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Department of Geology, The University, Hull, HU6 7RX, UK
* Sedimentology Branch, BP Exploration Co. Ltd, Britannic House, London EC2Y 9BU, UK
Flow separation is a common feature within alluvial channels that occurs at abrupt changes in the bed geometry. At a wide range of scales, it is a process that can exert considerable control over the segregation and deposition of heavy mineral grains. Fluid separation generates a region of high bed shear stress that can entrain heavy minerals, and a region of low velocity that is a preferred site for the deposition of denser particles. Significant concentrations of heavy minerals, sometimes up to eight times the background value, may be formed by flow separation processes. A review of the occurrence of flow separation illustrates that it may be responsible for the accumulation of heavy mineral grains at a range of geomorphological scales.
