VARIABILITY IN SURFACE AND DEEP-WATER CONDITIONS IN THE NORDIC SEAS DURING THE LAST INTERGLACIAL PERIOD

Stable isotope, foraminifera and ice rafted detritus (IRD) records cov ering the last interglacial (the Eemian) from 7 sediment cores in a tr ansect from the Norwegian to the Greenland Sea are presented. The perc entages of Neogloboquadrina pachyderma (s.) and Globigerina quinquelob a, foraminiferal content, and to some extent planktonic stable isotope records, demonstrate marked, regional changes in surface water condit ions. Importantly, the variability in the abundances of subpolar foram inifera and foraminiferal content are not coherent, implying that thes e two types of proxies fluctuated independently of each other and most likely reflect changes in sea surface temperature and surface water c arbonate 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 Norw egian current. Within the later warm intervals, higher heat flux to th e western part of the basin reflects a combination of a stronger Irmin ger current and/or a weaker east Greenland current. During the main co ld spell at similar to 124 ka, a diffuse Arctic front had a more south easterly location than today, and intrusion of Atlantic surface waters was probably limited to a narrow corridor in the Eastern Norwegian Se a. A general correspondence between minima in sea surface temperatures and light benthic delta(18)O may indicate enhanced influx of freshwat er to the basin within the cold events. At least in the Norwegian Sea, we find some evidence that the changes in surface water conditions ar e associated with changes in deep water ventilation. The majority of t he 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 an d salinity, which the deep water formation is depending on, may have b een disturbed by periodic increases in fresh water supply or variable influx of warm Atlantic surface waters. (C) 1998 Elsevier Science Ltd. All rights reserved.