FORMATION OF GLACIAL LANDFORMS DURING MIS 3-1 ON ANDØYA (69°N, 16°E), COASTAL NORTHERN NORWAY (Invited Presentation)

The Lofoten-Vesterålen region in northern Norway has been subject to Quaternary geology and palaeoclimate investigations for more than a century, mainly focusing on three topics: i) the timing and extent of the Last Glacial Maximum (LGM) ice cover, ii) the pattern of sea-level change and the age of raised beaches and shorelines, and iii) the possibility of ice-free areas before and during the LGM. Andøya (69°N, 16°E) is the northernmost island of the Vesterålen archipelago, and it is situated 8-15 km from the shelf-break. Its geographical position has two major implications with regard to ice-sheet boundary conditions: a proximity to northward flow of ocean currents, and to the margin of large continental ice sheets.

A compilation of more than 80 published and unpublished cosmogenic ¹⁰Be surface exposure ages from glacially transported boulders provides new information on the timing and extent of regional and local glaciation for the last glacial period. Evidence of local glaciers is recorded between 65 and 12 ka from boulders on marginal moraines, whereas glacially transported boulders (resting on bedrock) and boulders on marginal moraines show changes in the lateral and horizontal extent of the Scandinavian Ice Sheet between 40 and 25 ka. Insight into the dynamics of past terrestrial environments is moreover added by dating of relict talus-derived rock glaciers, showing activity between 30 and 15 ka. Bedrock surfaces providing ¹⁰Be surface exposure ages older than expected, either from ¹⁰Be dating of associated glacial boulders or independent data, are currently being reprocessed for AMS analysis of Al and Be to provide information on erosion rates.

The results show fluctuating local glaciers, as well as asynchronous timing of the maximum extent of regional and local glaciation. A reduction in heat transport could cause a rapid shift from a mild oceanic climate to a cold and continental climate regime with sea-ice cover, as indicated by the presence of periglacial and glacial landforms close to sea level. Past changes in heat and moisture transport can thus explain fluctuations in local glaciation in the Lofoten-Vesterålen region. Fluctuations of the continental ice sheet, on the other hand, must be attributed the integrated impact of large-scale atmospheric and oceanic circulation patterns over longer timescales.