The Palaeogene Faroe Islands Basalt Group (FIBG) comprises three eruptive sequences or formations, all emplaced into a subaerial environment during the development of the extensive continental flood basalt province that stretches from East Greenland through the Faroe Islands and into the Faroe-Shetland Basin. The Beinisvørð Formation, having a tabular-classic facies architecture, is composed of a sequence of simple flows each comprising a single sheet lobe. The Beinisvørð Formation is overlain by the distinctly contrasting Malinstindur Formation that has a compound-braided facies architecture. The Enni Formation occurs at the top of the sequence and consists of a mixture of simple and compound flows with tabular-classic and compound-braided facies architectures, respectively. Surface and internal characteristics of the sheet lobes of the Beinisvørð and Enni formations indicate emplacement through inflation, which is more obvious for the tube-fed compound flows of the Malinstindur and Enni formations. The difference between the simple and compound flow sequences of the FIBG is, most likely, linked to the manner in which the lava was supplied during the eruption and the eruptive style of the volcanic system. The sheet lobes were erupted over laterally extensive areas from fissure systems which had a continuous supply of lava, which contrasts with the tube-fed compound flows which were erupted in a gradual, piecemeal manner from pointsourced, low shield volcanoes with limited areal extents.

Palaeogene volcanism on the NW margin of the Faroe-Shetland Basin is represented by the Faroes Lava Group, within an age range of 57.5–60.56 Ma. The volcanic sequence comprises >1000 m of basaltic volcaniclastic rocks deposited in estuarine or marginal lagoons, overlain by three laterally-extensive formations of subaerial facies basaltic lavas: Lower, c. 3250 m; Middle, c. 1400 m; Upper, at least 900 m (top not preserved). The Lower and Upper formations comprise high-volume sheet flows, commonly with ferrallitized tops, interbedded with reddened, thin, fluvial claystone and basaltic siltstone deposits. Laterally-impersistent coals occur within the Lower Lava Formation. The Coal-bearing Formation (c. 20 m) was deposited in an overbank floodplain environment during an hiatus in the volcanism between the Lower and Middle formations. The Volcaniclastic Sandstone Sequence comprises hydroclastic and pyroclastic deposits which post-date the Coal-bearing Formation and represent a return to volcanism, prior to the eruption of the Middle Lava Formation which is mainly characterized by inflated pahoehoe flows. The onshore sequence of the Faroes Lava Group can be correlated with basaltic flows within the Faroe-Shetland Basin, where lavas in Well 205/9-1 are interpreted to be of Lower Lava Formation affinity, possibly erupted from a local vent system. Seismic and gravity mapping and modelling suggest that the offshore extension of the Lower Lava Formation, together with the oldest part of the Middle Lava Formation, comprise subaqueous hyaloclastites deposited in a prograding Gilbert-type lava delta system. The youngest part of the Middle Lava Formation and all of the Upper Lava Formation occur as subaerial facies lavas within the basin.

Palaeogene sedimentary basin development along the NE Atlantic margin was strongly influenced by a major period of magmatism associated with the initiation of ocean-floor spreading between NW Europe and East Greenland. Five elements to the magmatism in the Faeroe-Shetland Basin can be identified and related to the Palaeogene depositional sequences:(i) extensive lava fields and lavas from central complexes (the Erlend Complex for example) erupted into subaerial and marginal marine environments and consequently influenced sediment distribution within the basin; (ii) dyke swarms, which constitute the feeder system to the lava fields; (iii) sill complexes, possibly related to the fissure systems, which affect reservoir quality on a local scale; (iv) central igneous complexes overlying magma chambers which controlled clastic sedimentation patterns (Westray for example); (v) tuffs (for example the Balder Formation and Kettla Member) which aid correlation of reservoirs and seals.The main development of Paleocene sandstone reservoirs along the axis of the Faeroe-Shetland Basin appears to have been synchronous with the phases of thermal uplift along the basin margin and pulsed volcanism at c. 62 Ma, 58 Ma and 56.6-55 Ma. The major episodes of reservoir deposition may reflect the activity of the Iceland plume and provide independent evidence of the pulsed nature of the magmatism. This model integrates igneous, sedimentary and tectonic data with precise radiogenic ages and biostratigraphy. It allows detailed correlation of reservoirs and seals within the Paleocene play fairway and improves prediction of stratigraphic trapping styles common in this play.

Palaeocene volcanic activity is represented in west-central Skye, Inner Hebrides, Scotland, by a laterally extensive and thick pile of sub-aerial lavas mainly belonging to the alkali olivine basalt—hawaiite—mugearite—benmoreite—trachyte suite. The lavas are typical of many continental flood basalt suites and were principally fed from fissure eruptions similar to those of present day Iceland. Intercalated with the lavas are rare beds of heterogeneous volcaniclastic material, including breccias, conglomerates, sandstones and mudstones. The sequence forms a major portion of a larger volcanic field preserved within the NNE-SSW-elongated ‘Sea of the Hebrides’ sedimentary basin.Significant hiatuses in the volcanic activity are marked by deep-weathering profiles and thin sedimentary sequences comprising mudstones, ironstones, coals, sandstones and conglomerates. Palaeocurrent indicators and clast lithologies within the clastic sedimentary rocks indicate that erosion of a massif dominated by the Palaeocene Rum Igneous Complex and its roof rocks, c. 20 km to the S, provided abundant detritus to a river system which drained towards the N. Such sedimentary intercalations aid the stratigraphical subdivision of the lava field. Eight lava groups, each most likely with a different focus of fissure eruption, and divisible into mappable formations, together with two sedimentary formations, are recognised.The alkali olivine basalts are typically thin, with a tendency to form compound flows with limited lateral extents, whilst the hawaiites and mugearites are considerably thicker and cover large areas. Only very rarely are flow terminations observed. The original extents of the single benmoreite and rare trachytes cannot be determined from their limited erosional remnants. The more evolved flows tended to occur after brief hiatuses in the volcanic activity, indicated by well-developed lateritic tops to the underlying flows.The youngest preserved lava is a columnar-jointed olivine tholeiite with a MORB-like composition. The flow is at least 120 m thick and apparently ponded in a steep-sided palaeo-valley within the lava field.Three fault trends are recognised: parallel, normal and marginally oblique to the main NW-SEtrending regional dyke swarm, and dissect the lava field into a number of discrete blocks. The more significant of these faults may have been active during the development of the lava field, and in some instances instrumental in controlling the distribution of the flows.Later Tertiary erosion has removed an unknown thickness of material from the upper part of the lava field, the preserved thickness of which is estimated to be about 1·5 km.

The North Faroe-Shetland Basin (NFSB) Sill Complex is of late Paleocene/earliest Eocene age and was emplaced within Cretaceous and Paleocene sedimentary rocks, in places to depths as shallow as a few hundred metres below the contemporaneous basin floor. Intersections of the Complex occur in exploration wells drilled by the oil industry and indicate tholeiitic basaltic compositions. High quality 3D seismic data, obtained during hydrocarbon exploration along the NE Atlantic Margin, provide a unique view of an uneroded suite of these sheet-like intrusions in UK Quadrants 218 and 219 and indicate the multi-centred nature of the NFSB Sill Complex, with upward-fingering terminations from broad bowlshaped foci of intrusion. Where the intrusion depth is very shallow, depending upon the host lithology, sill emplacement has lead to the development of structures on the contemporaneous basin floor interpreted as submarine hyaloclastite-dominated vents, up to c. 2 km across and with heights of up to c. 100 m. Where intrusion depth is greater, ‘seismic chimney’ structures are interpreted as the fluidescape feeders of sedimentary-hydrothermal mounds. Subsequent differential compaction of sedimentary sections, with and without shallow-emplaced sills, has given rise to distinctive ‘eye’ structures, as seen in seismic sections.