title: The topography of a continental indenter: The interplay between crustal deformation, erosion, and base level changes in the eastern Southern Alps.
abstract: The topography of the eastern Southern Alps (ESA) reflects indenter tectonics causing crustal shortening, surface uplift, and erosional response. Fluvial drainages were perturbed by Pleistocene glaciations that locally excavated alpine valleys. The Late Miocene desiccation of the Mediterranean Sea and the uplift of the northern Molasse Basin led to significant base level changes in the far field of the ESA and the Eastern Alps (EA), respectively. Among this multitude of mechanisms, the processes that dominate the current topographic evolution of the ESA and the ESA-EA drainage divide have not been identified. We demonstrate the expected topographic effects of each mechanism in a one-dimensional model and compare them with observed channel metrics. We find that the normalized steepness index increases with uplift rate and declines from the indenter tip in the northwest to the foreland basin in the southeast. The number and amplitude of knickpoints and the distortion in longitudinal channel profiles similarly decrease toward the east. Changes in slope ofχ-transformed channel profiles coincide spatially with the Valsugana-Fella fault linking crustal stacking and uplift induced by indenter tectonics with topographic evolution. Gradients inχacross the ESA-EA drainage divide imply an ongoing, north directed shift of the Danube-ESA watershed that is most likely driven by a base level rise in the northern Molasse basin. We conclude that the regional uplift pattern controls the geometry of ESA-EA channels, while base level changes in the far field control the overall architecture of the orogen by drainage divide migration.
authors.affiliation: Department of Geography and Geology University of Salzburg Salzburg Austria.
authors.forename: J
authors.identifier: 0000-0003-0472-9125
authors.initials: J
authors.lastname: Robl
authors.affiliation: Department of Geography and Geology University of Salzburg Salzburg Austria.
authors.forename: B
authors.identifier: 0000-0002-0421-1337
authors.initials: B
authors.lastname: Heberer
authors.affiliation: Department of Geography and Geology University of Salzburg Salzburg Austria.
authors.forename: G
authors.initials: G
authors.lastname: Prasicek
authors.affiliation: Department of Geography and Geology University of Salzburg Salzburg Austria.
authors.forename: F
authors.initials: F
authors.lastname: Neubauer
authors.affiliation: Institute of Earth and Environmental Sciences-Geology University of Freiburg Freiburg im Breisgau Germany.
authors.forename: S
authors.identifier: 0000-0002-4780-284X
authors.initials: S
authors.lastname: Hergarten
keywords: European Southern Alps; base level change; channel metric; drainage divide migration; indenter tectonics; landscape evolution