Dynamic Permeability Related to Greisenization Reactions in Sn-W Ore Deposits: Quantitative Petrophysical and Experimental Evidence

Figure 4

Mineralogical and microtextural characteristics of the two-mica Panasqueira granite. (a) Photomicrograph displaying a general view of the two-mica granite (transmitted light). (b) Photomicrograph of matrix K-feldspars exhibiting typical perthitic textures (polarized transmitted light). (c) Phenocryst of K-feldspar marked by poikilitic textures (inclusions of biotite, albite, and apatite) (transmitted light). (d) Cathodoluminescence image of the same k-feldspar phenocryst displayed in (c). This grain exhibits blue and red luminescent zones corresponding to different chemical compositions (indicated on image) that are related to K-metasomatism of primary magmatic alkali feldspars (blue luminescent zones). (e) Large euhedral flake of biotite containing numerous zircon and apatite inclusions (transmitted light). (f) Phenocryst of albite with quartz and apatite inclusions. The chemical composition of albite is indicated on the photomicrograph (polarized transmitted light). (g and h) SEM-BSE images of albite displaying typical pitted textures marked by the occurrence of a dense network of micropores. Abbreviations from Whitney and Evans [45]. Ab: Albite; Ap: apatite; Bt: biotite; Kfs: K-feldspar; Ms: muscovite; Or: orthoclase; Qz: quartz; Zrn: zircon.

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