Abstract

The halogens are highly incompatible and fluid-mobile elements. They are most abundant in Earth surface reservoirs such as seawater and ocean sediments, and become concentrated in altered oceanic lithosphere through serpentinization. Subduction of altered oceanic lithosphere causes halogens to be recycled into the mantle, from where they may be returned to the surface through partial melting and magmatism at ocean islands. This makes halogens potentially excellent tracers of recycled subducted lithologies in the Earth’s mantle. However, our knowledge of the volatile composition of recycled mantle domains is limited by a lack of in situ samples of the downgoing lithospheric material. This talk will explore the geochemical cycling of halogens through subduction zones and into the deep mantle, drawing on analytical studies of the Leka ophiolite complex, the Reykjanes Ridge, and Iceland.