@article{fdi:010068348,
  title = {{T}emporal magma source changes at {G}aua volcano, {V}anuatu island arc},
  author = {{B}eaumais, {A}. and {B}ertrand, {H}. and {C}hazot, {G}. and {D}osso, {L}. and {R}obin, {C}laude},
  editor = {},
  language = {{ENG}},
  abstract = {{G}aua {I}sland (also called {S}anta {M}aria), from the central part of the {V}anuatu arc, consists of a large volcano marked by a caldera that hosts the active {M}ount {G}aret summit cone. {I}n this paper, a geochemical study including {S}r, {N}d, {P}b and {H}f isotopic compositions of 25 lavas emitted since 1.8 {M}a is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed ({M}ount {G}aret) the caldera forming event. {A}ll lavas show an island arc signature with enrichment in {LILE} and depletion in {HFSE}. {P}ost-caldera lavas define a medium-{K} calc-alkaline trend, whereas lavas from the former main cone have high-{K} calc-alkaline compositions. {C}ompared to the pre-caldera volcanic suite, the {M}ount {G}aret lavas have similar {T}h/{N}b (similar to 1.5), {N}d-143/{N}d-144 (similar to 0.51295) and {H}f-176/{H}f-177 (similar to 0.28316) ratios, but higher {B}a/{L}a (similar to 42 vs. similar to 27) and {S}r-87/{S}r-86 (0.70417 vs. 0.70405) ratios and lower {C}e/{P}b (similar to 2.7 vs. similar to 4.6), {L}a/{S}m (similar to 2.5 vs. similar to 4.0) and {P}b-206/{P}b-204 (18.105 vs. 18.176) ratios. {H}igh {T}h/{N}b and low {N}d and {H}f isotopic ratios compared to {N}-{MORB} suggest the contribution of similar to 2% of subducted sediment melt to the mantle source of {G}aua magmas. {M}ost of the observed differences between pre- and post-caldera lavas can be accounted for by the involvement of at least two portions of the mantle wedge, metasomatized by different slab-derived aqueous fluids. {I}n addition, the lower {L}a/{S}m (at a given {N}d-143/{N}d-144) ratios of {M}ount {G}aret lavas suggest a higher degree of partial melting (similar to 10-15%) compared to the pre-caldera lavas (similar to 5%). {T}he {S}anta {M}aria {P}yroclastic {S}eries ({SMPS}) eruption probably triggered the caldera collapse, in response to emptying of the magmatic chamber. {T}his event may have allowed new access to the surface for a geochemically distinct batch of magma issued from a separate magma chamber, resulting in the birth and construction of {M}ount {G}aret within the caldera. {A}s both magmatic suites were emitted over a very short time, the storage of their parental magmas beneath the volcano is still possible.},
  keywords = {{G}aua ; {V}anuatu ; {G}eochemistry ; {I}sotopes ; {S}ubduction ; {M}antle source ; {VANUATU} ; {GAUA} {VOLCAN}},
  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 = {30--47},
  ISSN = {0377-0273},
  year = {2016},
  DOI = {10.1016/j.jvolgeores.2016.02.026},
  URL = {https://www.documentation.ird.fr/hor/fdi:010068348},
}