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E&G Quaternary Science Journal An open-access journal of the German Quaternary Association
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Volume 66, issue 2 | Copyright
E&G Quaternary Sci. J., 66, 57-68, 2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 20 Dec 2017

Research article | 20 Dec 2017

10Be depth profiles in glacial sediments on the Swiss Plateau: deposition age, denudation and (pseudo-) inheritance

Lorenz Wüthrich1,2,3, Claudio Brändli3, Régis Braucher4, Heinz Veit1, Negar Haghipour3, Carla Terrizzano1,2,3, Marcus Christl5, Christian Gnägi1, and Roland Zech1,2,3 Lorenz Wüthrich et al.
  • 1Geographical Institute, University of Bern, 3012 Bern, Switzerland
  • 2Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
  • 3Geological Institute, ETH Zurich, 8093 Zurich, Switzerland
  • 4Aix-Marseille Université, CNRS–IRD–Collège de France, UMR 34 CEREGE, Technopôle de l'Environnement Arbois–Méditerranée, BP80, 13545 Aix-en-Provence, France
  • 5Laboratory of Ion Beam Physics, ETH Zurich, 8092 Zurich, Switzerland

Abstract. During the Pleistocene, glaciers advanced repeatedly from the Alps onto the Swiss Plateau. Numeric age control for the last glaciation is good and thus the area is well suited to test a method which has so far not been applied to till in Switzerland. In this study, we apply in situ produced cosmogenic 10Be depth profile dating to several till deposits. Three sites lie inside the assumed Last Glacial Maximum (LGM) extent of the Rhône and Aare glaciers (Bern, Deisswil, Steinhof) and two lie outside (Niederbuchsiten, St. Urban). All sites are strongly affected by denudation, and all sites have reached steady state, i.e., the 10Be production is in equilibrium with radioactive decay and denudational losses. Deposition ages can therefore not be well constrained. Assuming constant denudation rates of 5cmkyr−1, total denudation on the order of 100cm for sites within the extent of the LGM and up to tens of meters for older moraines are calculated. Denudation events, for example related to periglacial conditions during the LGM, mitigate the need to invoke such massive denudation and could help to explain high 10Be concentrations at great depths, which we here dub pseudo-inheritance. This term should be used to distinguish conceptionally from true inheritance, i.e., high concentrations derived from the catchment.

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