Experiments on self-channelized subaqueous fans emplaced by turbidity currents and dilute mudflows

The passage of turbidity currents over submarine fans often results in intense channelization. The channels are typically bounded by levees, and they vary from mildly to strongly meandering. The process of self-channelization remains, however, somewhat obscure. Preliminary experiments reported here demonstrate for the first time that self-channelization of subaqueous fans by turbidity currents can be reproduced at laboratory scale. The same experiments also illustrate self-channelization by dilute mudflows. The resulting weakly sinuous channels can be predominantly depositional, predominantly erosional, or some combination of the two. The channels can elongate to the length of the entire reach available for their formation. They can show both gradual shift and avulsion. A necessary condition for the formation of intricate channelization in the laboratory experiments appears to be a turbidity current that is insufficient to cover the entire area of the fan at any given time. Loose field analogs to the experimental channelized fans (i.e., analogs that are imprecise but contain many similarities) can often be found at the distal end of submarine fans. Two possible examples are cited, one from the Pochnoi system, Bering Sea, and one from the Gulf of Cadiz.