10.6084/m9.figshare.3454454.v1 Sarah C. Sherlock Sarah C. Sherlock Kevin A. Jones Kevin A. Jones R.Graham Park R.Graham Park Grenville-age pseudotachylite in the Lewisian: laserprobe <sup>40</sup>Ar/<sup>39</sup>Ar ages from the Gairloch region of Scotland (UK) Geological Society of London 2016 Lewisian laserprobe pseudotachylite data Ma IR mineral Ar UK Geology 2016-06-21 12:07:40 Dataset https://geolsoc.figshare.com/articles/dataset/Grenville-age_pseudotachylite_in_the_Lewisian_laserprobe_sup_40_sup_Ar_sup_39_sup_Ar_ages_from_the_Gairloch_region_of_Scotland_UK_/3454454 <p>Infrared laserprobe <sup>40</sup>Ar/<sup>39</sup>Ar dating has been used to date pseudotachylite and host-rock minerals from a crush belt in the Lewisian basement of Scotland. It has revealed complexity in the pseudotachylite data that is attributable to the presence of refractory host-rock clasts and mineral fragments in the pseudotachylite. In conjunction with the host-rock mineral laserprobe <sup>40</sup>Ar/<sup>39</sup>Ar data it has been possible to simplify the pseudotachylite data for the samples, and the preferred ages for these are: 980 ± 39 Ma, 999 ± 31 Ma and 1024 ± 30 Ma (2σ). These ages are the first record of Grenville-aged brittle deformation in the Lewisian. Further, this study serves to illustrate the complexity of dating pseudotachylites, and the advantages and limitations of the IR laserprobe applied to such materials. </p>