Research about Marysvale District

USGS1978

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 U.S. 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.

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USGS1950

The Papsy's Hope autunite prospect, Marysvale District, Piute County, Utah

The Papsy's Hope autunite prospect is in the eastern part of the Marysvale district, Piute County, Utah, about 1 1/2 miles northeast of the mines now operating. It is developed by two shallow cuts and a short incline shaft. One cut exposes a zone of fractures, sparse quartz veins, and scattered autunite. Most if the autunite is exposed within a north-south distance of 17 feet. The trend of the zone is not known. Samples across the autunite-bearing zone average 0.026 percent equivalent uranium. The deposit is in feldspar porphyry of the older Tertiary (Bullion Canyon) volcanics. The intrusive quartz monzonite that contains the deposits now being mined is in contact with quartz porphyry similar to the rocks exposed about 1500 feet west if the Papsy’s Hope prospect. In comparing the Papsy’s Pope prospect with the deposits now being mined, two major correlations have been observed. (1) The deposits at the Papsy’s Hope prospect and those at the Bullion Monarch and Prospector mined are immediately beneath the old erosion surface at the base if the y0ounger tertiary volcanics. The younger volcanics are still present a short distance to the nrth and south of the Papsy’s Hope perospect. (2) The deposits at the Papsy’s Hope prospect and at the Prospector mine are associated with completely silicified outcrops. These correlations may prove of value for prospecting, and further study of the m is in progress. Further prospecting would be necessary to determine the trend of the autunite-bearing zone and to expose it at greater depth. This could be done by trenching across the probable northeast-southwest trend of the zone, by drilling, and either extending the present inclines shaft, or, preferably, driving a new incline at a lower level.

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