Gong, C, Peakall, J, Wang, Y et al. (2 more authors) (2017) Flow processes and sedimentation in contourite channels on the northwestern South China Sea margin: A joint 3D seismic and oceanographic perspective. Marine Geology, 393. pp. 176-193. ISSN 0025-3227
Abstract
3D seismic data from the northwestern South China Sea margin, coupled with the quantification of oceanographic processes and morphological results, were used to infer three-dimensional flow processes and in turn sedimentation in contourite channels. Contour currents resulting from the Northern Pacific Deep Water (NPDW-CCs) flowing through the bends of contourite channels around a topographic high lead to an imbalance in the transverse direction, around the bend, between three competing forces (i.e., upslope directed Coriolis forces versus downslope directed centrifugal and pressure-gradient forces). The interface deflection of NPDW-CCs by Coriolis, pressure gradient, and centrifugal forces yields a helical flow cell consisting of upper return flows directed downslope and basal flows orientated upslope. Ekman boundary layers, at the base and flow interface, are also likely present leading to flows in the downslope direction. The helical flow cell in the bulk of contour currents, and Ekman boundary layers, constitute a Coriolis force-induced helical flow circulation, which we suggest promoted asymmetric intra-channel deposition (i.e., downslope deposition versus upslope erosion), forcing contourite channels to consistently migrate in an upslope direction. Such Coriolis force-induced helical flow circulation is evidenced by occurrence of volumetrically significant overbank deposits along downslope margins and by asymmetric channel cross-sections with steepened channel walls and truncation terminations along upslope margins. The Coriolis force-induced helical flow circulation exhibits subcritical flow conditions (represented by internal Froude numbers estimated as 0.04 to 0.19), and is sufficiently deep to spill out of the studied contourite channels, yielding overbank deposits along the downslope flanks of the contourite channels.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Published by Elsevier B.V. This is an author produced version of a paper published in Marine Geology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Contourite channels; Northwestern South China Sea margin; Coriolis forces; Helical flow circulation; Ekman boundary layer |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Institute for Applied Geosciences (IAG) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 17 Nov 2016 16:15 |
Last Modified: | 26 Jan 2018 10:15 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.margeo.2016.11.002 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:107683 |