The age of the Stillwater complex—a comparison of U-Pb zircon and Sm-Nd isochron systematics

A zircon U-Pb age of 2713 ± 3 Myr confirms the less precise age of about 2710 Myr (corrected for new decay constants of Jaffeyet al., 1971) obtained from the same sample of zircon from the Stillwater complex chill zone (Nunes and Tilton, 1971). This age compares with Sm-Nd mineral and whole-rock isochron ages of 2701 ± 8 Myr (Depaolo and Wasserburg, 1979); or 2706 ± 8 Myr if the Lugmairet al. (1975) normalization procedure is used. The agreement of these ages to within about 0.4% indicates that the λ₁₄₇ = 0.00654 × 10^?9yr^?1 value is less than 0.8% too large relative to the U decay constants determined by Jaffeyet al. (1971) and enables more correct geological syntheses to be made when working out detailed absolute age stratigraphies using precise data from both systems.