Revised chronostratigraphy of the Faroe Islands Basalt Group and the British Palaeogene Igneous Province : implications for Selandan-Thanetian palynofloral assemblages and correlation with the Faroe-Shetland Basin

The chronostratigraphy of the Faroe Islands Basalt Group, and thereby the entire North Atlantic Igneous Province, presents a long-standing controversy among government, industry and academic stakeholders with activities in the Faroe-Shetland region. The application of biostratigraphy, magnetostratigraphy, radio-isotopic dating and seismic analysis have all failed to agree on the absolute age span of the volcanic province. The lack of an externally consistent chronostratigraphic framework pose a risk to the hydrocarbon prospectivity in the economically important Faroe-Shetland Basin. This report provides a review of the onshore geology of the Faroe Islands Basalt Group and the British Palaeogene Igneous Province, and the contrasting age models for the emplacement of the North Atlantic Igneous Province are described in detail. New high-precision U/Pb zircon age determinations and palynological analyses of key stratigraphic sections from the Faroe Islands, Inner Hebrides and Northern Ireland are given. Available magnetostratigraphic, biostratigraphic and radio-isotopic age-constraining data from the literature and this study are assessed. It is demonstrated in detail how previous biostratigraphic interpretations, that constrain the collective pre- to syn-breakup eruptive products of the NAIP to the late Thanetian – early Ypresian (T40-T45), are fundamentally flawed. These interpretations have strongly influenced chronostratigraphic correlations between volcanically-saturated onshore basins and volcanically-starved offshore basins, and the portrayal of interaction between sedimentary and volcanic depositional processes in the Faroe-Shetland region. A consistent multidisciplinary age model for the protracted emplacement of the NAIP is presented, including absolute numerical age constraints and assessment of palynofloral assemblages from two key onshore occurrences of the Staffa Flora. The report also highlight the identification of remaining outstanding problems regarding the absolute chronostratigraphy for Palaeocene to early Eocene formations and sequences of the Faroe-Shetland Basin.