Pampean flat-slab

[1] It is thought that the subduction of the Juan Fernández Ridge, a chain of extinct volcanoes on the Nazca Plate, is the underlying cause of the Pampean flat-slab.

[2][3] The shallowing of subducted slab beneath north-central Chile and Argentina is linked to a series of changes in volcanism and tectonics.

The flat-slab has caused an uplift of Sierras Pampeanas which begun first in the north and then moved southwards over millions of years.

[2] The oldest noted uplift episode associated with Pampean flat-slab is that of Sierra de Aconquija (27 °S) from 7.6 to 6 million years ago (Ma) in the Late Miocene epoch.

Thrust front propagation of the Principal Cordillera has increased five-fold in from 15-9 Ma ago to the Pliocene and Early Quaternary.