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4. Knickpoints and crescentic bedform interactions in submarine channels

Author

Chen, Ye, primary, Parsons, Daniel R., additional, Simmons, Stephen M., additional, Williams, Rebecca, additional, Cartigny, Matthieu J. B., additional, Hughes Clarke, John E., additional, Stacey, Cooper D., additional, Hage, Sophie, additional, Talling, Peter J., additional, Azpiroz‐Zabala, Maria, additional, Clare, Michael A., additional, Hizzett, Jamie L., additional, Heijnen, Maarten S., additional, Hunt, James E., additional, Lintern, D. Gwyn, additional, Sumner, Esther J., additional, Vellinga, Age J., additional, and Vendettuoli, Daniela, additional

Published
2021
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5. Direct Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes

Author

Hage, Sophie, primary, Cartigny, Matthieu J.B., additional, Sumner, Esther J., additional, Clare, Michael A., additional, Hughes Clarke, John E., additional, Talling, Peter J., additional, Lintern, D. Gwyn, additional, Simmons, Stephen M., additional, Silva Jacinto, Ricardo, additional, Vellinga, Age J., additional, Allin, Joshua R., additional, Azpiroz‐Zabala, Maria, additional, Gales, Jenny A., additional, Hizzett, Jamie L., additional, Hunt, James E., additional, Mozzato, Alessandro, additional, Parsons, Daniel R., additional, Pope, Ed L., additional, Stacey, Cooper D., additional, Symons, William O., additional, Vardy, Mark E., additional, and Watts, Camilla, additional

Published
2019
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6. The depositional signature of high‐aggradation chute‐and‐pool bedforms: The build‐and‐fill structure.

Author

Slootman, Arnoud, Vellinga, Age J., Moscariello, Andrea, Cartigny, Matthieu J. B., and Ventra, Dario

Subjects
*HYDRAULIC jump, *OPEN-channel flow, *POTENTIAL flow, *HYDRAULIC control systems, *PLEISTOCENE Epoch, *QUARRIES & quarrying
Abstract

Chutes‐and‐pools are hybrid bedforms that occur in upper‐flow‐regime conditions, populating the stability field between antidunes and cyclic steps. Chutes‐and‐pools consist of a superimposition of a train of antidunes on a longer‐wavelength cyclic‐step instability. The presence of a hydraulic jump is more persistent in chutes‐and‐pools than the bores occasionally seen on breaking‐wave antidunes, yet not permanent as over cyclic‐step bedforms. The nature of chute‐and‐pool structures preserved in the depositional record is controlled largely by aggradation rate. This paper documents chute‐and‐pool structures generated beneath highly aggradational sediment density‐flows at the subaqueous toe‐of‐slope of a Pleistocene carbonate wedge. Quarry exposures enable the morphodynamic reconstruction of the sediment‐bed configuration that produced the identified structures. Wave‐breaking on growing antidunes occurred without the destruction of the antidune, which deviates from observations in low‐aggradation subaerial open‐channel flows. The antidune build‐up was followed by hydraulic jump controlled deposition in the antidune trough. Two‐dimensional depth‐resolved numerical simulations have been used to validate this process interpretation. The term aggradational chutes‐and‐pools is proposed for these bedforms, associated with the formation of build‐and‐fill structures consisting of interstratified convex lenses (in‐phase wave regime) and concave lenses (hydraulic jump regime). Such structures contrast with the scour‐and‐fill structures produced by low‐aggradation chutes‐and‐pools frequently described from subaerial open‐channel‐flow deposits. This study demonstrates a potential difference in flow behaviour between open‐channel flows and density flows in the supercritical regime. [ABSTRACT FROM AUTHOR]

Published
2021
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7. How to recognize crescentic bedforms formed by supercritical turbidity currents in the geologic record: insights from active submarine channels

Author

Hage, Sophie, Cartigny, Matthieu J.B., Clare, Michael A., Sumner, Esther J., Vendettuoli, Daniela, Hughes Clarke, John E., Hubbard, Stephen M., Talling, Peter J., Lintern, D. Gwyn, Stacey, Cooper D., Englert, Rebecca G., Vardy, Mark E., Hunt, James E., Yokokawa, Miwa, Parsons, Daniel R., Hizzett, Jamie L., Azpiroz-Zabala, Maria, and Vellinga, Age J.

Abstract

Submarine channels have been important throughout geologic time for feeding globally significant volumes of sediment from land to the deep sea. Modern observations show that submarine channels can be sculpted by supercritical turbidity currents (seafloor sediment flows) that can generate upstream-migrating bedforms with a crescentic planform. In order to accurately interpret supercritical flows and depositional environments in the geologic record, it is important to be able to recognize the depositional signature of crescentic bedforms. Field geologists commonly link scour fills containing massive sands to crescentic bedforms, whereas models of turbidity currents produce deposits dominated by back-stepping beds. Here we reconcile this apparent contradiction by presenting the most detailed study yet that combines direct flow observations, time-lapse seabed mapping, and sediment cores, thus providing the link from flow process to depositional product. These data were collected within the proximal part of a submarine channel on the Squamish Delta, Canada. We demonstrate that bedform migration initially produces back-stepping beds of sand. However, these back-stepping beds are partially eroded by further bedform migration during subsequent flows, resulting in scour fills containing massive sand. As a result, our observations better match the depositional architecture of upstream-migrating bedforms produced by fluvial models, despite the fact that they formed beneath turbidity currents.

Published
2018

8. How to recognize crescentic bedforms formed by supercritical turbidity currents in the geologic record: Insights from active submarine channels

Author

Hage, Sophie, primary, Cartigny, Matthieu J.B., additional, Clare, Michael A., additional, Sumner, Esther J., additional, Vendettuoli, Daniela, additional, Hughes Clarke, John E., additional, Hubbard, Stephen M., additional, Talling, Peter J., additional, Lintern, D. Gwyn, additional, Stacey, Cooper D., additional, Englert, Rebecca G., additional, Vardy, Mark E., additional, Hunt, James E., additional, Yokokawa, Miwa, additional, Parsons, Daniel R., additional, Hizzett, Jamie L., additional, Azpiroz-Zabala, Maria, additional, and Vellinga, Age J., additional

Published
2018
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10. How is a turbidite actually deposited?

Author

Zhiyuan Ge, Nemec, Wojciech, Vellinga, Age J., and Gawthorpe, Rob L.

Subjects
*TURBIDITES, *SAND dunes, *EARTH sciences, *TURBIDITY currents, *COMPUTATIONAL fluid dynamics, *MARINE pollution
Abstract

The article explores the general stratigraphic notion of a gross incompleteness of sedimentary record may then extend down to the deposition time scale of a single turbidite. It mentions that deposition of a classic turbidite by a surge-type turbidity current, as envisaged by conceptual models, as widely considered a discrete event of continuous sediment accumulation at a falling rate by the gradually waning density flow.

Published
2022
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