ISOLATED SEAMOUNTS AS WINDOWS INTO UPPER MANTLE GEOCHEMICAL HETEROGENEITY

ended

Hundreds of thousands to millions of seamounts unrelated to hotspot activity remain unexplored at the seafloor, either as isolated seamounts or as clusters. Most of them are located at remote sites within the ocean basins and they are not influenced by deep mantle upwelling processes or subduction/back-arc regimes, thus their composition and mechanisms of formation are intrinsically related to the upper mantle compositional nature and dynamics. For many years, the upper mantle has been considered as a homogeneous and depleted reservoir, nevertheless, the ever-growing isotopic data available suggest that heterogeneities are pervasively present throughout the mantle. The ISOSEA project aims to characterize upper mantle heterogeneity using the composition of non-hotspot isolated seamounts and seamount provinces as a window into the upper mantle. Using an integrated approach including petrological, geochemical, and geochronological evidence from the seamount province located south of the Mid-Pacific Mountains as the main case study, we intend to characterize their mantle sources in an effort to understand what is the origin and composition of enriched upper mantle heterogeneities that allow the formation of seamounts unrelated to hotspot activity. The results of this study could help lead to a paradigm shift of the composition of the upper mantle: from considering it as an inherently homogeneous depleted reservoir to a possibly highly heterogeneous one, containing enriched, recycled lithospheric components. The outcomes of the ISOSEA project will have a strong impact on the European and International scientific community, since they can be used to assess targets for future expeditions to unlock the secrets of the seafloor – the final frontier on our planet.