Abstract: Stratigraphic Simulation using an Improved Dual-Lithology Sediment Transport Model

Jennifer Carlson, Peter Flemings, John P. Grotzinger

We have developed a two-dimensional dual-component sediment transport model. The algorithm is based on a finite difference scheme to solve the

diffusion equation for each component. Diffusion coefficients, calculated from characteristic marine and non-marine constants, are linearly scaled based on the component fraction present in an active layer. Active layer thickness is determined by an exponential scaling of the underlying beds based on depth and a damping parameter. All erosion and deposition occurs in this layer. In considering multiple components, previous gradient-driven models have failed to demonstrate the capacity to attain equilibrium. Our model examines the relationship between sediment flux and bed composition in a steady-state stream. Bed composition records the relative velocities for different bedload size fractions. In a non-marine uniformly subsiding basin, equilibrium bed fractionation occurs due to diffu ivity differences. Erosion forms a coarse surface layer above a finer substrate. In marine deposition, non-marine diffusion constants were damped exponentially to the marine diffusion constants based on water depth. We generate unconformities during sea-level fall due to rapid bypass of coarse sediment, and trap sediment during sea-level rise. Tracking of components in this model creates the potential for more realistic basin-modelling predictions. Pavement generation results in more realistic erosion rates. Porosity and permeability can be derived using material composition, allowing simulation of compaction, fluid flow, and synthetic seismic profiles.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994