Frontier exploration and the North Atlantic Igneous Province: new insights from a 2.6 km offshore volcanic sequence in the NE Faroe–Shetland Basin

The Lagavulin exploration well 217/15-1Z penetrated a ~2.6 km thick volcanic sequence dominated by extrusive basaltic rocks spanning the Palaeocene-Eocene boundary in the NE Faroe-Shetland Basin (FSB). The well comprises one of the thickest drilled sequences through the North Atlantic Igneous Province. Integrated analysis of drill cuttings and wireline-log data reveals key volcanic lithofacies: i) tabular lava flows; ii) compound lava flows; iii) hyaloclastite; and iv) volcaniclastic rocks. The volcanic facies reveal two major sub-aqueous to sub-aerial sequences consistent with lava delta progradation. These sequences are separated by a volcanic hiatus represented by extensive reddened soils which preceded the re-submergence of the area. Emergence followed by submergence of the first lava delta is interpreted to record an intra-T40 transient uplift event near the Palaeocene-Eocene boundary. Basalts from the lower ~1.3 km have low TiO2 (<1.5 weight %) and low Zr/Y (2- 3), with olivine-phyric picrites towards the base (Mg# 70-82; olivine Fo85-91). The hiatus correlates precisely with a change to high TiO2 (2.5-3.2 weight %) high Zr/Y (>4) compositions which dominate the upper sequence. The associated change in lava geochemistry, transient uplift and volcanic hiatus appears consistent with a transient pulse of hot buoyant plume material passing beneath the area.