Bilan crustal et controle de la dynamique erosive et sedimentaire sur les mecanismes de formation de l'Altiplano

The Bolivian Altiplano corresponds to a broad piggyback basin located between the crustal duplexes of the eastern cordillera (linked with the underthrusting of the Brasilian shield) and the westvergent crustal thrusts of the precordillera, and western cordillera. A mechanism of underplating associated with the crustal erosion of the Chilean margin could allow, assuming a local-type isostatic behaviour, the acquisition of the topography of the basin by filling. In such a context, it is the end of endoreic drainage which is responsible for the decrease of the sedimentary overload and of the consecutive minor uplift of the Altiplano during the Upper Pliocene.