Experimental Work on Self-Formed Submarine Channels
Alessandro Cantelli1, Sara Johnson2, Gary Parker1, and Carlos Pirmez3
1 University of Illinois, Urbana, IL
2 University of Minnesota, Minneapolis
3 Shell International E&P, Inc, Houston, TX
Important questions regarding submarine channel formation still remain. In particular, the process of self-channelization continues to be poorly understood and needs investigation. Are the flows in the regime of turbidity currents or debris flows, or rather a combination of the two? What is the main mechanism responsible for submarine channel formation? How can we relate the characteristics of the flows with the channel formation?
In order to answer some of these questions, a set of preliminary laboratory experiments was performed at Saint Anthony Falls Laboratory (University of Minnesota), and for the first time experiments were able to demonstrate that self-channelization of subaqueous fans can be reproduced at laboratory scale.
The resulting weakly sinuous channels can be predominantly depositional, predominantly erosional or some combination of the two. The channels can elongate along the entire available length of the reach for their formation. They can demonstrate both gradual shift and avulsion. Experiments show other features typical of the submarine environment like upstream-migrating knickpoints, distal lobes, and channel bifurcations.
Rheological tests have been performed in order to understand the characteristics of the flow and in particular to evaluate if the channel formations are due to the action of a turbidity current, a debris flow, or a combination of the two.
In order to obtain high resolution data of the topography, grain size distributions, and flow characteristics, new instrumentation is being added to the experimental facility and the authors are confident that they will be able to show informative, detailed data on the evolution of submarine channel formation.