Heerema, Catharina J. and Talling, Peter J. and Cartigny, Matthieu J. and Paull, Charles K. and Bailey, Lewis and Simmons, Stephen M. and Parsons, Daniel R. and Clare, Michael A. and Gwiazda, Roberto and Lundsten, Eve and Anderson, Krystle and Maier, Katherine L. and Xu, Jingping P. and Sumner, Esther J. and Rosenberger, Kurt and Gales, Jenny and McGann, Mary and Carter, Lionel and Pope, Edward (2020) 'What determines the downstream evolution of turbidity currents?', Earth and planetary science letters., 532 . p. 116023.
Seabed sediment flows called turbidity currents form some of the largest sediment accumulations, deepest canyons and longest channel systems on Earth. Only rivers transport comparable sediment volumes over such large areas; but there are far fewer measurements from turbidity currents, ensuring they are much more poorly understood. Turbidity currents differ fundamentally from rivers, as turbidity currents are driven by the sediment that they suspend. Fast turbidity currents can pick up sediment, and self-accelerate (ignite); whilst slow flows deposit sediment and dissipate. Self-acceleration cannot continue indefinitely, and flows might reach a near-uniform state (autosuspension). Here we show how turbidity currents evolve using the first detailed measurements from multiple locations along their pathway, which come from Monterey Canyon offshore California. All flows initially ignite. Typically, initially-faster flows then achieve near-uniform velocities (autosuspension), whilst slower flows dissipate. Fractional increases in initial velocity favour much longer runout, and a new model explains this bifurcating behaviour. However, the only flow during less-stormy summer months is anomalous as it self-accelerated, which is perhaps due to erosion of surficial-mud layer mid-canyon. Turbidity current evolution is therefore highly sensitive to both initial velocities and seabed character.
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|Publisher Web site:||https://doi.org/10.1016/j.epsl.2019.116023|
|Publisher statement:||© 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license. (http://creativecommons.org/licenses/by/4.0/)|
|Date accepted:||07 December 2019|
|Date deposited:||13 January 2020|
|Date of first online publication:||19 December 2019|
|Date first made open access:||14 January 2020|
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