INSIGHTS FROM STRATIGRAPHIC MODELING - MUD-LIMITED VERSUS SAND-LIMITED DEPOSITIONAL SYSTEMS

Quantitative stratigraphic modeling provides new perspectives on the c ontrols on basin-fill stacking patterns, gross lithology distributions , and submarine fan deposition in siliciclastic systems. Our modeling relates basin-fill geometries to the ratio of space creation vs. sedim ent supply Facies components differentially distribute sand/mud mixtur es below rising base-level surfaces across a basin profile. We model a lluvial architecture, shoreline position, shelf width, and the occurre nce of turbidite sands as a function of relative base-level rise and v arying receiving-basin geometries. Slope unconformities and onlapping submarine fans are the erosional and depositional responses to changin g basin physiography. Sediment budgeting reveals two types of silicicl astic systems. Sand-limited systems develop in shallow basins or on ba sin-margin platforms; have broad, muddy, wave-graded shelves; and are subject to exposure and major basinward shifts of shoreline with minor sea level falls. Mud-limited systems develop during progradation into deep-water basins, have narrow shelves with turbidites in a base-of-s lope position, and are not particularly susceptible to major basinward shifts in facies. We emphasize the fundamental importance of basin ph ysiography and lithology budgeting, as well as sea level, in contrast to eustatically based models. In addition to accommodation and sedimen t supply, alluvial architecture and basin depth also act as primary co ntrols on shelf width, basin-fill geometry and submarine fan depositio n.