Morphology and Late Quaternary sedimentation on the North Faeroes slope and abyssal plain, North Atlantic

Abstract

Whilst the interplay between tectonics, glaciation and oceanography is reasonably well understood on some high-latitude margins, relatively little is known about the nature of Quaternary processes affecting the continental margin north of the Faeroe Islands. We therefore present side-scan sonar (GLORIA and TOBI) and 3.5 kHz data in combination with a new regional bathymetry in order to characterise and analyse the margin's physiography and the sedimentary processes that have occurred in the area during the Late Quaternary. Seven acoustic facies are identified and interpreted, in combination with published core records. The margin is subject to differing sedimentation regimes over glacial/interglacial cycles, relating to the changing importance of contouritic, hemipelagic, glacimarine and mass-movement processes. Mass movement is much more extensive than previously thought, with a total sediment volume of >2000 km3, similar to that of the Storegga Slide (5500 km3) and may occur primarily at glacial terminations. The downslope limit of instabilities is associated with a series of channels, focusing the deposition of distal, turbiditic sediments into the regional deep beyond. Together with glacigenic debris flows from the western margin of the North Sea Fan, mass-movement processes are identified to have affected 52–70% of the North Faeroes margin area. In contrast, distal glacimarine sedimentation, alternating with hemipelagic and contouritic development, is found on the remaining 30–48% of the margin during glacials, and hemipelagic and contouritic sedimentation are active across 90% of the margin in interglacial conditions. Despite a lack of any local, direct glacial influence, these observations on the relative importance of sedimentation processes are comparable with other glacially influenced passive margins.