Fig. 6
U–Pb data for rutile from two samples and for both samples together, plotted uncorrected for common Pb on concordia diagrams. Only analyses with ≥ 50 cps 207Pb are plotted; below this, Pb signals were not significantly above background and so did not yield reliable U–Pb ratios. n indicates the number of analyses considered as a fraction of the total number of analyses with ≥ 50 cps 207Pb; the total number of analyses including those with < 50 cps 207Pb is given in square brackets. a Wetherill concordia and b Tera-Wasserburg concordia plotting ratios as measured, both with an unanchored isochron plotted by Isoplot 3.7; lower intercept age and common Pb composition calculated from these isochrons are given as text. c Tera-Wasserburg concordia plotting measured ratios and with an isochron anchored to the Stacey–Kramers model Pb composition for 60 Ma; lower intercept ages are given as text. Our preferred ages are the anchored Tera-Wasserburg isochron ages (c), which are the most precise