Abstract The Palaeogene Erlend Volcano subcrops in the Faroe-Shetland Basin on the NE Atlantic Margin and was first recognized on the basis of its pronounced positive gravity and magnetic anomalies. Three hydrocarbon exploration wells (209/3-1; 209/4-1A; 209/9-1) have penetrated thick sequences of subaerial facies basaltic lavas and subaqueous volcanic breccias (the ‘Basaltic Suite’), overlying Palaeogene (Thanetian) and Cretaceous (Maastrichtian and Campanian) sedimentary rocks interbedded with medium to fine-grained silicic igneous rocks (the ‘Acidic Suite’). Detailed palynological and petrological analysis indicates that the basaltic rocks were contemporaneous with the Faroes Lower Lava Formation at c. 56.6-55 Ma, and were erupted into environments ranging between dry land and brackish to freshwater lagoons at the margin of a marine channel separating the Erlend Volcano from the Brendan’s Volcano to the north. The subjacent Acidic Suite is interpreted as a series of sills emplaced approximately contemporaneously with the volcanic rocks on the basis of their diachronous relationship with interbedded sedimentary rocks, together with high Thermal Alteration Index values of in situ fossils.

Abstract The Faroe-Shetland Basin (FSB) is a narrow but deep-rifted structure, trending NE-SW, with its orientation controlled by Caledonian basement thrusts. It lies between the Precambrian and Paleozoic Caledonian basement of the West Shetland Platform (part of the Orkney-Shetland Platform) and the Faroe Platform. It corresponds approximately to the topographical deep-water Faroe-Shetland Channel. It is bounded to the SW by the Sula Sgeir High and the Wyville-Thomson Ridge. The western margin lies under the flood basalts of the Faroe Platform and is imperfectly delimited. The NE margin is formed by the Erlend Central Complex (forming the Erlend Platform) (Figs 171 & 176).

Abstract: An overview of the distribution of volcanic facies units was compiled over the North Atlantic region. The new maps establish the pattern of volcanism associated with breakup and the initiation of seafloor spreading over the main part of the North Atlantic Igneous Province (NAIP). The maps include new analysis of the Faroe–Shetlands region that allows for a consistent volcanic facies map to be constructed over the entire eastern margin of the North Atlantic for the first time. A key result is that the various conjugate margin segments show a number of asymmetric patterns that are interpreted to result in part from pre-existing crustal and lithospheric structures. The compilation further shows that while the lateral extent of volcanism extends equally far to the south of the Iceland hot spot as it does to the north, the volume of material emplaced to the south is nearly double of that to the north. This suggests that a possible southward deflection of the Iceland mantle plume is a long-lived phenomenon originating during or shortly after impact of the plume.

Abstract: The Greenland–Iceland–Faroe Ridge Complex (GIFRC) has been forming since the opening of the NE Atlantic (<55 Ma), standing out as a prominent feature on all geoscientific datasets. Our interpretations have revealed several new potential abandoned rift centres, mapped as syncline and anticline structures. The synclines are suggested to be manifestations of former rift axes that were abandoned by rift jumps. These appear to be more common inside the GIFRC region than in the adjacent ocean basins, and can be confirmed by observations of cumulative crustal accretion data through time. A major post-40 Ma unconformity is proposed across the East Iceland Shelf, forming a distinct 16–20 myr-long hiatus that is covered by a thick, younger sedimentary section. Several seamounts were identified on multibeam datasets at around 1200 m water depth in the Vesturdjúp Basin, just south of the Greenland–Iceland Ridge. These seamounts appear to be younger in formation time than the surrounding ocean floor, possibly indicating a still active intraplate volcanic zone. Young tectonic features, such as faults, graben and transverse ridges, characterize the area and present a good example of the complexity of the GIFRC in comparison to the adjacent abyssal plain.

Abstract: The NE Atlantic region evolved through several rift episodes, leading to break-up in the Eocene that was associated with voluminous magmatism along the conjugate margins of East Greenland and NW Europe. Existing seismic refraction data provide good constraints on the overall tectonic development of the margins, despite data gaps at the NE Greenland shear margin and the southern Jan Mayen microcontinent. The maximum thickness of the initial oceanic crust is 40 km at the Greenland–Iceland–Faroe Ridge, but decreases with increasing distance to the Iceland plume. High-velocity lower crust interpreted as magmatic underplating or sill intrusions is observed along most margins but disappears north of the East Greenland Ridge and the Lofoten margin, with the exception of the Vestbakken Volcanic Province at the SW Barents Sea margin. South of the narrow Lofoten margin, the European side is characterized by wide margins. The opposite trend is seen in Greenland, with a wide margin in the NE and narrow margins elsewhere. The thin crust beneath the basins is generally underlain by rocks with velocities of >7 km s −1 interpreted as serpentinized mantle in the Porcupine and southern Rockall basins; while off Norway, alternative interpretations such as eclogite bodies and underplating are also discussed.

