Pleistocene apparent ages by U-Pb isotope and U-series methods for uranium ore in Dakota Sandstone near Gallup, New Mexico

Radiometric dates of a high-grade uranium ore from the Hogback No. 4 mine in Dakota Sandstone near Gallup, N. Mex., indicate a late Pleistocene age of mineralization. The ²⁰⁶Pb/²³⁸U and ²⁰⁷Pb/²³⁵U apparent ages of about 70 000 yr and 100000 yr, respectively, are discordant, but are in broad agreement with the discordant ²³⁰Th/²³⁸U and ²³¹Pa/²³⁵U apparent ages of 130000 yr and 78000 yr, respectively. Although it is not clear how the analyzed sample relates to the main period of mineralization at this mine, these dates are consistent with previous age limits suggested for Dakota Sandstone uranium-ores.