Page 211 - Microtectonics

7.4 · Classification of Porphyroblast-Matrix Relations 201

Fig. 7.17. Syntectonic chloritoid crystals (ottrelite variety) in slate. The central part of the main crystal does not contain any S , and the
i
strain shadows next to this part seem to be free of cleavage, suggesting that the core of the crystal may be pretectonic. Only one phase of
deformation can be recognised. Example of case e3 in Fig. 7.9. Curaglia, Switzerland. Width of view 1.8 mm. PPL

Fig. 7.18. Garnet porphyroblast in micaschist, syntectonic with respect to D . D folds, traced by included opaque grains, are gentle in the
2
2
garnet core becoming tighter towards the rim. S 2 shows clear deviation around the lower part of the crystal. No strain shadows have
developed, probably because the garnet grew in a mica-rich band. The crenulation cleavage (S ) and S (= S ) are mainly defined by
1
i
2
opaque minerals. Example of case f3 in Fig. 7.9. São Felix de Cavalcante, Goiás, Brazil. Width of view 3 mm. Polars at 45°