Experiments on Subaqueous Fans Emplaced by Turbidity Currents

CANTELLI, ALESSANDRO; FERNANDEZ, ROCIO LUZ; PIRMEZ, CARLOS; SYLVESTER, Z.; PARKER, GARY

Estados Unidos

Congreso; Fall meeting American Geophysical Union; 2008

American Geophysical Union

The passage of turbidity currents over submarine fans can locally become self-channelized. Self- channelized flows are typically sinuous and bounded by levees. The process of self-channelization remains, however, somewhat obscure. We have performed experimental work to investigate self-channelization of subaqueous fans and lobes at laboratory scale. The resulting weakly sinuous channels can be depositional, erosional, or some combination of the two. The channels elongate to the length of the reach available for their formation; in case of flume experiments, the reach is the size of the flume itself. They show both gradual shift and avulsion. Two necessary conditions for the formation of intricate channelization, in the laboratory experiments are: a) a multiplicity of grain sizes and b) turbidity currents that are insufficiently large to cover the entire area of the fan at any given time. We conducted a series of experiments to investigate the effects of changes in slope gradient and inflow concentration on the formation and evolution of channels and associated lobes. Change in slope is the main parameter to drive deposition of lobes. Different conditions were tested showing different lobe shapes and evolutional patterns. In order to validate the experiments, data are scaled to the field and compared with outcrop and seismic observations.