Abstract

The Andean uplift occurred before the main compressive stages of Andean tectogenesis. The study of clay minerals within intramountain basins allows to estimate the rate of uplift. The present-day pattern is used as a model. Two megatoposequences are distinguished: coastal zone to western cordillera and eastern cordillera to amazonian forest. Both sections show a vertical geochemical change every one thousand metres and evidence a geographical dissymetry. Located at sea level during the Oligocene the Andean basins underwent afterwards a complicated history. They were submitted to two epirogenesis stages : during the Miocene (uplift rate about 0.14 to 0.19 mm/year) and the Plio-Quaternary (uplift rate about 0.19 to 0.23 mm/year).

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