Abstract: This paper presents a summary of the stratigraphy and structure of the Faroese region. As the Faroese area is mostly covered by volcanic material, the nature of the pre-volcanic geology remains largely unproven. Seismic refraction data provide some indications of the distribution of crystalline basement, which probably comprises Archaean rocks, with the overlying cover composed predominantly of Upper Mesozoic (Cretaceous?) and Cenozoic strata. The Cenozoic succession is dominated by the syn-break-up Faroe Islands Basalt Group, which crops out on the Faroe Islands (where it is up to 6.6 km thick) and shelf areas; post-break-up sediments are preserved in the adjacent deep-water basins, including the Faroe–Shetland Basin. Seismic interpretation of the post-volcanic strata shows that almost every sub-basin in the Faroe–Shetland Basin has been affected by structural inversion, particularly during the Miocene. These effects are also observed on the Faroe Platform, the Munkagrunnur Ridge and the Fugloy Ridge, where interpretation of low-gravity anomalies suggests a large-scale fold pattern. The structure of the Iceland–Faroe Ridge, which borders the NW part of the Faroe area, remains ambiguous. The generally thick crust, together with the absence of well-defined seawards-dipping reflectors, may indicate that much of it is underlain by continental material.

Abstract The Faroe–Shetland Basin is located offshore NW Scotland on the SE margin of the Atlantic Ocean and comprises numerous sub-basins and intra-basin highs that are host to a number of significant hydrocarbon discoveries. The principal hydrocarbon discoveries are in Paleocene–Eocene strata, although earlier strata are known, and their existence is therefore intimately linked to the opening and evolution of the North Atlantic from 54 Ma. The final rifting and separation of Greenland from Eurasia is commonly attributed to the arrival of a mantle plume which impacted beneath Greenland during early Tertiary time. Moreover, the ensuing plate separation is commonly described in terms of instantaneous unzipping of the North Atlantic, whereas in reality proto-plate boundaries were more diffuse during their inception and the linked rift system which we see today, including connections with the Arctic, was not established until Late Palaeogene–Early Neogene time. From a regional analysis of ocean basin development, including the stratigraphic record on the adjacent continental margins, the significance of the Greenland–Iceland–Faroe Ridge and the age and role of Iceland, we propose a dual rift model whereby North Atlantic break-up was only partial until the Oligo-Miocene, with true final break-up only being achieved when the Reykjanes and Kolbeinsey ridges became linked. As final break-up coincides with the appearance of Iceland, this model negates the need for a plume to develop the North Atlantic with rifting reliant on purely plate tectonic mechanisms, lithospheric thinning and variable decompressive upper mantle melt along the rifts.

Abstract Lateglacial–Holocene fjord sediments in Little Loch Broom preserve evidence of extensive slope instability. The major area of reworking is in the outer loch and mid-loch sill region where ice-contact/ice-proximal deposits of the Lateglacial Assynt Glaciogenic Formation have been disrupted by sliding and mass-flow processes linked to the Little Loch Broom Slide Complex and the adjacent Badcaul Slide. Mass failure was instigated about 14–13 ka BP, and is probably the response of the landscape to deglaciation immediately following the removal of ice support during glacial retreat. An initial phase of translational sliding was followed by rotational sliding, as revealed by the superimposition of scallop-shaped slumps on a larger-scale rectilinear pattern of failure. Paraglacial landscape readjustment may also have been enhanced by episodic seismic activity linked to glacio-isostatic unloading. In the inner fjord, evidence of Holocene mass failure includes the Ardessie debris lobe and a discrete intact slide block preserved within the postglacial basinal deposits. The former is a localized accumulation linked to a fluvial catchment on the adjacent An Teallach massif. These mass-transport deposits may represent an ongoing response to paraglacial processes, albeit much reduced (relative to the major slides) in terms of sediment supply to the fjord.

Abstract A new deep-water borehole at the foot of the West Shetland Slope revealed a sequence of Late Pleistocene glacimarine sediments. This section comprises an interbedded sequence of muddy diamictons, with subordinate sandy muds with dropstones and matrix-poor sands and gravels. Integration of core data, seabed imagery and high-resolution seismic-reflection records indicate the succession is dominated by stacked glacigenic debris flows. Individual debris flows are composed of massive, clast-poor muddy diamicton, and are seperated by sandy muds and the sands and gravels. The mud units are interpreted as a combination of hemipelagic–glacimarine and distal ice-rafted deposits. The sands and gravels are interpreted as the result of bottom-current reworking of glacial and pre-glacial sediments. The new data support previous studies which suggest that Pleistocene ice sheets reached the edge of the West Shetland Shelf on several occasions, delivering large volumes of glacigenic sediment directly to the shelf edge and upper slope. These deposits became unstable, forming debris flows which transported the glacigenic sediments to the deep-water environment. Seabed imagery shows that the area around the borehole formed a focus for this style of deposition. A depositional model constructed from the new data is enhanced by the application of data from an ancient deep-water, glacially-influenced, succession from the Neoproterozoic Macduff Formation NE Scotland.

Abstract Seismic reflection profiles, shallow cores and seabed photography from the continental margin off NW Britain reveal the variety of bottom current influenced sedimentation in the northern Rockall Trough and Faroe–Shetland Channel. Types of sediment drifts identified include: (1) elongate drifts, both single, and multi-crested; (2) sheeted drift forms, varying from gently domed to flat-lying; and (3) isolated patch drifts, including moat-related drifts. Associated fields of localized sediment waves are developed with the elongate and gently domed, broad sheeted drifts. The contrasting style of sediment drift development reflects the complex interaction between bottom current regime, sediment supply and the bathymetry of the continental margin. The majority of the mounded/gently domed drifts occur in the northern Rockall Trough, with sheetform drifts commonly confined to the Faroe–Shetland Channel, a narrow basin which is an area of net sediment export rather than drift accumulation. Small patch drifts are present in both basins. Muddy, silty muddy and sandy contourites have been recognized from sediment cores sampling the uppermost parts of the drift sequences. Based on their glaciomarine character, the mid- to high-latitude contourites are referred to as glacigenic contourites. Both partial and complete con–tourite sequences are preserved; the former consist largely of sandy (mid-only) and top-only contourites. Modern sandy con–tourites have also been identified from seabed photographs on the Hebrides Slope. The contourites are recognized as a rippled mobile sand layer, reworked from a poorly sorted glaciomarine parent deposit.

Abstract The Faroe–Shetland Channel is an important conduit or gateway for the southward flow of cold bottom waters formed in the Norwegian Sea. This Norwegian Sea Overflow Water (NSOW) finds several spillover channels across the Wyville–Thomson Ridge, eventually descending into the northern Rockall Trough and Iceland Basin. The Neogene channel floor succession predominantly displays a broad sheeted drift geometry. Bottom current scours and channels were apparently inherited from an episode of enhanced bottom current activity in late Oligocene/early Miocene. The late Quaternary channel-floor succession is dominated by distal glaciomarine sediments, derived from the shelf and slope during glacial stages and mostly transported by ice-rafting. Glacigenic debris flows and minor turbidity currents were also active across the slope region. Consequently, the principal channel-floor facies are glacigenic contourites that show extensive bioturbation, rare primary structures, mixed composition and marked grain size variation. These features indicate the important influence of cyclical fluctuations in bottom current velocity throughout both stadial and interstadial or interglacial periods. However, the concentration of sandy contourites, erosive surfaces and top-only contourites during interstadials/interglacials and during phases of marked cooling or warming testify to the significance of climate-control on contourite deposition.