A regional assessment of the deglaciation history of the Swiss Plateau based on newly obtained and re-evaluated Be-10 cosmic-ray exposure ages

Author(s)

Felix Martin Hofmann, Alexander R. Groos, Ezequiel Garcia Morabito, Julian Struck, Christian Gnägi, Andreas Scharf, Georg Rugel, Silke Merchel, Roland Zech

Abstract

During marine oxygen isotope stage (MIS) 2, the Swiss Plateau temporarily hosted large piedmont lobe glaciers that retreated after their maximum advance back to the fringe of the Alps. The presence of moraines in this region indicates that overall glacier recession was punctuated by repeated phases of ice-marginal stability and re-advances. The timing of these events in the region formerly covered by the eastern lobe of the Rhône (or Valais) glacier has been controversial and remains poorly constrained due to the lack of chronological data. To fill this gap,

¹⁰Be cosmic-ray exposure (CRE) dating was applied to erratic boulders inside the assumed MIS 2 maximum extent of this piedmont lobe. An erratic boulder at an ice-marginal position upstream from the suspected MIS 2 maximum extent gave an age of about 19 ka. Erratic boulders at a presumably younger ice-marginal position (Brästenberg position) yielded an average age of ca. 20 ka. However, several erratic boulders beyond the Brästenberg position gave internally consistent, but stratigraphically too young ages of ca. 17 ka. We cannot rule out that glacier recession from the Brästenberg position began no later than 17 ka. CRE dating of a moraine of a presumably younger ice-marginal position (Solothurn position) gave unrealistically old ages and an incredibly young age (86 ka, 40 ka, and 4 ka). Carbon-14 CRE dating should be applied to provide additional information on the last deglaciation of the Swiss Plateau. Nevertheless, despite outlying ages, the presented chronological data contribute to an overall consistent and increasingly refined chronology of the last deglaciation of the Swiss Plateau when compared with 59 previously published CRE ages.

Organisation(s)

Isotope Physics

External organisation(s)

Helmholtz-Zentrum Dresden-Rossendorf, Albert-Ludwigs-Universität Freiburg, Universität Bern, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Friedrich-Schiller-Universität Jena, weg>punkt

Journal

Quaternary Science Advances

Volume

13

No. of pages

17

ISSN

2666-0334

DOI

https://doi.org/10.1016/j.qsa.2023.100124

Publication date

09-2023

Peer reviewed

Yes

Austrian Fields of Science 2012

105105 Geochemistry, 105127 Geochronology, 104002 Analytical chemistry, 104020 Radiochemistry

Keywords

ASJC Scopus subject areas

Earth-Surface Processes, Geology, Earth and Planetary Sciences (miscellaneous)

Portal url

https://ucris.univie.ac.at/portal/en/publications/a-regional-assessment-of-the-deglaciation-history-of-the-swiss-plateau-based-on-newly-obtained-and-reevaluated-be10-cosmicray-exposure-ages(b7590b21-7062-4abe-a9f3-344fb3c3f9b3).html