"ReactionPrinciple"asappliedtocertainMineralTransformationsinMigmatiticRocks

TheapplicationofN.L.Bowen'sreaction-principle(2',pp.177-198;3p.60)tothestudyofcertainigneoustexturesandthecrystallisationandcoolingofmagmashasbeenwidelyaccepted.Theplagioclaseseriesrangingfromthecalcicend-tothesodicisthebestexampleofacontinuousreactionseries,whiletheolivine-pyroxene-amphibole-biotiteseries-theexistenceofwhichcanbeeasilyconvincedbythepresenceofcoronastructureincertaingabbroicrock-isadiscontinuousseriesoffrequentoccurrence.Duringhisstudyofthemixedrocks-migmatites-ofaportionofaninjection-complexinNorthSutherland.Scotland(5),thewriterhasfoundcertainmineralchangeswhichmaybeinterpretedinthelightofBowen'sreaction-principle.Suchchanges,asaredifferentfromthoseoccurredinthecourseofthecoolingofamagma,weretakingplaceinasolidrock-systemunderhightemperature,strongstressandthedominantinfluenceofcertainchemicallyactive.fluidsrelatedtoagraniticmagma.