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Location, Evolution and Internal Geometries of Shelf Canyons; Pleistocene, Offshore Ebro Delta (Spain)

Ivan Fabuel-Perez1, Gianluca Badalini1, Jonathan Redfern2, and Richard Blight3
1 University of Manchester, Manchester, United Kingdom
2 North Africa Research Group, The Univeristy of Manchester, Manchester, United Kingdom
3 BG-Group, Reading

High-resolution 3D seismic data reveal a shallow Pleistocene canyons/channel system developed in the Ebro Continental Margin, Spain, and allow the depositional processes involved in the formation and evolution of these canyon/channel to be investigated.

The canyons show a meandering morphology in the proximal part, broadening to form wide straight valleys as they reach the shelf break. All of them originate along the shelf break and orientated perpendicular to the shelf break. The internal architecture of the canyons show predominantly parallel to sub-parallel deposits, interpreted to be interbedded sandstone and mudstone, which onlap the channels flanks and downlap onto the channel base. Each canyon shows at least two phases of erosion, representing different channel development phases within the canyon. These individual channel forms show a moderate to high degree of sinuosity along their entire length.

The formation of the canyon system is interpreted to be related to two main processes: (1) exposure and subaerial erosion of the shelf following relative sea level fall and formation of incised valleys; and (2) slope failure processes and subsequent headward propagation by retrogressive mass failure that lead to formation of canyons that capture the incurred valley system. The internal architecture and fill of the canyons/channels can also be related to changes in the relative sea level.