Palaeogene alpine tectonics and icelandic plume-related magmatism and deformation in Northern Ireland

The Cenozoic tectonic history of NW Europe is generally attributed to some combination of three principal controlling factors: North Atlantic opening, Alpine collision and formation of the Icelandic mantle plume. Using constraints from the high-resolution Tellus aeromagnetic survey of Northern Ireland, we show that Palaeogene tectonics can be attributed to approximately north-south Alpine-related compression, forming NNW-SSE-trending dextral and ENE-WSW-trending sinistral conjugate strike-slip faults, with the latter defined by kilometre-scale displacements along reactivated Caledonian or Carboniferous faults. This tectonism was, however, punctuated by pulsed magmatic intrusive and extrusive events, including four distinct dyke swarms that are attributed to NE-SW- to east-west-directed plume-related extension. Although this evidence shows, for the first time, that north-south Alpine compression was periodically overwhelmed by the dynamic stresses and uplift associated with pulsed mantle plume-related deformation, associated strike-slip faulting may have controlled the locus of volcanic activity and central igneous complexes, and the location of sedimentary depocentres.