Fig. 2

The concordia diagrams and the cathodoluminescence images. The diagrams were drawn by using Isoplot 4.15 (Ludwig 2012). In the concordia diagrams, red solid circles indicate concordant dates and blue open circles mean discordant dates within the error range of 1 sigma. The heavy line circles are the concordia ages with 2 sigma errors, calculated from the concordant data. The discordant data of TNG20-09 are not displayed because it is away from the concordant curve. The red open circles in the CL images signify the analytical spots