Preliminary investigations of U-Th-Pb systematics in uranium-bearing minerals from two granitic rocks from the Granite Mountains, Wyoming

Analyses of mineral separates from granites from the Granite Mountains, Wyoming, suggest that most of the thorium and at least half of the uranium are associated with biotite, epidote, and accessory minerals. Biotite and epidote contain most of the uranium and thorium in a drill core sample of granite that did not incur any appreciable amount of uranium loss during Tertiary time. None of the mineral ages, calculated from the uranium-lead, lead-lead, and thorium-lead systems, seem to be geologically significant. 18 refs