Age bounds from lead isotope data

Linear inference theory is used to compute upper and lower bounds for lead isotope growth curves. The bounds are consistent with lead isotopes extracted from a single, isotopically uniform source characterized byU/Pb andTh/Pb ratios which are non-decreasing functions of time. Uncertainties in model ages are determined directly from the bound curves. For world-wide stratiform deposits an uncertainty of less than 100 Ma is attainable and for shale-hosted lead deposits of the Canadian Cordillera the uncertainties can be less than 200 Ma.