Several authors 19, 20, 21, 22, 23 have suggested that this convergence slowdown is mainly related to the growth of the cordillera, as this creates large trench-perpendicular gradients of gravitational potential energy (GPE) that must be laterally supported by high shear stresses at the interplate megathrust, augmenting the frictional resistance to subduction of the Nazca plate. Available kinematic plate models 14, 15, 16, 17, 18 show a subsequent gradual decrease of convergence rate, from nearly 15 cm/yr to half of this value at present. Such a relationship has been suggested, for instance, to explain an increase in tectono-magmatic activity along with changes in the tectonic style following an acceleration of convergence during the birth of the Nazca plate after breakup of the Farallon plate in the late Oligocene-early Miocene 3, 4, 7, 9, 10, 11, 12, 13. This mechanism should consider the dynamic coupling between both converging plates at the subduction zone, connecting compressional tectonic events with changes in plate motion. However, the geodynamic mechanism explaining the occurrence of these compressional events as well as the causes for the along-strike variability of the associated crustal shortening remain controversial. Shortening has traditionally been related to the episodic development of compressional tectonic events that can be broadly recognized in the geological evolution of volcano-sedimentary basins, magmatic arcs and fault systems 3, 4, 7, 8, 9, 10. Segmentation is particularly obvious 5, 7 when considering variable amounts of Neogene crustal shortening, which ranges from more than 300 km at 20°S to less than 40 km at 40°S. This process left a marked along-strike segmentation of the continental margin 5, 6. The Andean Cordillera, an archetype of subduction-related mountain belts 1, 2, is the result of hundred million years of convergence between various oceanic plates and the western margin of South America 3, 4. These results allow to revise models of ongoing subduction orogeny at its type locality, emphasizing the role of upper plate deformation in the balance between kinematic energy associated with plate motion and gravitational potential energy stored in orogenic crustal roots. These changes are related to main tectono-magmatic events and require forces that are compatible with a range of geodynamic processes. Building on a compilation of plate finite rotations spanning the last 30 million years and using noise-mitigation techniques, we predict several short-term convergence changes that were unresolved in previous models. Here we show that the Neogene evolution of the Andean margin is primarily related to changes in convergence as observed in new high-resolution plate reconstructions.

Exploring a possible link to plate convergence has been impeded by the coarse temporal resolution of existing plate kinematic models. The Andean cordillera was constructed during compressive tectonic events, whose causes and controls remain unclear.

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