Process of transformation in the Norvegian Basin of warm and saline Atlantic surface water into a dense and deep return flow is the basis for the thermohaline convective heat transport which is important factor in climate changing. Sediment drifts are the most obvious and widespread features resulting from the interaction between Deep Western Boundary Current (DWBC) and deep-sea sediments along the margins of the North Atlantic. In the Iceland Basin deep currents mainly transporting sediments nearby NW European landmass are responsible for the formation of Hatton Drift on the north-western slope of Rockall Plateau.
Core AMK-4438 (depth 2240 m, length 3.2 m) samples and hydrographic data from the northern part of Hatton Drift are used for studying changes in current activity during Late Quaternary and Holocene. The composition of sediments is typically hemipelagic including nannofossils and foraminifera as dominant elements and terrigenous material as admixture. Age model for the core was constructed by 14C and 230Th/234U dating and correlation to the carbonate content. Oxygen Isotope Stages 1-6 were defined in core. Grain size analysis was carried out at 2 cm intervals.
Grain size data on the noncarbonate silt fraction were used to study fluctuations of DWBC associated to North Atlantic Deep Water (NADW). The most efficient recorder of fluctuating current velocity is the sortable silt fraction (10-63 μm), which is small enough to be influenced by currents of moderate strength, but large enough to be above the threshold of cohesive behavior. Mean size, peak height, modal size were used as parameters.
The changes recorded by the grain size parameters at core site suggest that in general DWBC velocity and NADW production were lower during cold stadials and higher during warm interstadials.