Toward a unified model for sediment transport from terrestrial source to abyssal-plain sink

Marine stratigraphy contains time-resolved information about the erosion of continents and its tectonic and climatic drivers. Quantitatively inverting marine stratigraphy for long-term terrestrial erosion histories requires numerical models that encompass the entire source-to-sink (S2S) system. Because inversion schemes require many model realizations to constrain free parameters against a misfit function, S2S models must be efficient (both in terms of allowing large time steps and scaling well for large problems) and have only a few parameters. Accordingly, most previous S2S models have treated seafloor evolution as a diffusion problem where sediment flux depends linearly on local topographic gradient. Such approaches have shown success in shallow marine settings like the continental shelf. However, they are less likely to apply to deeper marine environments where large deposits are observed and where nonlocal sediment transport processes (e.g., turbidity currents or marine debris flows) dominate sediment fluxes.

We present a unified modeling approach for coupling terrestrial and marine erosion, sediment transport, and deposition from the continent to the abyssal plain. Our model is based on the erosion-deposition family of models, where sediment flux is tracked across the landscape and seascape. Above sea level, erosion and deposition depend on river discharge, local slope, and sediment flux. Below sea level, local slope and sediment flux drive topographic change. The equations governing the terrestrial and marine domains take the same basic form such that a single semi-implicit numerical solution based on Gauss-Seidel iteration can be used across the whole S2S system. The solution scheme is near O(N) complexity in that the number of iterations required typically does not increase significantly with increasing grid resolution. The S2S model contains only five total parameters. We show preliminary analytical and numerical results and sensitivity analyses, and discuss the applicability of the model for the efficient inversion of deep marine stratigraphic data.