Different frequencies and triggers of canyon filling and flushing events in Nazaré Canyon, offshore Portugal
Different frequencies and triggers of canyon filling and flushing events in Nazaré Canyon, offshore Portugal
Submarine canyons are one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has importance for sediment budgets, carbon cycling, and geohazard assessment. Despite increasing knowledge of turbidity current triggers, the down-canyon variability in turbidity current frequency within most canyon systems is not well constrained. New AMS radiocarbon chronologies from canyon sediment cores illustrate significant variability in turbidity current frequency within Nazaré Canyon through time. Generalised linear models and Cox proportional hazards models indicate a strong influence of global sea level on the frequency of turbidity currents that fill the canyon. Radiocarbon ages from basin sediment cores indicate that larger, canyon-flushing turbidity currents reaching the Iberian Abyssal Plain have a significantly longer average recurrence interval than turbidity currents that fill the canyon. The recurrence intervals of these canyon-flushing turbidity currents also appear to be unaffected by long-term changes in global sea level. Furthermore, canyon-flushing and canyon-filling have very different statistical distributions of recurrence intervals. This indicates that the factors triggering, and thus controlling the frequency of canyon-flushing and canyon-filling events are very different. Canyon-filling appears to be predominantly triggered by sediment instability during sea level lowstand, and by storm and nepheloid transport during the present day highstand. Canyon-flushing exhibits time-independent behaviour. This indicates that a temporally random process, signal shredding, or summation of non-random processes that cannot be discerned from a random signal, are triggering canyon flushing events.
Submarine canyons, Turbidity currents, Sea level, Earthquakes, Geohazards, Sediment cores
89-105
Allin, Joshua R.
360b2637-6755-44fd-87ff-0e1eb4759c22
Hunt, James E.
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Talling, Peter J.
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Clare, Michael A.
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Pope, Ed
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Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
1 January 2016
Allin, Joshua R.
360b2637-6755-44fd-87ff-0e1eb4759c22
Hunt, James E.
eb7fbfb5-b1c9-4436-b7f6-18c8d13b7a0b
Talling, Peter J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Clare, Michael A.
b26da858-9c08-4784-aaa9-7092efcd94bd
Pope, Ed
2043c317-9ba0-4cbb-a47f-a36f9020417e
Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Allin, Joshua R., Hunt, James E., Talling, Peter J., Clare, Michael A., Pope, Ed and Masson, Douglas G.
(2016)
Different frequencies and triggers of canyon filling and flushing events in Nazaré Canyon, offshore Portugal.
Marine Geology, 371, .
(doi:10.1016/j.margeo.2015.11.005).
Abstract
Submarine canyons are one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has importance for sediment budgets, carbon cycling, and geohazard assessment. Despite increasing knowledge of turbidity current triggers, the down-canyon variability in turbidity current frequency within most canyon systems is not well constrained. New AMS radiocarbon chronologies from canyon sediment cores illustrate significant variability in turbidity current frequency within Nazaré Canyon through time. Generalised linear models and Cox proportional hazards models indicate a strong influence of global sea level on the frequency of turbidity currents that fill the canyon. Radiocarbon ages from basin sediment cores indicate that larger, canyon-flushing turbidity currents reaching the Iberian Abyssal Plain have a significantly longer average recurrence interval than turbidity currents that fill the canyon. The recurrence intervals of these canyon-flushing turbidity currents also appear to be unaffected by long-term changes in global sea level. Furthermore, canyon-flushing and canyon-filling have very different statistical distributions of recurrence intervals. This indicates that the factors triggering, and thus controlling the frequency of canyon-flushing and canyon-filling events are very different. Canyon-filling appears to be predominantly triggered by sediment instability during sea level lowstand, and by storm and nepheloid transport during the present day highstand. Canyon-flushing exhibits time-independent behaviour. This indicates that a temporally random process, signal shredding, or summation of non-random processes that cannot be discerned from a random signal, are triggering canyon flushing events.
Text
MARGO5786R1_accepted.pdf
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More information
Accepted/In Press date: 11 November 2015
Published date: 1 January 2016
Keywords:
Submarine canyons, Turbidity currents, Sea level, Earthquakes, Geohazards, Sediment cores
Organisations:
Geology & Geophysics, Marine Geoscience
Identifiers
Local EPrints ID: 386768
URI: http://eprints.soton.ac.uk/id/eprint/386768
ISSN: 0025-3227
PURE UUID: 6e6acc85-f9bb-4730-92fe-4601146e9546
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Date deposited: 01 Feb 2016 14:29
Last modified: 15 Mar 2024 05:23
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Contributors
Author:
Joshua R. Allin
Author:
James E. Hunt
Author:
Peter J. Talling
Author:
Michael A. Clare
Author:
Ed Pope
Author:
Douglas G. Masson
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