Table 3. Apparent CRE ages at nominal shielding.
All production rates were calculated using the equations of Eugster and Michel (24) for a nominal shielding of 40 g/cm2, with P21 modified to account for Na using the Na/Mg production rate at 40 g/cm2 of shielding from Hohenberg et al. (61). All production rates are based on the whole-rock composition determined by ICP-MS (see the Supplementary Materials), with SiO2 from Agee et al. (20). The weighted average ages, including production rate uncertainties, are shown in bold.
| Aliquot | 3He* | 21Ne† | 38Ar‡ | 78Kr§ | 83Kr¶ |
| CRE age ± 2σ (Ma) | CRE age ± 2σ (Ma) | CRE age ± 2σ (Ma) | CRE age ± 2σ (Ma) | CRE age ± 2σ (Ma) | |
| LLNL-UI-1 | — ± — | 4.05 ± 0.08 | 4.63 ± 0.16 | 12.26 ± 3.62 | 9.12 ± 3.04 |
| LLNL-UI-2 | — ± — | 4.1 ± 0.08 | 4.76 ± 0.28 | 11.22 ± 1.72 | 8.27 ± 1.92 |
| LLNL-UI-3 | — ± — | 4.05 ± 0.06 | 5.16 ± 0.3 | 13.24 ± 2.08 | 9.2 ± 2.36 |
| LLNL-UI-4 | 2.46 ± 0.48 | 5.18 ± 0.24 | 5.09 ± 0.8 | — ± — | — ± — |
| LLNL-UI-5 | 2.11 ± 0.14 | 4.42 ± 0.22 | 4.8 ± 0.26 | — ± — | — ± — |
| Weighted average|| | 2.14 ± 0.13 | 4.11 ± 0.26 | 4.77 ± 0.25 | 12.07 ± 1.24 | 8.73 ± 1.34 |
| MSWD | 1.96 | 23.43 | 2.63 | 1.13 | 0.23 |
| CRE age w/ PR unc.** | 2.14 ± 0.25 | 4.11 ± 0.49 | 4.77 ± 0.54 | 12.07 ± 1.73 | 8.73 ± 1.6 |
*Calculated using P3 = 7.54 × 10−13 mol/g per million years.
†Calculated based on total 21Ne, using P21 = 1.06 × 10−13 mol/g per million years.
‡Calculated assuming the trapped 38Ar/36Ar ratio is 0.189, using P38 = 4.78 × 10−15 mol/g per million years.
§Calculated using P78 = 1.12 × 10−17 mol/g per million years.
¶Calculated using P83 = 7.36 × 10−17 mol/g per million years.
||See the Supplementary Materials for details on weighted average calculations.
**Systematic uncertainties on cosmogenic nuclide production rates (PR unc.) are assumed to be 10%.