A rift-to-drift record of vertical crustal motions in the Faroe–Shetland Basin, NW European margin: establishing constraints on NE Atlantic evolution

Abstract

The Upper Paleocene–Eocene rock record in the Faroe–Shetland Basin is punctuated by a series of unconformities that reflect a persistent tectonic instability throughout the syn- to early post-breakup period, a duration of about 20 myr. A particular focus is on a Late Paleocene subaerial unconformity, herein termed the Flett unconformity, which has been argued to have formed in response to a transient pulse of mantle convective uplift associated with a proto-Iceland plume. However, ambiguity over its presumed correlation with the Faroe Islands Basalt Group combined with stratigraphic and palaeogeographical analysis of the Upper Paleocene–Eocene succession indicates that it is just one of a series of subaerial unconformities that are spatially linked to the same part of the Faroe–Shetland Basin. Most of these Late Paleocene–Eocene unconformities post-date volcanism, and their formation coincides with vertical motions associated with phases of uplift, inversion and compressional deformation linked to the growth of structures, such as the Wyville Thomson and Munkagrunnur ridges, and the Judd Anticline. These deformation phases are broadly coeval with intraplate and plate-boundary events in the wider NE Atlantic region. The possibility that the Flett unconformity had a similar tectonic origin should not be discounted.