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Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: New insights from flume experiments

Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: New insights from flume experiments
Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: New insights from flume experiments
Supercritical-flow phenomena are fairly common in modern sedimentary environments, yet their recognition and analysis remain difficult in the stratigraphic record. This fact is commonly ascribed to the poor preservation potential of deposits from high-energy supercritical flows. However, the number of flume data sets on supercritical-flow dynamics and sedimentary structures is very limited in comparison with available data for subcritical flows, which hampers the recognition and interpretation of such deposits. The results of systematic flume experiments spanning a broad range of supercritical-flow bedforms (antidunes, chutes-and-pools and cyclic steps) developed in mobile sand beds of variable grain sizes are presented. Flow character and related bedform patterns are constrained through time-series measurements of bed configurations, flow depths, flow velocities and Froude numbers. The results allow the refinement and extension of some widely used bedform stability diagrams in the supercritical-flow domain, clarifying in particular the morphodynamic relations between antidunes and cyclic steps. The onset of antidunes is controlled by flows exceeding a threshold Froude number. The transition from antidunes to cyclic steps in fine to medium-grained sand occurs at a threshold mobility parameter. Sedimentary structures associated with supercritical bedforms developed under variable aggradation rates are revealed by means of combining flume results and synthetic stratigraphy. The sedimentary structures are compared with examples from field and other flume studies. Aggradation rate is seen to exert an important control on the geometry of supercritical-flow structures and should be considered when identifying supercritical bedforms in the sedimentary record
0037-0746
712-748
Cartigny, Matthieu J.B.
d252d7b1-16c6-47b1-bf86-8087070934ce
Ventra, Dario
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Postma, George
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van Den Berg, Jan H.
1352a356-80dc-4f5f-87c3-37a7d66229db
Venditti, Jeremy
7ec03fec-48f0-4a9c-a2b5-8013e9933fc1
Cartigny, Matthieu J.B.
d252d7b1-16c6-47b1-bf86-8087070934ce
Ventra, Dario
75362ccc-9b38-4ddd-bfb7-2aac352e6ab0
Postma, George
9f590b3e-32fb-4959-b63b-d25dc07c4463
van Den Berg, Jan H.
1352a356-80dc-4f5f-87c3-37a7d66229db
Venditti, Jeremy
7ec03fec-48f0-4a9c-a2b5-8013e9933fc1

Cartigny, Matthieu J.B., Ventra, Dario, Postma, George, van Den Berg, Jan H. and Venditti, Jeremy (2014) Morphodynamics and sedimentary structures of bedforms under supercritical-flow conditions: New insights from flume experiments. Sedimentology, 61 (3), 712-748. (doi:10.1111/sed.12076).

Record type: Article

Abstract

Supercritical-flow phenomena are fairly common in modern sedimentary environments, yet their recognition and analysis remain difficult in the stratigraphic record. This fact is commonly ascribed to the poor preservation potential of deposits from high-energy supercritical flows. However, the number of flume data sets on supercritical-flow dynamics and sedimentary structures is very limited in comparison with available data for subcritical flows, which hampers the recognition and interpretation of such deposits. The results of systematic flume experiments spanning a broad range of supercritical-flow bedforms (antidunes, chutes-and-pools and cyclic steps) developed in mobile sand beds of variable grain sizes are presented. Flow character and related bedform patterns are constrained through time-series measurements of bed configurations, flow depths, flow velocities and Froude numbers. The results allow the refinement and extension of some widely used bedform stability diagrams in the supercritical-flow domain, clarifying in particular the morphodynamic relations between antidunes and cyclic steps. The onset of antidunes is controlled by flows exceeding a threshold Froude number. The transition from antidunes to cyclic steps in fine to medium-grained sand occurs at a threshold mobility parameter. Sedimentary structures associated with supercritical bedforms developed under variable aggradation rates are revealed by means of combining flume results and synthetic stratigraphy. The sedimentary structures are compared with examples from field and other flume studies. Aggradation rate is seen to exert an important control on the geometry of supercritical-flow structures and should be considered when identifying supercritical bedforms in the sedimentary record

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CartignyRevisedManuscriptJuly2013.pdf - Accepted Manuscript
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More information

Accepted/In Press date: 20 November 2013
Published date: April 2014
Organisations: Marine Geoscience

Identifiers

Local EPrints ID: 362837
URI: http://eprints.soton.ac.uk/id/eprint/362837
ISSN: 0037-0746
PURE UUID: a171ee8c-89f7-4c6d-897f-1a1994abe295

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Date deposited: 06 Mar 2014 16:51
Last modified: 09 Jan 2022 01:13

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Contributors

Author: Matthieu J.B. Cartigny
Author: Dario Ventra
Author: George Postma
Author: Jan H. van Den Berg
Author: Jeremy Venditti

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