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Knickpoints and crescentic bedform interactions in submarine channels

Chen, Ye; Parsons, Daniel R.; Simmons, Stephen M.; Williams, Rebecca; Cartigny, Matthieu J. B.; Hughes Clarke, John E.; Stacey, Cooper D.; Hage, Sophie; Talling, Peter J.; Azpiroz‐Zabala, Maria; Clare, Michael A.; Hizzett, Jamie L.; Heijnen, Maarten S.; Hunt, James E.; Lintern, D. Gwyn; Sumner, Esther J.; Vellinga, Age J.; Vendettuoli, Daniela

Authors

Ye Chen

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Dr Rebecca Williams Rebecca.Williams@hull.ac.uk
Senior Lecturer; Associate Dean for Student Experience

Matthieu J. B. Cartigny

John E. Hughes Clarke

Cooper D. Stacey

Sophie Hage

Peter J. Talling

Maria Azpiroz‐Zabala

Michael A. Clare

Jamie L. Hizzett

Maarten S. Heijnen

James E. Hunt

D. Gwyn Lintern

Esther J. Sumner

Age J. Vellinga

Daniela Vendettuoli



Abstract

Submarine channels deliver globally important volumes of sediments, nutrients, contaminants and organic carbon into the deep sea. Knickpoints are significant topographic features found within numerous submarine channels, which most likely play an important role in channel evolution and the behaviour of the submarine sediment-laden flows (turbidity currents) that traverse them. Although prior research has linked supercritical turbidity currents to the formation of both knickpoints and smaller crescentic bedforms, the relationship between flows and the dynamics of these seafloor features remains poorly constrained at field-scale. This study investigates the distribution, variation and interaction of knickpoints and crescentic bedforms along the 44km long submarine channel system in Bute Inlet, British Columbia. Wavelet analyses on a series of repeated bathymetric surveys reveal that the floor of the submarine channel is composed of a series of knickpoints that have superimposed, higher-frequency, crescentic bedforms. Individual knickpoints are separated by hundreds to thousands of metres, with the smaller superimposed crescentic bedforms varying in wavelengths from ca 16m to ca 128m through the channel system. Knickpoint migration is driven by the passage of frequent turbidity currents, and acts to redistribute and reorganize the crescentic bedforms. Direct measurements of turbidity currents indicate the seafloor reorganization caused by knickpoint migration can modify the flow field and, in turn, control the location and morphometry of crescentic bedforms. A transect of sediment cores obtained across one of the knickpoints show sand–mud laminations of deposits with higher aggradation rates in regions just downstream of the knickpoint. The interactions between flows, knickpoints and bedforms that are documented here are important because they likely dominate the character of preserved submarine channel-bed deposits.

Citation

Cartigny, M. J., Azpiroz-Zabala, M., Chen, Y., Parsons, D. R., Simmons, S. M., Williams, R., …Vendettuoli, D. (2021). Knickpoints and crescentic bedform interactions in submarine channels. Sedimentology, 68(4), 1358-1377. https://doi.org/10.1111/sed.12886

Journal Article Type Article
Acceptance Date Apr 15, 2021
Online Publication Date Apr 27, 2021
Publication Date 2021-06
Deposit Date May 25, 2021
Publicly Available Date Apr 28, 2022
Journal Sedimentology
Print ISSN 0037-0746
Electronic ISSN 1365-3091
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 68
Issue 4
Pages 1358-1377
DOI https://doi.org/10.1111/sed.12886
Keywords Crescentic bedforms; Knickpoints; Sedimentary records; Submarine channels; Turbidity currents
Public URL https://hull-repository.worktribe.com/output/3773733