Uranium-lead isotope systematics in uraniferous alkali-rich granites from the Granite Mountains, Wyoming; implications for uranium source rocks

Petrogenetic modeling of a potential uranium source rock, Granite Mountains, Wyoming

“…For a few samples, counting statistics for certain rare earths were poor (largely due to the interference of uranium), and the data reported in tables 1 and 2 were obtained by graphical extrapolation between the chondrite-normalized abundances of adjacent rare earths. Uranium and Th concentrations were deter-mined by isotope dilution and mass spectrometry for most of the samples (Stuckless and Nkomo, 1978). These values were supplemented by delayed-neutron determinations for U (Millard, 1976) and gamma-ray spectrometry determinations for Th Bush, 1966, 1967).…”

“…They proposed that this uranium was the source for the central Wyoming deposits. Subsequent, more detailed studies have shown that the upper 50 m (meters) of granite of Lankin Dome lost an average of 20 /ig/g (micrograms per gram) or about 80 percent of the original uranium (Rosholt and others 1973), and that uranium has been mobilized to depths in excess of 360 m (Stuckless and Nkomo, 1978). Analyses of the granite of Long Creek Mountain (Stuckless and Nkomo, 1978) and of the metamorphic rocks (Nkomo and Rosholt, 1972) suggest that these units have not lost as much uranium (in terms of either percent or absolute amount) as the granite of Lankin Dome.…”

“…This method of modeling allows examination of the variation in all the chemical variables simultaneously and can be used to determine the number of end members required to account for the variability in each variable to any degree specified. Geology from Stuckless and Nkomo (1978) and Peterman and Hildreth (1978).…”

Mineral resources of the Oregon Buttes Wilderness Study Area, Sweetwater County, Wyoming

“…The Battle Spring Formation was deposited as alluvial-fan material derived from the uplift of the Granite Mountains along the Emigrant Trail thrust fault (Love, 1970). Possible sources for the uranium in the Battle Spring include the granitic rocks of the Granite Mountains (Stuckless and Nkomo, 1978) or uraniumrich tuffaceous strata that once covered the area (Love, 1970;Harshman, 1972).…”

Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada

“…This is true both in saturated and in unsaturated zones. Solid granites have been shown to have lost as much as 90 percent of their uranium in both of these zones and to depths of several hundred meters (Stuckless and Nkomo, 1978;Smellie and Stuckless, 1985;Stuckless and others, 1986). Studies indicate that uranium has been lost from labile sites such as grain boundaries and microfractures or where sorbed onto metallic oxides (Stuckless and Nkomo, 1980;Zielinski and others, 1981).…”