中国东部全新世百年尺度环境演化的海洋记录

全新世 冲绳海槽及邻近陆架 短期气候突变事件 东黄海暖流系统
常凤鸣 2006-01 项目
【英文摘要】The project purposes reconstructing the Holocene environment variation history in the Okinawa Trough and it's adjacent continental shelf. Based on a multivariable approach utilizing foraminifer and pollen, geochemistry, sedimentology and mineralogy, it studied the evolution of marine environmental conditions during the Holocene in the study area. The study found out the response characteristics of the study region to the periodical fluctuations of environment on millennial-scale, the abrupt climate events, and the El Ni?o variability occurring during the Holocene. The study shown that during the Holocene, three periods of the regional climate changes can be identified. During the early Holocene it shifted gradually from cold to warm; the middle Holocene Climatic Optimum was warm; and the optimum climate was replaced by a cool and fluctuant one during the late Holocene. And, global high-frequency cycles, including the millennial scale cycle and the atmosphere-ocean inter-oscillation induced multi-decadal cycles such as the PDO and NAO, are assuredly exist in the study region.Comparison of our results with the ice core and terrestrial paleoclimatic records in the Chinese continent and other regions of the world suggested they are almost comparable and strongly coupled. This study reconstructed the evolution process of w arm current system of the East China Sea and the Yellow Sea during the Holocene. modern Tsushima W arm Curent began to develop along with the rising of sea 1evel and finally form ed at about 8.5 ka BP, The Yellow Sea W arm Curent has appeared at about 6.4 ka BP.The study is important to enrich the marine records of the Holocene environmental changes in the Low-latitude areas, and will improve our understanding of the connection between the different records of the global. Also, it will be significant on discussion of the mechanisms for global climate and environment variability during the Holocene
【中文摘要】项目以冲绳海槽及邻近陆架为目标区域,利用有孔虫及孢粉、地球化学、沉积学等古环境替代指标,分析了全新世研究区内的海洋水文参数、上层水体机构、生产力、不同水体的活动等环境条件的演化特征和过程,查明冲绳海槽及其邻近陆架对全新世环境千年尺度的周期性波动、短期气候突变事件以及El Ni?o 等的响应特征。研究发现全新世区域气候经历了早全新世的渐暖期、中全新世温暖的适宜期和晚全新世变冷的波动期的三段式演化, 期间也确实存在包括数千年尺度的周期旋回到大气-海洋系统内部振荡所致的等数十年尺度的高频振荡。研究初步查明了由黑潮暖流、对马暖流和黄海暖流组成的黄东海暖流系统演化过程,发现现代东黄海暖流系统是伴随着末次冰消期以来黑潮的演化和海平面的脉冲式上升而形成与演化的,地理边界条件是非常重要的控制因素,约全新世8.5 ka左右, 现代对马暖流正式形成,约6.4 ka左右黄海暖流开始出现。对比发现研究区记录的全新世气候演化的总体趋势及波动与我国大陆及全球其他区域的记录是基本一致的。该成果对于充实中低纬度地区全新世环境变化的海洋记录,理解全球不同记录间的关系,进而探讨全新世气候环境变化的机制有重要的科学意义。