ELEvATE: Elevated Low Relief Landscapes in Mountain belts: Active Tectonics or glacial Reshaping? The Eastern Alps as Natural Laboratory.
The project ELEvATE will focus on the evolution of elevated low relief landscapes (plateaus) in active mountain ranges. The project is funded by the Austrian Science Fund (FWF) and the government of Salzburg for a period of three years and started in April 2019.
Abstract of the Research Proposal
Elevated low relief landscapes are an abundant feature in mountain ranges worldwide. This peculiar topographic pattern, which is indicated by a transition from increasing to decreasing slopes with elevation, has been explained by temporal changes in climate or tectonics. This ultimately culminates in two opposing hypotheses:
The hypothesis of glacial reshaping explains the large scale topographic pattern by a buzz-saw style erosion of glaciers above and localized excavation of valleys below the snowline of ice covered regions, respectively. Elevated low relief landscapes must then occur within a formerly glaciated part of the mountain range, at or above the equilibrium line altitude. In the Alps, they must have formed after the mid-Pleistocene climate transition. Elevated low relief and incised landscapes form simultaneously, whereas the degree of glacial reshaping and the size of low relief surfaces increase with the duration of glacial occupation.
The hypothesis of fluvial prematurity explains the topographic pattern of low relief landscapes at high elevations and incised landscapes at low elevations by a recent uplift event, where the two contrasting landscape types represent the ancient and recent tectonic regime, respectively. In this scenario low relief landscapes are uplifted first and dissected subsequently, with the result that their size decreases with time. Within this interpretation, elevated low relief surfaces are not correlated to the glacial extent and may have formed before the mid-Pleistocene transition.
In order to proof or refute these two opposing hypotheses we propose to perform a study in the Eastern Alps where both glaciated and never-glaciated regions exist in direct spatial proximity. We pose three specific questions that will be answered by this project. (1) Where do we observe elevated low-relief landscapes and incised landscapes within the Eastern Alps? (2) When did low relief- and incised landscapes form and at which rates? (3) How did the observed topographic pattern evolve over time?
To reach these goals we will perform a series of analyses in two adjacent areas that were and were not covered by ice during the Pleistocene glaciations. The two key areas are perfectly complementary as they feature a similar lithological and structural inventory but differ with respect to their glacial history. We plan three major work packages: (1) We will map the regional pattern of elevated low relief and incised landscapes by compiling existing maps and analyzing digital elevation models. (2) We will apply cosmogenic nuclide dating to determine the absolute age of landforms (via cave proxies) and compute incision rates. (3) We will model multiple scenarios to constrain the time-dependent evolution of elevated low relief and incised landscapes during cold and warm climate conditions.
By integrating the results of these three methodically independent work packages, we are well-positioned to proof or refute the two opposing hypotheses in order to infer drivers of landscape evolution in the Eastern Alps. Beyond the Eastern Alps, findings from this project will have far reaching implications on the understanding of relief formation and destruction in mid-latitude mountain ranges.