Transportation of beryllium with H₂O at high pressures: Implication for magma genesis in subduction zones

Abstract

The degree of transportation of beryllium with H 2 O is measured under the upper mantle P/T conditions in order to examine the incorporation of 10 Be in subduction zone magmas. 5.4±0.3% of original beryllium in the starting serpentinite is extracted with H 2 O from the system through the dehydration reaction of serpentine at 850°C and 1.5 GPa. It follows that the partial melting of oceanic lithosphere including 10 Be‐rich sediment layer is not necessarily required for inclusion of the isotope in island‐arc lavas. We suggest that the dehydration processes in the subducted slab and mantle wedge materials dragged downward by the slab subduction govern the concentration of 10 Be in arc lavas.