Deep Current-Controlled Sedimentation in the Western North Atlantic

摘要

With its multiple sources of sediment and bottom water, the North Atlantic Ocean experiences active redistribution of sediments. North Atlantic bottom waters originate around Antarctica, in the Norwegian Sea the Mediterranean, and the Labrador Sea. Sediment is supplied from continental land-masses, oceanic islands (notably Iceland) and from surface biological production. Water movements are controlled principally by differing densities of the water masses, and the ocean currents tend to follow the contours of the sea floor. Where interfaces of steep density gradient intersect the seafloor, internal tides and high-frequency internal waves may resuspend sediments. The Gulf Stream, and warm-core and cold-core mesoscale eddies apparently contribute to the variability of current velocity at great depths and help to erode and redistribute sediments. The most important depositional products of this current activity are the great 'sediment drifts'. These features probably contain a detailed record of the fluctuations in bottom-current activity of the North Atlantic.