Variability in surface and deep water conditions in the Nordic Seas during the last interglacial period
Variability in surface and deep water conditions in the Nordic Seas during the last interglacial period
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DOI：
10.1016/s0277-3791(98)00038-9
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发表时间：
1998-01-01
影响因子：
4
通讯作者：
Sejrup, HP
中科院分区：
文献类型：
--
作者：
Fronval, T;Jansen, E;Sejrup, HP
本文报道了从挪威海到格陵兰海的一个剖面中的7个沉积岩芯的末次间冰期（Eemian）的稳定同位素、有孔虫和冰筏碎屑（IRD）记录。厚皮新红球藻Neogloboquadrina pachyderma（s.）和Globigerina quinqueloba，有孔虫含量，并在一定程度上的稳定同位素记录，表明地表水条件的显着，区域性变化。重要的是，在亚极地有孔虫和有孔虫含量的丰度的变化是不连贯的，这意味着这两种类型的代理波动彼此独立，最有可能反映在海面温度和地表水碳酸盐生产力的变化，分别。古海洋学重建显示了海洋学锋的显著运动。在最温暖的时期，北极锋位于现在位置的西边，至少在冰岛海地区。在126-125 ka，这很可能是由于一个更强或更偏西的挪威电流。在较晚的温暖的间隔，较高的热通量西部的盆地反映了一个较强的Irminger电流和/或较弱的东格陵兰电流的组合。在类似于124 ka的主要寒流期间，一个扩散的北极锋比今天有一个更东南的位置，大西洋表面沃茨的入侵可能仅限于一个狭窄的走廊在挪威东部海。海表温度最低值和浅底栖三角洲（18）O之间的一般对应关系可能表明，在寒冷事件中，淡水流入盆地的量增加。至少在挪威海，我们发现一些证据表明，在地表水条件的变化与深水通风的变化。大多数波动可能与北欧海洋内温盐环流偶尔中断或减少有关。在最早的Eemian，这可能是由于融水强迫。在末次间冰期的剩余部分，深水形成所依赖的温度和盐度之间的微妙平衡可能受到淡水供应周期性增加或大西洋温暖表层沃茨的可变流入的干扰。(C)1998爱思唯尔科技有限公司版权所有。
Stable isotope, foraminifera and ice rafted detritus (IRD) records covering the last interglacial (the Eemian) from 7 sediment cores in a transect from the Norwegian to the Greenland Sea are presented. The percentages of Neogloboquadrina pachyderma (s.) and Globigerina quinqueloba, foraminiferal content, and to some extent planktonic stable isotope records, demonstrate marked, regional changes in surface water conditions. Importantly, the variability in the abundances of subpolar foraminifera and foraminiferal content are not coherent, implying that these two types of proxies fluctuated independently of each other and most likely reflect changes in sea surface temperature and surface water carbonate productivity, respectively. Paleoceanographic reconstructions demonstrate significant movements of the oceanographic fronts. At the warmest periods, the Arctic front was located far west of the present-day location, at least within the Iceland Sea region. At 126-125 ka, this was most probably due to a stronger or more westerly located Norwegian current. Within the later warm intervals, higher heat flux to the western part of the basin reflects a combination of a stronger Irminger current and/or a weaker east Greenland current. During the main cold spell at similar to 124 ka, a diffuse Arctic front had a more southeasterly location than today, and intrusion of Atlantic surface waters was probably limited to a narrow corridor in the Eastern Norwegian Sea. A general correspondence between minima in sea surface temperatures and light benthic delta(18)O may indicate enhanced influx of freshwater to the basin within the cold events. At least in the Norwegian Sea, we find some evidence that the changes in surface water conditions are associated with changes in deep water ventilation. The majority of the fluctuations may be related to occasional breakdown or reduction of the thermohaline circulation within the Nordic seas. In the earliest Eemian, this could result from meltwater forcing. During the remaining part of the last interglacial the fine balance between temperature and salinity, which the deep water formation is depending on, may have been disturbed by periodic increases in fresh water supply or variable influx of warm Atlantic surface waters. (C) 1998 Elsevier Science Ltd. All rights reserved.