Lithodynamic Studies near the Northwest Atlantic Mid-Ocean Channel

Resumo

In AMK-4474 marine sediment core, retrieved from the northern part of the eastern (left) levee of the Northwest Atlantic Mid-Ocean Channel, two stratigraphic units were identified. The lower unit is represented by the Late Quaternary fine-grained sediments of the upper turbidite sequences. The presence of a 17–24 µm mode in grain-size distributions within the thin interlayers of silt in the lower unit may reflect a sorting of sedimentary material by the spillover of turbidity currents. The process is similar to the contour currents activity. This allows applying an indicator of the contour current speed–sortable silt (SS) content–to estimate the intensity of the spill-over current. The upper unit, formed during the last 26 ka, is represented by pelagic sediments. The presence of the fine-grained interlayer in the upper unit of AMK-4474 core is apparently due to a decrease in IRD supply to the study area.