The north Atlantic igneous province

• Main Authors: Saunders, A. D., Fitton, J. G., Kerr, Andrew Craig, Norry, M. J., Kent, R. W.
• Other Authors: Mahoney, John J., Coffin, Millard F.
• Format: Book Part
• Language: unknown
• Published: American Geophysical Union 1997
• Subjects: GC Oceanography; QE Geology; Baffin Island; Canada; Greenland; Kangerlussuaq; Baffin; Iceland; North Atlantic
• Online Access: https://orca.cardiff.ac.uk/id/eprint/9608/; https://doi.org/10.1029/GM100p0045

The North Atlantic Igneous Province extends from eastern Canada to the British Isles, a pre-drift distance of almost 2000 km. The igneous rocks are predominantly basaltic, but differentiates and anatectic melts are also represented. Two major phases of igneous activity can be discerned. Phase 1 began about 62 m.y. ago with continent-based magmatism in Baffin Island, W and SE Greenland, the British Isles, and possibly central E Greenland (the Lower Basalts around Kangerlussuaq). Phase 2 began about 56 m.y. ago and is represented by seaward-dipping reflector sequences (SDRS) along the continental margins, the Main Series basalts in central E Greenland, the Greenland-Faeroes Ridge, and Iceland. Contamination by continental crust was prevalent during Phase 1 but also occurred during Phase 2, especially during the formation of the early SDRS. Although it is unnecessary to involve the continental lithosphere mantle in the formation of Phase 1 or Phase 2 magmas, it is not possible to completely exclude it. We argue that the Iceland plume played a pivotal role in the formation of the North Atlantic Igneous Province because (1) the simultaneous and widespread initiation of activity requires a major thermal event in the mantle; (2) some of the magmas associated with Phase 1 were highly magnesian, indicating that the liquids and, by implication, the mantle source regions were unusually hot; (3) the SDRS were emplaced subaerially or into shallow water, indicating buoyant support by the mantle during rifting and breakup; and (4) the isotopic and compositional diversity recorded in present-day Icelandic basalts is observed in many of the Palaeocene sequences, after crustal contamination and pressure of melt segregation are taken into account. The widespread and simultaneous activity of Phase 1 activity requires an abnormally high mantle flux rate. This may be associated with the arrival of a start-up plume, but alternatively it represents the arrival of a pulse of hot mantle, following a period of weak plume activity during ...