Abstract: Seismic refraction data and results from receiver functions were used to compile the depth to the basement and Moho in the NE Atlantic Ocean. For interpolation between the unevenly spaced data points, the kriging technique was used. Free-air gravity data were used as constraints in the kriging process for the basement. That way, structures with little or no seismic coverage are still presented on the basement map, in particular the basins off East Greenland. The rift basins off NW Europe are mapped as a continuous zone with basement depths of between 5 and 15 km. Maximum basement depths off NE Greenland are 8 km, but these are probably underestimated. Plate reconstructions for Chron C24 ( c. 54 Ma) suggest that the poorly known Ammassalik Basin off SE Greenland may correlate with the northern termination of the Hatton Basin at the conjugate margin. The most prominent feature on the Moho map is the Greenland–Iceland–Faroe Ridge, with Moho depths >28 km. Crustal thickness is compiled from the Moho and basement depths. The oceanic crust displays an increased thickness close to the volcanic margins affected by the Iceland plume.

Abstract: We present a revised tectonostratigraphy of the Jan Mayen microcontinent (JMMC) and its southern extent, with the focus on its relationship to the Greenland–Iceland–Faroe Ridge area and the Faroe–Iceland Fracture Zone. The microcontinent’s Cenozoic evolution consists of six main phases corresponding to regional stratigraphic unconformities. Emplacement of Early Eocene plateau basalts at pre-break-up time (56–55 Ma), preceded the continental break-up (55 Ma) and the formation of seawards-dipping reflectors (SDRs) along the eastern and SE flanks of the JMMC. Simultaneously with SDR formation, orthogonal seafloor spreading initiated along the Ægir Ridge (Norway Basin) during the Early Eocene (C24n2r, 53.36 Ma to C22n, 49.3 Ma). Changes in plate motions at C21n (47.33 Ma) led to oblique seafloor spreading offset by transform faults and uplift along the microcontinent’s southern flank. At C13n (33.2 Ma), spreading rates along the Ægir Ridge started to decrease, first south and then in the north. This was probably complemented by intra-continental extension within the JMMC, as indicated by the opening of the Jan Mayen Basin – a series of small pull-apart basins along the microcontinent’s NW flank. JMMC was completely isolated when the mid-oceanic Kolbeinsey Ridge became fully established and the Ægir Ridge was abandoned between C7 and C6b (24–21.56 Ma).

Abstract: A new regional compilation of seamount-like oceanic igneous features (SOIFs) in the NE Atlantic points to three distinct oceanic areas of abundant seamount clusters. Seamounts on oceanic crust dated 54–50 Ma are formed on smooth oceanic basement, which resulted from high spreading rates and magmatic productivity enhanced by higher than usual mantle plume activity. Late Eocene–Early Miocene SOIF clusters are located close to newly formed tectonic features on rough oceanic crust in the Irminger, Iceland and Norway basins, reflecting an unstable tectonic regime prone to local readjustments of mid-ocean ridge and fracture zone segments accompanied by extra igneous activity. A SOIF population observed on Mid-Miocene–Present rough oceanic basement in the Greenland and Lofoten basins, and on conjugate Kolbeinsey Ridge flanks, coincides with an increase in spreading rate and magmatic productivity. We suggest that both tectonic/kinematic and magmatic triggers produced Mid-Miocene–Present SOIFs, but the Early Miocene westwards ridge relocation may have played a role in delaying SOIF formation south of the Jan Mayen Fracture Zone. We conclude that Iceland plume episodic activity combined with regional changes in relative plate motion led to local mid-ocean ridge readjustments, which enhanced the likelihood of seamount formation. Supplementary material: Figures detailing NE Atlantic seamounts and SOIF distribution, and the location of earthquake epicentres are available at https://doi.org/10.6084/m9.figshare.c.3459729

Abstract The geometry, orientation and distribution of deformation bands and fractures in eolian sandstones, siltstones and shales of the San Rafael Desert and Moab Fault area have been investigated. The results show that deformation bands, which are cataclastic in eolian sandstones and disaggregation structures in siltstones, are unevenly distributed throughout the damage zone in the form of individual bands, deformation band zones and deformation band clusters. The density of bands increases with increasing grain size. In thin (<3 m) eolian sandstones deformation band frequency is significantly lower than in thicker eolian sandstones, whereas above this thickness the frequency seems not to be related to layer thickness. Furthermore, large faults do not develop higher concentrations of deformation bands. Somewhat simplified, this suggests that damage zone growth occurs by expansion into its hanging wall and footwall. Still, the highest concentrations of deformation bands occur close to the main fault, which is of importance when considering their effect on fluid flow. Their general fault-parallel conjugate arrangements favour intra-damage zone flow parallel to rather than perpendicular to the fault.