Some possible geologic relationships in the formation of uranium 235 from curium 247

Abstract

(RME-4093) A mechanism for the derivation of U/sup 2//sup 3//sup 5/ from Cm/sup 2//sup 4//sup 7/ is considered as a possile source of U/sup 2//sup 3//sup 5/ enrichment in radioactive rare earth minerals. The presence of Cm/sup 2//sup 4//sup 7/ in early earth materials is predictsble on the basis of synthesis through nuclear reactions and from extrapolations of abundances of lighter nuclides. The chemistry of curium reflects a geochemical similarity to rare- earth elements and possile incorporation in rare-earth minerals. The amount ot enrichment of U/sup 2//sup 3/5/sup / that might be expected from Cm/sup 2//sup 4// sup 7/ decay is calculated for monazite for several geologic ages. Within the limits of the parameters considered, Cm/sup 2//sup 4/>s7< s would not provide sufficient U/sup 2//sup 3/5/sup / enrichment to be of economic consequence, but its possile existence in early geologic time may be of interest in geochronology studies. Underestimnation of Cm/sup 2//sup 4//sup 7/ abundance may affect significantly the probability for finding interesting variations in U/ sup 2//sup 3//sup 5/: U/sup 2//sup 3//sup 8/ ratios. (auth)