By storing and transporting vast amounts of energy derived from solar insolation, the oceans play an important role in shaping Earth’s climate. On the largest scale, ocean currents smooth the temperature gradients between the equator and the poles by redistributing excess energy from the tropics to higher latitudes. Much of this excess heat is transported by the so-called Ocean Conveyor Belt (Broecker, 1991), a global network of ocean currents driven by thermohaline convection. Changes in the pattern and strength of thermohaline circulation affect the redistribution of heat, and thereby significantly influence climate on local to global scales.

The reconstruction of paleocurrents has long been a subject of paleoceanographic research. Among the various methods employed in tracing paleocurrents (and modern currents), the Sm-Nd isotope system is experiencing ever increasing attention. First applied in an oceanographic context by O’Nions et al. (1978), it is by now established as a standard tool, as shown by numerous recent publications (e.g. Rutberg et al., 2000; Tütken et al., 2002; Weldeab et al., 2002; Benson et al., 2003; Farmer and Barber, 2003; Piotrowski et al., 2004; Bayon et al., 2002, 2003, 2004; Lacan and Jeandel, 2001, 2004, 2005, and many more). Two lines of application of the Sm-Nd isotope system to oceanography/paleoceanography can be distinguished, both of which were followed for this thesis.

The first approach uses the isotopic composition of Sm and Nd hosted in detrital minerals to infer the provenance of terrigenous sediments. This information can be used to draw conclusions about the direction and distance of sediment delivery. The second approach uses the isotopic signature of Nd as a tracer of different water masses. Due to the oceanic residence time of Nd being shorter than the global turnover rate of seawater (500-1000 years vs ~1000 years; Tachikawa et al., 2003), different bodies of water acquire distinct Nd isotopic signatures as a function of the age of adjacent continents. Apart from directly analyzing the Nd isotopic compositions of water samples to trace the modern distribution of different watermasses (e.g. Lacan and Jeandel, 2001, 2004), suitable archives of seawater-derived Nd can be employed to study paleocurrents. Possible archives are fossil remains of marine organisms (e.g. foraminifers; Burton and Vance, 2000), or, most widely used for the recent geological past, Fe-Mn nodules and crusts (e.g. Frank et al., 2002). With slow growth rates on the order of mm/Ma, however, Fe-Mn nodules do not offer the high temporal resolution necessary to study Late Quaternary climate change. Attention has therefore recently turned to authigenic Fe-Mn oxyhydroxides finely dispersed throughout the sediment column (e.g. Rutberg et al., 2000; Bayon et al., 2002, 2003, 2004; Piotrowski et al., 2004).

For this thesis, both lines of application of the Sm-Nd isotope system to paleoceanography were followed. The samples were taken from a sediment core collected from the Yermak Plateau in the north-eastern Fram Strait. Situated between Greenland and the Svalbard Archipelago, the Fram Strait is the only deep connection between the Arctic Ocean and, via the Greenland-Iceland-Norwegian (Nordic) Seas, the North Atlantic. The Nordic Seas are an area of deep-water formation important for the global thermohaline circulation. There, the processes of deep-water formation are in a state of equilibrium that is most sensitive to changes in surface water salinity, which, in turn, is strongly influenced by the outflow of water of low salinity from the Arctic Ocean. This makes the history of water exchange between the Atlantic and the Arctic Ocean through the Fram Strait a subject of key interest for climate research.

In particular, it was attempted to reconstruct the provenance of sediments deposited on the western Yermak Plateau over the last 129 000 years. This was done by analyzing samples from the sediment core and from poten