Timing and drivers of exhumation and sedimentation in the eastern Peruvian Andes: Insights from thermokinematic modelling

Buford Parks, V. M., McQuarrie, N., Falkowski, S. , Perez, N. D. and Ehlers, T. A. (2023) Timing and drivers of exhumation and sedimentation in the eastern Peruvian Andes: Insights from thermokinematic modelling. Earth and Planetary Science Letters, 620, 118355. (doi: 10.1016/j.epsl.2023.118355)

Abstract

This study assesses the impact of fold-thrust belt driven deformation on the topographic evolution, bedrock exhumation and basin formation in the southeastern Peruvian Andes. We do this through a flexural and thermokinematically modelled balanced cross-section. In addition, published thermochronology samples from low-elevation (river canyons) and high-elevation (interfluves) and Cenozoic sedimentary basin datasets along the balanced cross-section were used to evaluate the age, location, and geometry of fault-driven uplift, as well as potential relationships to the timing of ∼2 km of canyon incision. The integrated structural, thermochronologic, and basin data were used to test the sensitivity of model results to various shortening rates and durations, a range of thermophysical parameters, and different magnitudes and timing of canyon incision. Results indicate that young apatite (U-Th)/He (AHe) canyon samples from ∼2 km in elevation or lower are consistent with river incision occurring between ∼8–2 Ma and are independent of the timing of ramp-driven uplift and accompanying erosion. In contrast, replicating the young AHe canyon samples located at >2.7 km elevation requires ongoing ramp-driven uplift. Replicating older interfluve cooling ages concurrent with young canyon ages necessitates slow shortening rates (0.25–0.6 mm/y) from ∼10 Ma to Present, potentially reflecting a decrease in upper plate compression during slab steepening. The best-fit model that reproduces basin ages and depositional contacts requires a background shortening rate of 3–4 mm/y with a marked decrease in rates to ≤0.5 mm/y at ∼10 Ma. Canyon incision occurred during this period of slow shortening, potentially enhanced by Pliocene climate change.

• Item Type: Articles
• Additional Information: This work was supported by NASA headquarters under the NASA Earth and Space Science Fellowship program - Grant 80NSSC17K0388 to V.M.B.; National Science Foundation (NSF) Grant EAR-1842172 to N.M. and Deutsche Forschungsgemeinschaft (German Research Foundation) grant FA 1489/1-1 to S.F.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Falkowski, Dr Sarah and Ehlers, Professor Todd A.

Creator Roles

Falkowski, S.: Writing – review and editing, Validation, Investigation, Funding acquisition, Conceptualization
Ehlers, T. A.: Writing – review and editing, Validation, Supervision, Resources, Conceptualization

• Authors: Buford Parks, V. M., McQuarrie, N., Falkowski, S., Perez, N. D., and Ehlers, T. A.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Earth and Planetary Science Letters
• Publisher: Elsevier
• ISSN: 0012-821X
• Published Online: 04 September 2023
• Copyright Holders: Copyright: © 2023 The Author(s)
• First Published: First published in Earth and Planetary Science Letters 620: 118355
• Publisher Policy: Reproduced under a Creative Commons licence