HR: 0800h
AN: GP31B-0834    [Abstracts]
TI: Holocene Centennial to Millennial-Scale Climatic Variability: Insights From High-Resolution Magnetic Analyses of the last 10 cal. kyr off North Iceland (IMAGES core MD99-2275).
AU: * Rousse, S
EM: rousse@mag.ig.erdw.ethz.ch
AF: LSCE, CNRS-CEA, Avenue de la Terrasse, Bat 12, Gif-sur-Yvette, 91198 France
AU: * Rousse, S
EM: rousse@mag.ig.erdw.ethz.ch
AF: now at ETH-Hoenggerberg, Schafmattstrasse, 30, Zurich, CH-8093 Switzerland
AU: Kissel, C
EM: kissel@lsce.cnrs-gif.fr
AF: LSCE, CNRS-CEA, Avenue de la Terrasse, Bat 12, Gif-sur-Yvette, 91198 France
AU: Laj, C
EM: laj@lsce.cnrs-gif.fr
AF: LSCE, CNRS-CEA, Avenue de la Terrasse, Bat 12, Gif-sur-Yvette, 91198 France
AU: Eiriksson, J
EM: jeir@rhi.hi.is
AF: University of Iceland, Science Insitute, Reykjavik, IS-101 Iceland
AU: Knudsen, K
EM: Karenluise.knudsen@geo.au.dk
AF: University of Aarhus, Department of Earth Sciences, Aarhus, DK-8000 Denmark
AB: High resolution magnetic analysis has been performed on the top 25 m of core MD99-2275 (66ø33.06'N, 17ø41.59'W; 440 m water depth) taken with the R. V. Marion Dufresne from the mid- outer shelf off North Iceland. This is a key boundary region for climate changes related to atmospheric and oceanographic variations, influenced by the moving limit between the cold and warm water masses at the Polar Front and the low depression track with its associated westerlies situated across Iceland. A precise age model based on tephrochronology was previously reported for this core and has allowed to determine precise timing of significant variations in the magnetic concentration and grain-size over the last 10000 cal. yr BP. Our record shows a clear increase in oceanographic instability from about 6 cal. kyr BP to the present compared with the previous period. The Holocene `climatic optimum', identified in North Iceland between about 9 and 6 cal. kyr BP, is characterized by minor variations in the magnetic record. A tendency to a decrease of the magnetic content toward the present will be discussed in terms of variations in the strength of the Irminger Current. Shorter oscillations are also identified, the youngest one (AD 1020 to AD 1330) corresponding in time to the Medieval Warm Period. The older ones (around 3.5 and 5 cal. kyr BP) might be associated with increased activity of the warm saline Irminger Current related to stronger input of North Atlantic waters into the Nordic seas. Spectral analysis of selected magnetic parameters also demonstrates centennial scale periodicities, which are more clearly expressed in the last 6 cal. kyr BP than in the previous period. This record therefore shows that the Holocene climate was more unstable than generally assumed hitherto, and it demonstrates the importance of high-resolution climatic studies of this recent time period to improve climate model predictions.
DE: 4267 Paleoceanography
DE: 4558 Sediment transport
DE: 1512 Environmental magnetism
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting