make a columnar Core DLC70-3 with typical high depositional rate as the research object which is located in northern margin area of central mud zone in South Yellow Sea where is influenced by the Yellow Sea Warm Current, using AMS14C dating, OSL dating and symbolic stratigraphical identificaition to set up an accurate geochronologic framework; through changes of ketene content in biomarkers and palaeo-sea surface temperature (UK37), combined with the completed micropaleontological proxy analysis to explore the key evolution process of Yellow Sea Warm Current during the late Pleistocene; To carry out the synthetic study on biomarkers index with a long time scale which is seldom developed in the core sediments of the deep water in South Yellow Sea before, and mainly to discuss the changes of primary productivity of phytoplankton and community structure and their response to the evolution of the Yellow Sea Warm Current recorded by the marine strata. Furthermore, compared with the existing relative research results about Yellow Sea Warm Current of this area during Holocene, we hope to finally find out the formation and evolution processes and the sedimentary environmental effects of palaeo-Yellow Sea Warm Current ever since late Pleistocene.

黄海暖流是黄海唯一的一支输运外海高温高盐水的海流，是黄海最主要的热量和盐分供应者，它的形成及强弱变化对黄海海域的海洋环境和沉积体系都存在重要影响。在前期已有研究基础上，本项研究拟以南黄海中部泥质区北缘受黄海暖流影响的典型高沉积速率柱状岩心DLC70-3孔为研究对象，利用AMS14C测年、光释光（OSL）测年和标志性地层识别等建立精确的年代框架，并通过生物标志物中烯酮含量和古海水表层温度（UK37）变化，结合已完成的微体古生物指标来探讨古黄海暖流晚更新世期间的关键演化过程；开展南黄海深水区岩心沉积物中之前很少进行的长时间尺度生物标志物指标的综合研究，重点讨论海相地层记录的浮游植物初级生产力和群落结构的变化，以及对黄海暖流消长演化的响应。并进一步与前人已有的本区域全新世黄海暖流相关研究结合，最终查明晚更新世以来古黄海暖流的形成演化过程和沉积环境效应。

黄海暖流和黄海冷水团是黄海非常典型的两种水文现象，它们的形成及强弱变化对黄海海域的海洋环境和沉积体系都存在重要影响。前人的研究主要集中在黄海暖流和冷水团全新世以来的形成演化尺度上，而更长时间尺度的研究仍然是一片空白。本项目对采自南黄海北部的钻孔（DLC70-3，孔深71.2 m)进行了高分辨磁性地层学研究，揭示B/M（布容/松山界限）极性转换界线位于该钻孔的59.08 m。底栖有孔虫反映的本钻孔三个较厚的海相地层分别对应MIS5~MIS9、MIS11-MIS17和MIS19-MIS21高海平面时期的沉积。底栖有孔虫冷水种、TOC、TS、Mo以及长链不饱和烯酮含量等指标指示了黄海暖流和冷水团中更新世以来的形成演化过程，它们主要受到海平面变化和区域构造沉积作用的双重影响。黄海暖流和冷水团在MIS5e-MIS9, MIS19 和 MIS21的高海平面时期都非常强盛。而它们有时候并不是同时存在，如在MIS5a-5d阶段存在较强的冷水团，而不存在黄海暖流。本研究将极大的完善我们对于本区域黄海暖流和冷水团长时间尺度形成演化机制方面的理解。