ABSTRACT: Numerical Prediction of the Sediment Characteristics, Including Carbon Content, of Basin Fill

James P. M. Syvitski

The time and space-dependent properties of sediment deposited within a graben are explored. Predictions are based on numerical simulation using actualistic inputs to SEDFLUX--a two-dimensional finite difference model wherein a parabolic equation is solved explicitly at time steps of less than one year. The model simulates the deposition of bed load at a river mouth, basin fill through deposition by sediment gravity flows, hemipelagic sedimentation, and longer term downslope diffusion of sediment by creep and slides. Both basin-wide or site-specific predictions may be specified by the user; these include shoreline progradation (or retreat) rates, accumulation rates, changes in the sea-floor slope, and sea-floor sediment characteristics. Changes in the sediment source function over time sea level oscillations, and fluctuations in the diffusion coefficient (linked to slide activities) are related to the changing properties of basin sediments.

Of particular relevance to the petroleum industry is a new subroutine added to the model so as to predict the content of organic carbon in both the turbidite sands and the basin muds. The carbon content is calculated from the addition of fluvial-transported terrestrial carbon and from marine primary production that together are partly consumed at the sea-floor due to microbial oxidation.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990