@article{fdi:010062256,
  title = {{T}racking {L}ate-{P}an-{A}frican fluid composition evolution in the ductile crust of {M}adagascar : insight from phase relation modelling of retrogressed gneisses (province of {F}ianarantsoa)},
  author = {{G}anne, {J}{\'e}r{\^o}me and {N}edelec, {A}. and {G}regoire, {V}. and {G}ouy, {S}. and de {P}arseval, {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he basement of {M}adagascar has been submitted to a strong reworking during a late {P}an-{A}frican ({D}2) shearing event. {T}he influence of the relevant fluid transfer on phase relationships is investigated on a calc-silicate gneiss belonging to the {I}kalamavony domain, deformed and retrogressed, from low-temperature amphibolite to upper-greenschist metamorphic conditions. {T}he rock is characterized by different generations of pyroxene growing with epidote as coronitic structures around relics of garnet and magnetite. {P}hase diagram sections are commonly used to study phase relationships as a function of pressure and temperature in closed-systems. {H}ere, the thermodynamic system has been considered as only open for the fluid components (i.e. {H}2{O}, {CO}2 and {O}-2) in order to discuss the interaction between fluid flow and mineral phase evolution occurring during {D}2 deformation. {P}rediction in terms of phase composition and modal proportion of {P}-{T}-{MH}2{O}-{CO}2-{O}2 phase diagrams (using {P}erple-{X} calculations) are in good agreement with natural observations. {T}hey suggest that a large input of aqueous-carbonic fluid throughout the "paragneiss" during the exhumation of the rocks led to the destabilisation of the early {F}e3+-rich garnet (andradite) and magnetite. {T}hermodynamic modelling illustrates how the replacement of such mineral assemblage by {F}e2+-rich pyroxene (diopside), sphene, epidote and plagioclase (anorthite-rich) then amphibole (actinolite) and {K}-feldspar has preferentially been controlled by the amount of {H}2{O} and {CO}2 brought through minor shear zones during the {D}2 reworking, rather than by change of the effective bulk rock composition.},
  keywords = {{S}hear zone ; {C}hannelized fluid-flow ; {P}-{T}-{MH}2{O}-{CO}2-{O}2 phase diagram ; {E}xhumation ; {M}adagascar ; {P}an-{A}frican ; {MADAGASCAR}},
  booktitle = {},
  journal = {{J}ournal of {A}frican {E}arth {S}ciences},
  volume = {94},
  numero = {{SI}},
  pages = {100--110},
  ISSN = {1464-343{X}},
  year = {2014},
  DOI = {10.1016/j.jafrearsci.2013.10.004},
  URL = {https://www.documentation.ird.fr/hor/fdi:010062256},
}