Intra-Ordovician deformation in southeast Ireland: evidence from the geological setting, geochemical affinities and U-Pb zircon age of the Croghan Kinshelagh granite

U-Pb dating of zircons from the Croghan Kinshelagh alkali granite in southeast Ireland suggests a mid-Caradoc emplacement age of 454 plus or minus 1 Ma. Age and geochemical data of granite and volcanic rocks indicate that they are the products of major Ordovician magnetic episode which generated the Avoca Volcanic Belt and other Ordovician volcanoes in eastern Ireland. The closure of the Iapetus Ocean or events of local origin are responsible for the intra-Ordovician deformation in the volcanic rocks and sediments.