HR: 1340h
AN: PP33B-1281    [Abstracts]
TI: In situ 10Be ages constraining the glacial, periglacial and sea-level history of Andøya, northern Norway
AU: * Linge, H
EM: henriette.linge@geo.uib.no
AF: Bjerknes Centre for Climate Research, Allégaten 55, Bergen, 5007, Norway
AU: Dahl, S
EM: svein.dahl@geog.uib.no
AF: Bjerknes Centre for Climate Research, Allégaten 55, Bergen, 5007, Norway
AU: Dahl, S
EM: svein.dahl@geog.uib.no
AF: Department of Geography, University of Bergen, Fosswinckelsgate 6, Bergen, 5020, Norway
AU: Bakke, J
EM: jostein.bakke@geog.uib.no
AF: Bjerknes Centre for Climate Research, Allégaten 55, Bergen, 5007, Norway
AU: Bakke, J
EM: jostein.bakke@geog.uib.no
AF: Department of Geography, University of Bergen, Fosswinckelsgate 6, Bergen, 5020, Norway
AU: Fabel, D
EM: Derek.Fabel@ges.gla.ac.uk
AF: Department of Geographical and Earth Sciences, East Quadrangle, Main Building University of Glasgow, Glasgow, G12 8QQ, United Kingdom
AB: Northwards transport of Atlantic water by the Norwegian Current warms the Norwegian Arctic coast 5-10°C above the annual mean for latitude 69°N. A reduction in heat transport would cause a shift from anomalously warm and maritime open-ocean climate to a cold and continental regime with continuous/seasonal sea-ice cover. Palaeoclimatic archives from this region thus facilitate testing of key hypotheses on the role of ocean, sea-ice, atmospheric processes, and feedbacks in driving Arctic climate variability during the shift from glacial to peak interglacial climates. Its proximity to the shelf break and diversity of geomorphological features has made the island Andøya (69°N, 15°E) a key area for reconstructing ice-age history and palaeoclimatic investigations for more than a century. Even if lacustrine sediments span the last 20 ka, however, evidence has not yet been conclusive with regard to the ice-sheet extent during the Late Weichselian glacial maximum (~LGM) and the Late Glacial phase. We have measured in-situ cosmogenic 10Be in surface rock samples from selected marginal moraine ridges formed by continental ice sheets and local glaciers, glacial erratics, ice-moulded bedrock, fossil rock glaciers and raised shorelines in order to resolve the Late Weichselian glacial, periglacial and sea level history of northern Andøya. The results so far show that the most comprehensive glacial erosion phase occurred prior to 40 ka with glacial erosion up to at least 100 m asl on both the western and eastern side of the northern part of the island. Small talus-derived rock glaciers on the eastern side were active around 30-25 ka, implying that any ice sheet present at that time must have been thinner than 200 m. Remnants of marginal moraines formed by a local glacier isolated from the continental ice sheet on the western side give >25 10Be ka. Beach ridges on the western side of the island developed at c. 20 m asl suggest a limited ice extent around 20 ka. Younger marginal moraine formed by low-elevation cirque- and valley glaciers show a maximum extent around 18-16 ka. Talus- derived rock glaciers on the western side of the island overrun the c. 20 ka shoreline and became inactive c. 15 ka, constraining the timing of suitable conditions for rock glacier formation close to the present sea level.
DE: 1105 Quaternary geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1824 Geomorphology: general (1625)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting