An auspicious landscape: Quantifying transient glacial incision in the Patagonian Andes from ~6 Ma to present
- 1University of California, Berkeley, CA USA 94720 (chelsea.d.willett@gmail.com)
- 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA USA 94709
- 3Lawrence Livermore National Lab, Nuclear and Chemical Sciences, Livermore, CA USA 94550
- 4Yale University, New Haven, CT USA 06511
- 5University of California, Santa Cruz, CA USA 95064
The topography, climate, and geology of the central Patagonian Andes provide an auspicious natural laboratory to track long-term rates of erosion in a dynamic mountainous landscape. Herein, we report a mountain-scale record of erosion rates in the central Patagonian Andes from >10 million years (Ma) ago to present, which covers the transition from a fluvial to alpine glaciated landscape. Apatite (U-Th)/He ages of 72 granitic cobbles from alpine glacial deposits show slow erosion before ~6 Ma ago, followed by a two- to three-fold increase in the spatially averaged erosion rate of the source region after the onset of alpine glaciations and a 15-fold increase in the top 25% of the distribution. This transition is followed by a pronounced decrease in erosion rates over the past ~3 Ma. We ascribe the pulse of fast erosion to local deepening and widening of valleys, which are characteristic features of alpine glaciated landscapes. The subsequent decline in local erosion rates may represent a return toward a balance between rock uplift and erosion.
How to cite: Willett, C., Ma, K., Brandon, M., Hourigan, J., Christeleit, E., and Shuster, D.: An auspicious landscape: Quantifying transient glacial incision in the Patagonian Andes from ~6 Ma to present, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3278, https://doi.org/10.5194/egusphere-egu21-3278, 2021.