The origin of Na-alkaline lavas revisited: new constraints from experimental melting of amphibole-rich metasomes+lherzolite at uppermost mantle pressure

Abstract We present a new experimental dataset for reaction experiments between natural amphibole-clinopyroxene metasomes (hornblendite) and synthetic lherzolite that produced Na-rich alkaline melts. Experiments were conducted at 1, 3 4 GPa 1000–1300 °C. The generated melts range from foidite over basanite to phonotephrite. At 1 1000 1100 °C amphibole decompression-breakdown products generate phonotephritic melt. Among the breakdown components rhönite was found be stable up GPa. melt compositions are affected by phlogopite melting shift more foiditic compositions. find of hornblendites with produce wehrlitic residues different olivine/clinopyroxene ratios. Wehrlite formation does not always require separate metasomatic processes but can direct by-product volcanism. applied metasome model magmas Kula volcanic province, Turkey, show phonotephrite cover whole known lava compositional trend therefore basanite-phonotephrite mixing. A comparison high-pressure (3–4 GPa) nephelinite data shows overlap many major, minor, trace elements differences in SiO 2 , FeO, TiO argue do represent primary