--> Abstract: Process Models Describing the Architecture of Submarine Channel-Levee Systems, by Kenneth I. Skene; #90078 (2008)

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Process Models Describing the Architecture of Submarine Channel-Levee Systems

Kenneth I. Skene
Geologic Modelling, ExxonMobil Upstream Research, Houston, TX

An analytical and numerical model describing the downstream flow of an overbanking turbidity current are used to explore controls on levee architecture. An analytical solution to the conservation equations for momentum, mass, and sediment indicates that the down- and across-channel lengthscales in levee architecture (levee e-folding width and e-folding length, respectively) depend on channel dimensions and the character of the through-channel flow. Using available observational data and the minimum variance method to apply the hydraulic geometry equations, it was found that the model compares well with observations. Direct measurements of turbidity current flow available from Reserve Fan, Lake Superior, provided additional tests for the model, and the model was again found to compare well with observations. Relaxing the assumptions made to analytically solve the conservation equations (constant flow thickness and constant channel dimensions) requires that these same equations be solved numerically. Allowing channel geometry to vary smoothly in the downstream direction with channel depth and channel slope decreasing shows that the assumptions made in the analytical solution generally hold. However, the results from the numerical model suggest that flow parameters while not constant do slowly vary downstream. A significant consequence of this variation is that the particle settling velocity of sediments deposited on the levee should show a predictable downstream decrease. It should be noted that neither model unequivocally reproduces the complexity observed in submarine channel-levee architecture. However the models do offer some insight into what are the relevant observations and physical constraints that will be essential to future modeling efforts.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas