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

Figure 6

SEM-BSE images displaying the microtextural evolution induced by the greisenization of the Panasqueira granite. (a) Porous texture in a greisenized granite sample showing the heterogeneous distribution of the porosity. A microporous pocket and a microcrack are labeled. (b) Enlargement of a microporous pocket showing the intergranular porosity corresponding to spaces around muscovite grains. (c) Porous texture in greisen showing large pores corresponding to spaces around muscovite grains (this section was made from the sample shown in Figure 2(b), 1). (d) Porous greisen, in which a large amount of hydrothermal apatite has crystallized during the late hydrothermal stages. (e) Large void space fringed by euhedral quartz, which has crystallized from the pore’s edge. (f) SEM-BSE image showing hydrothermal overgrowth of muscovite forming greisen and pore space partially infilled by hydrothermal apatite. (g) Fe and (h) Al chemical maps prepared from the section shown in (f). Abbreviations from Whitney and Evans [45]. Ab: albite; Ap: apatite; Ms: muscovite; Qz: quartz.

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