Abstract

Critical shear velocities and geostrophic current velocities were calculated from measured grain sizes and settling velocities using a Shields-type threshold curve of particle movement and assuming bedload transport for particles that were found to be transported by currents. Because this reconstruction of the current velocities is based on the coarsest transported component that could be recognized in the sediment, the resulting current velocities represent a maximum flow speed that was effective during deposition of sediment. The shape of the settling-velocity distributions identifies the dominant type of deposition that controlled the accumulation of sediment: residual, well-sorted, or low-energy depositional.

The resulting pattern of reconstructed maximum geostrophic current velocities in the Norwegian-Greenland Sea reflects the known features of present-day thermohaline circulation, which is influenced by the bathymetry at many places. Reconstructed current velocities are higher in areas where the cross section of meridional flows is restricted by topographic barriers. The distribution of the depositional characters shows that residual and well-sorted sediment types are generally associated with higher current velocities in areas of strong geostrophic currents (e.g., Fram Strait and East Greenland continental slope). The low-energy depositional sediment type is widespread in the basins of the eastern Norwegian-Greenland Sea, where lower reconstructed maximum current velocities occur. The high reconstructed velocities on the Spitsbergen Bank can be attributed to the disturbance from storm waves in shallower water depths.

You do not currently have access to this article.