Simulating Coastal Systems Tracts Using the Shoreface Translation Model
Published:January 01, 1999
Peter J. Cowell, Peter S. Roy, Jelmer Cleveringa, Poppe L. de Boer, 1999. "Simulating Coastal Systems Tracts Using the Shoreface Translation Model", Numerical Experiments in Stratigraphy: Recent Advances in Stratigraphic and Sedimentologic Computer Simulations, John W. Harbaugh, W. Lynn Watney, Eugene C. Rankey, Rudy Slingerland, Robert H. Goldstein, Evan K. Franseen
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The shoreface translation model (STM) incorporates advances in the theory for coastal responses to changes in relative sea level, exposing some well-entrenched misconceptions about the formation of transgressive and regressive strata at chronosomal scales. The STM is a mass-conserving, morphological-behavior model that provides added generality to the updated theory by allowing for open sediment budgets (on the shoreface and in the lagoon) and time-dependent changes in shoreface and barrier geometries. Both the theoretical basis and application of the STM give neutral transgression for balanced sediment budgets on gently sloping surfaces undergoing a marine transgression. Under these conditions, no transgressive strata are formed, and the land surface being transgressed is not disturbed en masse. Consequently, shoreface-ravinement surfaces are not necessarily inherent by-products of transgression as assumed previously. Simulated transgressive strata are laid down (aggradational transgressions) only if there is a positive net littoral sediment supply (from deltaic sources or erosion of shoreline promontories), significant deposition in the lagoon (due to trapping of fine marine sediments or direct fluvial inputs), or both. Shoreface-ravinement surfaces are produced only under conditions of negative littoral sediment budgets or if the land surface being transgressed is steeper than the shoreface (degradational transgressions).
For negative sediment budgets, simulated shoreface ravinements form on low-gradient surfaces without seaward sediment displacement or genetically related aggradation of the seabed farther offshore. Ravinements also can develop during progressive deepening of the shoreface during transgression and highstands. Simulated highstand ravinements are consistent with, and provide an alternative explanation for, coarse-sand lags found on the lower shoreface of many accommodation-dominated shelves today. Simulated forced regression results in massive in-situ reworking of the highstand shelf surface, inevitably producing a strandplain stratum characterized by (1) an unconformity at its base and (2) shoreface isochrons, as opposed to the landward-dipping, backbarrier isochrons that characterize transgressive barriers (which consist of washover and tidal-delta sand deposits).
The revised approach to simulating each of these intrachronosomal-forming processes has significance for sequence models and the interpretation of stratigraphic data at basin-fill scales.
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Numerical Experiments in Stratigraphy: Recent Advances in Stratigraphic and Sedimentologic Computer Simulations
Numerical Experiments in Stratigraphy: Recent Advances in Stratigraphic and Sedimentologic Computer Simulations - This volume presents the results derived from a three-day workshop held at the University of Kansas, Lawrence, Kansas, from May 15 through May 17, 1996. The objectives of the workshop were to document, characterize, demonstrate, and compare different computing procedures that have been utilized in simulating stratigraphic sequences. Both inverse and forward simulation modeling procedures are represented. The results of the workshop and the papers assembled here include: (1) an enhanced understanding of similarities and differences between models and modeling philosophies, (2) increased communication among modeling groups and geoscientists, (3) critical evaluation of applications and assessment of how models have been utilized, and (4) improvements and refinements in techniques for generating and describing model input and output.