Fig. S11.

Reproducibility of standards. Our data are shown in open circles, and published values are shown as black squares. Dotted lines show the mean and 2σ of the δ²³⁸U of all analyses. (A) Measurements of HU-1 solution. (B) Measurements of Stanford CRM-129a and (C) separate aliquot of CRM-129a obtained from ASU. (D) Measurements of rock standard BCR-2. Error bars are 2 SE on the measurement (internal precision) for our data and 2 SD on total replicates for published data. Each data point represents a measurement of a total of eight replicates of BCR-2 (dissolved from powder), illustrated here by subscripts. (E) Measurements of internal carbonate standard DWP. Error bars are 2 SE on the measurement (internal precision) for our data. A total of six complete replicates of DWP (dissolved from powder) were measured, as denoted by the subscripts. Raw data are also presented in Dataset S1.