Short post about the thin section of biotite-kyanite carbonaceous schist from Keivy, Kola peninsula, Russia. The rock was invloved in processes of muscovitization, staurolitization, alteration, retrogressive metamorphism etc. I would like to show several pictures of Al2[SiO4]O modifications and high aluminous phases.
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| Fig. 1. All three Al2[SiO4]O modifications that has been formed due to different processes occured here. Kyanite as a paramorphose after andalusite, sillimanite as a product of thermal reaction, andalusite as relict in newly formed muscovite aggregate. XPL. |
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| Fig. 2. The same field, PPL. |
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| Fig. 3. Staurolitization. Staurolite replaces kyanite crystal. PPL. |
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Fig. 4. Fibrous sillimanite aggregate, muscovitization and chloritization of biotite. PPL. |
The pictures show complex and multi-step process of metamorphism of highly aluminous metasediments.
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