@article{PAR00014177,
  title = {{P}-{V}-{T}-{X} evolution of olivine-hosted melt inclusions during high-temperature homogenization treatment},
  author = {{S}chiavi, {F}. and {P}rovost, {A}. and {S}chiano, {P}ierre and {C}luzel, {N}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}uring low-high temperature ({T}) cycles imposed on olivine-hosted melt inclusions ({MI}s) we observe a systematic increase in homogenization temperature ({T}-h) with time, regardless of their initial major-element and {H}2{O} contents. {B}ubble persistence at high {T} suggests that inclusion internal pressure ({P}-int) is lower than its original, trapping pressure. {W}e explore how reversible and irreversible processes modify the composition ({X}), volume ({V}) and {P}-int of heated {MI}s, and compare the results of theoretical modeling with experimental observations of {MI}s from {FAMOUS} {Z}one ({FZ}, {M}id-{A}tlantic {R}idge) and {L}a {S}ommata ({SOM}, {V}ulcano, {A}eolian {I}slands) basaltic samples. {D}ue to olivine dissolution at inclusion walls and thermoelastic deformation, {P}-int-{V}-{X} conditions change significantly upon heating. {O}livine dissolution induces changes in major-element composition (i.e., enrichment in {F}e and {M}g), morphology and volume (up to +25% at 1500 degrees {C}). {W}e provide equations for the thermoelastic deformation of olivine bearing a two-phase, liquid-gas inclusion for the end-member cases of chemical equilibrium and no exchange between gas and liquid. {T}hese equations allow {P}-int-{V} evolution to be related to variations in bubble volume fraction. {U}pon heating, both {P}-int and {V} variations are smaller in the presence of a gas bubble than for a homogeneous liquid inclusion, at the same {T}. {D}issolution-reprecipitation and thermoelastic deformation of the olivine host are reversible processes, so initial {P}-int-{V}-{X} conditions are restored upon cooling. {O}n the contrary, water loss from {MI}s and plastic deformation of the olivine host are processes that irreversibly lower {P}-int, and account for the systematic increase of {T}-h with time. {O}ur theoretical and experimental investigations suggest that the increase of {T}-h in volatile-rich {SOM} {MI}s is mainly related to progressive release of water. {C}ompared to larger {MI}s located at a similar distance from the olivine rim, smaller {MI}s show a faster increase in {T}-h with time, consistent with the effects of diffusive water loss. {N}onetheless, we cannot exclude the combined effect of incipient plastic deformation, which would enhance water loss by diffusion along dislocations. {T}he increase in {T}-h in volatile-poor {FZ} {MI}s is driven mainly by elasto-plastic deformation of the olivine host, which becomes more marked with increasing {T} and decreased distance from {MI} wall to olivine rim. {O}ccurrence of plastic deformation in {FZ} olivines is testified by dislocation patterns observed around inclusions. {I}n general, conducting homogenization experiments at 1 atm prevents {MI} homogenization happening at a {T}-h equal to entrapment {T}. {T}his is due to a drop in {P}-int caused by the elastic deformation that affects olivine phenocrysts bearing pressurized {MI}s during magma ascent. {P}redicted increase in {T}-h ranges from a few degrees to tens of degrees depending on entrapment conditions, melt composition and volatile contents.},
  keywords = {{ATLANTIQUE} ; {MEDITERRANEE} ; {EOLIENNES} {ILES}},
  booktitle = {},
  journal = {{G}eochimica et {C}osmochimica {A}cta},
  volume = {172},
  numero = {},
  pages = {1--21},
  ISSN = {0016-7037},
  year = {2016},
  DOI = {10.1016/j.gca.2015.09.025},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00014177},
}