Fig. 3


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Photomicrographs, SEM-BSE and SEM-CL images showing the textural characteristics of white-mica and quartz composing the two-mica granite and greisen of Panasqueira. (a) General view displaying the mineralogical composition and the texture of the two-mica granite. (b) SEM-BSE image of larges flakes of magmatic white-mica displaying unzoned microtexture. (c) SEM-CL image of euhedral magmatic quartz phenocryst composing the two-mica granite of Panasqueira. This quartz exhibits a relatively weakly contrasted concentric growth zoning. (d) General view displaying the mineralogical composition and the texture of greisen. Note that vugs developed during greisenization were infilled by euhedral hydrothermal quartz and late sulfides and carbonate assemblages. (e) SEM-BSE image of white-mica composing the greisen of Panasqueira. These white-micas exhibit a strong zoning corresponding to hydrothermal overgrowth of primary magmatic white-mica of the two-mica granite. (f) SEM-BSE image of euhedral hydrothermal quartz infilling vug of greisen. Transmitted light (f) and SEM-CL (g) images of remnants of primary magmatic euhedral quartz phenocryst partially altered during greisenisation. These quartz exhibit hydrothermal overgrowths characterized by lower luminescence intensity than primary euhedral quartz phenocrysts cores. In some cases the primary concentric growth zoning are conserved. The CL-dark structures correspond to healed fractures underlined by fluid inclusions trails in transmitted light. Ab: Albite; Bt: Biotite; Kfs: K-feldspar; Wmca: White-mica; Qz: Quartz.

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