Palaeogene magmatism in the Faeroe–Shetland Basin: influences on uplift history and sedimentation

Abstract

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: 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; dyke swarms, which constitute the feeder system to the lava fields; sill complexes, possibly related to the fissure systems, which affect reservoir quality on a local scale; central igneous complexes overlying magma chambers which controlled clastic sedimentation patterns (Westray for example); 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.