Factors controlling the morphology and internal sediment architecture of moats and their associated contourite drifts

Type Article
Date 2023-08
Language English
Author(s) Wilckens Henriette1, 2, Schwenk Tilmann1, Lüdmann Thomas3, Betzler Christian3, Zhang Wenyan4, Chen Jiayue4, Hernandez-Molina F.Javier5, Lefebvre Alice2, Cattaneo AntonioORCID6, Spiess Volkhard1, Miramontes Elda1, 2
Affiliation(s) 1 : Faculty of Geosciences, University of Bremen, 28359 Bremen, Germany
2 : MARUM – Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
3 : Institute for Geology, University of Hamburg, 20146 Hamburg, Germany
4 : Institute of Coastal Systems, Helmholtz-Zentrum Hereon, 21502 Geesthacht, Germany
5 : Department of Earth Sciences, Royal Holloway University of London, Egham TW20 0EY, Surrey, UK
6 : UMR 6538 GEO-OCEAN, Ifremer, Univ Brest, CNRS, Univ. Bretagne-Sud, 29280 Plouzané, France
Source Sedimentology (0037-0746) (Wiley / Blackwell), 2023-08 , Vol. 70 , N. 5 , P. 1472-1495
DOI 10.1111/sed.13093
WOS© Times Cited 5
Keyword(s) Bottom current, contourite drift, geomorphology, moats, sediment transport, sedimentary processes

The interaction of sedimentary systems with oceanographic processes in deep-water environments is not well understood yet, despite its importance for palaeoenvironmental reconstructions, and for a full understanding of source-to-sink sediment transport. The aim of this study is to improve the understanding of how contourite moats, elongated depressions formed by bottom currents associated with contourite drifts, develop and of the link between moat-drift system morphology and bottom current dynamics. This study provides a systematic comparison of 185 cross-sections of moat-drift systems distributed at 39 different locations worldwide, and a detailed analysis of the morphology of six moats that cover a wide range of typical geological and hydrodynamic settings. Additionally, in situ measured current data were analysed to better link hydrodynamics to moat morphology. The median of all profiles across all moat-drift systems reveals a 50 m relief, a width of 2.3 km, a relief to width ratio of 0.022, a slope angle of 6°, a drift angle of 3° and a concave-up shaped morphology. Moats can be over 100 km long. Some moats are driven by sediment erosion while others are depositional and primarily exist due to differential sedimentation inside the moat compared to the drift alongside the moat. A new sub-classification of moat-drift systems based on their stratigraphy is proposed. This classification distinguishes moats depending on the degree of erosion versus deposition. No relation is found between latitude and moat-drift morphology or stratigraphy in the analysed examples. The combined data indicate that a steeper slope focuses the current more than a gentle slope, resulting in an increase of the relief-width ratio and drift angle. Thus, this study provides new insides into the interaction of ocean currents with sedimentary morphology, which thereby affects the evolution of a poorly understood deepwater sedimentary system.

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Wilckens Henriette, Schwenk Tilmann, Lüdmann Thomas, Betzler Christian, Zhang Wenyan, Chen Jiayue, Hernandez-Molina F.Javier, Lefebvre Alice, Cattaneo Antonio, Spiess Volkhard, Miramontes Elda (2023). Factors controlling the morphology and internal sediment architecture of moats and their associated contourite drifts. Sedimentology, 70(5), 1472-1495. Publisher's official version : https://doi.org/10.1111/sed.13093 , Open Access version : https://archimer.ifremer.fr/doc/00823/93490/