Aperçu pétrologique et structural de la Galice cristalline

Recent contributions by penologists of Leiden University to the present state of knowledge concerning crystalline Galicia are summarized. An enumeration of the most important rock-types is given and their grouping in geotectonic units is attempted. The structural and metamorphic history is outlined and shown to comprise a variety of pre-hercynian (pre-Cambro-ordovician) as well as hercynian and post-hercynian elements. It is argued that originally geosynclinal rocks of the pre-hercynian orogen (frequently attaining the eclogite, granulite or charnockite metamorphic facies) were intruded by Cambro-ordovician granitic rocks, and were subsequently incorporated in the hercynian orogen, where they were re-deformed, predominantly to N-S trending isoclinal folds, and re-metamorphosed, locally reaching a wet anatextitic climax in the cordieriteamphibolite facies of Winkler. The hercynian orogenic cycle is claimed to have terminated in W. Galicia with further episodes of tectonization and recrystallization, and with retrograde metamorphism and granitic intrusions of an increasingly high-level nature. A synoptic table, presenting a tentative correlation of geological events in crystalline Galicia, is appended.