In the Irish and British Caledonides, the early Ordovician Grampian Orogeny was the result of collision between the Laurentian rifted margin and an oceanic island arc. The Connemara terrain in western Ireland differs in position and character from all other parts of the exposed Dalradian rocks of the Grampian Orogen in lying south of the collided arc and fore-arc, and in having north-verging fold nappes that developed synchronously with the intrusion of huge volumes of calc-alkaline magmas that provided the heat for regional Barrovian metamorphism. We have tested this hypothesis with a numerical model, which demonstrates its admissablity. Connemara is not a terrane, displaced with respect to the remainder of the Grampian Orogen but was overridden, northwards, by the arc and its fore-arc basin (South Mayo Trough), frontal ophiolite complex (Deer Park) and accretionary complex (Killadangan). Deposition in the South Mayo Trough occurred below sea level and above the evolving Grampian Orogen, which developed on a hyper-extended rifted margin bounded to the north by the Clew Bay Line.
↵1 This paper is part of a special issue that honors the careers of Kevin C. Burke and John F. Dewey.
- Received July 22, 2015.
- Accepted October 19, 2015.
- Published on the NRC Research Press Web site at http://cjes.nrc.ca on November 10, 2016.
- Published by NRC Research Press