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The role of discharge variability in determining alluvial stratigraphy

Nicholas, Andrew P.; Sambrook Smith, Gregory H.; Amsler, Mario L.; Ashworth, Philip J.; Best, James L.; Hardy, Richard J.; Lane, Stuart N.; Orfeo, Oscar; Parsons, Daniel R.; Reesink, Arnold J.H.; Sandbach, Steven D.; Simpson, Christopher J.; Szupiany, Ricardo N.

Authors

Andrew P. Nicholas

Gregory H. Sambrook Smith

Mario L. Amsler

Philip J. Ashworth

James L. Best

Richard J. Hardy

Stuart N. Lane

Oscar Orfeo

Arnold J.H. Reesink

Steven D. Sandbach

Christopher J. Simpson

Ricardo N. Szupiany

Abstract

We illustrate the potential for using physics-based modeling to link alluvial stratigraphy to large river morphology and dynamics. Model simulations, validated using ground penetrating radar data from the Río Paraná, Argentina, demonstrate a strong relationship between bar-scale set thickness and channel depth, which applies across a wide range of river patterns and bar types. We show that hydrologic regime, indexed by discharge variability and flood duration, exerts a first-order influence on morphodynamics and hence bar set thickness, and that planform morphology alone may be a misleading variable for interpreting deposits. Indeed, our results illustrate that rivers evolving under contrasting hydrologic regimes may have very similar morphology, yet be characterized by marked differences in stratigraphy. This realization represents an important limitation on the application of established theory that links river topography to alluvial deposits, and highlights the need to obtain field evidence of discharge variability when developing paleoenvironmental reconstructions. Model simulations demonstrate the potential for deriving such evidence using metrics of paleocurrent variance.

Journal Article Type Article
Publication Date 2016-01
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 44
Issue 1
Pages 3-6
Institution Citation Nicholas, A. P., Sambrook Smith, G. H., Amsler, M. L., Ashworth, P. J., Best, J. L., Hardy, R. J., …Szupiany, R. N. (2016). The role of discharge variability in determining alluvial stratigraphy. Geology, 44(1), 3-6. https://doi.org/10.1130/G37215.1
DOI https://doi.org/10.1130/G37215.1
Keywords Alluvial stratigraphy, River morphology, Dynamics, Río Paraná, Argentina, Discharge variability
Publisher URL http://geology.gsapubs.org/content/44/1/3
Additional Information Copy of article first published in: Geology, 2015, v.44, issue 1.

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Copyright Statement
© 2015 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.



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