During the Palaeogene, the NW European continental margin was the site of intense volcanic activity in response to lithospheric thinning and, ultimately, at c. 55 Ma, the formation of a new ocean crust (e.g. White 1988, 1992; Saunders et al. 1997) (Fig. 14.1). Along the west coast of Scotland, vestiges of this period of magmatism take the form of continental (flood) lava sequences, together with shallow intrusive centres and associated lava shields, dyke swarms and sill complexes (Emeleus & Bell 2003). The igneous activity spanned the interval c. 60.5 Ma to 55 Ma and appears to have been intermittent, with significant hiatuses between periods of rapid growth of the lava fields and intrusive activity (Bell & Jolley 1997).
The magmatism is attributed to the impact of the protoIceland plume at the base of the lithosphere, which produced approximately contemporaneous volcanic and intrusive activity between NW Europe and Arctic Canada. The siting of the lava fields was largely controlled by crustal thinning events in the Mesozoic (Thompson & Gibson 1991), whereas the location of the central complexes was strongly influenced by considerably older lineaments. Subsequently, ocean floor spreading took place between NW Europe and East Greenland and between central West Greenland and Baffin Island. The magmas that were erupted or emplaced at the time of continental breakup were not typical of plumes sourced from deep levels in the mantle, and involved much MORB-like material, derived from the upper (depleted) mantle (Saunders et al. 1997). The rate of melt production