Low-Ca boninite formation by second-stage melting of spinel harzburgite residues at mature subduction zones: new evidence from veined mantle xenoliths from the West Bismarck Arc

We report the abundances of major and lithophile trace elements and volatiles (H2O, Cl and S) in orthopyroxenite veins cutting mantle-derived, spinel harzburgite xenoliths from the active Ritter volcano in the West Bismarck Arc (Papua New Guinea). The veins preserve sulfide-bearing glass coexisting with crystals. The glass formed by the quench of residual liquids left after crystallisation of abundant orthopyroxene, variable amounts of...