Feeling the pulse? Paleogene chronostratigraphy of Northern Ireland and the north of Ireland temporally coupled to the North Atlantic Igneous Province

Abstract The roles of plume and rift dynamics as drivers of the Paleogene North Atlantic Igneous Province (NAIP) continue to be contested. Despite their distal location from the proto-Icelandic plume, the Paleogene intrusive and extrusive rocks of Northern Ireland and the north of Ireland have been reported to contain some of the oldest and youngest magmatism within the NAIP. This record, seemingly decoupled from that of the broader NAIP, represents a challenge for reconstructions that rely solely on plume models. By integrating transboundary aeromagnetic surveys and targeted high-precision zircon U-Pb geochronology, we develop a revised chronostratigraphic framework for this segment of the NAIP, with activity from ca. 61.6 Ma to 55.9 Ma, and reduce its duration by up to ~8 m.y. to just ~5.5 m.y. The framework now supports a regionwide correlation for the onset of NAIP magmatism that is concurrent with established depositional events and indicates that magmatism did not extend beyond the “rift to drift” transition in the North Atlantic shortly after ca. 56 Ma. The new constraints indicate that rifting did not drive the active stress regime within ~1 m.y. of the onset of magmatism and favors a pulsing proto-Icelandic plume head impacting the distal corners of the NAIP throughout its duration.