Page 210 - Microtectonics

200 7 · Porphyroblasts and Reaction Rims

Fig. 7.15. Syntectonic garnet porphyroblast in garnet-kyanite schist showing about 45° of dextral rotation with respect to S during growth.
e
Note the continuity between S i and S e , marked by opaque-poor bands that are continuous inside and outside the crystal. S e is deflected around
the porphyroblast and a poorly developed strain shadow is visible at its lower left-hand side. A late syntectonic porphyroblast of kyanite occurs
at the upper left side of the garnet where it overgrew a strain cap. Example of case e1 in Fig. 7.9. Leiden Collection. Width of view 17 mm. PPL

Fig. 7.16. Syntectonic ‘spiral-S i ’ garnet showing apparent dextral rotation with respect to S e of approximately 300°, as deduced from the
inclusion pattern of opaque minerals. Note the sharply curved trails of opaque inclusions in quartz-rich areas; these areas represent
included strain shadows (cf. Fig. 7.37). Example of case e2 in Fig. 7.9. Rio Grande do Sul, Brazil. Width of view 5.5 mm. Polars at 45°