摘要
利用东海中陆架EY02 1孔的柱状样品对底栖有孔虫动物群进行了定量分析研究,结合Q型因子分析及AMS14C测年数据,对东海中陆架古水团演化进行了初步探讨。Q型因子分析得到5个主因子,方差累积贡献为84.9%,这5个有孔虫组合在钻孔相关层位上反映特定的古水团特征。主因子1为Elphidiummagellanicum组合,代表低温低盐沿岸水团(5～10m);主因子2为Bolivinarobusta组合,代表中陆架水团(50～100m);主因子3为Protelphidiumtuberculatum组合,代表外延的古黄海冷水团;主因子4为Florilusdecorus组合,代表内陆架水团(0～50m);主因子5为Epistominellanaraensis组合,代表水体较凉的水深大于30m的内陆架水团。结果表明,冰后期以古长江冲淡水为主体的低温低盐沿岸水团、中陆架水团及内陆架水团交替影响EY02 1孔附近中陆架。在氧同位素3期以古长江冲淡水为主体的东海沿岸流与外延的古黄海冷水团控制着有孔虫组合。在氧同位素5a—5c期间,EY02 1孔附近中陆架可能已受到古黄海冷水团的影响。该孔顶部11 4m含大量贝壳的细砂沉积可能对应氧同位素1期U2层潮流沙脊脊部沉积,细砂平均沉积速率高达0 877mm/a。
Ages from benthic foraminifers from core EY02-1 were based on AMS ()^(14)C datings using mixed benthic foraminiferal samples. Q-mode factor analysis was employed on 65 samples and 33 benthic foraminiferal species with relative abundance of more than 2% at least in three samples, and we recognized five varimax factors which accounted for 84.9% of the variance. These five foraminifer assemblages reflected specific characters of paleo-water-masses in interrelated layers of core EY02-1. Factor 1 (Elphidium magellanicum assemblage) represented the paleo-coastal current (5~10 m depth) with low temperature and low salinity; Factor 2 (Bolivina robusta assemblage) represented the mid-shelf water (50~100 m depth); Factor 3 (Protelphidium tuberculatum assemblage) represented the extension paleo-cold-water-mass of the Yellow Sea; Factor 4 (Florilus decorus assemblage) represented the inner shelf shallow water (0~50 m depth); Factor 5 (Epistominella naraensis assemblage) represented the cold inner shelf shallow water (>30 m depth).The above results indicated that the middle shelf of the north East China Sea near the core EY02-1 was influenced by the East China Sea Coastal Current dominated by the Yangtze River freshwater, the mid-shelf water, and the inner shelf shallow water alternately in the postglacial period. In the period of marine isotope 3 foraminiferal assemblages were controlled by the East China Sea Coastal Current dominated by the Yangtze River freshwater and the extension paleo-cold-water-mass of the Yellow Sea. The middle shelf of the north East China Sea near the core EY02-1 might be influenced by the extension paleo-cold-water-mass of the Yellow Sea for the period from MIS5a to MIS5c. The above 11.4 m fine sand deposit with lots of shells was referred to be the ridge deposit of the U2 tidal sand ridge in the period of MIS1, its average sedimentation rate was calculated as 0.877 mm/a for the period from the present to 12 kaBP.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2004年第1期43-50,共8页
Marine Geology & Quaternary Geology
基金
中国科学院知识创新工程项目(KZCX3 SW 220)
国家自然科学基金项目(40176019)
国家重点基础研究发展规划资助项目(G2000046703)
关键词
底栖有孔虫
定量分析
Q型因子分析
古水团演化
平均沉积速率
东海中陆架
benthic foraminiferal assemblage
Q-mode factor analysis
paleo-water-mass evolution
average sedimentation rate
the middle continental shelf of East China Sea
