@Article{Fayek:2000, author = {M. Fayek and T.M. Harrison and M. Grove and C. Coath}, title={A rapid in situ method for determining the ages of uranium oxide minerals: evolution of the {C}igar {L}ake deposit, {A}thabasca basin}, journal={Int. Geol. Rev.}, year={2000}, volume={42}, number={}, month={Feb}, pages={163--171}, note={}, annote={}, keywords={11 nuclear fuel cycle and fuel materials ; uranium deposits; Saskatchewan; isotope dating; uraninites; mineralization; hematite; magnetization; coffinite}, url={}, doi={}, abstract={The authors present a rapid and accurate technique for making in situ U-Pb isotopic measurements of uranium oxide minerals that utilizes both electron and ion microprobes. U and Pb concentrations are determined using an electron microprobe, whereas the isotopic composition of Pb for the same area is measured using a high-resolution ion microprobe. The advantages of this approach are: mineral separation and chemical digestion are unnecessary; homogeneous uranium oxide standards, which are difficult to obtain, are not required; and precise and accurate U-Pb ages on $\sim$10$\mu$m spots can be obtained in a matter of hours. The authors have applied their method to study the distribution of U-Pb ages in complexly intergrown uranium oxides from the unconformity-type Cigar Lake uranium deposit, Saskatchewan, Canada. In situ U-Pb results from early formed uraninite define a well-correlated array on concordia with upper and lower intercepts of 1,467$\pm$63 Ma and 443$\pm$96 Ma ($\pm$1$\sigma$), respectively. The 1,467 Ma age is interpreted as the minimum age of mineralization and is consistent with the age of clay-mineral alteration ($\sim$1477 Ma) and magnetization of diagenetic hematite (1,650 to 1,450 Ma) that is associated with these unconformity-type uranium deposits and early diagenesis of the Athabasca Basin sediments. In situ U-Pb isotopic analysis of uraninite and coffinite can document the Pb*/U heterogeneities that can occur on a scale of 15 to 30$\mu$m, thus providing relatively accurate information regarding the timing of fluid interactions associated with the evolution of these deposits.} }