Multiproxy reconstruction of rapid paleooceanographic changes in the SW Barents Sea during the Late Glacial- Early Holocene transition

The main objective of this study is to examine the Late Glacial - Early Holocene variability of the North Atlantic Current with focus on the zonal component of this meridional transport during the transition from glacial to interglacial conditions. The investigated sediment core is from 409 m water depth, SW Barents Sea, and the site is today influenced by Atlantic Water from the zonal branch of North Atlantic Current, the North Cape Current, and fresher water masses from the Norwegian Coastal Current. Both the North Atlantic Current and the North Cape Current are important components in the meridional overturning circulation system of the North Atlantic. Eight AMS 14C dates show that the core covers the last 20.000 cal yr BP with a resolution of centennial scale during Late Glacial - Early Holocene. The core has been analyzed with regard to planktic foraminiferal assemblages using the larger than 100 μm size fraction, number of IRD, and planktic and benthic δ13C and δ18O isotopes. Furthermore, a range of physical and chemical analyses have been carried out on the bulk sediment samples; δ13C, MSCL, grain size distributions, TOC and CaCO3. The results show that between 13.700-12.700 cal yr BP (Allerød) planktic foraminifera are found indicating seasonally open water conditions. The fauna is dominated by the species Neogloboquadrina pachyderma (sin) reflecting very cold surface water conditions while high flux of planktic foraminifera and increased values of TOC and CaCO3 generally indicate enhanced primary production. High amounts of IRD indicate transportation by sea ice or icebergs while relatively large difference between benthic and planktic δ18O isotope values signals stratified water masses. High production and stratified water masses are probably caused by a combination of a close position to the sea ice edge and an increased subsurface influx of the Atlantic water mass. The time interval between ca. 12.700-11.000 cal yr BP (Younger Dryas) is a low productivity period as very few planktic and benthic foraminifera are found. Low primary productivity is also shown by low TOC and CaCO3 content in the sediment. This is probably due to perennial sea ice. This is supported by the change to even finer grained sediments during this period as perennial sea ice would hamper influx of coarser material. From ca. 11.000-7.000 cal yr BP (Holocene) the foraminiferal fauna show an overall dominance by Turborotalita quinqueloba and high foraminiferal flux. This indicates a close proximity to the Arctic Front and its high nutrient concentration. Low IRD counts signify an end of transportation by sea ice or icebergs while relatively small difference between benthic and planktic δ18O isotope values signals a weak stratification of the water masses generated by a continuous eastward influx of Atlantic Water into the SW Barents Sea during the early Holocene.