@article{fdi:010057094,
  title = {{M}ineralogical and numerical approaches to establish the pre-eruptive conditions of the mafic {L}ican {I}gnimbrite, {V}illarrica {V}olcano ({C}hilean {S}outhern {A}ndes)},
  author = {{L}ohmar, {S}. and {P}arada, {M}. and {G}utierrez, {F}. and {R}obin, {C}laude and {G}erbe, {M}. {C}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {L}ican {I}gnimbrite represents a large explosive basaltic andesite event in the eruptive history of the {V}illarrica {V}olcano, an active stratovolcano of the {S}outhern {A}ndean {V}olcanic {Z}one. {A} mineralogical study of this ignimbrite indicates important disequilibrium features. {R}esoption textures were observed around {C}a-rich ({A}n(74-92); {G}roup 1) and more sodic ({A}n(35-44); {G}roup 2) plagioclase phenocryst cores. {R}ims on these phenocrysts as well as microlites grew with an intermediate composition ({A}n(47-63); {G}roup 3). {L}ow- and high-{M}g clinopyroxene and orthopyroxene phenocrysts were also identified; most of them showing reverse {M}g zoning. {B}ased on these mineralogical data and thermodynamic modeling, an increase of about 200 degrees {C} in temperature (from similar to 900-1000 degrees to similar to 1100-1150 degrees {C}), a decompression of similar to 400 bar (equivalent to similar to 1.5 km) and a decrease in {H}2{O} content in the melt of similar to 1.6 wt.% are identified during crystallization. {A}ddition of hot magma from below would have caused heating of the reservoir with the consecutive ascent of magma pulses, {H}2{O} exsolution and convective mixing (compositional and/or thermal mixing). {A} numerical model using the {F}inite {E}lement {M}ethod was developed to assess the response of the {L}ican {I}gnimbrite reservoir upon conductive heating by 200 degrees {C} by mafic underplating; this model indicates a rapid (tens of years) temperature homogenization of this system, with ascending magma plumes with velocities as high as 6 m/h. {B}ecause the {L}ican {I}gnimbrite erupted at the end of the {P}leistocene glaciation, glacial unloading could have also contributed to depressurization of the reservoir.},
  keywords = {{I}gnimbrite ; {C}ompositional mixing ; {T}hermal mixing ; {R}eservoir heating ; {V}illarrica {V}olcano},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {235},
  numero = {},
  pages = {55--69},
  ISSN = {0377-0273},
  year = {2012},
  DOI = {10.1016/j.jvolgeores.2012.05.006},
  URL = {https://www.documentation.ird.fr/hor/fdi:010057094},
}