Cenozoic tectonics of the High Andes of west-central Argentina (30–36°S latitude)

Abstract

The structure of the Central Andes shows three distinctive segments characterized by different geometries. These geometries are superimposed on the present large-scale plate tectonic setting characterized by distinct subduction segments. The northern La Ramada segment is a thick-skinned fold and thrust belt formed by tectonic inversion of a Late Triassic rift. The central Aconcagua segment consists of a thin-skinned fold and thrust belt while the southern Malargüe segment like the first one is a thick-skinned fold and thrust belt developed by tectonic inversion of a Late Triassic-Early Jurassic rift system during late Cenozoic times. The amount of shortening gradually decreases from north to south, as indicated by the crustal roots of the Central Andes. The different geometries along the Principal Cordillera controlled the abrupt changes in the shortening among segments. The structure of Precordillera and Sierras Pampeanas has also been considered in order to account for the total shortening. In the La Ramada segment the main shortening occurred in the Precordillera; in the Aconcagua segment in the Principal Cordillera while in the Malargüe segment the shortening is widely distributed in a broader Principal Cordillera, because south of the flat-slab subduction segment the Precordillera and Sierras Pampeanas are missing.