Abstract

Distinctive, laterally widespread surfaces, here termed megaflute erosion surfaces, provide evidence of widespread erosion and sediment bypass in a turbidite system and offer insights into the mechanisms by which small-scale turbidite channels can be initiated. The surfaces are erosional into sandstone, are ornamented by exceptionally large flutes, and are overlain by fine-grained facies that onlap the relief of the surface. These surfaces can be traced laterally into deeper erosional surfaces that define sandstone-filled turbidite channels. Once formed, the channels provided a pathway for subsequent turbidity currents while the flanking, slightly elevated megaflute surfaces accumulated fine-grained sediment via overbank and flow stripping processes. These observations imply that the channels were formed by single, high-magnitude, low-frequency turbidity currents and were filled by a succession of lower magnitude, higher frequency flows.

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