Ages analysis, trace elements and relative frequencies of foraminifera snd diatoms from sediment cores AvH248260-2 and AvH248260-1, Ameralik Fjord, SW Greenland

A multiproxy record including benthic foraminifera, diatoms and XRF data of a marine sediment core from a SW Greenland fjord provides a detailed reconstruction of the oceanographic and climatic variations of the region during the last 4400 cal. years. The lower part of our record represents the final termination of the Holocene Thermal Maximum. After the onset of the 'Neoglaciation' at approximately 3.2 ka cal. BP, the fjord system was subject to a number of marked hydrographical changes that were closely linked to the general climatic and oceanographic development of the Labrador Sea and the North Atlantic region. Our data show that increased advection of Atlantic water (Irminger Sea Water) from the West Greenland Current into the Labrador Sea was a typical feature of Northeast Atlantic cooling episodes such as the 'Little Ice Age' and the 'European Dark Ages', while the advection of Irminger Sea Water decreased significantly during warm episodes such as the 'Mediaeval Warm Period' and the 'Roman Warm Period'.Whereas the 'Mediaeval Warm Period' was characterized by relatively cool climate as suggested by low meltwater production, the preceding 'Dark Ages' display higher meltwater runoff and consequently warmer climate. When compared with European climate, these regional climate anomalies indicate persisting patterns of advection of colder, respectively warmer air masses in the study region during these periods and thus a long-term seesaw climate pattern between West Greenland and Europe.

本数据集包含格陵兰西南部峡湾海洋沉积物岩芯的多代理记录（multiproxy record），涵盖底栖有孔虫（benthic foraminifera）、硅藻（diatoms）与X射线荧光光谱（XRF）数据，可精细重建过去4400个校准年以来该区域的海洋学与气候变化特征。本记录的下段对应全新世大暖期（Holocene Thermal Maximum）的最终结束阶段。在约3.2千年校准年前的新冰期（Neoglaciation）启动后，该峡湾系统经历了一系列显著的水文变化，这些变化与拉布拉多海（Labrador Sea）及北大西洋区域（North Atlantic region）的整体气候与海洋学演化紧密相关。本研究数据显示，西格陵兰洋流（West Greenland Current）携带的大西洋海水（伊尔明格海水，Irminger Sea Water）向拉布拉多海的平流输送（advection）增强，是东北大西洋冷期（如小冰期（Little Ice Age）与欧洲黑暗时代（European Dark Ages））的典型特征；而在中世纪暖期（Mediaeval Warm Period）、罗马暖期（Roman Warm Period）等暖期阶段，伊尔明格海水的平流输送则显著减弱。尽管中世纪暖期以相对寒冷的气候为特征（低融水产生量可佐证这一点），但其之前的欧洲黑暗时代却拥有更高的融水径流量（meltwater runoff），对应更为温暖的气候。与欧洲气候对比后，这些区域气候异常表明，在上述时段内，研究区域持续存在冷、暖空气团平流输送的特征模式，进而反映了西格陵兰与欧洲之间长期存在的跷跷板气候格局（seesaw climate pattern）。