A Lower Devonian age for the Corvock Granite and its significance for the structural history of South Mayo and the Laurentian margin of western Ireland

The Silurian Croagh Patrick succession, which crops out just south of a fundamental Caledonian structural zone near Clew Bay, western Ireland, is series psammites and pelites with strong penetrative cleavage. These rocks are intruded by the Corvock granite. A suite minor intrusions associated granite contains regional cleavage whereas undeformed. New U–Pb dates 413 +7 / –4 Ma for strongly cleaved sill 410 ± 4 main granite, closely constrain age crystallization coeval formation as Lower Devonian (Lochkovian or Pragian), implying syn- to late-kinematic emplacement. data consistent evidence sinistral shear shown Ox Mountains granodiorite northeast dated at 412.3 0.8 Ma. This superimposed on Ordovician South Mayo Trough. localisation deformation interpreted being due its position restraining bend during motion segment Fair Head – Bay Line north. Contemporaneous in syn-kinematic Donegal batholith suggests transfer this intra-Grampian structure rather than simple along-strike linkage Highland Boundary Fault Scotland. Our new indicate diachronous late early history Irish Scottish Caledonides also support previous interpretations between these areas Appalachian orogens.