Significant contribution of seamounts to the oceanic rare earth elements budget

Abstract

The rare earth elements (REEs) are a crucial resource frequently used as proxies for reconstructing paleomarine environmental conditions. However, there is limited understanding regarding the marine REEs cycling. In addition, the relationship between benthic diffusion of REEs and seamounts, remain unclear. Here we present the concentration profiles of REEs and trace elements in porewater and seawater from both the seamounts area and abyssal plain. Our results evidenced that the concentration of dissolved porewater REEs, Mn and Al in sediments in proximity of seamount are much higher than those at the abyssal plain. This is attributed to the substantial benthic diffusion of REEs to the ocean. The REEs enrichment processes in porewater at uneven seafloor are based mainly on re-suspension associated with the strong currents and/ or partial dissolution of detrital from seamounts. We suspect this process may occur in other world regions with seamounts and infer that these sediments may account for a significant contributor to the oceanic REEs budget.