The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Turbidite depositional architecture across three interconnected deep-water basins on the north-west African margin

Turbidite depositional architecture across three interconnected deep-water basins on the north-west African margin
Turbidite depositional architecture across three interconnected deep-water basins on the north-west African margin
The Moroccan Turbidite System (MTS) on the north-west African margin extends 1500 km from the head of the Agadir Canyon to the Madeira Abyssal Plain, making it one of the longest turbidite systems in the world. The MTS consists of three interconnected deep-water basins, the Seine Abyssal Plain (SAP), the Agadir Basin and the Madeira Abyssal Plain (MAP), connected by a network of distributary channels.
Excellent core control has enabled individual turbidites to be correlated between all three basins, giving a detailed insight into the turbidite depositional architecture of a system with multiple source areas and complex morphology. Large-volume (> 100 km3) turbidites, sourced from the Morocco Shelf, show a relatively simple architecture in the Madeira and Seine Abyssal Plains. Sandy bases form distinct lobes or wedges that thin rapidly away from the basin margin and are overlain by ponded basin-wide muds.
However, in the Agadir Basin, the turbidite fill is more complex owing to a combination of multiple source areas and large variations in turbidite volume. A single, very large turbidity current (200-300 km3 of sediment) deposited most of its sandy load within the Agadir Basin, but still had sufficient energy to carry most of the mud fraction 500 km further downslope to the MAP. Large turbidity currents (100-150 km3 of sediment) deposit most of their sand and mud fraction within the Agadir Basin, but also transport some of their load westwards to the MAP. Small turbidity currents (< 35 km3 of sediment) are wholly confined within the Agadir Basin, and their deposits pinch out on the basin floor.
Turbidity currents flowing beyond the Agadir Basin pass through a large distributary channel system. Individual turbidites correlated across this channel system show major variations in the mineralogy of the sand fraction, whereas the geochemistry and micropalaeontology of the mud fraction remain very similar. This is interpreted as evidence for separation of the flow, with a sand-rich, erosive, basal layer confined within the channel system, overlain by an unconfined layer of suspended mud.
Large-volume turbidites within the MTS were deposited at oxygen isotope stage boundaries, during periods of rapid sea-level change and do not appear to be specifically connected to sea-level lowstands or highstands. This contrasts with the classic fan model, which suggests that most turbidites are deposited during lowstands of sea level. In addition, the three largest turbidites on the MAP were deposited during the largest fluctuations in sea level, suggesting a link between the volume of sediment input and the magnitude of sea-level change.
sediment cores, turbidites, turbidity currents
0037-0746
669-695
Wynn, Russell B.
72ccd765-9240-45f8-9951-4552b497475a
Weaver, Philip P.E.
c063e3ea-7779-4a03-be52-c8b83e135bfb
Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Stow, Dorrik A.V.
888764b3-5e4d-49bf-96fd-32ba7f6f8356
Wynn, Russell B.
72ccd765-9240-45f8-9951-4552b497475a
Weaver, Philip P.E.
c063e3ea-7779-4a03-be52-c8b83e135bfb
Masson, Douglas G.
edd44c8b-38ca-45fb-8d0d-ac8365748a45
Stow, Dorrik A.V.
888764b3-5e4d-49bf-96fd-32ba7f6f8356

Wynn, Russell B., Weaver, Philip P.E., Masson, Douglas G. and Stow, Dorrik A.V. (2002) Turbidite depositional architecture across three interconnected deep-water basins on the north-west African margin. Sedimentology, 49 (4), 669-695. (doi:10.1046/j.1365-3091.2002.00471.x).

Record type: Article

Abstract

The Moroccan Turbidite System (MTS) on the north-west African margin extends 1500 km from the head of the Agadir Canyon to the Madeira Abyssal Plain, making it one of the longest turbidite systems in the world. The MTS consists of three interconnected deep-water basins, the Seine Abyssal Plain (SAP), the Agadir Basin and the Madeira Abyssal Plain (MAP), connected by a network of distributary channels.
Excellent core control has enabled individual turbidites to be correlated between all three basins, giving a detailed insight into the turbidite depositional architecture of a system with multiple source areas and complex morphology. Large-volume (> 100 km3) turbidites, sourced from the Morocco Shelf, show a relatively simple architecture in the Madeira and Seine Abyssal Plains. Sandy bases form distinct lobes or wedges that thin rapidly away from the basin margin and are overlain by ponded basin-wide muds.
However, in the Agadir Basin, the turbidite fill is more complex owing to a combination of multiple source areas and large variations in turbidite volume. A single, very large turbidity current (200-300 km3 of sediment) deposited most of its sandy load within the Agadir Basin, but still had sufficient energy to carry most of the mud fraction 500 km further downslope to the MAP. Large turbidity currents (100-150 km3 of sediment) deposit most of their sand and mud fraction within the Agadir Basin, but also transport some of their load westwards to the MAP. Small turbidity currents (< 35 km3 of sediment) are wholly confined within the Agadir Basin, and their deposits pinch out on the basin floor.
Turbidity currents flowing beyond the Agadir Basin pass through a large distributary channel system. Individual turbidites correlated across this channel system show major variations in the mineralogy of the sand fraction, whereas the geochemistry and micropalaeontology of the mud fraction remain very similar. This is interpreted as evidence for separation of the flow, with a sand-rich, erosive, basal layer confined within the channel system, overlain by an unconfined layer of suspended mud.
Large-volume turbidites within the MTS were deposited at oxygen isotope stage boundaries, during periods of rapid sea-level change and do not appear to be specifically connected to sea-level lowstands or highstands. This contrasts with the classic fan model, which suggests that most turbidites are deposited during lowstands of sea level. In addition, the three largest turbidites on the MAP were deposited during the largest fluctuations in sea level, suggesting a link between the volume of sediment input and the magnitude of sea-level change.

This record has no associated files available for download.

More information

Published date: 2002
Keywords: sediment cores, turbidites, turbidity currents

Identifiers

Local EPrints ID: 6163
URI: http://eprints.soton.ac.uk/id/eprint/6163
ISSN: 0037-0746
PURE UUID: 2e8ffdda-7509-4168-b19d-42de7d873595

Catalogue record

Date deposited: 30 Jun 2004
Last modified: 09 Nov 2021 06:07

Export record

Altmetrics

Contributors

Author: Russell B. Wynn
Author: Philip P.E. Weaver
Author: Douglas G. Masson
Author: Dorrik A.V. Stow

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×