『Abstract
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 concerted 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.
Keywords: exhumation; Alps; helium; low-temperature thermochronology』
1. Introduction
2. Geologic setting
2.1. Southern Alps
2.2. The Adamello Complex
2.3. Po Plain-Adriatic foredeep
3. Low-temperature thermochronometry
3.1. Theory
3.2. Method
3.3. Thermochronometric results
3.3.1. AFT
3.3.2. (U-Th-Sm)/He ages
4. Quantitative interpretation: timing and rates of exhumation
4.1. AER estimates
4.2. Quantitative interpretation: numerical modeling
4.2.1. Resolution tests
4.2.2. Inversion parameterization
4.2.3. Inversion results
5. Discussion
5.1. Oligocene-Early Miocene exhumation?
5.2. Late Miocene onset of exhumation
5.3. Western vs. Eastern and Southern Alps
6. Conclusion
Acknowledgments
Appendix A. Supporting information
References