Erosion rate maps highlight spatio-temporal patterns of uplift and quantify sediment export of the Northern Andes

Abstract

Erosion rates are widely used to assess tectonic uplift and sediment export from mountain ranges. However, the scarcity of erosion rate measurements often hinders detailed tectonic interpretations. Here, we present 25 new cosmogenic nuclide-derived erosion rates from the Northern Andes of Colombia to study spatio-temporal patterns of uplift along the Central and Eastern Cordillera. Specifically, we combine our new and published erosion rate data with precipitation-corrected normalized channel steepness measurements for building high-resolution erosion rate maps. We find that erosion rates in the southern Central Cordillera are relatively uniform and average ~0.3 mm/a, whereas rapidly eroding canyons dissect slowly eroding, low-relief surfaces in the northern Central Cordillera. We interpret that long-term, steep slab subduction has led to an erosional steady-state in the southern Cordillera Central, whereas in the northern Cordillera Central, Late Miocene slab flattening caused an acceleration in uplift, to which the landscape has not yet equilibrated. The Eastern Cordillera also displays pronounced erosional disequilibrium, with a slowly eroding central plateau rimmed by faster eroding western and eastern flanks. Our maps suggest recent topographic growth of the Eastern Cordillera, with deformation focused along the eastern flank, which is also supported by balanced cross-sections and thermochronologic data. Spatial gradients in predicted erosion rates along the eastern flank of the Eastern Cordillera suggest transient basin-ward migration of thrusts. Finally, using our erosion maps to infer millennial-scale sediment fluxes, we find that the Eastern Cordillera exports nearly four times more sediment than the Central Cordillera. Our analysis shows that accounting for spatial variations in erosion parameters and climate gradients reveals important variations in tectonic forcing that would otherwise be obscured in traditional river profile analyses. Moreover, given relationships between tectonic, and topographic evolution, we hypothesize that the dynamic landscape evolution of the Northern Andes revealed by our erosion maps is mostly linked to spatio-temporal variations in slab dip with potentially superposed effects from inherited Mesozoic rift structures.

Morpho‐Tectonics of Transpressional Systems: Insights From Analog Modeling

“…Muscovite 40 Ar/ 39 Ar dates are older outside this valley at ∼250 … 425 Ma (van der Lelij et al., 2016). Cosmogenic radionuclide dating (Ott et al., 2023) and low‐temperature thermochronology (Pérez‐Consuegra et al., 2022) from the central and western Colombian Andes (Figure 10c) show the highest erosion/denudation rates in the lofted Cauca valley (1 km elevation) along the Romeral‐Cauca fault systems. Though perhaps coincidentally, we note that the trend of the main valley in each natural prototype supports the observed differences between the final configurations of the presented high and low erosion models.…”