Title: Along-strike variations in the timing of exhumation in the eastern Peruvian Andes

Sarah Falkowski, Todd A. Ehlers

University of Tübingen, Germany

Event: GeoKarlsruhe 2021

Date: 2021

DOI: 10.48380/dggv-2jvh-xf26

Different controls and couplings between tectonics and climate-driven erosion have been suggested to explain the topographic and structural architecture of the Andes. One aspect of controversial discussions is the late Neogene incision of the Central Andean Plateau margin that has been interpreted as either the effect of climate change and increased river discharge on an already high plateau, or the effect of relatively young surface uplift. On the eastern flank of the Andean Plateau, ~4 Ma incision has been reported for two canyons in Bolivia and southeastern Peru (over a distance of >1250 km). However, there are still too many uncertainties concerning the spatio-temporal patterns of crustal shortening, erosion, and surface uplift to evaluate climatic and tectonic influences, especially in Peru. Studies that evaluate climate, erosion, and deformation histories in concert as well as along-strike continuations or variations are needed.

We contribute an extension of existing low-temperature thermochronometer data from three, up to 190-km-long transects spanning the Andean Plateau, the Eastern Cordillera including canyons and high-elevations, and the Subandean Zone in southeastern Peru. We present 46 new apatite (U-Th)/He (~1–41 Ma), 23 new zircon (U-Th)/He (~4–284 Ma), 21 new apatite fission-track (~3–63 Ma), and 11 new zircon fission-track dates (~14–37 Ma) from a total of 53 bedrock samples. We evaluate a representative set of samples' thermal histories with respects to deformation and incision of the plateau margin and discuss along-strike variations in the exhumation signal (onset and magnitude).

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