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.

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.

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

• Journal Article Type: Article
• Acceptance Date: Apr 8, 2018
• Online Publication Date: Apr 19, 2018
• Publication Date: May 22, 2018
• Deposit Date: Jul 17, 2018
• Publicly Available Date: Oct 27, 2022
• Journal: Journal of Geophysical Research: Oceans
• Print ISSN: 2169-9291
• Publisher: American Geophysical Union
• Peer Reviewed: Peer Reviewed
• Volume: 123
• Issue: 5
• Pages: 3668-3684
• DOI: https://doi.org/10.1029/2017jc013463
• Keywords: Turbidity currents; Turbidites; Pulsed turbidites
• Public URL: https://hull-repository.worktribe.com/output/816962
• Publisher URL: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2017JC013463
• Related Public URLs: http://eprints.whiterose.ac.uk/129624/
• Contract Date: Jul 17, 2018