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Recent sedimentation patterns in deep basins of the Scotia Sea: Interaction between gravitational and contour-current processes



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Abstracts Volume
3rd Deep-Water Circulation Conference (2017):
Multidisciplinary Perspective
September 14-16, 2017 @ Wuhan
College of Marine Science and Technology, China University of Geosciences (Wuhan)
Recent sedimentation patterns in deep basins of the Scotia Sea: Interaction
between gravitational and contour-current processes
A. López-Quirós1, F.J. Lobo1, C. Escutia1, F. Bohoyo2, F.J. Hernández-Molina3, D. Evangelinos1,
A. Salabarnada1, M. García1, L.F. Pérez4, J. Rodríguez-Fernández1, A. Maldonado1
1 Instituto Andaluz de Ciencias de la Tierra, CSIC-UGR, Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain.
2 Instituto Geológico y Minero de España, Ríos Rosas, 23, 28003, Madrid, Spain.
3 Department of Earth Sciences, Royal Holloway University of London, Ogham, Surrey TW20 0EX, UK.
4 Geological Survey of Denmark and Greenland, Geophysical Department, Øster Volga 10, DK-1350 Copenhagen
K, Denmark.
The southern Scotia Sea contains a host of small, deep (up to 4000 m water depths) oceanic
basins and continental banks mainly influenced by two deep-water masses: the Circumpolar Deep
Water (CDW) and the Weddell Sea Deep Water (WSDW). The aim of the present study is to
document the variability of bottom current deposition registered in contourite drifts and their
temporal and/or spatial interaction with gravitational processes, mainly represented by Mass
Transport Deposits-MTDs, in two of these oceanic basins (Ona and Dove basins). Ona Basin is the
westernmost basin of the southern Scotia Sea, whereas Dove Basin is situated in the south-central
Scotia Sea. Both basins are characterized by an irregular physiography dictated by the occurence of
several structural highs.
This work analyses a high-resolution geophysical database comprising multibeam bathymetric
data and very high-resolution sub-bottom profiles. Most of these data were collected onboard the RV
Hespérides during the SCAN-2001, 2004, 2008 and 2013 cruises. In addition, hydrographic data
have been extracted from the World Ocean Database using the ODV software to document the water
column properties.
Extensive sheeted drifts with sub-parallel stratified acoustic facies mainly cover Ona Basin,
while plastered drifts prevail in Dove Basin. The contourite drifts have been formed by the flow of
the CDW/WSDW in Ona Basin and the WSDW in Dove Basin which has been constrained by the
structural hights. Chaotic facies in lenticular shapes interpreted as MTDs appear interbedded within
the stratified facies and extend up to the abyssal plains. The complex structural morphology plays a
key role in sedimentation, as basement highs focus current deposition favoring the formation of
basement-controlled drifts and trigger widespread gravitational processes. As a consequence, the
interplay between gravitational and bottom current processes plays a key role in most of the deep
basins of the Scotia Sea.
Keywords: Scotia Sea, Ona and Dove basins, Contourites, Seafloor morphology, Bottom-current
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