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

A numerical model of a turbidity current driven by poorly-sorted sediment i s 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 flo w of a subsiding turbidity current. The depth-integrated model can treat mu ltiple size fractions of suspended sediment, ranging from clay to coarse sa nd. The model is implemented in a sensitivity study by varying inflow fract ions of suspended sediments. Computed results clearly indicate that a modes t increase in fine sediment content in the inflow dramatically increases th e 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 s imulated deposit is observed in computations performed with multiple,grain sizes. (C) 2000 Elsevier Science Ltd All rights reserved.