Grain-size controls on the morphology and internal geometry of river-dominated deltas

Burpee, Alexander P.; Slingerland, Rudy L.; Edmonds, Douglas A.; Parsons, Daniel; Best, Jim; Cederberg, James; McGuffin, Andrew; Caldwell, Rebecca; Nijhuis, Austin; Royce, Jordan

Abstract

Predictions of a delta's morphology, facies, and stratigraphy are typically derived from its relative wave, tide, and river energies, with sediment type playing a lesser role. Here we test the hypothesis that, all other factors being equal, the topset of a relatively noncohesive, sandy delta will have more active distributaries, a less rugose shoreline morphology, less topographic variation in its topset, and less variability in foreset dip directions than a highly cohesive, muddy delta. As a consequence its stratigraphy will have greater clinoform dip magnitudes and clinoform concavity, a greater percentage of channel facies, and less rugose sand bodies than a highly cohesive, muddy delta. Nine self-formed deltas having different sediment grain sizes and critical shear stresses required for re-entrainment of mud are simulated using Deflt3D, a 2D flow and sediment-transport model. Model results indicate that sand-dominated deltas are more fan-shaped while mud-dominated deltas are more birdsfoot in planform, because the sand-dominated deltas have more active distributaries and a smaller variance of topset elevations, and thereby experience a more equitable distribution of sediment to their perimeters. This results in a larger proportion of channel facies in sand-dominated deltas, and more uniformly distributed clinoform dip directions, steeper dips, and greater clinoform concavity. These conclusions are consistent with data collected from the Goose River Delta, a coarse-grained fan delta prograding into Goose Bay, Labrador, Canada. A reinterpretation of the Kf-1 parasequence set of the Cretaceous Last Chance Delta, a unit of the Ferron Sandstone near Emery, Utah, USA uses Ferron grain-size data, clinoform-dip data, clinoform concavity, and variance of dip directions to hindcast the delta's planform. The Kf-1 Last Chance Delta is predicted to have been more like a fan delta in planform than a birdsfoot delta.

Citation

Burpee, A. P., Slingerland, R. L., Edmonds, D. A., Parsons, D., Best, J., Cederberg, J., …Royce, J. (2015). Grain-size controls on the morphology and internal geometry of river-dominated deltas. Journal of Sedimentary Research, 85(6), 699-714. https://doi.org/10.2110/jsr.2015.39

• Journal Article Type: Article
• Acceptance Date: Mar 4, 2015
• Online Publication Date: Jun 1, 2015
• Publication Date: 2015-05
• Deposit Date: Dec 22, 2016
• Publicly Available Date: Dec 22, 2016
• Journal: Journal of Sedimentary Research
• Print ISSN: 1527-1404
• Publisher: Society for Sedimentary Geology (SEPM)
• Peer Reviewed: Peer Reviewed
• Volume: 85
• Issue: 6
• Pages: 699-714
• DOI: https://doi.org/10.2110/jsr.2015.39
• Keywords: Delta; Stratigraphy; Ferron sandstone; Cohesion; Clinoform
• Public URL: https://hull-repository.worktribe.com/output/446633
• Publisher URL: http://jsedres.geoscienceworld.org/content/85/6/699
• Additional Information: This is the author's accepted manuscript of an article published in Journal of sedimentary research, 2015, v.85 issue 6.