Abstract Talc-phengite intergrowths were identified in epizone rocks from the Beni Mezala unit (Internal Zone of the Rif). These rocks show the non-common assemblage quartz-K-feldspar-albite-phengite-talc-vermiculite-chlorite/vermiculite mixed-layers. Although X-ray diffraction patterns indicate the presence of talc, talc could not be observed petrographically. In contrast, transmission electron microscopy indicates that white mica consists of nanometer-sized intergrowths of phengite and talc. At the scanning electron microscope scale, these micas show anomalously high contents of Fe + Mg composition (with an average value of 0.51 atoms per formula unit, apfu). The subtraction of the talc component from the mica formula allowed to obtain a mica with a limited phengitic substitution K0.91Na0.03(Al1.74 Fe2+0.23Mg0.03Ti0.03)Σ=2.03(Si3.18Al0.82) which permits an estimation of minimum pressure (P)

中文翻译：

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来自 Rif Cordillera（摩洛哥北部）内部区域的低品位变质岩中滑石-白云母组合的证据

摘要 在 Beni Mezala 单元（Rif 的内部区域）的表带岩石中发现了滑石 - phengite 共生体。这些岩石显示出不常见的组合石英-钾长石-钠长石-闪长石-滑石-蛭石-绿泥石/蛭石混合层。尽管 X 射线衍射图表明存在滑石，但在岩相学上无法观察到滑石。相比之下，透射电子显微镜表明白色云母由纳米级的菱镁矿和滑石的共生体组成。在扫描电子显微镜范围内，这些云母显示出异常高的 Fe + Mg 成分含量（每个分子式单位 apfu 的平均值为 0.51 个原子）。从云母分子式中减去滑石组分可以得到具有有限表层取代 K0.91Na0.03(Al1.74 Fe2+0.23Mg0.03Ti0.03)Σ=2.03(Si3.18Al0.03) 的云母。