A new approach for reconstructing glacier variability based on lake sediments recording input from more than one glacier |
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| Authors: | Kristian Vasskog Øyvind Paasche Atle Nesje John F Boyle HJB Birks |
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| Institution: | 1. Department of Earth Science, University of Bergen, Allégaten 41, N-5007 Bergen, Norway;2. Bjerknes Centre for Climate Research, Allégaten 55, N-5007 Bergen, Norway;3. Bergen Marine Research Cluster, University of Bergen, Professor Keysers Gate 8, N-5020 Bergen, Norway;4. School of Environmental Sciences, University of Liverpool, Roxby Building, Liverpool L69 7ZT, United Kingdom;5. Department of Biology, University of Bergen, PO Box 7803, N-5020 Bergen, Norway;6. Environmental Change Research Centre, University College London, London, WC1E 6BY, UK;7. School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK |
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| Abstract: | We explore the possibility of building a continuous glacier reconstruction by analyzing the integrated sedimentary response of a large (440 km2) glacierized catchment in western Norway, as recorded in the downstream lake Nerfloen (N61°56’, E6°52’). A multi-proxy numerical analysis demonstrates that it is possible to distinguish a glacier component in the ~ 8000-yr-long record, based on distinct changes in grain size, geochemistry, and magnetic composition. Principal Component Analysis (PCA) reveals a strong common signal in the 15 investigated sedimentary parameters, with the first principal component explaining 77% of the total variability. This signal is interpreted to reflect glacier activity in the upstream catchment, an interpretation that is independently tested through a mineral magnetic provenance analysis of catchment samples. Minimum glacier input is indicated between 6700–5700 cal yr BP, probably reflecting a situation when most glaciers in the catchment had melted away, whereas the highest glacier activity is observed around 600 and 200 cal yr BP. During the local Neoglacial interval (~ 4200 cal yr BP until present), five individual periods of significantly reduced glacier extent are identified at ~ 3400, 3000–2700, 2100–2000, 1700–1500, and ~ 900 cal yr BP. |
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