Taking the Land Out of Landlab: Building a Marine Sequence-Stratigraphic Model Using Landlab

Despite its name, landlab is not just for building terrestrial-based models but can, in addition, be used for creating a wide range of models from any domain. As an example of this capability, we present a sequence-stratigraphic model, Sequence, we have built using a collection of terrestrial and marine-focused landlab components.

Sequence is a modular 2D (i.e., profile) sequence stratigraphic model written in Python using the Landlab toolkit. The geophysical framework includes major factors that affect accommodation space from both the terrestrial and the marine: tectonics and faulting, eustatic sea level, flexural isostatic compensation of sediment and water, sediment compaction, and hypopycnal sediment plumes. All of these processes are represented as individual, standalone landlab components that can be used and combined to build new models.

Sequence models the evolution of stratigraphy on a continental margin with time scales that range from thousands to millions of years. Most sediment transport and deposition occurs during infrequent energetic events (i.e., storms, floods). For these longer time frame simulations, Sequence uses a scale-integral approach in which differential equations represent the net effect of sediment transport and deposition for each depositional environment over a longer (i.e., on the order of a hundred year) timescale. A moving-boundary formulation tracks the shore line and divides the domain into coastal plain, continental shelf, and upper and lower slope/rise. Submarine sediment transport and deposition is modeled as nonlinear diffusion with a diffusion coefficient inversely proportional to water depth. Sediment lithology is tracked as a mixture of two grain sizes corresponding to sand and mud with separate transport functions.