Postulated model of uranium occurrence in the central mining area, Marysvale District, West-Central Utah

Uranium in the central mining area of Marysvale, Utah occurs in hydrothermal veins cutting granitic and volcanic rocks in the eastern source area of the Mount Belknap Volcanics. A preliminary model for the origin of the veins envisages deposition in near-surface fractures above an unexposed pluton that may host a porphyry-type ore deposit. This model is based on the work in progress by the US Geological Survey, and embodies all presently available data from field mapping, literature study, fluid inclusion studies, and diverse geochemical and isotopic studies. Recent advances in uranium geochemistry have been particularly helpful. The work is not yet complete so this model should be considered as a progress report suggesting possible targets for exploration and testing; such testing would in turn lead to refinements in the model and to a clearer understanding of vein-type uranium deposits in general. 2 figures