Low-grade metamorphism within the Welsh sector of the paratectonic Caledonides

Mineral assemblages within metabasites from the paratectonic Caledonides of Wales show that the grade of metamorphism was predominantly within the prehnite‐pumpellyite facies, although green‐schist fades assemblages occur in the more central parts of the region. General agreement with this pattern of metamorphism is seen in recent studies of illite crystallinity and conodont colour. Comparison with other regions suggests that all of the paratectonic Caledonides of the British Isles has suffered a low‐grade of regional metamorphism during late Caledonian times.