HR: 0800h
AN: PP51A-0193    [Abstracts]
TI: The Holocene in the South-Western Barents Sea: Large Scale Natural Climatic and Oceanographic Variability
AU: * Risebrobakken, B
EM: bjorg.riesebrobakken@bjerknes.uib.no
AF: Bjerknes Centre for Climate Research, Allegaten 55, Bergen, 5007, Norway
AU: Ivanova, E
AF: Shirshov Institute of Oceanology RAS, 36 Nakhimovsky Prosp., Moscow, 117997, Russian Federation
AU: Moros, M
AF: Bjerknes Centre for Climate Research, Allegaten 55, Bergen, 5007, Norway
AU: Moros, M
AF: Institut für Ostseeforchung, Seestrase 15, Rostock-Warnemünde, 18119, Germany
AU: Yamskova, E
AF: Shirshov Institute of Oceanology RAS, 36 Nakhimovsky Prosp., Moscow, 117997, Russian Federation
AU: Ovsepyan, Y
AF: Moscow State University, Leninskiye gory, Moscow, 119889, Russian Federation
AB: Results from a high-resolution multi-proxy study of the Holocene section of the gravity core PSh-5159N from the Ingøydjupet depression in the south-western Barents Sea will be presented. The site is located within the pathway of Atlantic Water that enters the Barents Sea in the North Cape Current. The combined use of planktic and benthic oxygen isotopes, planktic and benthic foraminifer counts, foraminifer SST estimate using the WAPLS method, grain size and XRD data provide an opportunity to detect changes in subsurface and bottom water temperatures, stratification of the water column, and to investigate connections to large-scale movements in the marginal ice zone and front position. Due to a possible hiatus 5-2.5 ka BP, focus will be on the early and the late Holocene. During the earliest phase of the Holocene, 11-9.8 ka BP, the oxygen isotopes reflect low surface salinity. The site was probably covered by sea ice, at least during winter. Summer melting possible introduced a low salinity surface layer, similar to what is seen in the northern Barents Sea today. As the marginal sea ice zone moved further north and eastward, the front followed, and between 9.8-8 ka BP, the front was located close to the site, and along the western Barents Sea margin. Increased advection of Atlantic Water is indicated from 7.7-6.5 ka BP. At this time a clear indication of warmer subsurface water masses are seen, and the signal is seen not only locally at this site, but regionally. The last 2.5 ka BP is characterised by large-scale variability, both in the bottom and subsurface water. Generally warmer bottom water indicates warmer winter conditions than earlier in the Holocene. Somewhat colder conditions are recorded in the subsurface, and at times the front seems to have been located in vicinity of the site. There are also indications of somewhat increased sediment deposition from sea ice, compared to the early Holocene. Trough the Holocene, the gradient between planktic and benthic oxygen isotopes has generally been higher than the present gradient between the subsurface and bottom water, indicating stronger stratification of the water column. Some of the variance of the stratification is probably related to the location of the core of the Atlantic Water in the North Cape Current, and how that would influence the site. The changes in the inflow of Atlantic Water through the Barents Sea Opening are influenced by the regional atmospheric forcing and wind pattern, and the persistence of these over time. Presently, there is also a strong seasonal aspect to the strength of the inflow, and probably this has to be taken into account when making paleoceanographic interpretations from the area.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting