@article{fdi:010072326,
  title = {{T}he genetic relationship between andesites and dacites at {T}ungurahua volcano, {E}cuador},
  author = {{N}auret, {F}. and {S}amaniego, {P}ablo and {A}ncellin, {M}. {A}. and {T}ournigand, {P}. {Y}. and {L}e {P}ennec, {J}ean-{L}uc and {V}lastelic, {I}. and {G}announ, {A}. and {H}idalgo, {S}. and {S}chiano, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{V}olcanic eruptions of intermediary and silica-rich magmas (andesites, dacites and rhyolites) in convergent arc settings generate voluminous and explosive eruptions that can strongly affect human activity and have significant environmental impacts. {I}t is therefore crucial to understand how these magmas are generated in order to anticipate their potential impact. {A}t convergent margins, primitive magmas (primitive basalts and/or andesites) are derived from the mantle wedge and they are progressively modified by physical and chemical processes operating between the melting zone and the surface to produce silica-rich magmas. {I}n order to elucidate the relationship between andesites and dacites, we focus on {T}ungurahua volcano, located in the {E}cuadorian {A}ndes. {W}e collected a set of samples comprising such lithologies that were erupted during the last 3000 year {BP}. {T}his relatively short period of time allows us to assume that the geodynamic parameters remain constant. {P}etrology and major-trace element compositions of these lavas have already been examined, and so we performed a complementary {P}b-{S}r isotope study in order to determine the nature and origin of the components involved in andesite and dacite genesis. {S}r isotopes range from 0.70417 to 0.70431, and {P}b isotope compositions range from 18.889 to 19.154 for {P}b-206/{P}b-204, from 15.658 to 15.696 for {P}b-207/{P}b-204, and from 38.752 to 38.918 for {P}b-208/{P}b-204. {D}acites display a remarkably homogeneous {P}b isotopic composition, with higher {P}b-206/{P}b-204 values for a given {P}b207-208/{P}b-204 compared to andesites. {A}ndesites show notable {P}b-207/{P}b-206 variations for a given {S}i{O}2 content, whereas dacites have lower and homogenous {P}b-207/{P}b-206 values. {A}ndesite and dacite altogether plot in a roughly triangular distribution, with dacitic magmas systematically plotting at the high {S}i{O}2 and {S}r-87/{S}r-86 and low {P}b-207/{P}b-206 fields. {B}ased on our new dataset, we show that at least 3 different components are required to explain the {T}ungurahua compositional and isotope variation: one corresponds to the mantle, the second has a deep origin (slab component or lower crust), and a mixture between these two components explains andesite heterogeneity. {T}he third component is derived from the underlying upper continental crust. {W}hile andesites are derived from deep components, dacites are derived from the andesitic magmas that underwent an assimilation-fractional crystallization ({AFC}) process with incorporation of the local metamorphic basement. {F}inally, we used the geochemical and isotopic data to produce a model of the magmatic plumbing system beneath {T}ungurahua, consistent with geophysical and experimental petrology constraints. {W}e conclude that melt migration and storage in the upper crust appears to be a key parameter for controlling volcanic behavior though time.},
  keywords = {{EQUATEUR} ; {TUNGURAHUA} {VOLCAN}},
  booktitle = {},
  journal = {{J}ournal of {V}olcanology and {G}eothermal {R}esearch},
  volume = {349},
  numero = {},
  pages = {283--297},
  ISSN = {0377-0273},
  year = {2018},
  DOI = {10.1016/j.jvolgeores.2017.11.012},
  URL = {https://www.documentation.ird.fr/hor/fdi:010072326},
}