Maillet Patrick auteur aut IRD Monzier Michel auteur aut IRD Lefèvre C. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Matthew and Hunter, the two southernmost active volcanoes of the New Hebrides island arc (southwest Pacific) differ markedly from the other (mainly tholeitic) Quaternary volcanoes of this arc. Geodynamically related to the New Hebrides subduction zone, they also lie close to the southern limb of the active expanding ridge of the North Fiji Basin. Both volcanoes are made up of acid, medium-K, calcalkaline orogenic andesites, containing a variety of inclusions (pyroxene- and gabbroic cumulates, as well as doleritic cognate inclusions). This paper presents the first systematic petrographic and chemical study of these volcanics and their inclusions. Trace-element geochemistry and rare-earth element modelling suggest that the two volcanoes developed from successive batches of similar parental magmas, originating from limited partial fusion of garnet peridotite in the mantle wedge. Various degrees of fractional crystallization ot these batches led to the formation of three volcanic suites: Hunter (little fractionated), West-Matthew (moderately fractionated) and East-Matthew (highly fractionated). Moreover, on Matthew island, no correlation exists between the degree of fractionation and the eruptive chronology, the youngest edifice (West-Matthew) being less evolved than the older on (East-Matthew). (Résumé d'auteur) specialized MAGMATISME CALCOALCALIN ROCHE VOLCANIQUE PETROGRAPHIE ANALYSE CHIMIQUE ELEMENT EN TRACE GEOCHIMIE MODELISATION INCLUSION PACIFIQUE TROPICAL SUD OUEST NOUVELLE CALEDONIE REGION 064PETRO 30 1-27 1986 0377-0273 https://www.documentation.ird.fr/hor/fdi:010017468 10.1016/0377-0273(86)90065-X 0377-0273 [F B010017468] https://www.documentation.ird.fr/hor/fdi:010017468 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_6/b_fdi_49-50/010017468.pdf IRD - Base Horizon / Pleins textes 1999-04-27 2020-08-03 fdi:010017468 fre