Regional Variscan structure in southern Ireland follows a gentle arcuate trend of ca. 25° concave to the SE that apparently follows the geometry of the Cantabrian Orocline (NW Iberia) when Iberia is restored to its position prior to the opening of the Biscay Bay. We report paleomagnetic results from Devonian and Carboniferous rocks in southern Ireland: (i) a pervasive and consistent remagnetization during the Late Carboniferous and (ii) an average rotation of ~25° counterclockwise with respect to the Global Apparent Polar Wander Path and kinematically compatible with the Cantabrian Orocline. These results support the participation of Laurussia in the formation of the Cantabrian Orocline involving, at least, southern Ireland and the South Portuguese Zone (S Iberia). We conclude that a Greater Cantabrian Orocline extends beyond its current boundaries to include shear zones in the Variscan hinterland and the Rheic Ocean suture, thereby enlarging its size to plate-scale affecting as it does the Laurussia and Gondwana margins.

We want to thank Mark Dekkers for discussion and useful comments. Brenton Fairey, Thomas Groenewegen and Aidan Kerrison are thanked for laboratory assistance. This research is funded by the Netherlands Organization for Scientific Research (NWO). We are in debt with the insights, discussion and constructive comments provided by Rob van der Voo and Emilio Pueyo. DPG would like to thank a postdoctoral grant from ISES (project no. WA.146101.2.656). This paper is a contribution to IUGS-UNESCO's IGCP projects no. 574 “Bending and Bent Orogens, and Continental Ribbons”, no. 597 “Amalgamation and Breakup of Pangaea” and no. 648 “Supercontinent Cycles & Global Geodynamics”.

Peer reviewed