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Geomorphology of Ona Basin, southwestern Scotia Sea (Antarctica): Decoding the spatial variability of bottom-current pathways

Geomorphology of Ona Basin, southwestern Scotia Sea (Antarctica): Decoding the spatial variability of bottom-current pathways
Geomorphology of Ona Basin, southwestern Scotia Sea (Antarctica): Decoding the spatial variability of bottom-current pathways
Ona Basin, the westernmost oceanic basin in the southern Scotia Sea, is affected by the opposite flows of Circumpolar Deep Water (CDW) and Weddell Sea Deep Water (WSDW); thus, it represents a key location for exploring seafloor morphologies influenced by bottom currents. The present study aims to capture the spatial arrangement of recent subsurface contourite features, assuming a latitudinal influence of water masses and the interactions between along- and downslope processes, in order to contribute to the knowledge of regional deepwater flow pathways and to the sedimentary model of small sediment-starved oceanic basins. To this end, the investigation combines an interpretation of multibeam bathymetry and parametric echo sounder seismic data complemented with hydrological data. The distribution of morpho-sedimentary features in Ona Basin reveals two major domains. The southern margin of the basin can be regarded as a mixed/hybrid system containing abundant sediment drifts with channels and contourite moats and a lateral continuity interrupted by downslope morphologies. In contrast, the northern abyssal setting comprises relatively homogeneous large sheeted drifts with superimposed sediment waves, mounded drifts, and several scattered erosive features, likely reflecting the more distinct influence of deepwater contourite processes. Our work demonstrates that tectonic features in the southern basin control the interaction between deepwater along- and downslope processes, as the westward flow of the WSDW is deflected, channelized, and intensified along its westward route. In the northern region, the study indicates an overall clockwise rotation of the WSDW flow, with the spatial and vertical variability of CDW and WSDW affecting the distribution of bottom-current features around seamounts and/or structural highs. The results underscore the importance of sloping interphases in the water mass vertical structure, the degree of basin confinement, and the influence of local bathymetric elevations in sedimentation models of small sediment-starved oceanic basins.
0025-3227
López-Quirós, Adrián
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Lobo, Francisco J.
4a7db2f3-d8cd-4b19-a130-4583bdd68eb8
Escutia, Carlota
0ec26deb-bd11-43c0-80b2-58186da90d64
García, Marga
52d484cf-dacf-451a-9b00-5ca1351c4411
Hernández-Molina, F. Javier
256ca467-a4e8-4f24-9ff1-23bd2ab8d28d
Pérez, Lara F.
7263ce0e-40c4-4a89-9f4e-306acf59c00e
Bohoyo, Fernando
6c159131-f550-4583-984e-1d0e55d0708e
Evangelinos, Dimitris
379afac0-ca31-4249-9253-35ec7cf9b10c
Salabarnada, Ariadna
6389c6c4-d0cd-4956-9c5c-ed2d7864ec97
Maldonado, Andrés
0fc21d2e-95f7-4b2c-906d-47e754bbda9f
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
López-Quirós, Adrián
1bb26984-7979-4ae6-8e8c-ef4477aa30d6
Lobo, Francisco J.
4a7db2f3-d8cd-4b19-a130-4583bdd68eb8
Escutia, Carlota
0ec26deb-bd11-43c0-80b2-58186da90d64
García, Marga
52d484cf-dacf-451a-9b00-5ca1351c4411
Hernández-Molina, F. Javier
256ca467-a4e8-4f24-9ff1-23bd2ab8d28d
Pérez, Lara F.
7263ce0e-40c4-4a89-9f4e-306acf59c00e
Bohoyo, Fernando
6c159131-f550-4583-984e-1d0e55d0708e
Evangelinos, Dimitris
379afac0-ca31-4249-9253-35ec7cf9b10c
Salabarnada, Ariadna
6389c6c4-d0cd-4956-9c5c-ed2d7864ec97
Maldonado, Andrés
0fc21d2e-95f7-4b2c-906d-47e754bbda9f
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6

López-Quirós, Adrián, Lobo, Francisco J., Escutia, Carlota, García, Marga, Hernández-Molina, F. Javier, Pérez, Lara F., Bohoyo, Fernando, Evangelinos, Dimitris, Salabarnada, Ariadna, Maldonado, Andrés and Naveira Garabato, Alberto C. (2020) Geomorphology of Ona Basin, southwestern Scotia Sea (Antarctica): Decoding the spatial variability of bottom-current pathways. Marine Geology, 422, [106113]. (doi:10.1016/j.margeo.2020.106113).

Record type: Article

Abstract

Ona Basin, the westernmost oceanic basin in the southern Scotia Sea, is affected by the opposite flows of Circumpolar Deep Water (CDW) and Weddell Sea Deep Water (WSDW); thus, it represents a key location for exploring seafloor morphologies influenced by bottom currents. The present study aims to capture the spatial arrangement of recent subsurface contourite features, assuming a latitudinal influence of water masses and the interactions between along- and downslope processes, in order to contribute to the knowledge of regional deepwater flow pathways and to the sedimentary model of small sediment-starved oceanic basins. To this end, the investigation combines an interpretation of multibeam bathymetry and parametric echo sounder seismic data complemented with hydrological data. The distribution of morpho-sedimentary features in Ona Basin reveals two major domains. The southern margin of the basin can be regarded as a mixed/hybrid system containing abundant sediment drifts with channels and contourite moats and a lateral continuity interrupted by downslope morphologies. In contrast, the northern abyssal setting comprises relatively homogeneous large sheeted drifts with superimposed sediment waves, mounded drifts, and several scattered erosive features, likely reflecting the more distinct influence of deepwater contourite processes. Our work demonstrates that tectonic features in the southern basin control the interaction between deepwater along- and downslope processes, as the westward flow of the WSDW is deflected, channelized, and intensified along its westward route. In the northern region, the study indicates an overall clockwise rotation of the WSDW flow, with the spatial and vertical variability of CDW and WSDW affecting the distribution of bottom-current features around seamounts and/or structural highs. The results underscore the importance of sloping interphases in the water mass vertical structure, the degree of basin confinement, and the influence of local bathymetric elevations in sedimentation models of small sediment-starved oceanic basins.

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More information

Accepted/In Press date: 28 December 2019
e-pub ahead of print date: 13 January 2020
Published date: April 2020

Identifiers

Local EPrints ID: 439765
URI: http://eprints.soton.ac.uk/id/eprint/439765
ISSN: 0025-3227
PURE UUID: 6736adda-cc1f-4c7a-94c4-e15b61e2c84e

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Date deposited: 01 May 2020 16:40
Last modified: 06 Oct 2020 19:17

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