Graphic and algebraic solutions of the discordant lead-uranium age problem

Uranium-bearing minerals that give lead-uranium and lead—lead ages that are essentially in agreement, i.e. concordant, generally are considered to have had a relatively simple geologic history and to have been unaltered since their deposition. The concordant ages obtained on such materials are, therefore, assumed to approach closely the actual age of the minerals. Many uranium-bearing samples, particularly uranium ores, give the following discordant age sequences; Pb²⁰⁶U²³⁸Pb²⁰⁷Pb²⁰⁶⪡Pb²⁰⁷U²³⁵