Rare Earth Elements as tracers for past ocean chemistry

The rare earth elements (REE) are transported and transformed coherently in the environment, yet subtle differences in their chemical properties cause variable fractionation patterns. In the ocean, their relatively long residence times (centuries to millennia) allow REE to be advected across basins while recording fractionation processes en route. Scavenging onto sinking particles – especially metal oxides and organic matter – leads to their burial on the seafloor, where their abundances can be further modified by early diagenetic processes. The fraction of REE preserved in sediments enters the geological record where it can be used to reconstruct past ocean chemistry provided their marine geochemical cycling is understood well enough.Here we present REE concentration data from authigenic phases of a global suite of marine sediments. We assess which environmental parameters they predominantly relate with, how early diagenesis affects the archived REE, and whether authigenic REE can be used to reconstruct past ocean chemistry and particle fluxes.