Fine-sediment transport and the depositional record in wave-supported mud flows

Abstract:

Gravitational flux of wave-supported mud flows is a key mechanism in the transport of fine sediment across continental shelves. A better understanding of the physical parameters controlling the resuspension, transport and deposition associated with this process can improve the modeling of sediment from source to sink and the interpretation of the stratigraphic record. The dynamics of wave-supported mud flows is highly complex due to (1) modulation of turbulence by the presence of sediment in a transitional boundary layer, (2) flocculation, erodibility and non-Newtonian behavior of cohesive sediments, and (3) the presence of a small but potentially significant sand fraction. Hence, a fully integrated approach of field observation, laboratory experiments and numerical simulation is necessary. The purpose of this presentation is to provide the most up-to-date synopsis of turbulence-resolving simulations and laboratory observation of wave-supported mud flows, specifically regarding turbulence attenuation by the fine fraction, the role of hindered settling, and turbulence augmentation due to bedforms (anorbital ripples) resulting from a small coarse fraction (coarse silt to fine sand) in the grain-size distribution. New directions integrating lab and field observations of sediment suspension and depositional signatures associated with event evolution are proposed in order to refine the conceptual/phenomenological models of wave-supported mud flows.