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Architecture and sediment dynamics of the Mauritania Slide Complex

Architecture and sediment dynamics of the Mauritania Slide Complex
Architecture and sediment dynamics of the Mauritania Slide Complex
Large-scale mass wasting is an important sedimentary process along the northwest African margin, and is related to high sediment accumulation rates under an ocean margin upwelling regime. Although the margin is generally arid with limited fluvial input, additional sediment supply comes from wind-borne Saharan dust. Recent mapping of the margin off Mauritania has revealed a major sediment slide, here called the Mauritania Slide Complex, as it comprises elements of true sliding as well as more mobile distal debris flow. Seismic data image stacked slide deposits separated by undisturbed stratified sediments indicating that undisturbed sediment accumulation was interrupted by several phases of slope failure. A series of stepped headwalls, 25–100 m high, represents the source area of the youngest slide event, which most likely occurred as retrogressive type of failure. The area of seafloor affected by this mass movement is 30,000 km2, while the deposit volume is 600 km3. The uppermost debrite unit, which has been 14C dated at 10.5–10.9 ka, forms a broad tongue extending down to the lower slope. This debrite comprises a vertical succession of three different layers of matrix types, with a predominantly outer shelf source at the base and pelagite-dominated composition at the top. The complete sequence of three layers was deposited at a mid slope position, whereas only the upper layers reached the lower slope. A thick pile of sediments with outer shelf/upper slope derived biogenic and terrigenous debris-rich sediments at the base and hemipelagic sediments on top failed at an upper to mid slope location and disintegrated into a layered debris flow on its down-slope journey.
Mass wasting, Slide/debris flow complex, NW-African margin
0264-8172
17-33
Henrich, Rüdiger
243d4193-683d-455a-9c4e-e90c6000e465
Hanebuth, Till J.J.
ff4d89c5-033b-4d42-a2b8-8fc85acd2bd3
Krastel, Sebastian
4d9bf243-610a-4875-8c03-cd975c9f8542
Neubert, Nadja
28252b05-dd06-46e9-9e02-f467787db975
Wynn, Russell B.
72ccd765-9240-45f8-9951-4552b497475a
Henrich, Rüdiger
243d4193-683d-455a-9c4e-e90c6000e465
Hanebuth, Till J.J.
ff4d89c5-033b-4d42-a2b8-8fc85acd2bd3
Krastel, Sebastian
4d9bf243-610a-4875-8c03-cd975c9f8542
Neubert, Nadja
28252b05-dd06-46e9-9e02-f467787db975
Wynn, Russell B.
72ccd765-9240-45f8-9951-4552b497475a

Henrich, Rüdiger, Hanebuth, Till J.J., Krastel, Sebastian, Neubert, Nadja and Wynn, Russell B. (2008) Architecture and sediment dynamics of the Mauritania Slide Complex. Marine and Petroleum Geology, 25 (1), 17-33. (doi:10.1016/j.marpetgeo.2007.05.008).

Record type: Article

Abstract

Large-scale mass wasting is an important sedimentary process along the northwest African margin, and is related to high sediment accumulation rates under an ocean margin upwelling regime. Although the margin is generally arid with limited fluvial input, additional sediment supply comes from wind-borne Saharan dust. Recent mapping of the margin off Mauritania has revealed a major sediment slide, here called the Mauritania Slide Complex, as it comprises elements of true sliding as well as more mobile distal debris flow. Seismic data image stacked slide deposits separated by undisturbed stratified sediments indicating that undisturbed sediment accumulation was interrupted by several phases of slope failure. A series of stepped headwalls, 25–100 m high, represents the source area of the youngest slide event, which most likely occurred as retrogressive type of failure. The area of seafloor affected by this mass movement is 30,000 km2, while the deposit volume is 600 km3. The uppermost debrite unit, which has been 14C dated at 10.5–10.9 ka, forms a broad tongue extending down to the lower slope. This debrite comprises a vertical succession of three different layers of matrix types, with a predominantly outer shelf source at the base and pelagite-dominated composition at the top. The complete sequence of three layers was deposited at a mid slope position, whereas only the upper layers reached the lower slope. A thick pile of sediments with outer shelf/upper slope derived biogenic and terrigenous debris-rich sediments at the base and hemipelagic sediments on top failed at an upper to mid slope location and disintegrated into a layered debris flow on its down-slope journey.

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More information

Published date: January 2008
Keywords: Mass wasting, Slide/debris flow complex, NW-African margin

Identifiers

Local EPrints ID: 63931
URI: http://eprints.soton.ac.uk/id/eprint/63931
ISSN: 0264-8172
PURE UUID: 1e3828ac-c182-4893-a49a-81ac2b1c0998

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Date deposited: 19 Nov 2008
Last modified: 15 Mar 2024 11:45

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Contributors

Author: Rüdiger Henrich
Author: Till J.J. Hanebuth
Author: Sebastian Krastel
Author: Nadja Neubert
Author: Russell B. Wynn

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