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Fill, flush or shuffle: How is sediment carried through submarine channels to build lobes?

Heijnen, Maarten S.; Clare, Michael A.; Cartigny, Matthieu J.B.; Talling, Peter J.; Hage, Sophie; Pope, Ed L.; Bailey, Lewis; Sumner, Esther; Gwyn Lintern, D.; Stacey, Cooper; Parsons, Daniel R.; Simmons, Stephen M.; Chen, Ye; Hubbard, Stephen M.; Eggenhuisen, Joris T.; Kane, Ian; Hughes Clarke, John E.

Authors

Maarten S. Heijnen

Michael A. Clare

Matthieu J.B. Cartigny

Peter J. Talling

Sophie Hage

Ed L. Pope

Lewis Bailey

Esther Sumner

D. Gwyn Lintern

Cooper Stacey

Daniel R. Parsons

Ye Chen

Stephen M. Hubbard

Joris T. Eggenhuisen

Ian Kane

John E. Hughes Clarke



Abstract

Submarine channels are the primary conduits for land-derived material, including organic carbon, pollutants, and nutrients, into the deep-sea. The flows (turbidity currents) that traverse these systems can pose hazards to seafloor infrastructure such as cables and pipelines. Here we use a novel combination of repeat seafloor surveys and turbidity current monitoring along a 50 km-long submarine channel in Bute Inlet, British Columbia, and discharge measurements from the main feeding river. These source-to-sink observations provide the most detailed information yet on magnitude-frequency-distance relationships for turbidity currents, and the spatial-temporal patterns of sediment transport within a submarine channel-lobe system. This analysis provides new insights into mass redistribution, and particle residence times in submarine channels, as well as where particles are eventually buried and how that is recorded in the deposits. We observe stepwise sediment transport down the channel, with turbidity currents becoming progressively less frequent with distance. Most flows dissipate and deposit within the proximal (< 11 km) part of the system, whilst longer run-out flows then pick up this sediment, ‘shuffling’ it further downstream along the channel. This shuffling occurs mainly through upstream migration of knickpoints, which can generate sediment bypass along the channel over timescales of 10–100 yrs. Infrequent large events flush the channel and ultimately transport sediment onto the lobe. These flushing events can occur without obvious triggers, and thus might be internally generated. We then present the first ever sediment budget analysis of an entire submarine channel system, which shows that the river input and lobe aggradation can approximately balance over decadal timescales. We conclude by discussing the implication of this sediment shuffling for seafloor geohazards and particle burial.

Citation

Heijnen, M. S., Clare, M. A., Cartigny, M. J., Talling, P. J., Hage, S., Pope, E. L., …Hughes Clarke, J. E. (2022). Fill, flush or shuffle: How is sediment carried through submarine channels to build lobes?. Earth and planetary science letters, 584, Article 117481. https://doi.org/10.1016/j.epsl.2022.117481

Journal Article Type Article
Acceptance Date Mar 1, 2022
Online Publication Date Mar 14, 2022
Publication Date Apr 15, 2022
Deposit Date Mar 14, 2022
Publicly Available Date Oct 27, 2022
Journal Earth and Planetary Science Letters
Print ISSN 0012-821X
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 584
Article Number 117481
DOI https://doi.org/10.1016/j.epsl.2022.117481
Keywords Submarine channel; Turbidity current; Flushing; Source to sink; Bypass; Lobe
Public URL https://hull-repository.worktribe.com/output/3949144

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Copyright Statement
© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/)





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