Isotopic evidence for iron mobility during subduction

摘要: Subduction zones are one of the most important sites chemical interchange between Earth’s surface and interior. One means explaining high Fe3+/ΣFe ratios oxidized nature primary arc magmas is transfer sulfate (SOX), carbonate (CO3–), and/or iron (Fe3+) bearing fluids from slab to overlying mantle. Iron mobility Fe stable isotope fractionation in influenced by redox state presence chlorine sulfur anions. Here we use isotopes (δ56Fe) as a tracer serpentinites Western Alps metaophiolites, which represent remnants oceanic lithosphere that have undergone subduction-related metamorphism devolatilization. A negative correlation (R2 = 0.72) observed serpentinite bulk δ56Fe provides first direct evidence for release Fe-bearing during devolatilization subduction zones. The progressive loss isotopically light with increasing degree prograde consistent sulfate-rich hypersaline fluids, preferentially complex form Fe(II)-SOX or Fe(II)-Cl2 species. can therefore be used slab-derived fluids.