"The Dells granite of central Arizona, an alkaline granite containing accessory fluorite and tourmaline, contains anomalously high amounts of uranium. Gamma-ray spectrometry, x-ray fluorescence, petrographic, and autoradiographic methods were used to determine the contents and distribution of equivalent U, Th, K, and ten major element oxides within the granite pluton. The range of uranium content is 0 to 39.7 parts per million (ppm) with the mean equivalent U content 8.8 ppm; eTh, 26.8 ppm; and K, 4.8%. The average uranium content is about twice the average of western United States granites, the thorium content slightly less than average. The Th/U ratio varies from less than 2.0 to greater than 10.0, indicating both enrichment and depletion of uranium relative to thorium.
Uranium contents greater than +1 standard deviation occur in two main localized zones within this highly alkaline granite. These total about 13 million square feet in area. Thorium distribution is similar to uranium. Radioactive accessory minerals containing U and/or Th are present within biotite grains of these zones. Enrichment of uranium and thorium in the localized areas may be the result of deposition by late-stage magmatic fluids rich in volatiles such as water and fluorine. Depletion of uranium is the result of the intense weathering of the granite, which has mobilized and removed both uranium and iron. Intense jointing provides conduits for oxidizing ground and surface water. Assuming a leaching depth of 100 feet and 25% removal of uranium by leaching, as much as 13,000,000 pounds of uranium may have been removed from the high uranium content areas of the granite and circulated in surface and ground waters. Surrounding and overlying sediments and the granite body itself provide possible sites for enrichment of this mobilized uranium into economic concentrations along oxidation-reduction boundaries at depth"--Abstract, page ii.
Proctor, Paul Dean, 1918-1999
Grant, S. Kerry
Geosciences and Geological and Petroleum Engineering
M.S. in Geology and Geophysics
V. H. McNutt Memorial Foundation
University of Missouri--Rolla
x, 90 pages
Yavapai County, Arizona
© 1982 Kenneth Stewart Fleck, All rights reserved.
Thesis - Open Access
Radioactive substances -- Arizona -- Yavapai County
Granite -- Arizona -- Yavapai County
Radioactivity -- Measurement
Uranium ores -- Arizona -- Yavapai County
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Fleck, Kenneth Stewart, "Radiometric and petrochemical characteristics of the Dells granite, Yavapai County, Arizona" (1982). Masters Theses. 4084.