Climatically versus tectonically forced erosion in the Alps: Thermochronometric constraints from the Adamello Complex, Southern Alps, Italy

We apply (U–Th–Sm)/He dating and fission-track thermochronometry of apatites to the Adamello Complex located in the Southern European Alps. Our goal is to constrain exhumation rates since the Miocene, in particular, to determine whether the increase in sedimentation documented in the foreland basins since 5 Ma is recorded in cooling rates of the Southern Alps. Thermochronometry provides a cooling rate for rocks, which can be converted to an exhumation rate through thermal modeling, thereby quantifying the amount of rock exhumed at different time scales. Apatite fission-track and (U–Th–Sm)/He analyses all record Miocene ages. We find no evidence for an increase in exhumation rate during the Plio-Pleistocene. The results of our exhumation rate estimates and tectono-geomorphic modeling suggest that unroofing during thrust propagation of the Southern Alps in the Late Miocene drove most of the exhumation, while changes in relief, mainly associated with Plio-Pleistocene climate change, likely did not affect the Adamello Complex. The findings from this study combined with other studies highlight that there appears to be a gradient across the Alps, with more intensive Plio-Pleistocene erosion in the Western and Central Alps compared to the Eastern and Southern Alps.

► We apply low-temperature thermochronology in the Southern European Alps.
► Exhumed AHe partial retention zone limits total exhumation since the Miocene.
► Two main pulses of exhumation in the Miocene were likely driven by tectonics.
► No significant local relief development affected the thermochronologic results.
► Highlights an east–west discordance in Plio-Pleistocene exhumation of the Alps.