The late Neogene-Quaternary exhumation history of the European Alps is
the subject of controversial findings and interpretations, with several
thermochronological studies arguing for long-term steady state
exhumation rates, while others have pointed to late Miocene-Pliocene
exhumation pulses associated with tectonic and/or climatic changes.
Here, we perform inverse thermal-kinematic modeling on dense
thermochronological data sets combining apatite fission track (AFT) data
from the literature and recently published apatite (U-Th-Sm)/He (AHe)
data along the upper Rhone valley (Aar and Aiguilles Rouges massifs,
Swiss Alps) in order to derive precise estimates on the denudation and
relief history of this region. We then apply forward numerical modeling
to interpret cooling paths quantified from apatite He-4/He-3
thermochronometry, in terms of denudation and relief-development
scenarios. Our modeling results highlight the respective benefits of
using AFT/AHe thermochronology data and He-4/He-3 thermochronometry for
extracting quantitative denudation and relief information. Modeling
results suggest a late Miocene exhumation pulse lasting until similar to
8-10 Ma, consistent with recently proposed exhumation histories for
other parts of the European Alps, followed by moderate (similar to
0.3-0.5 km Myr(-1)) denudation rates during the late Miocene/Pliocene.
Both inverse modeling and He-4/He-3 data reveal that the late stage
exhumation of the studied massifs can be explained by a significant
increase (similar to 85-100%) in local topographic relief through
efficient glacial valley carving. Modeling results quantitatively
constrain Rhone valley carving to 1-1.5 km since similar to 1 Ma. We
postulate that recent relief development within this part of the Swiss
Alps is climatically driven by the onset of major Alpine glaciations at
the mid-Pleistocene climate transition.