『Abstract
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.
Keywords: western Alps; Pliocene erosion rate; geophysical relief;
isostatic rebound.』
Introduction
Mean erosion rate in the western Alps
Spatial distribution of erosion and its geophysical response
Calculation on the isostatic response
Discussion and conclusions
Acknowledgments
References cited