Drivers of canyon incision in the Peruvian Andes: Tectonics, precipitation, and drainage basin capture

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Abstract
The drivers behind the marked 2- to 3-km relief canyons carved into the ca. 3.7-km-high Andean Plateau remain debated, with proposed triggers ranging from plateau surface uplift to precipitation-enhanced erosion. We integrate a surface processes model with published cross-section–derived estimates of structural geometry, kinematics, and shortening rates, as well as precipitation estimates from global atmospheric circulation models, to assess whether the geometry, sequential fault motion, and resulting surface uplift can reproduce plateau morphology. Endorheic basins form where uplift on faults exceeds incision. A decrease in shortening after ~10 Ma allows rivers to compete with uplift and incise into endorheic basins at the plateau edge. Two modeled basin capture events at ~7 to 5 Ma and ~3.5 to 0.5 Ma, coupled with climate-driven discharge fluctuations, markedly increase rivers’ discharge, erosion, and sediment transport, facilitating canyon incision and highlighting the importance of basin captures in canyon formation along the northeastern edge of the Andean Plateau.

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