Migration behavior of naturally occurring radionuclides at the Nopal I uranium deposit, Chihuahua, Mexico
1997; Elsevier BV; Volume: 26; Issue: 1-4 Linguagem: Inglês
10.1016/s0169-7722(96)00058-7
ISSN1873-6009
AutoresJames D. Prikryl, David A. Pickett, William M. Murphy, English C. Pearcy,
Tópico(s)Geochemistry and Geologic Mapping
ResumoOxidation of pyrite at the Nopal I uranium deposit, Peña Blanca district, Chihuahua, Mexico has resulted in the formation of Fe-oxides/hydroxides. Anomalous U concentrations (i.e. several hundred to several thousand ppm) measured in goethite, hematite, and amorphous Fe-oxyhydroxides in a major fracture that crosscuts the deposit and the absence of U minerals in the fracture suggest that U was retained during secondary mineral growth or sorbed on mineral surfaces. Mobilization and transport of U away from the deposit is suggested by decreasing U concentrations in fracture-infilling materials and in goethite and hematite with distance from the deposit. Greater than unity 234U238U activity ratios measured in fracture-infilling materials indicate relatively recent ( < 1 Ma) U uptake from fluids that carried excess 234U. Systematic decreases in 234U238U activity ratios of fracture materials with distance from the deposit suggest a multistage mobilization process, such as remobilization of U from 234U-enriched infill minerals or differential or diminished transport of U-bearing solutions containing excess 234U.
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