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

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. In, Mosher, D.C., Shipp, C., Moscardelli, L., Chaytor, J., Baxter, C., Lee, H. and Urgeles, R. (eds.) Submarine mass movements and their consequences: 4th International Symposium, Austin, Texas, 9th-11th November 2009. 4th International Symposium on Submarine Mass Movements and their Consequences Dordrecht, Netherlands, Springer, 463-474. (Advances in Natural and Technological Hazards Research 28). (doi:10.1007/978-90-481-3071-9_38).


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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 deposi-tional processes within such flows may be complex and spatially variable.

Item Type: Book Section
Digital Object Identifier (DOI): doi:10.1007/978-90-481-3071-9_38
ISBNs: 9789048130702 (hardback)
Subjects: Q Science > QE Geology
Divisions : University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
University Structure - Pre August 2011 > National Oceanography Centre (NERC)
National Oceanography Centre (NERC) > Marine Geoscience
ePrint ID: 72248
Accepted Date and Publication Date:
Date Deposited: 02 Feb 2010
Last Modified: 31 Mar 2016 13:04

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