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Scaling analysis of multipulsed turbidity current evolution with application to turbidite interpretation

Ho, Viet Luan; Dorrell, Robert M.; Keevil, Gareth M.; Burns, Alan D.; McCaffrey, William D.

Authors

Viet Luan Ho

Gareth M. Keevil

Alan D. Burns

William D. McCaffrey



Abstract

Deposits of submarine turbidity currents, turbidites, commonly exhibit upward‐fining grain size profiles reflecting deposition under waning flow conditions. However, more complex grading patterns such as multiple cycles of inverse‐to‐normal grading are also seen and interpreted as recording deposition under cycles of waxing and waning flow. Such flows are termed multipulsed turbidity currents, and their deposits pulsed or multipulsed turbidites. Pulsing may arise at flow initiation, or following downstream flow combination. Prior work has shown that individual pulses within multipulsed flows are advected forward and merge, such that complex longitudinal velocity profiles eventually become monotonically varying, although transition length scales in natural settings could not be predicted. Here we detail the first high frequency spatial (vertical, streamwise) and temporal measurements of flow velocity and density distribution in multipulsed gravity current experiments. The data support both a process explanation of pulse merging and a phase‐space analysis of transition length scales; in prototype systems, the point of merging corresponds to the transition in any deposit from multipulsed to normally graded turbidites. The scaling analysis is limited to quasi‐horizontal natural settings in which multipulsed flows are generated by sequences of relatively short sediment failures (10 km) sequences of breaches or where pulsing arises from combination at confluences of single‐pulsed flows, such flows may be responsible for the pulsing signatures seen in some distal turbidites, >100 km from source.

Journal Article Type Article
Publication Date May 22, 2018
Journal Journal of Geophysical Research: Oceans
Print ISSN 2169-9291
Electronic ISSN 2169-9291
Publisher American Geophysical Union
Peer Reviewed Peer Reviewed
Volume 123
Issue 5
Pages 3668-3684
APA6 Citation Ho, V. L., Dorrell, R. M., Keevil, G. M., Burns, A. D., & McCaffrey, W. D. (2018). Scaling analysis of multipulsed turbidity current evolution with application to turbidite interpretation. Journal of Geophysical Research: Oceans, 123(5), 3668-3684. https://doi.org/10.1029/2017jc013463
DOI https://doi.org/10.1029/2017jc013463
Keywords Turbidity currents; Turbidites; Pulsed turbidites
Publisher URL https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2017JC013463
Related Public URLs http://eprints.whiterose.ac.uk/129624/
Copyright Statement © 2018. American Geophysical Union. All Rights Reserved.

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