New chronological constraints on the timing of Late Pleistocene glacier advances in northern Switzerland

Dorian Gaar,Hans Rudolf Graf,Frank Preusser

doi:10.5194/egqsj-68-53-2019

Abstract

Abstract. Deposits of the Reuss Glacier in the central northern Alpine foreland of Switzerland are dated using luminescence methodology. Methodological considerations on partial bleaching and fading correction of different signals imply the robustness of the results. An age of ca. 25 ka for sediment directly overlying basal lodgement till corresponds well with existing age constraints for the last maximal position of glaciers of the northern Swiss Alpine Foreland. Luminescence ages imply an earlier advance of Reuss Glacier into the lowlands during Marine Isotope Stage 4. The presented data are compared to findings from other parts of the Alps regarding glacier dynamics and palaeoclimatological implications, such as the source of precipitation during the Late Pleistocene.

Highlights

Investigating the extent, geometry and timing of past ice sheets and glacier networks allows for the detection of atmospheric circulation patterns during the Late Pleistocene, as an important contribution for a better understanding of natural climate dynamics (Stokes et al, 2015)
It has to be noted that the term Last Glacial Maximum (LGM) is ambiguous: it is either used to refer to the maximum of global cooling during Marine Isotope Stage (MIS) 2 or the last maximum of global ice volume, both of which are inferred from deep marine sediment records
We present a new set of luminescence ages further constraining the timing of glacial advances in the Reuss Glacier system, situated in between the areas occupied by the main lobes of the Rhine Glacier and Valais Glacier during the Late Pleistocene (Figs. 1, 3)

Summary

Introduction

Investigating the extent, geometry and timing of past ice sheets and glacier networks allows for the detection of atmospheric circulation patterns during the Late Pleistocene, as an important contribution for a better understanding of natural climate dynamics (Stokes et al, 2015). Continental records indicate that most ice sheets and glaciers reached their last most extensive position between 26.5 and ka ago, with the onset of deglaciation mainly just after ka (Clark et al, 2009). It appears that in some regions the maximum extent of glaciers after the Last Interglacial was not synchronous with the peak of MIS 2 (cf Hughes et al, 2013), with important and not yet entirely deciphered indications for past circulation. Jimenez-Sanchez et al (2013) suggest that the last local glacial maximum in the Pyrenees occurred during MIS 4 and that glaciers during MIS 2 were of substantially smaller extent

Methods

Results

Discussion

Conclusion