Summary The British Palaeogene Igneous Province records the palaeomagnetic field at a time when it had returned to a reversing state following the Cretaceous Normal Superchron. Whilst the province is well studied for palaeomagnetic directions, palaeointensity results remain scarce. New palaeointensity and palaeomagnetic directional results are presented from a Palaeocene basaltic dyke swarm on the Sleat Peninsula, Skye (NW Scotland). The mean palaeomagnetic direction from 24 dykes has declination 356.7° and inclination 60.0°. The corresponding palaeopole lies at 75.2°N, 181.8°E with associated 95 per cent confidence interval, A95, of 6.6° which is close to, but distinguishable from, previous results from this swarm. The angular dispersion of virtual geomagnetic poles (VGPs), SB, was 17.9 ± 3.2°, consistent with stationary VGP dispersion throughout the Palaeogene. Three experimental palaeointensity methods were attempted: Shaw Double Heating Technique, thermal Thellier, and microwave Thellier. Palaeointensity experiments were successful from two dykes giving results of 15.8 ± 2.3 μT and 12.0 ± 3.4 μT which correspond to virtual dipole moments of 27 ± 4 ZAm2 and 21 ± 6 ZAm2. These are notably weaker than the long-term average and the recent field. Additionally, we present proof-of-concept of a novel method for estimating palaeointensity. The preliminary method was applied to results from the thermal Thellier experiments and is based on reproducing non-ideal Arai plot behaviour using a phenomenological model of thermal remanent magnetisation. This inversion highlighted laboratory field orientation as a major control on Arai plot shape with antiparallel fields predicted and observed to cause major distortions. It produced similar palaeointensity results to the conventional approach but derived from significantly more specimens.
Murray et al. (Thu,) studied this question.