subglacial erosion; cosmogenic nuclides; Alpine Lateglacial; European Alps; 10Be 14C 36Cl; Holocene; Last Glacial Maximum; overdeepening; cirque formation
Wirsig Christian, Ivy-Ochs Susan, Reitner Jürgen M., Christl Marcus, Vockenhuber Christof, Bichler Mathias, Reindl Martin (2017), Subglacial abrasion rates at Goldbergkees, Hohe Tauern, Austria, determined from cosmogenic 10Be and 36Cl concentrations, in Earth Surface Processes and Landforms
, 42(7), 1119-1131.
Wirsig Christian (2017), Constraining the timing of deglaciation of the High Alps and rates of subglacial erosion with cosmogenic nuclides, in Quaternary Science Journal
, 65(2), th 1-th 2.
Wirsig Christian, Ivy-Ochs Susan, Akçar Naki, Lupker Maarten, Hippe Kristina, Wacker Lukas, Vockenhuber Christof, Schlüchter Christian (2016), Combined cosmogenic 10Be, in situ 14C and 36Cl concentrations constrain Holocene history and erosion depth of Grueben glacier (CH), in Swiss Journal of Geosciences
, 109(3), 379-388.
Wirsig Christian, Zasadni Jerzy, Christl Marcus, Akçar Naki, Ivy-Ochs Susan (2016), Dating the onset of LGM ice surface lowering in the High Alps, in Quaternary Science Reviews
, 143, 37-50.
Bichler Mathias, Reindl Martin, Reitner Jürgen M., Drescher-Schneider Ruth, Wirsig Christian, Christl Marcus, Hajdas Irka, Ivy-Ochs Susan (2016), Landslide deposits as stratigraphical markers for a sequence-based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps, in Boreas
, 45(3), 537-551.
Wirsig Christian, Zasadni Jerzy, Ivy-Ochs Susan, Christl Marcus, Kober Florian, Schlüchter Christian (2016), A deglaciation model of the Oberhasli, Switzerland, in Journal of Quaternary Science
, 31(1), 46-59.
Ivy-Ochs Susan (2015), Glacier variations in the European Alps at the end of the last glaciation, in Cuadernos de investigación geográfica
, 41(2), 295-315.
The unique and immediately recognizable shape of the Alps, the deep U-shaped valleys separated by narrow serrated ridges, the stepped longitudinal valley profiles, and the rounded bowl-shape of the cirques are the direct evidence of the power of glaciers. Fundamental knowledge on how glaciers change landscape, erode down into their valleys, and generate sediment all depend on quantitative understanding of how fast glaciers erode at their base. As in SNF-funded project 200021-135448, we combine detailed geomorphological mapping, sedimentological study, ArcGIS-based morphometric analysis with cosmogenic nuclide measurements to understand the temporal and spatial patterns of modification of the Alps by glaciers. We take advantage of the capabilities of cosmogenic nuclides to be used as both chronometers (10Be) and tools for determining depth of glacial erosion into bedrock (combination of 10Be, 36Cl and 14C). 36Cl is useful because it is produced at greater quantities than 10Be peaking about 30 cm down into rock. Our results from the project indicate that the mismatch of 10Be and 36Cl can be used to reveal how deeply a glacier has eroded. In situ 14C in quartz is required for Holocene cirque sites to determine how long the glacier covered the cirque floor during the latest Holocene. Development of U-shaped valleys has been studied here we address the more challenging task of understanding how cross-valley riegels and associated overdeepenings form. Our focus in this project is two-fold: 1) to investigate how fast and in what spatial patterns valley and cirque glaciers erode their bedrock beds, and 2) to elucidate the extent and timing of extreme cold events of the early Alpine Lateglacial during the so-called ‘mystery interval’ of the last glacial termination. The ‘mystery interval’ is the period between about 19000 and 15000 yr ago when ice core records for the Greenland ice sheet indicate extremely cold conditions while mountain glaciers globally and most notably in the Alps were undergoing strong retreat. Events during this time period are linked to changes in North Atlantic circulation and should therefore impose a strong signal on the Alps which lie directly downwind. Understanding climate patterns during this time interval in the Alps requires absolute dating of the landform record of extreme cold pulses: moraines formed by glacier advances and rock glaciers. We augment our study of past climates through equilibrium lines of paleoglaciers constrained by moraines, with the study and cosmogenic nuclide dating of relict rock glaciers. The lowest elevation of a now inactive rock glaciers tells us the lower limit of discontinuous permafrost for the time when it was active (mean annual air temperature < 2 °C). We have identified several candidate study sites in Switzerland and Austria that allow us to study north south patterns across the Alps during the Lateglacial. Quantitative knowledge about how the processes of subglacial erosion work and at what rates are crucial for understanding and modeling the ways that glaciers control relief and overall elevation of mountain ranges.We will operate with a 4th year for PhD student C. Wirsig to complete cosmogenic nuclide measurements and research articles, with final completion of his dissertation in late summer 2015, and a new PhD student (N.N.) to begin after C. Wirsig has finished in fall 2015. For additional advisory capacity in the in situ 14C in quartz measure-ments, as well as expertise in ArcGIS and MATLAB we request 30% post-doc salary for Dr. Kristina Hippe. Her work in this project will be supported also through matching funds from Ion Beam Physics ETH.This project is directly in line with the research that S. Ivy-Ochs has pursued for more than 20 years, whose focus is on using cosmogenic nuclides to understand basic landscape changing processes within the framework of detailed field work. At Ion Beam Physics we are uniquely positioned to combine the three cosmogenic nuclides, 10Be, 14C and 36Cl, to study glacial erosion and the timing of glacier occupation in the Alps.