grenat hélicitique

CONT: Le grenat hélicitique possède des inclusions se disposant en spirale.
OBS: hélicitique : Caractérise les minéraux disposés en forme de spirale dans une roche métamorphique ayant subit une rotation.

CONT: A spectacular example of synkinematic porphyroblast growth is provided by the so-called snowball garnets, which have spiral trails of inclusions that indicate rotation of either the garnet or the matrix foliation during garnet growth.
CONT: Garnets in certain metamorphic rocks contain inclusion fabrics whose geometry is very similar to that of the model. Such syntectonic, snowball, or rotational garnets, as they have previously been termed, can be studied in three dimensions.
OBS: Pinwheel garnet and snowball garnet are designations sometimes applied to those garnets whose inclusions appear to have been rotated. These garnets occur sporadically in foliated metamorphic rocks. Although their presence in diverse rocks has been interpreted variously, present-day consensus appears to be that they represent rotation during growth under conditions of dynamic metamorphism that involved differential pressures.