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Identifying topographic and erosion rate response to tectonic and climatic forcing remains challenging. This is in part because of the difficulty in isolating the respective roles of climate and tectonics. Here we exploit 2500 thermochronometric data points collected over several decades of research, using a new inverse technique, to image the space-time evolution of erosion rate across the European Alps over the past 35 m.y. The most striking feature of our results is a two- to three-fold increase in erosion rate over the past 2 m.y. exclusively within the Western and Central Alps. This increase appears to be controlled by the inferred high rock uplift rate due to the progressive detachment of the European slab under the Western Alps. The similarity in mean elevation between the Western and Eastern Alps indicates a surprisingly low topographic response to this differential tectonic forcing, and points to the role of enhanced glacial erosion in response to surface uplift. [ABSTRACT FROM AUTHOR]

Detrital cooling ages from the pro-foreland and retro-foreland basins of the European Alps record distinctive exhumation trends that correlate with orogenic wedge states inferred from thrust front propagation rates. Periods of rapid hinterland exhumation correlate with relatively slow propagation of deformation toward the foreland and are interpreted to represent subcritical wedge conditions, whereas periods of slow hinterland exhumation correlate with rapid propagation of deformation toward the foreland and indicate supercritical wedge conditions. Similar lag time trends recorded in both the pro-foreland and retro-foreland thus mimic orogenic wedge behavior and suggest that local tectonics and/or climate events do not overprint the regional signal. [ABSTRACT FROM AUTHOR]

The relative intensity of tectonic and climatic forcing in the western European Alps has been a matter of debate since the recognition of a signifi cant increase in denudation rates over the past few million years. We address this question by quantitatively correlating the spatial pattern of long-term exhumation rates with those of potential short-term tectonic, climatic, and morphologic variables. We find that present-day rock-uplift rates (as measured by geodesy relative to a specific reference point) and mean elevation are correlated with long-term exhumation rates, whereas relief, present-day precipitation, discharge, stream power, and released seismic energy are not, or are only weakly, correlated. We attribute the lack of correlation between long-term exhumation and precipitation to a strong temporal variability in climate and erosional processes during Pliocene-Pleistocene time. The correlations among present-day rock-uplift rates, present-day elevations, and long-term exhumation rates suggest that rockuplift rates have been sustained for millions of years, consistent with rock-uplift rates being the isostatic response to crustal unloading. The lack of a correlation of the released seismic energy with either rock uplift or long-term exhumation denies active tectonics supporting evidence. [ABSTRACT FROM AUTHOR]

In addition to the well-known Variscan and Alpine orogenic cycles, a Permian thermal event occurred in the European Alps. The geodynamic background of this event is not well understood. Here we suggest that the event is a reflection of lithospheric thinning accompanied by magmatic underplating causing partial melting of the lower crust and low-pressure—high-temperature metamorphism. The event was terminated by Early Triassic opening of the Meliata ocean and was followed by sag-stage subsidence during slow lithospheric cooling. This last stage of the evolution allowed the onset of the Mesozoic marine evolution with the orogen-wide formation of Triassic carbonate platforms well known from the Dolomites and the Northern Calcareous Alps. The combined evidence for magmatism, metamorphism, and late subsidence identifies the Permian event of the Alps as an excellent example of underplating events suggested as a cause for low-pressure–high-temperature terrains worldwide. [ABSTRACT FROM AUTHOR]

The high elevation and deep incision of the Alps have traditionally been used as an argument for recent tectonic activity that has elevated the belt and increased erosion rates. Normal faulting and horizontal extension, however, dominate current tectonic activity, and isostatic compensation of thinning crust should lead not to increased but to decreased mean elevations. Here we test the idea that enhanced Quaternary erosion of the Alps and isostatic compensation of the mass removed can account for the distribution of present-day geodetically measured rates of vertical movement in the western Alps. Using geophysical relief and Kuhlemann's estimated average erosion rate for the Alps, we quantify the spatial distribution of erosion and the volume of eroded rock, respectively. From these, we obtain a map of rock eroded within a given time span. The calculated isostatic response of the Alpine lithosphere to erosional unloading for a variety of values of the flexural rigidity of the Alpine lithosphere reaches a maximum of ~500 m since 1 Ma in the inner Swiss Alps, and vertical movement extends across the entire belt, including peri-Alpine basins. Assuming a steady erosion rate since 1 Ma, this rebound accounts for half of the measured vertical motion of 1.1 mm/yr in the southern Valais. Thus, a significant fraction (~50%) of the present-day vertical movement results from the isostatic response to enhanced erosion during Plio-Quaternary time. [ABSTRACT FROM AUTHOR]

At the end of the Miocene, the European Alps ceased outward expansion, and tectonic uplift and exhumation shifted into the orogen interior. This shift is consistent with a change from orogenic construction to orogenic destruction, reflecting an increase in the ratio of erosional flux to accretionary flux. The coincidence of this change with an increase in sediment yield from the Alps suggests a climate-driven increase in erosional flux. The timing of deformation and sediment release from the southern Alps indicates that the tectonic change occurred synchronous with the last phase of the Messinian salinity crisis. We attribute the increase in erosional flux to a climatic shift to wetter conditions throughout Europe, likely augmented by the base-level fall that occurred during the Mediterranean dessication. This climate change is represented in the stratigraphic record by the Lago Mare deposits of the Mediterranean salinity crisis. [ABSTRACT FROM AUTHOR]

A lithospheric model scaled for density and viscosity was shortened obliquely in front of an indenter whose shape and orientation match those of the South Alpine indenter. Deformation was initially localized into subparallel sets of conjugate transpressive thrusts. These structures evolved into folds, which were strongly amplified and converged closer together during ongoing shortening, finally forming a series of tight antiforms. At the same time, this tightly folded structure locally accommodated significant orogen-parallel extension, attaining 100% in front of the leading edge of the indenter, but only 15% on the scale of the entire model. The internal architecture and fault pattern of the model in map view are very similar to those of the Tauern Window in the Eastern Alps, emphasizing the importance of localization of folding and shortening rather than orogen-parallel extension for its formation. [ABSTRACT FROM AUTHOR]