Data Repository Item TData Set S2. (U-Th)/He and U/Pb data for double-dated zircons from Blue Lead sand sample (U-Th)/He data U-Pb data Analysis Ft corr age +/- half-width mass U Th Th/U U Th age +/- Th/U (Ma) (mm) (mg) (ppm) (ppm) (ppm) (ppm) (Ma) BL-S1z14 0.885 74.5 1.5 94 43.0 344 144 0.43 444 230 88.5 0.8 0.52 BL-S1z18 0.871 106.3 2.2 78 37.1 163 47 0.29 153 31 147.0 2.4 0.20 BL-S1z30 0.765 113.7 2.3 39 8.1 237 53 0.23 157 28 148.4 1.6 0.18 BL-S1z47 0.869 94.4 1.9 75 35.8 426 166 0.40 332 116 109.0 1.1 0.35 BL-S1z48 0.767 98.2 2.1 53 2.9 270 205 0.78 205 82 1742.1 9.3 0.40 BL-S1z57 0.835 77.7 1.7 65 14.0 738 354 0.49 779 360 87.4 0.7 0.46 BL-S1z62 0.832 82.2 1.8 69 11.8 192 75 0.40 329 122 160.1 1.3 0.37 BL-S1z69 0.898 74.2 1.7 116 38.8 735 220 0.31 698 345 95.7 0.8 0.49 BL-S1z70 0.829 94.1 2.1 69 8.0 102 66 0.66 134 86 2499.5 10.1 0.64 BL-S1z78 0.845 99.9 2.2 65 18.7 185 61 0.34 117 36 159.2 2.0 0.30 BL-S1z100 0.822 85.4 1.8 58 12.2 269 124 0.47 104 29 110.7 1.9 0.28