T225 From Alpine Glaciers to Ice Sheets: Understanding Glacial Dynamics, Landscapes, and Environmental Change

Wednesday, 7 November 2018
8:00 AM - 12:00 PM
Room 136-137

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

Paper number: T225-8
Program: Technical Sessions
Time: 9:45 AM – 10:05 AM

Authors

  • Henriette Linge Presenting Author
    University of Bergen and Bjerknes Centre for Climate Research, Bergen
  • Svein Olaf Dahl
    University of Bergen and Bjerknes Centre for Climate Research, Bergen
  • Derek Fabel
    Scottish Universities Environmental Research Centre, East Kilbride
  • Sheng Xu
    Scottish Universities Environmental Research Centre, East Kilbride
  • Jesper Olsen
    Aarhus University, Aarhus C

Abstract

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A compilation of more than 80 published and unpublished cosmogenic 10Be surface exposure ages from glacially transported boulders provides new information on the timing and extent of regional and local glaciation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.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-317092

© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.