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Communication Dans Un Congrès Année : 2019

Germanium concentration associated to sphalerite recrystallization: an example from the Pyrenean Axial Zone

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Alexandre Cugerone
  • Fonction : Auteur
  • PersonId : 1034678
Bénédicte Cenki-Tok
Emilien Oliot
Manuel Munoz
  • Fonction : Auteur
  • PersonId : 1026932
Alain Chauvet
Fabrice Barou
Stefano Salvi

Résumé

Germanium (Ge) is often found as trace element in undeformed sphalerite (ZnS). However, the presence of Ge-minerals (oxides, chloritoids and/or sulphides with up to 70 wt% Ge) is remarkable in Pb-Zn deposits from the Variscan Pyrenean Axial Zone. Their abundance is controlled by the chemical and/or the mechanical processes that affect rare element concentration from sulphides which have undergone deformation and metamorphism. In this study, we document the microstructures and chemical heterogeneities in sphalerite, based on EBSD (electron backscatter diffraction) coupled to LA-ICPMS in situ analyses. Deformation induces the dynamic recrystallization of sphalerite. Recrystallized domains have low Ge contents (1-50 ppm Ge) whereas porphyroclastic sphalerite grains commonly show higher Ge concentrations (up to 650 ppm Ge). Ge-minerals (up to 70 wt% Ge) are exclusively hosted by the Ge-poor recrystallized domains. We propose that Ge was removed from the sphalerite crystal lattice during sulphide recrystallization, and was subsequently concentrated in Ge-minerals, leaving behind a Ge-depleted fine-grained recrystallized sphalerite matrix. Numerous sulphide ore types enriched in rare elements like Pyrenean deposits may present recrystallization features and we suggest evaluating the potential of such deposits by integrating chemical and structural informations at the micrometer scale using state-of-the-art analytical techniques in exploration methods.

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Dates et versions

hal-02915316 , version 1 (02-09-2020)

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  • HAL Id : hal-02915316 , version 1

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Alexandre Cugerone, Bénédicte Cenki-Tok, Emilien Oliot, Manuel Munoz, Alain Chauvet, et al.. Germanium concentration associated to sphalerite recrystallization: an example from the Pyrenean Axial Zone. 15th SGA Biennial Meeting on Life with Ore Deposits on Earth, Aug 2019, Glasgow, United Kingdom. ⟨hal-02915316⟩
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