YSDP102钻孔有孔虫动物群与南黄海东南部古水文重建

PALEO-HYDROLOGICAL RECONSTRUCTION OF THE SOUTHERN YELLOW SEA INFERRED FROM FORAMINIFERAL FAUNA IN CORE YSDP102

所研究的YSDP1 0 2钻孔岩心 (33°49.496′N ,1 2 5°45.0 0 9′E)是由韩国能源研究所和中国国土资源部海洋地质研究所于 1 995年 8月联合取自南黄海东南部水深 62m的巨厚泥质沉积区内 ,岩心长 60 65m。通过对岩心沉积物中浮游和底栖有孔虫动物群的分析 ,结合相应的AMS1 4 C测年数据 ,对黄海暖流及与其相伴生的南黄海东南部冷水体的形成及演化进行了初步的探讨。结果表明 ,黄海暖流及与其相伴生的南黄海东南部冷水体形成于距今约640 0日历年前。形成伊始 ,冷水体处于明显的强势状态 ,而暖流的强度却相对较弱 ,这一过程约持续了 2 2 0 0年左右 ,是南黄海东南部巨厚泥质沉积区的主要堆积期。直到距今 42 0 0日历年前后 ,黄海暖流的影响强度开始加强 ,冷水体相对减弱 ,直至达到现代的水文状态。

The Yellow Sea Warm Current (YSWC),as a major current in the Yellow Sea plays an important role in controlling heat and salt transfer,circulation structure and sedimentation environment in the region. We studied when the YSWC and its accompanying cold water body were formed ,and how did they evolve after formation based on foraminiferal communities in the Southeastern Yellow Sea Mud. Core YSDP102 (33°49.496′N,125°45.009′E)of 60.65m long,was drilled from the thick muddy deposit area at water depth of 62m in the southeastern Yellow Sea (off northwest of Cheju Island). Planktonic and benthic foraminiferal census in the 183 sediment samples from the core were analyzed and age control was based on AMS 14 C datings using mixed benthic foraminiferal samples. Q mode factor analysis was employed on 46 benthic foraminiferal species with relative abundance of more than 2% in at least three samples. The results indicate that the YSWC and the southeastern Yellow Sea Cold Water Body were formed at 6400 cal. yrs BP. From 6400 to 4200 cal. yrs BP,the bottom cold water mass was extremely active and had strong upwelling,so the southeastern Yellow Sea Cold Water Body was relatively strong and the YSWC was relatively weak. Since 4200 cal. yrs BP,the YSWC began to enhance gradually and is the strongest at present. Comparatively,the bottom cold water mass had experienced a weakening process and ended up with the weakest condition presently.