Jeff Peakall¹, Bill McCaffrey¹, Ben Kneller²

(1) University of Leeds, Leeds, United Kingdom
(2) University of California, Santa Barbara, CA

ABSTRACT: Sinuous Submarine Channels: Evolution and Flow Processes

Sinuous submarine channels have drawn strong analogies with meandering rivers in terms of their evolution and range of geomorphological and architectural features. The strength of this analogy is reassessed here, and a new model is proposed for the evolution of high-sinuosity, aggradational leveed channels. This model predicts that submarine channels do not undergo the downstream translation and lateral migration characteristic of meandering systems, but instead evolve to an equilibrium planform before undergoing near vertical aggradation. Sinuous leveed channels should therefore produce isolated ribbons of thalweg deposits of predictable three-dimensional geometry, with significant variations between bend apex and bend cross-over positions.

A simple model of the flow structure and evolution of turbidity currents in submarine channels is also proposed. This model predicts that flows are highly stratified, have significant supra-levee thicknesses, and form broad overbank bodies of low-concentration fluid. These predictions challenge existing concepts of overbank flow in submarine channels such as flow stripping. Widespread, low-concentration overbank flow would produce spatially extensive levee beds with high initial connectivity, and these deposits might subsequently be only partly disrupted by much smaller areal slumps and slides. This model suggests that the high connectivities observed in recent discoveries in levee deposits are not anomalous.

In summary, a new three-dimensional model for the evolution and deposits of sinuous submarine leveed channels is presented. This model is coupled with a flow process model which provides a coherent set of process explanations for the primary sedimentary data on submarine channels including the observed connectivities in levee deposits.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado