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Earth Surface Dynamics An interactive open-access journal of the European Geosciences Union

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Earth Surf. Dynam., 4, 895-909, 2016
https://doi.org/10.5194/esurf-4-895-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
22 Dec 2016
Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps
Jean L. Dixon1,2, Friedhelm von Blanckenburg1,3, Kurt Stüwe4, and Marcus Christl5 1German Research Centre for Geosciences GFZ, Potsdam, Germany
2Department of Earth Sciences and the Institute on Ecosystems, Montana State University, Bozeman, MT, USA
3Department of Geosciences, Freie Universität Berlin, Berlin, Germany
4Institute of Earth Sciences, University of Graz, Graz, Austria
5Laboratory for Ion Beam Physics, ETH Zürich, Zürich, Switzerland
Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion and glaciation sustain isostatic uplift and topography in a decaying orogen. But some parts of the Alps may still be actively uplifting via deep lithospheric processes. We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial-scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope–elevation and slope–area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the easternmost, non-glaciated basins range from 40 to 150 mm ky−1 and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift. By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm ky−1 and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than 2 orders of magnitude. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings but is strongly overprinted by past glacial climate and its topographic legacy.

Citation: Dixon, J. L., von Blanckenburg, F., Stüwe, K., and Christl, M.: Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps, Earth Surf. Dynam., 4, 895-909, https://doi.org/10.5194/esurf-4-895-2016, 2016.
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Short summary
We quantify the glacial legacy of Holocene erosion at the eastern edge of the European Alps and add insight to the debate on drivers of Alpine erosion. We present the first data explicitly comparing 10Be-based erosion rates in previously glaciated and non-glaciated basins (n = 26). Erosion rates vary 5-fold across the region, correlating with local topography and glacial history. Our approach and unique study site allow us to isolate the role of glacial topographic legacies from other controls.
We quantify the glacial legacy of Holocene erosion at the eastern edge of the European Alps and...
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