Geochemical and Os isotopic characteristics of a fresh harzburgite in the Hayachine-Miyamori ophiolite: Evidence for melting under influx of carbonate-rich silicate melt in an infant arc environment

Abstract

Os isotopic composition (¹⁸⁷Os/¹⁸⁸Os = 0.1235) of a refractory harzburgite in the Hayachine-Miyamori ophiolite is subchondritic, indicating the long-term depletion of Re. Such an unradiogenic Os isotopic signature is consistent with the less oxidized condition at subduction initiation. The major and trace element characteristics of the harzburgite, together with its petrography and relatively high modal abundance of clinopyroxene, suggest an involvement of a carbonate-rich silicate melt during melt extraction in arc setting.