--> Abstract: Flow Efficiency Controls on the Geometry and Location of Turbidite Sheet Systems, by William D. McCaffrey, Benjamin C. Kneller, and Omar Al-Ja'aidi; #90914(2000)
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William D. McCaffrey1, Benjamin C. Kneller2, Omar Al-Ja'aidi2
(1) Leeds University, Leeds, United Kingdom
(2) Leeds University

Abstract: Previous HitFlowNext Hit efficiency controls on the geometry and location of turbidite sheet systems

Previous HitFlowNext Hit efficiency gives a relative measure of the distance a Previous HitflowNext Hit may travel. It is a characteristic of the Previous HitflowNext Hit, and is therefore independent of topographic effects. In flows of higher efficiency, the transport phase is prolonged, thus elongating the deposit, or displacing it distally. Although early workers stressed the importance of the fine-grained component of the sediment budget on Previous HitflowNext Hit efficiency, new work outlined here illustrates that this is only one of a number of linked controls, which include: 1. the suspended sediment grainsize distribution, 2. suspension density and 3. Previous HitflowNext Hit volume. The presence of a significant fine-tail to the sediment budget controls Previous HitflowNext Hit efficiency through the mechanisms of buoyancy enhancement for the coarser-grained suspended sediment component, reduced rates of momentum loss due to low mud deposition rates and friction reduction; suspension density affects Previous HitflowNext Hit efficiency principally through its impact upon the Previous HitflowNext Hit momentum, whilst suspension volume controls Previous HitflowNext Hit efficiency principally by affecting the shear velocities. We present experimental data on scaled, sediment-bearing turbidity currents which model the deposition of basin-floor turbidite sheet sands. These illustrate that each of the controls outlined above has a characteristically different effect upon the volume and geometry of the resultant deposit. Previous HitDeterminingNext Hit paleo-Previous HitflowNext Hit efficiency can be important when predicting the loci of sand deposition, and we discuss the pitfalls of making this assessment from core. Recent work has illustrated that cycles in the calibre of sediment delivered to the shelf edge may be related to sea-level, and we evaluate the effects of corresponding allocyclic cyclicity in Previous HitflowTop efficiency upon large-scale system development.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana