The movement of magma through the shallow crust and the impact of subsurface sill complexes on the hydrocarbon systems of prospective sedimentary basins has long been an area of interest and debate. Based on 3D seismic reflection and well data, we present a regional analysis of the emplacement and magmatic plumbing system of the Palaeogene Faroe-Shetland Sill Complex (FSSC), which is intruded into the Mesozoic and Cenozoic sequences of the Faroe-Shetland Basin (FSB). Identification of magma flow directions through detailed seismic interpretation of approximately 100 sills indicates that the main magma input zones into the FSB were controlled primarily by the NE-SW basin structure that compartmentalise the FSB into its constituent sub-basins. An analysis of well data shows that potentially up to 88% of sills in the FSSC are <40 m in thickness, and thus below the vertical resolution limit of seismic data at depths at which most sills occur. This resolution limitation suggests that caution needs to be exercised when interpreting magmatic systems from seismic data alone, as a large amount of intrusive material could potentially be missed. The interaction of the FSSC with the petroleum systems of the FSB is not well understood. Given the close association between the FSSC and potential petroleum migration routes into some of the oil/gas fields (e.g. Tormore), the role the intrusions may have played in compartmentalisation of basin fill needs to be taken fully into account to further unlock the future petroleum potential of the FSB.

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 TiO 2 (<1.5 weight %) and low Zr/Y (2-3), with olivine-phyric picrites towards the base (Mg# 70-82; olivine Fo 85-91). The hiatus correlates precisely with a change to high TiO 2 (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.

The Faroe Islands Basalt Group (FIBG)