末次冰消期以来冲绳海槽沉积动力特征及其对黑潮演化的指示

The Okinawa Trough is the bathyal back-arc basin of the East China Sea, located on the transitional zone of the shallow sea and the deep ocean with rich sediments source, dominated by the boundary stream in the western Pacific –Kuroshio current and by East Asian monsoon. It is the important target area for research on the "source to sink", sea and land interaction as well as past global change. Due to deep water since the late pleistocene ice age has not been exposed, the continuously sedimentary strata contribute to the preservation of palaeo-environmental information. Although the paleoenvironment study of the trough have been carried out before and a lot of achievements have been achieved, however, mostly concentrated on micropaleontology and its signal extraction and research. Whereas the sedimentary terrigenous source signal and the comprehensive sedimentary dynamic index are deficient, especially the latter is lacking. Futher more, the climate during the last deglaciation and holocene have fluctuated a lot in the context of global warming accompanying frequent climatic events. It is of great theoretical and practical significance to study the climate change and regional response during this period to the understanding of modern climatic environment and prediction of future climate. This project is intended to be based on multi-parameter identification and comprehensive sedimentary dynamic index of sediment source and the establishment of fine chronostratigraphic framework, find out sedimentary dynamic characteristics and its response to the Kuroshio evolution since the last deglaciation period; through the comparative analysis with the high and low latitude climatic indexes to explore the response mechanism of the Kuroshio evolution to regional and global climate change.

冲绳海槽是我国东海外缘一半深海弧后盆地，地处陆架浅海和深海大洋的过渡带上，沉积物来源丰富，受西太平洋边界流（黑潮）和东亚季风控制，是“源汇”研究、海陆相互作用和过去全球变化研究的重要靶区。由于水深较大晚更新世冰期未曾出露海表，沉积地层连续有利于古环境信息的保存。尽管对海槽的古环境研究已取得大量成果，但大都集中在古生物及其信号的提取和研究，而沉积陆源信号和综合沉积动力指标的提取较欠缺，尤其是后者的提取和应用更是缺乏。末次冰消期和全新世在全球气温变暖的大背景下气候多次波动，气候事件频发，研究这期间的气候变化和区域响应对现代气候环境的认识和未来气候的预测具有重要理论和现实意义。本项目拟通过沉积物来源多参数识别和综合沉积动力指标以及精细年代地层框架的建立，查明末次冰消期以来沉积动力特征及其对黑潮演化的响应，通过与高低纬度气候指标的对比分析探讨黑潮演化对区域和全球气候变化的响应机制。

冲绳海槽是我国东海外缘一半深海弧后盆地，地处陆架浅海和深海大洋的过渡带上，沉积物来源丰富，受源自热带低纬地区的西太平洋边界流（黑潮）和来自高伟西伯利亚地区东亚冬季风控制，是“源汇”研究、海陆相互作用和过去全球变化研究的重要靶区。由于水深较大晚更新世冰期里未曾出露，一直处于深海或半深海环境，沉积地层连续有利于古环境信息的保存。尽管对海槽的古环境研究已取得大量成果，但大都集中在古生物及其信号的提取和研究，而沉积陆源信号和综合沉积动力指标的提取及其与古生物指标的结合研究仍较欠缺。末次冰消期和全新世在全球气温变暖的大背景下气候多次波动，气候事件频发，研究这期间的气候变化和区域响应对现代气候环境的认识和未来气候的预测具有重要理论和现实意义。本项目通过沉积物来源多参数识别和综合沉积动力指标以及精细年代地层框架的建立，进一步澄清了末次冰消期以来沉积物源与动力指标对黑潮演化的响应，通过与高低纬度气候指标的对比分析探讨了黑潮演化对区域和全球气候变化的响应机制。进一步明确了冲绳海槽的沉积物来源，定量分析了主要来源。重建了过去400ka北太平洋中层水演化过程，并结合气候模拟结果，查明了北太平洋中层延迟崩溃与南大洋冰消期增温及北太平洋净降水量增加导致海水盐度下降的密切关系。揭示了末次冰消期冲绳海槽中部表层和温跃层水体温度的演化的脱耦现象及其控制因素，其演化分别与北半球高纬和低纬热带太平洋海洋与气候过程有密切联系。进一步研究表明，末次冰消期以来冲绳海槽温跃层温盐条件受热带太平洋类ENSO过程的调节及黑潮强度的控制。发现了全新世北太平洋副热带环流明显增强及其对于北太平洋海表温度的调控作用。通过进一步与高分辨率的热带太平洋气候变化记录的比较研究，发现全新世北太平洋副热带环流的增强与热带辐合带的同步南移直接相关。