CONICET | Buscador de Institutos y Recursos Humanos

Traditionally, the long-term landscape evolution of the southern Buenos Aires ranges of east central Argentina has been related to theinfluence of the Andean orogeny. We describe the large-scale morphological units and associated weathering products in the Tandilia andVentania ranges. Two main planation surfaces are encountered at varying altitudes in different sectors of these ranges. The lower surface ischaracterized by roots of kaolinized weathering profiles in the Tandil area and silicified conglomerates around Sierra de La Ventana. In aninterpretative model linking the range morphogenesis to the tectonosedimentary evolution of the bordering Salado and Colorado Basins, wesuggest that the main morphogenetic stages are related to the late Jurassic-early Cretaceous south Atlantic rifting and Miocene tectonicreactivation induced by the Andean orogeny. Thus, the uplifted surfaces appear much older than commonly believed: pre-Cretaceous andPaleogene. Although they contradict recent results of apatite fission-track studies along the South America and South Africa passive margins,the implied low denudation rates (w4 m/My) can be explained by the limited Meso-Cenozoic uplift suffered by the southern Buenos Aires ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.w4 m/My) can be explained by the limited Meso-Cenozoic uplift suffered by the southern Buenos Aires ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.w4 m/My) can be explained by the limited Meso-Cenozoic uplift suffered by the southern Buenos Aires ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.

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