@article{PAR00011266,
  title = {{E}xperimental melting of hydrous peridotite-pyroxenite mixed sources : constraints on the genesis of silica-undersaturated magmas beneath volcanic arcs},
  author = {{S}orbadere, {F}. and {M}edard, {E}. and {L}aporte, {D}. and {S}chiano, {P}ierre},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he most primitive arc magmas expressed as melt inclusions in forsteritic olivine display silica-undersaturated, nepheline normative compositions, sometimes associated with high {C}a{O} contents. {I}nvolvement of a heterogeneous mantle source containing an amphibole-bearing clinopyroxene-rich component is often mentioned to account for the origin of these magmas. {H}owever, the proportions and the role of such mantle source component in arc magma genesis remains a matter of debate. {T}o better understand the generation of silica-undersaturated magmas in arcs and the role of clinopyroxenites during arc magma genesis, we have performed melting experiments on a heterogeneous hydrous mantle (hydrous lherzolite mixed with variable amounts of amphibole-bearing clinopyroxenite) at 1 {GP}a under oxidizing conditions (close to the fayalite-magnetite-quartz: {FMQ}-buffer). {U}nlike under anhydrous conditions, pyroxenites and peridotites have similar solidus temperatures under hydrous conditions, but the melt productivity still increases with increasing fraction of pyroxenite in the source. {F}or peridotite-rich sources (up to 50% clinopyroxenite) the presence of orthopyroxene buffers the partial melts to compositions identical in terms of major elements to regular peridotite melts. {W}hen orthopyroxene leaves the residue (above 50% of pyroxenite), melts become nepheline-normative, with {C}a{O}/{A}l2{O}3 ratios >1. {C}omparison between experimental melts produced by melting homogeneous mixed sources (homogeneous melting) and aggregated melts from heterogeneous sources (heterogeneous melting) shows that the later are more silica-undersaturated and richer in {C}a{O}. {O}ur experiments confirm that nepheline-normative melt inclusions have sampled pure or poorly-mixed clinopyroxenite melts from a heterogeneous mantle source, while hypersthene-normative lavas are likely to result from a more advanced stage of magma mixing. {A}mphibole-clinopyroxenite heterogeneities in the mantle wedge could originate by density-driven delamination of lower crustal cumulates consisting of clinopyroxene amphibole olivine. {P}artial melts of these cumulates can be efficiently extracted and suffer only little interaction with surrounding peridotites before their entrapment as melt inclusions; alternatively, they can react with peridotite to form secondary orthopyroxene-free metasomatic veins, which may also contribute to the source of silica-undersaturated arc magmas.},
  keywords = {experimental petrology ; amphibole-bearing clinopyroxenite ; hydrous ; peridotite ; partial melting ; nepheline-normative melts},
  booktitle = {},
  journal = {{E}arth and {P}lanetary {S}cience {L}etters},
  volume = {384},
  numero = {},
  pages = {42--56},
  ISSN = {0012-821{X}},
  year = {2013},
  DOI = {10.1016/j.epsl.2013.09.026},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00011266},
}