(a) Cathodoluminescence images of 31 zircon grains separated from the tuff for LA-ICP-MS U-Pb analyses. Red circles indicate the laser ablation area of the 35-μm diameter. IT1-IT31 are the sample numbers shown in Table 3. (b) Tera-Wasserburg diagram (207Pb/206Pb vs 238U/206Pb) of the LA-ICP-MS U-Pb analyses of 31 zircon grains separated from the tuff sample (Fig. 5d). (c) Weighted mean 206Pb/238U age (32.61 ± 0.49 Ma) for 11 concordant zircons, ranging from 90% to 110% of the concordance.