About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 3. (March)

First Page: 573

Last Page: 573

Title: Constraints on Origin of Granitic Uranium-Source Rock, Granite Mountains, Wyoming: ABSTRACT

Author(s): D. B. Wenner, J. S. Stuckless, K. K. Chang

Article Type: Meeting abstract


The origin of the granite of Lankin Dome from the Granite Mountains is of special interest to uranium geologists because of its spatial association with the large uranium deposits in central Wyoming and because the granite lost more than 5.5 × 1010 kg of uranium at approximately the same time as the surrounding deposits formed. Furthermore, the granite has been shown to be the source of the sediments that host the uranium ores. Thus, recognition of similar granites may lead to the discovery of hidden uranium deposits.

Chemical and radioisotope studies have suggested that the granite of Lankin Dome was derived from a sedimentary protolith. Stable isotope studies support this hypothesis and show that this granite is anomalously enriched in O18 relative to other Archean granites in Wyoming. ^dgrO18 values for the granite of Lankin Dome, the Louis Lake batholith, and the granite of the Owl Creek Mountains are 8.44 ± 0.34 (n = 36), 7.45 ± 0.40 (n = 15), and 7.43 ± 0.17 (n = 4), respectively. Investigations in progress indicate that the northern Laramide Range may be composed of more than one granite, and that at least part of the Archean granite has lower ^dgrO18 values than the mean observed in the Granite Mountains. Altered rocks within the granite of La kin Dome are anomalously depleted in O18, which suggests interaction with meteoric waters. The effects of this event on the uranium history are being investigated.

The combined oxygen and chemical data suggest at least a partly pelitic protolith, which was probably enriched in uranium, for the granite of Lankin Dome. By analogy, other crustally derived granites, within an area of general uranium enrichment, may prove to be favorable uranium source rocks.

End_of_Article - Last_Page 573------------

Copyright 1997 American Association of Petroleum Geologists