北大西洋北部中全新世以来古海洋环境记录

Mid-to late-Holocene Paleoceanographic Changes in the Northern North Atlantic

利用主成分分析法对冰岛北部陆架MD99-2275孔中全新世以来沉积物硅藻数据进行研究发现,5000—3000aB.P.,冰岛北部陆架表层古海水温度逐渐上升,来自印明格暖流的北大西洋暖水对该区域的影响有所增强。自3000aB.P.以来,表层海水温度开始稳步下降,北大西洋暖水水团的影响逐步减弱,而来自东格陵兰寒流和东冰岛海流的极地冷水水团的影响显著加强。在晚全新世气候逐渐变冷的过程中,发生了几次短期而显著的气候变冷事件,分别出现在3000—2600aB.P.,1300—1000aB.P.及600—200aB.P.。该中晚全新世古海洋环境记录与格陵兰冰芯(GSIP2)氧同位素气候记录存在良好的对应关系,也与冰岛北部陆架其他海水温度记录有较好的一致性。而冰岛北部陆架区域海底地形的复杂性和海流分布的差异性,以及所采用研究方法的不同则导致该区域各古海水温度记录之间也存在一定的差异性。

A high-resolution diatom record from core MD99-2275 revealed the paleoceanographic changes on the northern North Atlantic since 5000 cal. yr BP by Principal Component Analysis. The sea surface temperature increased gradually between 5000 and 3000 cal. yr BP as a result of increasing influence of the North Atlantic water mass from the Irminger Current. It started to decrease apparently since 3000 cal. yr BP due to the decreasing influence of the warm Atlantic water and enhanced influence of the Polar and Arctic water mass from the East Greenland Current and East Icelandic Current. Abrupt decrease in sea surface temperatures and enhanced influence of Polar and Arctic water are reflected superimposed on the late Holocene cooling trend during 3000-2600, 1300-1000 and 600-200 cal. yr BP. The sea surface temperature record from core MD99-2275 corresponds well with the δ80 record from the GISP2 and is generally consistent with other sea surface temperature records on the North Icelandic shelf.