Geodynamic Processes in Andean Orogeny

The Andes have formed over tens of millions of years as the Nazca Plate sinks beneath the South American Plate, generating a complex interplay of tectonic, magmatic and surface processes. Subduction drives mantle‐wedge hydration, slab rollback and variable slab dip, leading to alternating zones of strong plate coupling and decoupling. As the slab descends, dehydration reactions release fluids that weaken the plate interface and influence arc magmatism, while changes in slab angle control crustal shortening, isostatic uplift and foreland basin evolution. Regions of flat‐slab subduction, where the slab underthrusts the continental lithosphere at low angles, produce elevated topography, widespread deformation and anomalous seismicity. Conversely, steeper subduction leads to focused magmatic arcs and rapid crustal thickening. Over time the balance between plate convergence rates, slab buoyancy, mantle flow and surface erosion shapes the distribution of seismic and volcanic hazards, the development of high plateaux and the sedimentary record preserved in retroarc basins.

Research from Nature Portfolio

Recent studies have quantified how mantle hydration and flexure influence seismicity along the southern Central Andes trench. By integrating seismic tomography with three‐dimensional slab geometry, researchers have mapped variations in the Vp/Vs ratio as a proxy for water content. They show that hydrated regions in the mantle and at the plate interface correlate with background seismicity, whereas anhydrous zones concentrate elastic strain and host potential megathrust segments. In parallel, investigations into the mechanics of flat‐slab evolution have revealed that transient episodes of horizontal convergence and sub‐slab mantle overpressure can maintain low‐angle subduction for millions of years. These findings clarify the links between plate retreat, mantle flow and periodic slab tearing that restore normal dip and drive cyclic orogenic dynamics.

Geodynamic Processes in Andean Orogeny publication trend

The graph below shows the total number of articles in geodynamic processes in andean orogeny across all publications each year (not limited to Nature Index journals).

Technical terms

Orogeny: The process of mountain building through tectonic plate interactions.

Subduction zone: A region where one tectonic plate descends beneath another into the mantle.

Flat‐slab subduction: A style of subduction in which the descending plate remains nearly horizontal beneath the continental lithosphere.

Crustal shortening: Horizontal compression of the crust that leads to folding, thrusting and thickening.

Seismic tomography: A method for imaging the subsurface by analysing variations in seismic wave velocities.

Vp/Vs ratio: The ratio of compressional (P‐wave) to shear (S‐wave) seismic velocities, used to infer material properties and fluid content in the mantle.

References

1. The influence of mantle hydration and flexure on slab seismicity in the southern Central Andes. Communications Earth & Environment (2023).
2. Unraveling the tectonic evolution of the Andean hinterland (Argentina and Chile, 30°S) using multi-sample thermal history models. Earth and Planetary Science Letters (2024).
3. Two-Dimensional Geothermal Model of the Peruvian Andes above the Nazca Ridge Subduction. Energies (2023).
4. Sedimentary record of plate coupling and decoupling during growth of the Andes. Geology (2016).
5. South-American plate advance and forced Andean trench retreat as drivers for transient flat subduction episodes. Nature Communications (2017).