Results of in situ LA-ICP-MS U-Pb zircon dating. (a) Cathodoluminescence images of representative zircon grains. Scale bars represent a length pf 20 μm and the quoted ages in Ma are calculated from ²⁰⁶Pb/²³⁸U ratios. (b, c, d) Concordia plots for tonalites SJL, MAR and FIG, respectively. MSWD and p-value are for concordance and equivalence. The two uncertainties are reported as 2σ.