The role of discharge variability in determining alluvial stratigraphy

Nicholas, A.P.; Sambrook Smith, G.H.; Amsler, M.L.; Ashworth, P.J.; Best, J.L.; Hardy, R.J.; Lane, S.N.; Orfeo, O.; Parsons, D.R.; Reesink, A.J.H.; Sandbach, S.D.; Simpson, C.J.; Szupiany, R.N.

doi:10.1130/g37215.1

The role of discharge variability in determining alluvial stratigraphy

Nicholas, A.P.; Sambrook Smith, G.H.; Amsler, M.L.; Ashworth, P.J.; Best, J.L.; Hardy, R.J.; Lane, S.N.; Orfeo, O.; Parsons, D.R.; Reesink, A.J.H.; Sandbach, S.D.; Simpson, C.J.; Szupiany, R.N.

Authors

A.P. Nicholas

G.H. Sambrook Smith

M.L. Amsler

P.J. Ashworth

J.L. Best

Professor Richard Hardy r.j.hardy@durham.ac.uk
Professor

S.N. Lane

O. Orfeo

D.R. Parsons

A.J.H. Reesink

S.D. Sandbach

C.J. Simpson

R.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.

Citation

Nicholas, A., Sambrook Smith, G., Amsler, M., Ashworth, P., Best, J., Hardy, R., …Szupiany, R. (2016). The role of discharge variability in determining alluvial stratigraphy. Geology, 44(1), 3-6. https://doi.org/10.1130/g37215.1

Journal Article Type	Article
Acceptance Date	Oct 13, 2015
Online Publication Date	Nov 11, 2015
Publication Date	Jan 1, 2016
Deposit Date	Oct 13, 2015
Publicly Available Date	Nov 11, 2016
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
DOI	https://doi.org/10.1130/g37215.1
Public URL	https://durham-repository.worktribe.com/output/1429590