Andean geodynamics and Amazon evolution coupled to Paleoclimate models

Abstract

In the last decade, different geodynamic numerical models were proposed to explain the evolution of the drainage pattern observed in northern South America during the Cenozoic, invoking dynamic topography induced by mantle convection, Andean orogeny, flexure of the lithosphere and surface processes of erosion and sedimentation. Through the use of these numerical models, it was possible to quantify the relative importance of each process on the formation and evolution of the present Amazon drainage system, connecting the Andes with the Brazilian Equatorial Margin. However, the representation of the climate evolution in these models is oversimplified, assuming geometrically defined orographic precipitation or constant rate throughout the model. To assess the impact of a more realistic representation of the precipitation rate, in this project we intend to use paleoclimate numerical models coupled to the present tectono-sedimentary simulations, verifying how the variation of precipitation through space and time can affect the denudation history of the Andean cordillera and consequently the landscape evolution in Amazonia. Conversely, the Andean orogeny style obtained in the numerical experiments will be incorporated in the paleoclimate models, evaluating the influence of the gradual growth of the cordillera on the convective rainfall in the western portion of Amazonia. Low-temperature thermochronological data will be used as constraints for the numerical experiments, giving important informations about the exhumation history of the Andean cordillera. Additionally, published stratigraphic data from the interior and marginal sedimentary basins will be compared to the numerical results. (AU)