Conventional sequence stratigraphic models distinguish between "forced" and "unforced" regressive strata through the character of topsets (no aggradation during forced regression) and style of shoreline trajectory (descending in forced regressive strata, flat to rising in unforced regressive strata). However, because present models contain implicit assumptions about sediment supply and the response of coastal plain and fluvial depo-systems to relative falls and rises in sea level, these two scenarios may be an over simplification of a more complex reality. To explore these dynamics, Prince and Burgess investigate how topset aggradation might develop during relative fall in sea level using a simple diffusional stratigraphic forward model. Although not always the case, these falling stage models demonstrate that occurrence of falling-stage topset aggradation in ancient strata has important implications for the accurate identification of systems tracts, for reconstruction of relative sea-level curves and for prediction of sediment bypass into deep-marine settings.
Numerical modeling of falling-stage topset aggradation: Implications for distinguishing between forced and unforced regressions in the geological record by Guy D. Prince and Peter M. Burgess