Journal of the Geological Society; January 2007; v. 164; no. 1;
p. 67-71; DOI: 10.1144/0016-76492005-179
© 2007 Geological Society of London
A quantitative model for deposition of thin fluvial sand sheets
John A. Fisher1,4,
David Waltham1,
Gary J. Nichols1,2,
Carmen B.E. Krapf3 and
Simon C. Lang3
1 1Department of Geology, Royal Holloway University of London, Egham TW20 0EX, UK
2 2The University Centre in Svalbard, P.O. Box 156, N-9171 Longyearbyen, Norway
3 3Australian School of Petroleum (ASP), University of Adelaide, Adelaide, SA 5005, Australia
4 4Present address: BG-Group, 100 Thames Valley Park Drive, Reading RG6 1PT, UK (e-mail: john.fisher@bg-group.com)
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.
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