Fig. 8

Uncertainty of the ²⁰⁷Pb*/²⁰⁶Pb* model dates for the reference material EarlyTime 1 × calculated from the data processed with varying blank parameters: blank value, blank uncertainty, and uncertainty of the blank isotopic composition. The data processing parameters are described in the caption of Fig. 7. The data are calculated using the uncertainties of the measured isotopic ratios and uncertainties of the spike isotopic compositions as shown in the footnote of the Additional file 1: Table S1. Model dates and their uncertainties are calculated from two-point ²⁰⁷Pb/²⁰⁶Pb versus ²⁰⁴Pb/²⁰⁶Pb isochrons that include primordial Pb as the second point (initial isotopic composition), regressed in IsoplotR (Vermeesch 2018) using the default maximum likelihood model. The data points corresponding to default values of the blank parameters are encircled. Blue and red lines show total uncertainties and blank-related uncertainty components, respectively. Horizontal black dashed line shows the level of uncertainty from measured isotopic ratios and spike isotopic compositions at zero blank. A Uncertainty of the ²⁰⁷Pb*/²⁰⁶Pb* model date versus blank value (picograms). B Uncertainty of the ²⁰⁷Pb*/²⁰⁶Pb* model date versus relative uncertainty (%) of the blank. C Uncertainty of the ²⁰⁷Pb*/²⁰⁶Pb* model date versus uncertainty of the blank isotopic composition, expressed as a multiplier to the accepted value of the Pb blank uncertainty at RSES ANU in 2020–2022