Study of radioactive equilibrium in Carnotite ores of the Colorado Plateau

The purpose of this study was to determine the age of Colorado Plateau carnotite. In addition to quantitative analyses of uranium and lead, the radium-uranium equilibrium of each sample was studied. Of the 12 samples studied, 10 are deficient in radium. If a minimum age of 130 million years is chosen for the enclosing sediments, 11 samples are deficient in lead. This deficiency may be explained by (1) leaching of lead or (2) assuming too great an age. Three samples, chosen for lead-isotope analysis, have Pb²⁰⁷/Pb²⁰⁶