Abstract - The Cenozoic tectonics of NW Europe is generally attributed to some combination of three principal controlling factors: North Atlantic opening, Alpine collision and Icelandic mantle plume activity. The relative contribution of each of these factors is the subject of debate. Using constraints derived from the Tellus high resolution geophysical survey, we suggest that the Palaeocene tectonics of Northern Ireland, which hosts extensive exposures of early Palaeocene igneous rocks from the North Atlantic Igneous Province, involved Alpine-related strike-slip faulting caused by approximately N-S compression, punctuated by pulsed magmatic intrusive and extrusive events associated with NE-SW to E-W directed plume-related extension. Strike-slip faulting conforms to conjugate pairs of NNW-striking dextral and ENE-striking sinistral faults, with the latter defined by kilometre-scale displacements of older reactivated Caledonian/Carboniferous faults. The known onshore occurrence of Palaeocene intrusive central complexes and extrusive flood basalts, and the identification herein of four distinct dyke swarms is consistent with pulsed mantle plume activity as previously diagnosed from offshore submarine fans. Whilst the background tectonic deformation arising from approximately N-S Alpine compression is periodically overwhelmed by plume-related deformation (e.g. to form dyke swarms), related strike-slip faulting may have controlled the location of volcanic and sedimentary depocentres and of igneous intrusive complexes.
Abstract of talk given to:
Irish Geological Research Meeting, Trinity College Dublin, February 2009.