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Investigating the timing, processes and deposits of one the World¹s largest submarine gravity flows: the 'Bed 5 event' off northwest Africa

Investigating the timing, processes and deposits of one the World¹s largest submarine gravity flows: the 'Bed 5 event' off northwest Africa
Investigating the timing, processes and deposits of one the World¹s largest submarine gravity flows: the 'Bed 5 event' off northwest Africa
An extensive dataset of shallow sediment cores is used here to describe one of the World's most voluminous and extensive submarine gravity flows. The Bed 5 event, dated at ~60 ka, originated on the upper slope offshore Atlantic Morocco, in the vicinity of Agadir Canyon. The volume of initial failure was ~130 km3 of sediment, and the failure appeared to rapidly disintegrate into a highly mobile turbidity current. Widespread substrate erosion beneath the flow occurred up to 550 km from the interpreted source, and is estimated to have added a further 30 km3 of sediment. The flow spread upon exiting Agadir Canyon, with deposition occurring across both the Agadir Basin and Seine Abyssal Plain. Evidence for flow transformations and linked turbidite-debrite development can be found in both basins, and there are also indications for sediment bypass and fluid mud behaviour. A portion of the flow subsequently spilled out of the western Agadir Basin, and passed through the Madeira Channels prior to deposition on the enclosed Madeira Abyssal Plain at 5,400 m water depth. The total run-out distance along the flow pathway is about 2,000 km, with only about half of the pathway confined to canyon or channel environments. Our results show that large-volume submarine landslides can rapidly disintegrate into far-traveling fluid turbidity currents, and that depositional processes within such flows may be complex and spatially variable.
9789048130702
28
463-474
Springer
Wynn, R.B.
72ccd765-9240-45f8-9951-4552b497475a
Talling, P.J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Stevenson, C.J.
ec2d8d50-8c4c-4547-8751-fc5cec559849
Cronin, B.T.
490f1878-f086-450e-a8a7-698595339f03
Le Bas, T.P.
f0dbad80-bb38-412c-be77-b8b9faef1854
Mosher, D.C.
Shipp, C.
Moscardelli, L.
Chaytor, J.
Baxter, C.
Lee, H.
Urgeles, R.
Wynn, R.B.
72ccd765-9240-45f8-9951-4552b497475a
Talling, P.J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Stevenson, C.J.
ec2d8d50-8c4c-4547-8751-fc5cec559849
Cronin, B.T.
490f1878-f086-450e-a8a7-698595339f03
Le Bas, T.P.
f0dbad80-bb38-412c-be77-b8b9faef1854
Mosher, D.C.
Shipp, C.
Moscardelli, L.
Chaytor, J.
Baxter, C.
Lee, H.
Urgeles, R.

Wynn, R.B., Talling, P.J., Masson, D.G., Stevenson, C.J., Cronin, B.T. and Le Bas, T.P. (2010) Investigating the timing, processes and deposits of one the World¹s largest submarine gravity flows: the 'Bed 5 event' off northwest Africa. Mosher, D.C., Shipp, C., Moscardelli, L., Chaytor, J., Baxter, C., Lee, H. and Urgeles, R. (eds.) In Submarine mass movements and their consequences: 4th International Symposium, Austin, Texas, 9th-11th November 2009. Springer. pp. 463-474 . (doi:10.1007/978-90-481-3071-9_38).

Record type: Conference or Workshop Item (Paper)

Abstract

An extensive dataset of shallow sediment cores is used here to describe one of the World's most voluminous and extensive submarine gravity flows. The Bed 5 event, dated at ~60 ka, originated on the upper slope offshore Atlantic Morocco, in the vicinity of Agadir Canyon. The volume of initial failure was ~130 km3 of sediment, and the failure appeared to rapidly disintegrate into a highly mobile turbidity current. Widespread substrate erosion beneath the flow occurred up to 550 km from the interpreted source, and is estimated to have added a further 30 km3 of sediment. The flow spread upon exiting Agadir Canyon, with deposition occurring across both the Agadir Basin and Seine Abyssal Plain. Evidence for flow transformations and linked turbidite-debrite development can be found in both basins, and there are also indications for sediment bypass and fluid mud behaviour. A portion of the flow subsequently spilled out of the western Agadir Basin, and passed through the Madeira Channels prior to deposition on the enclosed Madeira Abyssal Plain at 5,400 m water depth. The total run-out distance along the flow pathway is about 2,000 km, with only about half of the pathway confined to canyon or channel environments. Our results show that large-volume submarine landslides can rapidly disintegrate into far-traveling fluid turbidity currents, and that depositional processes within such flows may be complex and spatially variable.

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More information

Published date: 2010
Venue - Dates: 4th International Symposium on Submarine Mass Movements and their Consequences, Austin TX, USA, 2009-11-09 - 2009-11-11
Organisations: Marine Geoscience

Identifiers

Local EPrints ID: 72248
URI: http://eprints.soton.ac.uk/id/eprint/72248
ISBN: 9789048130702
PURE UUID: 48c09e11-6e54-4033-9ce2-617debf0213c

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Date deposited: 02 Feb 2010
Last modified: 13 Mar 2024 21:23

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Contributors

Author: R.B. Wynn
Author: P.J. Talling
Author: D.G. Masson
Author: C.J. Stevenson
Author: B.T. Cronin
Author: T.P. Le Bas
Editor: D.C. Mosher
Editor: C. Shipp
Editor: L. Moscardelli
Editor: J. Chaytor
Editor: C. Baxter
Editor: H. Lee
Editor: R. Urgeles

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