Several well-preserved subduction complexes display a sharp textural contrast between coarse-grained trench sediments and overlying fine-grained lower-slope deposits. This relationship can be explained in part by the role of submarine canyons in sedimentation along the trench slope. Large submarine canyons funnel coarse terrigenous debris directly to the trench floor, effectively bypassing depositional sites along the lower slope. Smaller canyons are commonly blocked by tectonic ridges along the trench slope, and, as a result, coarse detritus is trapped within upslope basins. Because of sediment bypassing and upslope trapping, deposits on the lower slope are generally finer grained, consisting largely of hemipelagic muds and lutite turbidites.

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