@article{fdi:010068349,
  title = {{M}agma transfer and degassing budget : application to the 2009-2010 eruptive crisis of {M}t {G}aret ({V}anuatu arc)},
  author = {{M}etrich, {N}. and {B}ertagnini, {A}. and {G}araebiti, {E}. and {V}ergniolle, {S}. and {B}ani, {P}hilipson and {B}eaumais, {A}. and {N}euville, {D}. {R}.},
  editor = {},
  language = {{ENG}},
  abstract = {{M}t {G}aret, on {G}aua {I}sland, is one of the active volcanoes of the {V}anuatu arc. {W}e report here a new dataset on lapilli and lava erupted during {M}t {G}aret unrest in 2009-2010 and on products of the older activity of {G}aua composite volcano. {T}he present-day magma of {M}t {G}aret is a trachy-andesite (52 wt.% {S}i{O}2) with relatively high {R}b/{T}h (14.6) and {B}a/{L}a (41) ratios compared to the {G}aua pre- and syn-caldera series, but typical of the central part of {V}anuatu arc. {I}ts mineral assemblage is mainly composed of plagioclase ({A}n(86-36)) and clinopyroxene ({F}s(5-16)) which display significant chemical variations, patchy zones, surface dissolution, and oscillatory zoning that imply episodes of high undercooling and growth rates. {T}he paragenesis is complemented by {F}e-{T}i oxides and scarce olivine ({F}o(72-73)). {T}he melt inclusions are ubiquitous and their compositions cover a chemical spectrum from basalt to trachy-andesite. {V}olatile-rich basaltic inclusions ({H}2{O}: 2.7 wt.%, {S}: 0.15 wt.%, and {C}l: 0.22 wt%) are preserved in {M}g-rich clinopyroxene whereas the majority of the melt inclusions is volatile poorer with, <= 1.0 wt.% of {H}2{O}, <= 0.05 wt.% of {S}, and 0.25-0.27 wt.% of {C}l. {A}t 1100 degrees {C} the measured viscosity of anhydrous magma of {M}t {G}aret is 10(3.5) {P}a s. {A}dding 0.8 to 2.5 wt.% of {H}2{O} decreases the melt viscosity by 0.5 to two orders of magnitude. {C}ombining data on bulk rocks, minerals, and their melt inclusions together with the very first published gas fluxes acquired during the same period of activity, we propose that the high sulfur outgassing in 2009-2010 was produced by the degassing of a basaltic magma batch (similar to 0.027 km(3)) emplaced in a shallow reservoir. {T}his scenario would require temperature and {H}2{O}-loss driven resorption/crystallization, magma mixing, and exsolution of an early gas phase rich in {H}2{O}, and. {S}. {W}e suggest here the 2009-2010 activity to be sustained by the existence of thermal convection driven at the bottom of the magma reservoir by cooling, and in which the bubbles are small enough to be stagnant. {T}he most energetic phases are better explained by an additional gas volume, associated to the crystallization of titanomagnetite microcrysts which significantly enhance bubble nucleation. {T}he ultimate step of crystal growth prior to eruption suggests magma ascent within few hours.},
  keywords = {{V}anuatu arc ; {M}elt inclusions ; {V}olatiles ; {M}elt viscosity ; {B}ubbly magma ; {T}hermal convection ; {VANUATU} ; {GAUA}},
  booktitle = {{U}nderstanding volcanoes in the {V}anuatu arc},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {322},
  numero = {{N}o {S}p{\'e}cial},
  pages = {48--62},
  ISSN = {0377-0273},
  year = {2016},
  DOI = {10.1016/j.jvolgeores.2015.06.003},
  URL = {https://www.documentation.ird.fr/hor/fdi:010068349},
}