The influence of flow parameters on turbidite slope channel architecture

Turbidite slope channels are analogous to fluvial channels in that they tend towards graded equilibrium profiles. The gap between the equilibrium profile and the actual sediment surface defines the accommodation, and it is the creation or removal of accommodation that governs the architectural style of turbidite channels on the slope. The factors that determine the tangent to the profile at a given point are the flow density, the flow thickness and the maximum settling velocity (a proxy for grain-size) of suspended sediment. These factors combine in a simple hydraulic relationship that illustrates how changes in these parameters affect the equilibrium gradient. In concept, graded channels behave like many sinuous fluvial systems in that the channels migrate laterally with little or no aggradation. Decrease in flow density or thickness, or increase in grain-size steepens the gradient and creates accommodation, allowing channels to aggrade. In fact without changes in other factors such as base level, channel aggradation should only occur when flow properties change. Increase in flow density or thickness, or decrease in grain-size reduce the gradient and remove accommodation, leading to erosional channels. Both long and short term changes tend from erosional to aggradational, with a tendency towards smaller and perhaps muddier flows with time. (C) 2003 Elsevier Ltd. All rights reserved.