THE MESOZOIC TO EARLY TERTIARY OPENING OF THE NORTH ATLANTIC AND ITS IMPACT ON THE DEVELOPMENT OF THE FAEROE-SHETLAND BASIN SYSTEM

Triassic/Early Jurassic deformation was partitioned into a broad rift-system that linked from continental Europe, through the North Sea, and northwards into the East Greenland/Norway system. This rift-system also extended along the western margin of Ireland and the UK where it reactivated many older post-Caledonian basin elements. The subsequent Middle to Late Jurassic rift-system, so prominent in Mid Norway and the North Sea, did not extend in any substantial way through the Faeroe Shetland basin-system. The Faeroe-Shetland basin-system was established as a major sediment depocenter by rifting in the late Early Cretaceous (Apto-Albian.) Initial rifting was oblique to earlier Paleozoic and Mesozoic rift-trends. Pre-rift basin elements are offset by a series of prominent transfer systems (e.g. the Judd Transfer system.) The stretch for the Cretaceous event was very high and as a consequence, substantial portions of the basin are interpreted to be underlain by fault planes. Additional rifting in the early Tertiary significantly modified the basin configuration and created the present-day form of the principal ridges that frame the basin – the Rona Ridge, the Westray Ridge, the ‘Central’ Ridge, and the Corona Ridge. Many of the Cretaceous basin-margin fault-systems were reactivated and new Paleocene faults formed a high angle to earlier Paleozoic and Mesozoic trends. In addition to the well-documented Faeroes Group lavas, large volumes of igneous material were intruded into the deep basinal areas in the Late Paleocene. Preferential intrusion caused localised fault reactivation and inversion and resulted in the formation of small hangingwall folds. Following the breakup of the North Atlantic, differential subsidence created a deepwater trough (the Faeroe-Shetland Channel where water depths are in excess of 1700 metres) and tilted strata on the basin flanks. Inversion, beginning in the Eo-Oligocene, created a series of arches and monoclines throughout the region. The distribution was strongly controlled and partitioned by earlier transfer systems as the underpinning basement architecture was reactivated.

Abstract Co-authored by the Atlantic Margin Operating Unit Team Members