1 Department of Geoscience, Science and Technology, Aarhus University2 Department of Bioscience - Arctic Research Centre, Høegh Guldbergs Gade, Department of Bioscience, Science and Technology, Aarhus University3 Aarhus Universitet4 Department of Earth Sciences, Faculty of Science, Aarhus University, Aarhus University5 International Centre, Universityadministration, Aarhus University, Aarhus University6 GEUS7 Department of Geoscience, Science and Technology, Aarhus University
Marine sediments analyzed from cores taken in Placentia Bay, Newfoundland, located in the Labrador Sea, captured oceanographic and climatic changes from the end of the Younger Dryas through the Holocene. Placentia Bay is an ideal site to capture changes in both the south-flowing Labrador Current and the north-flowing Gulf Stream, currents which are closely tied to the strength of the North Atlantic sub-polar gyre and the North Atlantic Oscillation. Changes in the atmospheric and oceanographic circulation patterns in the North Atlantic after the last glacial period are inferred from faunal assemblages, mineralogy and dinoflagellate analyses. During the 2007 Akademik Ioffe cruise, three cores were taken from Placentia Bay: AI07-10G, which represents the time period ca. 10.4 cal kya BP to the present; AI07-12G, representing the last 5.7 cal kya; and AI07-14G, representing 12.7 to 9.8 cal kyr BP. These cores have been analyzed using several climate proxies, including benthic foraminifera, diatoms, IP25, dinoflagellate cysts and XRF. Together, these cores provide high-resolution records of the changes in climatic conditions over the last ca. 13,000 years in the southern Labrador Sea. After the Younger Dryas ended, the beginning of the warmer early Holocene was recorded by an increase in productivity-linked foraminiferal and diatom assemblages, as well as a drop in the presence of the sea-ice indicator IP25 in core 14G (Pearce et al., 2012). Variability in atmospheric circulation during the Holocene was analyzed in core 12G and used to reconstruct changes in the mode of the North Atlantic Oscillation during the late Holocene by analysis of exotic pollen grains. Sea-surface conditions during the late Holocene in Placentia Bay reflect a decrease in the strength of the Labrador Current, based on warmer sea-surface temperatures and a simultaneous decline in Arctic water export, from ~4000 cal years to ~3000 cal years BP, which falls into the overall large-scale trend of cooling during the last ~5000 years of the Late Holocene, based on concentrations of exotic pollen in the core (Jessen et al., 2011). Preliminary results from analyses of core 10G indicate that the core contains a full Holocene record of climatic conditions in Placentia Bay inferred from foraminiferal and diatom assemblage analyses, which are expected to align with results from previous studies using the cores from the 2007 Akademik Ioffe cruise. Jessen, C. A., Solignac, S., Nørgaard-Pedersen, N., Mikkelsen, N., Kuijpers, A., and Seidenkrantz, M.-S., 2011, Exotic pollen as an indicator of variable atmospheric circulation over the Labrador Sea region during the mid to late Holocene: Journal of Quaternary Science, v. 26, no. 3, p. 286-296 Pearce, C., Reynisson, N. F., Massé, G., Kristiansen, S. M., Kuijpers, A., and Seidenkrantz, M. S., 2012, Rapid oceanic changes at the Younger Dryas termination inferred from diatom analysis offshore Newfoundland, XXII International Diatom Symposium.