Major and trace element concentrations of sediments from the IODP Exp302 sites

We analyzed a suite of sediment samples recovered in the central Arctic Ocean for major, trace, and rare earth elements in order to assess changes in terrigenous source material throughout the Cenozoic. The terrigenous component consists of two end-members. Input from a shale-like composition dominates bulk sediments, especially those deposited during the Paleocene and since the Miocene, and may represent sediment supply from the eastern Laptev Sea. Therefore, even though the environment and transport mechanisms may have varied from ice free to ice dominated, sequences of the early Paleogene and later Neogene appear to have been influenced by a single major terrigenous source. This suggests similar transport capabilities and trajectories for both ocean and drift currents through significant parts of the Cenozoic. Influence from a more mafic source appears to be more important through the early Eocene to the middle Miocene and most likely represents material from the western Laptev Sea or Kara Sea. Thus, Eocene major changes in surface water productivity appear broadly synchronous with those in terrigenous provenance. A combination of regional sea level variations, local shelf processes, and transport mechanisms are among the more probable causes for the observed source changes. Although the assignment of sources using chemistry presently is constrained by a lack of data from certain regions (e.g., eastern Siberian Sea) our results generally agree with inferences based on mineralogy or radiogenic isotopes and shed further light on long-term reconstructions of the central Arctic Ocean.