@article{fdi:010092008,
  title = {{U}nravelling the magmatic and hydrothermal evolution of rare-metal granites through apatite geochemistry and geochronology : the {V}ariscan {B}eauvoir granite ({F}rench {M}assif {C}entral)},
  author = {{R}ocher, {O}. and {B}allouard, {C}. and {R}ichard, {A}. and {M}onnier, {L}. and {C}arr, {P}. and {L}aurent, {O}. and {K}hebabza, {Y}. and {L}ecomte, {A}. and {B}ouden, {N}. and {V}illeneuve, {J}. and {B}arr{\'e}, {B}. and {F}ullenwarth, {P}. and {L}eisen, {M}athieu and {M}ercadier, {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{P}eraluminous rare-metal granites ({PRMG}s) represent highly differentiated crustal granites characterised by extreme enrichment in metals, such as {L}i, {S}n, {N}b, {T}a, {W}, and {B}e. {T}his geochemical specificity is considered to be the result of a succession of magmatic and hydrothermal processes, the importance and individual impact of which are still debated. {I}n this study, we investigate the magmatic and hydrothermal evolution of the {B}eauvoir leucogranite, a world-class {PRMG} from the {F}rench {P}aleozoic {V}ariscan belt, through extensive characterisation of suprasolidus to subsolidus apatite. {W}e employ a multi-tracing approach, combining in-situ elemental composi- tions (major, trace, and halogen elements), oxygen isotopic systematics, and {U}-{P}b geochronology. {F}our major magmatic and hydrothermal stages were identified through apatite petrography and {U}-{P}b geochronology. {M}agmatic apatite crystallised at 314.6 f 4.7 (2s) {M}a. {D}ecrease in the amplitude of the {E}u anomaly in magmatic apatite from the deeper to shallower granitic units record an increase in the oxygen fugacity (f{O}2) of the magma with differentiation, likely contributing to the crystallisation of a first and predominant cassiterite gener- ation. {M}agmatic apatite {REE} patterns show significant tetrad effects; they reflect the exsolution of magmatic fluids involved in the precipitation of early hydrothermal apatite replacing igneous minerals or precipitating within veins during greisenisation episode dated at 314.3 f 5.5 {M}a and 311.7 f 8.1 {M}a. {E}arly hydrothermal apatite, charac- terised by enrichment in {S}r or {S} and {M}n-{REE} depletion along with variable {B}r/{I} ratios and delta 18 {O} compositions down to negative values, record mixing dynamics between two fluid end-members: (i) magmatic fluids, and (ii) oxidising meteoric fluids partially reequilibrated with country rocks. {M}eteoric fluids progressively invaded the {B}eauvoir {PRMG} at temperatures >= 450 degrees {C} and triggered precipitation of a second generation of cassiterite during mixing with magmatic fluids. {T}wo late, non-magmatic, hydrothermal events are dated at 268.3 f 20.4 {M}a and 148.5 f 26.6 {M}a. {R}elated apatite is marked by specific mineralogical and geochemical features such as high {A}s contents and heavy oxygen isotope signatures. {T}hey are proposed to be linked to extension-related regional hydrothermal fluid cir- culation that contributed to metal endowment ({U}, {F}-{B}a-{P}b-{Z}n) in the crystalline basement and overlying sedi- mentary cover of {W}estern {E}urope following the {V}ariscan {O}rogeny. {O}ur results demonstrate that apatite is a key mineral to decipher the role of magmatic and hydrothermal processes leading to ore deposition and remobilisation in {PRMG}s, in relation with geodynamic evolution. {A}patite records of external fluid incursions at near-solidus conditions highlight the open system nature of the {B}eauvoir {PRMG}, which is crucial for developing fully integrated metallogenic models applicable to similar deposits.},
  keywords = {{A}patite ; {M}agmatic ; {H}ydrothermal ; {R}are-metal granite ; {B}eauvoir ; {FRANCE}},
  booktitle = {},
  journal = {{C}hemical {G}eology},
  volume = {670},
  numero = {},
  pages = {122400 [33 p.]},
  ISSN = {0009-2541},
  year = {2024},
  DOI = {10.1016/j.chemgeo.2024.122400},
  URL = {https://www.documentation.ird.fr/hor/fdi:010092008},
}