A Pleistocene contourite sequence from the Björn Drift, located on the eastern flank of the Reykjanes Ridge, was recovered at IODP Expedition 395 Site U1554G. Previous work has linked drift sedimentation at this site from ~3.6 Ma onward to the development of Iceland–Scotland Overflow Water (ISOW), suggesting that the Björn Drift may preserve changes in both sediment supply and bottom current sorting. Here, we use bulk-sediment ICP-MS geochemistry to test whether the lithostratigraphic transition from older Unit II to younger Unit I records a reorganization of sediment transport within the drift system. Preliminary results reveal several partly independent geochemical associations rather than a single, uniform lithologic trend. Unit II is relatively enriched in mafic-sensitive elements, including Ti, Sc, Cr, and V, as well as high field strength elements such as Zr, Hf, Nb, and Ta. These patterns are consistent with a greater contribution of mafic detritus and/or enhanced hydraulic concentration of denser minerals. In contrast, Unit I is characterized by higher K, Rb, Cs, and Th concentrations, indicating an increased contribution from K-bearing clay minerals and fine-grained siliciclastic detritus. The Unit II–I transition therefore represents a reorganization of distinct sedimentary components rather than a synchronous shift in all measured elements. These geochemical contrasts reveal compositional heterogeneity that is not apparent from the broadly similar silty-clay lithologies identified during shipboard description. They suggest that the lithostratigraphic transition reflects changes in sediment supply, transport pathways, bottom current sorting, or a combination of all. This geochemical framework provides a basis for evaluating how sediment routing at Björn Drift evolved during the Early Pleistocene and whether later changes, including those associated with the Mid-Pleistocene Transition, were expressed through basin-wide reorganization or through process-specific changes in sediment provenance and transport.

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