The Relationship between Surface Water Masses, Oceanographic Fronts and Paleoclimatic Proxies in Surface Sediments of the Greenland, Iceland, Norwegian Seas

Abstract

A detailed study of paleoclimatic proxy data (stable isotopes, planktonic foraminiferal census data, carbonate content, and Ice Rafted Detritus (IRD)) in the surface sediments of the Greenland, Iceland and Norwegian Seas (GIN-seas) shows that different proxies are closely related to the surface water masses, to the position of oceanic fronts and to the sea ice extent. Both stable isotopes, foraminifers and sedimentological data differentiate between Polar water with extensive sea ice cover, Arctic water with only seasonal sea ice cover, and warm Atlantic water. The fronts that border these surface water masses are also well defined. Polar water is characterized by lower carbon and oxygen isotope values than Arctic water, and a slightly lower content of Neogloboquadrina pachyderma sinistral in the Polar Front region. Carbonate content is low and IRD input is high in Polar waters. Arctic water has highest carbon and oxygen isotope values, and is completely dominated by N. pachyderma sin. The Arctic Front is reflected by a clear isotopic gradient and by a strong switch from N. pachyderma sin. dominance to Globigerina quinqueloba dominance. Atlantic Water is defined by lower carbon and oxygen isotope values and by dominance of N. pachyderma dextral and increased amounts of Globigerina bulloides. The results have implications for paleoceanographic reconstructions of cold environments and point to the possibility of better defining sea ice margins and convective regions as well as frontal positions in past high latitude oceans. Applying these results to the Last Glacial Maximum and the Younger Dryas indicates more dynamic and less sea ice covered surface conditions in the GIN-seas than in earlier reconstructions.