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New insights into the morphology, fill, and remarkable longevity (>0.2 m.y.) of modern deep-water erosional scours along the northeast Atlantic margin

Record type: Article

A series of large-scale erosional scours are described from four modern deep-water canyon and/or channel systems along the northeast Atlantic continental margin. Regional-scale geophysical data indicate that most scours occur in zones of rapid flow expansion, such as canyon and/or channel termini and margins. High-resolution images of the scours cover ?25 km² at 2 × 2 m pixel size, and were obtained at depths of 4200–4900 m using Autosub6000, an autonomous underwater vehicle equipped with an EM2000 multibeam bathymetry system. Sedimentological and microfossil-based chronological data of scour fills and interscour areas were obtained via accurately located piston cores that targeted specific sites within imaged areas. These core data reveal a number of key findings. (1) Deep-water scours can be very long lived (>0.2 m.y. ) and may undergo discrete phases of isolation, amalgamation, and infilling. (2) Deep-water scours can develop via a composite of cutting and filling events with periodicities of between tens of thousands and hundreds of thousands of years. (3) Immediately adjacent scours may have strikingly different sedimentological histories and do not necessarily evolve contemporaneously. (4) Scour infills are typically out of phase with sedimentation in intrascour areas, having thin sands internally and thick sands externally, or thick muds internally and thin muds externally. (5) Erosional hiatuses within scour fills may represent hundreds of thousands of years of time, and yet leave little visible record. Four distinct morphologies of scour are identified that range from 40 to 3170 m wide and 8 to 48 m deep: spoon shaped, heel shaped, crescent shaped, and oval shaped. Isolated scours are shown to coalesce laterally into broad regions of amalgamated scour that may be several kilometers across. The combined morphosedimentological data set is used to examine some of the putative formative mechanisms for scour genesis.

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Citation

Macdonald, H.A., Wynn, R.B., Huvenne, V.A.I., Peakall, J., Masson, D.G., Weaver, P.P.E. and McPhail, S.D. (2011) New insights into the morphology, fill, and remarkable longevity (>0.2 m.y.) of modern deep-water erosional scours along the northeast Atlantic margin Geosphere, 7, (4), pp. 845-867. (doi:10.1130/GES00611.1).

More information

Published date: August 2011
Organisations: Marine Geoscience, Ocean Technology and Engineering

Identifiers

Local EPrints ID: 195597
URI: http://eprints.soton.ac.uk/id/eprint/195597
ISSN: 1553-040X
PURE UUID: c16b1fb2-05bd-4b63-b765-3e0247a41b9b

Catalogue record

Date deposited: 23 Aug 2011 13:16
Last modified: 18 Jul 2017 11:24

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Contributors

Author: H.A. Macdonald
Author: R.B. Wynn
Author: V.A.I. Huvenne
Author: J. Peakall
Author: D.G. Masson
Author: P.P.E. Weaver
Author: S.D. McPhail

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