The role of physicochemical processes in controlling sediment transport and deposition in turbidity currents

Experimental results are presented that illustrate the role of chemical and electrostatic particle–particle interactions in controlling sediment transport in turbidity currents. These experiments were conducted in a small laboratory channel to allow good control of the background water chemistry. Both kaolinite clay and silica particles were used to generate the turbidity currents, and both sodium and calcium chloride were used to prepare background solutions with a wide range of ionic strengths (salinities). The zeta potential of kaolinite was found to vary considerably under the range of experimental conditions used, and this produced a significant variation in the size distribution of these particles. As a result, kaolinite deposition from the turbidity current increased greatly with background salt concentration. Silica remained highly negatively charged under all experimental conditions, and the behavior of silica turbidity currents did not change with salinity. These results demonstrate that the behavior of turbidity currents is dependent on the composition of the associated sediments and the background water chemistry.