The shallowing of subducted slab beneath north-central Chile and Argentina is linked to a series of changes in volcanism and tectonics.
Deformation of crust The flat-slab has caused an
uplift of
Sierras Pampeanas which begun first in the north and then moved southwards over millions of years. 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. As the flat slab migrated from west to east under South America, so did volcanic activity, until it vanished 1.9 Ma ago, about from the Pacific, far to the east of
ordinary subduction volcanism. Migration of the volcanic activity to the east meant that in the
Principal Cordillera magmatic activity ended as early as 8.6 Ma ago. ==References==