Role of fine-grained sediment in turbidity current flow dynamics and resulting deposits

摘要

A numerical model of a turbidity current driven by poorly-sorted sediment is developed. The model is applied to study the role that finer fractions of suspended sediment play in the evolution of a submarine fan due to the flow of a subsiding turbidity current. The depth-integrated model can treat multiple size fractions of suspended sediment, ranging from clay to coarse sand. The model is implemented in a sensitivity study by varying inflow fractions of suspended sediments. Computed results clearly indicate that a modest increase in fine sediment content in the inflow dramatically increases the sand carrying capacity of a turbidity current. It is also found that clay is more effective than fine or coarse silt in maintaining the momentum and the identity of a current. Downstream fining and gradual thinning of the simulated deposit is observed in computations performed with multiple grain sizes.