Time Relations Between Folding, Metamorphism and the Emplacement of Granite in Rosguill, County Donegal

Rosguill is an area in which the time relationships between folding, metamorphism and the emplacement of granite can be demonstrated. During the first phases of the structural history two slides were developed which were folded during four succeeding deformation-episodes; a regional metamorphism was imposed at this period and was then followed by diapthoresis. Migmatitic gneisses, associated with a pronounced metamorphism, cut across the pre-existing structures. A xenolithic granodiorite was emplaced after these gneisses, and evidence is presented which suggests that this mass marks a later phase in the activity of the migmatite.