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Newly recognised turbidity current structure can explain prolonged flushing of submarine canyons

Newly recognised turbidity current structure can explain prolonged flushing of submarine canyons
Newly recognised turbidity current structure can explain prolonged flushing of submarine canyons
Seabed-hugging flows called turbidity currents are the volumetrically most important process transporting sediment across our planet and form its largest sediment accumulations. We seek to understand the internal structure and behavior of turbidity currents by reanalyzing the most detailed direct measurements yet of velocities and densities within oceanic turbidity currents, obtained from weeklong flows in the Congo Canyon. We provide a new model for turbidity current structure that can explain why these are far more prolonged than all previously monitored oceanic turbidity currents, which lasted for only hours or minutes at other locations. The observed Congo Canyon flows consist of a short-lived zone of fast and dense fluid at their front, which outruns the slower moving body of the flow. We propose that the sustained duration of these turbidity currents results from flow stretching and that this stretching is characteristic of mud-rich turbidity current systems. The lack of stretching in previously monitored flows is attributed to coarser sediment that settles out from the body more rapidly. These prolonged seafloor flows rival the discharge of the Congo River and carry ~2% of the terrestrial organic carbon buried globally in the oceans each year through a single submarine canyon. Thus, this new structure explains sustained flushing of globally important amounts of sediment, organic carbon, nutrients, and fresh water into the deep ocean.
2375-2548
Azpiroz, Maria
3b207eec-af03-4f88-99f8-3e8d2e8a49f6
Cartigny, Matthieu J.B.
bda1b79b-7e11-4790-8238-b86d80a88bb3
Talling, Peter J.
cda7fee6-bdff-4987-b203-450d1ce01179
Parsons, Daniel R.
59f2673a-9c73-437a-8865-52d52830a3aa
Sumner, Esther
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
Clare, Michael A.
b26da858-9c08-4784-aaa9-7092efcd94bd
Simmons, Stephen M.
1aa65c10-98f2-4e55-aa91-9e6edcd9c5ab
Cooper, Cortis
72afb5d7-91f3-4a60-b5d1-1e6908b903ae
Pope, Ed L.
2043c317-9ba0-4cbb-a47f-a36f9020417e
Azpiroz, Maria
3b207eec-af03-4f88-99f8-3e8d2e8a49f6
Cartigny, Matthieu J.B.
bda1b79b-7e11-4790-8238-b86d80a88bb3
Talling, Peter J.
cda7fee6-bdff-4987-b203-450d1ce01179
Parsons, Daniel R.
59f2673a-9c73-437a-8865-52d52830a3aa
Sumner, Esther
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
Clare, Michael A.
b26da858-9c08-4784-aaa9-7092efcd94bd
Simmons, Stephen M.
1aa65c10-98f2-4e55-aa91-9e6edcd9c5ab
Cooper, Cortis
72afb5d7-91f3-4a60-b5d1-1e6908b903ae
Pope, Ed L.
2043c317-9ba0-4cbb-a47f-a36f9020417e

Azpiroz, Maria, Cartigny, Matthieu J.B., Talling, Peter J., Parsons, Daniel R., Sumner, Esther, Clare, Michael A., Simmons, Stephen M., Cooper, Cortis and Pope, Ed L. (2017) Newly recognised turbidity current structure can explain prolonged flushing of submarine canyons. Science Advances, 3 (10). (doi:10.1126/sciadv.1700200).

Record type: Article

Abstract

Seabed-hugging flows called turbidity currents are the volumetrically most important process transporting sediment across our planet and form its largest sediment accumulations. We seek to understand the internal structure and behavior of turbidity currents by reanalyzing the most detailed direct measurements yet of velocities and densities within oceanic turbidity currents, obtained from weeklong flows in the Congo Canyon. We provide a new model for turbidity current structure that can explain why these are far more prolonged than all previously monitored oceanic turbidity currents, which lasted for only hours or minutes at other locations. The observed Congo Canyon flows consist of a short-lived zone of fast and dense fluid at their front, which outruns the slower moving body of the flow. We propose that the sustained duration of these turbidity currents results from flow stretching and that this stretching is characteristic of mud-rich turbidity current systems. The lack of stretching in previously monitored flows is attributed to coarser sediment that settles out from the body more rapidly. These prolonged seafloor flows rival the discharge of the Congo River and carry ~2% of the terrestrial organic carbon buried globally in the oceans each year through a single submarine canyon. Thus, this new structure explains sustained flushing of globally important amounts of sediment, organic carbon, nutrients, and fresh water into the deep ocean.

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Accepted/In Press date: 13 September 2017
e-pub ahead of print date: 4 October 2017
Published date: October 2017

Identifiers

Local EPrints ID: 414921
URI: https://eprints.soton.ac.uk/id/eprint/414921
ISSN: 2375-2548
PURE UUID: ff9e98ee-b388-4321-8814-13a9a7a2f72a

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Date deposited: 17 Oct 2017 16:30
Last modified: 13 Mar 2019 19:20

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