Origin and Evolution of the Central Andes: Deserts, Salars, Lakes, and Volcanoes

Abstract

The Central Andes region is a young, noncollisional, active orogen, formed as a consequence of the subduction of the Nazca oceanic plate underneath the South American continental plate. It achieves its greatest expression between 15° and 28°S, where a 30° subduction angle appears. The Central Andes appears delimited by two flat slab regions, both dipping 5 E: the Peruvian segment to the north and the Pampean segment to the south. The building of the Andes occurred in consecutive stages during Cenozoic times. Crust fusion at 1200 °C generated magma that reached the surface, resulting in a great volcanic arc that currently mostly constitutes the boundaries between the Andean countries (Peru, Bolivia, Chile, and Argentina). The crust deformation prompted the uplifting of a tectonic cordillera (the Eastern Cordillera) and the Volcanic Cordillera (Central Volcanic Zone), generating a first-order basin, the Altiplano–Puna High Plateau. The Andes are growing vertically and pushing horizontally to the east, creating the folding of the Subandean Ranges. The isostatic compensation was balanced by the sinking of the great Chaco Plain or foreland. The Eastern Andes has become an orographic barrier to the wet Amazonic winds. The Altiplano–Puna Plateau has turned into an arid region where salars, salt lakes, springs, and hot springs have formed. Deserts, salars, lakes, and volcanoes are the product of several factors such as the geology, tectonics, and climate typical of the endogenous and exogenous dynamics of the Central Andes.