Over much of its length, the Andean Orogen is characterised by a bulk east-vergent geometry and a progressive eastward (cratonward) migration of individual arc-orogenic elements. A departure from this general model occurs in the Sierras Pampeanas region of central western Argentina where a terrane of active basement uplifts is currently developing to the east of the main Cordillera. Apatite fission track (AFT) data from uplifted Precambrian and Phanerozoic basement rocks of the Sierras Pampeanas constrains the tectonic development of this terrane and indicates that deformation associated with exhumation may have propagated broadly westward since the Late Miocene. Two important pre-Andean cooling events have been identified during the Permo-Carboniferous (~280-300 Ma) and the Early-Middle Jurassic (~170-200 Ma). The onset of Andean deformation is represented by a cooling event during the Late Paleocene-Middle Eocene. This cooling was followed by a period of Middle-Late Miocene reheating, in response to foreland basin-style sedimentation. Exhumation, and possible westward migration of the exhumation "front" in the Sierras Pampeanas, commenced during the Late Miocene-Pliocene to the east of the Precordillera fold-thrust belt. The apparent convergence of deformation in these two terranes, and the progressive closure of Mio-Pliocene intermontane basins in the Sierras Pampeanas may reflect the early stages of Andean plateau-uplift. The relative timing of plateau development along-strike, would suggest that lateral thickening of the orogen is progressing southwards at least from the latitude of central Bolivia (~20° S). Furthermore, the time-space coincidence between basement uplift and flattening of the subducted slab beneath the Sierras Pampeanas suggests that a relationship exists between relatively rapid westward displacement of the terrane and the dynamics of plate interaction.