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An evaluation of along- and down-slope sediment transport processes between Goban Spur and Brenot Spur on the Celtic Margin of the Bay of Biscay

An evaluation of along- and down-slope sediment transport processes between Goban Spur and Brenot Spur on the Celtic Margin of the Bay of Biscay
An evaluation of along- and down-slope sediment transport processes between Goban Spur and Brenot Spur on the Celtic Margin of the Bay of Biscay
Multi-beam bathymetry and backscatter, 3.5 kHz pinger profiles, side-scan sonar and seabed samples have been examined to evaluate along- and down-slope sedimentary processes along the Celtic Margin shelf and upper slope in water depths of 200 to 1500 m. The continental shelf and slope are indented and dissected by major canyon systems. The shelf is characterised by major northeast–southwest trending sand banks that are orthogonal to the shelf edge. Along the shelf edge, several fields of asymmetric sandwaves oriented orthogonal to the canyon axes indicate sediment transport into the canyon heads. Less commonly, sandwaves with weak asymmetry suggest sediment transport onto the shelf. These may be reworked and are partly overprinted by more recent sandwaves. Down-slope sediment transport by turbidity currents is the dominant process through the major canyons. Recent faulting has also played a role in canyon development. Turbidity currents are most likely initiated by faulting, and/or slope failure of the walls that bound the canyon head drainage basins and sediment migration from the shelf. This leads to deep incision of sinuous thalwegs in the upper reaches of canyon floors and downcutting and sediment transport on the mid to lower continental slope. The canyons are V-shaped in the upper reaches and become U-shaped progressively down-slope, suggesting they represent either a transition from erosive to depositional processes or sediment bypass conduits carrying sediment between the shelf and abyssal plain. Over-bank spill from canyons leads to deposition of unconfined turbidite deposits (muds) on the intervening canyon spurs.
sedimentary processes, morphology, Celtic Margin, multi-beam bathymetry, sediment waves, submarine canyons
0037-0738
99-116
Cunningham, M.J.
bfcdc551-3910-4f91-9339-4fb8cd33e0ff
Hodgson, S.
745600cf-b91f-4f39-9b5e-4f76989d268f
Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Parson, L.M.
8985a003-911e-402e-a858-3ecbd09d6771
Cunningham, M.J.
bfcdc551-3910-4f91-9339-4fb8cd33e0ff
Hodgson, S.
745600cf-b91f-4f39-9b5e-4f76989d268f
Masson, D.G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Parson, L.M.
8985a003-911e-402e-a858-3ecbd09d6771

Cunningham, M.J., Hodgson, S., Masson, D.G. and Parson, L.M. (2005) An evaluation of along- and down-slope sediment transport processes between Goban Spur and Brenot Spur on the Celtic Margin of the Bay of Biscay. Sedimentary Geology, 179 (1-2), 99-116. (doi:10.1016/j.sedgeo.2005.04.014).

Record type: Article

Abstract

Multi-beam bathymetry and backscatter, 3.5 kHz pinger profiles, side-scan sonar and seabed samples have been examined to evaluate along- and down-slope sedimentary processes along the Celtic Margin shelf and upper slope in water depths of 200 to 1500 m. The continental shelf and slope are indented and dissected by major canyon systems. The shelf is characterised by major northeast–southwest trending sand banks that are orthogonal to the shelf edge. Along the shelf edge, several fields of asymmetric sandwaves oriented orthogonal to the canyon axes indicate sediment transport into the canyon heads. Less commonly, sandwaves with weak asymmetry suggest sediment transport onto the shelf. These may be reworked and are partly overprinted by more recent sandwaves. Down-slope sediment transport by turbidity currents is the dominant process through the major canyons. Recent faulting has also played a role in canyon development. Turbidity currents are most likely initiated by faulting, and/or slope failure of the walls that bound the canyon head drainage basins and sediment migration from the shelf. This leads to deep incision of sinuous thalwegs in the upper reaches of canyon floors and downcutting and sediment transport on the mid to lower continental slope. The canyons are V-shaped in the upper reaches and become U-shaped progressively down-slope, suggesting they represent either a transition from erosive to depositional processes or sediment bypass conduits carrying sediment between the shelf and abyssal plain. Over-bank spill from canyons leads to deposition of unconfined turbidite deposits (muds) on the intervening canyon spurs.

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Published date: 2005
Keywords: sedimentary processes, morphology, Celtic Margin, multi-beam bathymetry, sediment waves, submarine canyons

Identifiers

Local EPrints ID: 17485
URI: https://eprints.soton.ac.uk/id/eprint/17485
ISSN: 0037-0738
PURE UUID: c0d01a54-d718-41c1-bef0-83218b29f170

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Date deposited: 10 Oct 2005
Last modified: 17 Jul 2017 16:38

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Contributors

Author: M.J. Cunningham
Author: S. Hodgson
Author: D.G. Masson
Author: L.M. Parson

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