The Northwest African slope apron: a modern analogue for deep-water systems with complex seafloor topography

The Northwest African slope apron is an interesting modern analogue for dee p-water systems with complex seafloor topography. A sediment process map of the Northwest African continental margin illustrates the relative roles of different sedimentary processes acting across the entire margin. Fine-grai ned pelagic and hemipelagic sedimentation is dominant across a large area o f the margin, and is considered to result from 'background' sedimentary pro cesses. Alongslope bottom currents smooth and mould the seafloor sediments, and produce bedforms such as erosional furrows, sediment waves and contour ite drifts. Downslope gravity flows (debris avalanches, debris flows and tu rbidity currents) are infrequent but important events on the margin, and ar e the dominant processes shaping the morphology of the slope and rise. The overall distribution of sedimentary facies and morphological elements on th e Northwest African margin is characteristic of a fine-grained elastic slop e apron. However, the presence of numerous volcanic islands and seamounts a long the margin leads to a more complex distribution of sedimentary facies than is accounted for by slope apron models. In particular, the distributio n and thickness of turbidite sands are controlled by the location of the br eak-of-slope, which is itself controlled by the pre-existing submarine topo graphy. (C) 2000 Elsevier Science Ltd. All rights reserved.