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Flow substrate interactions in aggrading and degrading submarine channels

Anjali M. Fernandes, James Buttles and David Mohrig
Flow substrate interactions in aggrading and degrading submarine channels
Journal of Sedimentary Research (June 2020) 90 (6): 573-583

Abstract

Connecting real-time measurements of current-bed interactions to the temporal evolution of submarine channels can be extremely challenging in natural settings. We present a suite of physical experiments that offer insight into the spectrum of interactions between turbidity currents and their channels, from i) detachment-limited erosion to ii) transport-limited erosion to iii) pure deposition. In all three cases channel sinuosity influenced patterns of erosion and deposition; the outsides of bends displayed the highest erosion rates in the first two cases but showed the highest deposition rates in the third. We connect the evolution of these channels to the turbulence of the near-bed boundary layer. In the erosional experiments the beds of both channels roughened through time, developing erosional bedforms or trains of ripples. Reynolds estimates of boundary-layer roughness indicate that, in both erosional cases, the near-bed boundary layer roughened from smooth or transitionally rough to rough, whereas the depositional channel appears to have remained consistently smooth. Our results suggest that, in the absence of any changes from upstream, erosion in submarine channels is a self-reinforcing mechanism whereby developing bed roughness increases turbulence at the boundary layer, thereby inhibiting deposition, promoting sediment entrainment, and enhancing channel relief; deposition occurs in submarine channels when the boundary layer remains smooth, promoting aggradation and loss of channel relief.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 90
Serial Issue: 6
Title: Flow substrate interactions in aggrading and degrading submarine channels
Affiliation: Denison University, Department of Geosciences, Granville, OH, United States
Pages: 573-583
Published: 202006
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 57
Accession Number: 2020-056632
Categories: Sedimentary petrologyGeomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: University of Texas at Austin, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 202016
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