LINKING CONTINENTAL EROSION AND MARINE MULTI-LITHOLOGY COUPLING TRANSPORT AND DEPOSITION: AN APPLICATION TO THE OGOOUÉ DELTA, GABON
Résumé
Limited attention has been given to linking continental erosion to marine transport and sedimentation in
large-scale landscape evolution models. Although either of the two environments has been thoroughly
investigated, the details of how erosional events are recorded in the sedimentary and stratigraphic records have
not been studied in a consistent quantitative manner. Here we present results obtained from a new numerical
model for marine multi-lithology (sand and silt) coupling transport and deposition that is directly coupled to
FastScape, a landscape evolution model that solves the continental stream power law and hillslope diffusion
equation using fully implicit and O(n) algorithms. The model of marine multi-lithology coupling transport and
deposition is simulated by a nonlinear 2D diffusion model where a source term represents mass flux arising
from continental river erosion. We are trying to develop a Bayesian inversion and optimisation scheme with
synthetic data to validate the model. The efficient model will then be used to undertake an inversion of
stratigraphic data on a natural example, Ogooué Delta, Gabon, by performing a large number of simulations.
By comparing cross-section of that delta and sand and silt fraction through depth, the transport coefficients of
sand and silt in the ocean environment and variations in sea level are hopefully obtained. Using our model, we
will not only show the manner in which the stratigraphic record of the Ogooué Delta responds to tectonic and
climate events on adjacent continents but also shows how it is controlled by the coefficients for continental
river erosion, and better constrains the nature and timing of erosional events