Investigating the effects of glacial shearing of sediment on luminescence |
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| Institution: | 1. Department of Geography, University of Sheffield, Winter Street, Sheffield S10 2TN, UK;2. Department of Earth Sciences, University of Aarhus, Denmark;3. Scottish Universities Environmental Research Centre, East Kilbride, UK;1. School of Environmental Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK;2. Department of Geography, Durham University, Durham, DH1 3LE, UK;1. GFZ German Research Centre for Geosciences, Section 5.1 Geomorphology, Potsdam, Germany;2. IRAMAT-CRP2A, Université Bordeaux Montaigne, Maison de l’Archéologie, Esplanade des Antilles, 33607 Pessac Cedex, France;3. Institute for Geography, University of Cologne, 50923 Cologne, Germany;4. Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Remote Sensing Group, Halsbrücker Strasse 34, 09599 Freiberg, Germany;5. Geographical Institute, Geomorphology, University of Bayreuth, 95440 Bayreuth, Germany;1. Department of Earth Sciences, ETH, 8092 Zurich, Switzerland;2. Center for Nuclear Technologies, Technical University of Denmark, DTU – Risø Campus, Roskilde, Denmark;3. Netherlands Centre for Luminescence Dating, Soil Geography and Landscape Group, Wageningen University, Wageningen, The Netherlands;4. Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands;5. Nordic Laboratory for Luminescence Dating, Department of Geoscience, Aarhus University, DTU Risø Campus, Denmark;6. Geological Survey of Norway, POB 6315 Sluppen, 7491 Trondheim, Norway;7. Natural History Museum of London, Cromwell Road, London SW7 5BD, UK;8. Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland;9. Department of Physical Geography and Quaternary Geology, Stockholm University, 10691 Stockholm, Sweden;10. Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095-1567, USA;11. Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan;12. Department of Earth Sciences, Indian Institute of Technology, Bombay, Powai 400 076, India;13. Institute of Earth Surface Dynamics, University of Lausanne, Geopolis 3232, 1015 Lausanne, Switzerland;1. Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany;2. German Research Centre for Geosciences (GFZ), Climate Dynamics and Landscape Development, Potsdam, Germany;3. Institute of Earth Surface Dynamics, University of Lausanne, Switzerland;4. Institute of Geosciences, University of Potsdam, Potsdam, Germany;5. Institute of Geology, University of Innsbruck, Innsbruck, Austria;6. German Federal Office for Radiation Protection (BfS), Berlin, Germany |
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| Abstract: | Previously reported low luminescence of basal glacial sediment has raised the possibility that processes operating at the ice–bedrock interface have the potential to reset (or ‘bleach’) natural luminescence signals (Swift et al., 2011). This finding indicates that certain types of glacial sediment (for example, sub-glacial diamicts) might be amenable to dating using luminescence-based techniques. Using a purpose-built ring-shear apparatus situated in a light-controlled environment, we have investigated the potential for mineral grains to be reset when subjected to conditions similar to those experienced by sediment that has undergone transport at the ice–bedrock interface. Reported here are the preliminary results of an initial experiment that used medium quartz sand with a naturally-acquired palaeodose of ∼4.3 Gy that had been obtained from a relict dune system. Incremental sampling during the shearing experiment and measurements were made to track changes in the luminescence properties of the sand as strain/shearing increased. The results indicate that increased strain/shearing resulted in an increase in the number of zero-dose grains and evolution of the De distribution from unimodal to multimodal. In light of the very much longer shearing distances that sub-glacial sediment would endure in nature, these results would appear to suggest that geomechanical processes at the ice–bed interface of glaciers and ice sheets may be a viable mechanism for resetting sediment. |
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