Experiments on incipient channelization of submarine fans

Abstract

Experiments on the formation of channelized submarine fans by the passage of successive turbidity currents are presented. Channels similar to subaerial rivers are found in many submarine fans. The inception of channels on submarine fans, which are essentially depositional environments, can be explained in terms of the lateral distribution of the rates of deposition and erosion of suspended sediment associated with a passing turbidity current. The experiments reported here supplement the findings of a numerical model developed earlier to study the inception of channel-levee systems on submarine fans. The experimental setup is a simple replication of a surface at the base of a continental slope receiving a turbidity current from a canyon. The turbidity current was generated by releasing a sediment-water mixture of low sediment concentration from an overhead tank into a quiescent water body held in a rectangular tank. The bottom slope of the tank was varied between 3 and 10%. Two sediment sizes, with geometric mean sizes of 71 μm and 110 μm were used. The bed profile was measured after the completion of each run. A 2-D depth-averaged numerical model of turbidity current was then run with the input conditions from the experiment. The resulting bed profiles were compared with the measured data. Generally good agreement between the experimental and numerical findings is observed.