A quantitative model for deposition of thin fluvial sand sheets

• Published in: Journal of the Geological Society Vol. 164; no. 1; pp. 67 - 71
• Main Authors: Fisher, John A, Waltham, David, Nichols, Gary J, Krapf, Carmen B. E, Lang, Simon C
• Format: Journal Article
• Language: English
• Published: London Geological Society of London 01-01-2007; The Geological Society of London; Geological Society; Geological Society Publishing House
• Subjects: Australasia; Australia; bedload; channel geometry; clastic sediments; Crystalline rocks; Douglas Creek terminal splay; Earth sciences; Earth, ocean, space; eolian features; Exact sciences and technology; floods; Fluid dynamics; fluvial features; Geology; grain size; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Lake Eyre; mathematical methods; modern analogs; prediction; quantitative analysis; sand; sand sheets; sed rocks, sediments; Sedimentary petrology; sediments; Shear stress; South Australia; stream gradient; stream transport; streamflow; suspension; thickness; transport; two-dimensional models; velocity; Australia; Lake Eyre; South Australia; models; sand; sandstone deposits; interpretation; Australasia; sand sheets; transport; fluid dynamics; grains
• ISSN: 0016-7649; 2041-479X
• DOI: 10.1144/0016-76492005-179

Sheetfloods are typically invoked as the mechanism responsible for the kilometre-scale transport of sand-sized sediment grains in shallow-gradient fluvial systems. This concept is based on the lateral extent of ancient thin, sheet sandstone deposits rather than on fluid dynamics, which has resulted in a loosely constrained model for sheetfloods. This study tested the conceptual mechanism by developing a depth-averaged, 2D computational fluid dynamics model. The model results compare well against observations from modern deposits at Lake Eyre to provide a quantitative, physically sound basis for sheetfloods that can be applied in ancient and modern settings to constrain otherwise qualitative interpretations.