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Continental-scale erosion and transport laws: application to the evolution of the African topography

Abstract : The African topography is characterized by elevated regions, such as the South-African plateau (> 1000 m), which do not relate to any orogenic or convergent setting. Several models have been proposed to account for these topographic anomalies, but could not be discriminated because clear geological constraints were lacking. To solve for this, fluxes of silico-clastic sediments preserved in the margins have been recently quantified (Helm et al, symposium 16), and the evolution of the continental surface can be re-assessed from re-interpreted paleogeographic constraints (Guillocheau et al, symposium 16) and from low-temperature thermochronology. To interpret these data and place quantitative constraints on the spatio-temporal evolution of the continental surface over the last ~180 Myr, we derive erosion and transport laws that may apply at large spatial and temporal scales. They are tested in light of physical experiments of relief production, and in light of available data on present-day denudation rates and sediment yield measured in large ( 104 kmƒ) river basins. We subsequently implement these laws in a numerical model that investigates quantitatively the histories of surface uplift and topography in Africa that are consistent with all the data. Our approach is validated by the capacity of the model to reproduce the various geological constraints, and provides useful guidelines to quantitatively interpret sedimentary fluxes and paleogeographies in terms of paleotopographies.
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Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, July 25, 2007 - 3:44:17 PM
Last modification on : Friday, April 5, 2019 - 8:03:15 PM

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Martine Simoes, Jean Braun, François Guillocheau, Catherine Helm, Delphine Rouby, et al.. Continental-scale erosion and transport laws: application to the evolution of the African topography. Réunion des Sciences de la Terre 2006, Dec 2006, Dijon, France. pp.186. ⟨insu-00165291⟩

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