HR: 0800h
AN: PP51A-0192    [Abstracts]
TI: Paleoceanographic Variability During the Late Glacial-Early Holocene Transition in the South western Barents Sea.
AU: * Soerensen, S A
EM: Steffen.Sorensen@ig.uit.no
AF: Department of Geology, University of Tromsoe, Dramsveien 201, Tromsoe, 9037, Norway
AU: Husum, K
AF: Department of Geology, University of Tromsoe, Dramsveien 201, Tromsoe, 9037, Norway
AU: Hald, M
EM: morten.hald@ig.uit.no
AF: Department of Geology, University of Tromsoe, Dramsveien 201, Tromsoe, 9037, Norway
AU: Knies, J
AF: Geological Survey of Norway, Leiv Eirikssons vei 39, Trondheim, 7040, Norway
AB: We have investigated a sediment core from a local depression, Ingoydjupet, at 409 m water depth SW Barents Sea in the northern North Atlantic. This location is at present influenced by Atlantic water masses from the North Cape Current and a fresher water mass from the Norwegian Coastal Current. Both currents are important players in the meridional overturning circulation of the North Atlantic. The radiocarbon chronology of the core yields a centennial scale time resolution enabling a detailed temporal study of the paleoceanographic changes. The core has been analyzed for microfossil distribution of planktonic foraminifera at the > 100 μm fraction, geochemistry and grain size. At ca. 10.700 cal yr BP planktonic foraminifera are introduced. Coarser sedimentary grains including IRD disappear, indicating a marine environment no longer influenced by iceberg rafting. This coincides with the final stages in the deglaciation of the Fennoscandian ice sheet. A continuous planktonic fauna is established at around 10.500 cal yr BP. The fauna has a pronounced dominance of Turborotalita quinqueloba from 10.500 - to 7.000 cal yr BP suggesting a strong continuous influx of Atlantic water into the SW Barents Sea and a close proximity to the Arctic Oceanic Front. A cooling of the surface water is indicated by a strong increase of Neogloboquadrina pachyderma (sin) lasting from 8.700 - 8.400 cal yr BP. Taking the uncertainty in the age model into account, this event relates to the 8.2 ka cold event, which has previously been recognized in the North Atlantic region, including the Barents Sea. The benthic and planktonic δ¹³C - and δ¹⁸O isotope values, measured on Cassidulina neoteretis and T. quinqueloba respectively, show a parallel fluctuation pattern signalling a vertical mixing of the water masses during the late Weichselian – early Holocene transition. The relative differences in both the δ¹³C and δ¹⁸O isotope signal between surface and bottom water masses can be attributed to variations in temperature, salinity and primary production in the photic zone. In addition, analyses of biological silica and CaCO₃ show a low production and δ¹³C measurements indicate a marine origin of the organic matter in the sediment during this time interval.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 1051 Sedimentary geochemistry
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 3030 Micropaleontology (0459, 4944)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting