Abstract: Abstract: Rare Earth and Other Trace Elements as Prospecting Guides in Grants Mineral Belt, New Mexico

Douglas G. Brookins, Walter C. Reise, J. Lee Moon

Uranium in sandstone-type deposits is known to be associated with high concentrations of Mo, Se, V, and As, as these elements are transported as oxyanions and thus segregated from most other trace elements. Further, these elements commonly precipitate at about the same Eh-pH conditions as uranium. Unfortunately, as uranium is redistributed by local oxidation so, too, are Mo, Se, and As. Only vanadium tends to leave "fingerprints" behind as vanadium ions fixed in the octahedral sites of clay minerals. However, high vanadium contents by themselves may not serve as a direct guide for tracing uranium, because its original or later movement may have been unrelated to uranium movement.

In the Grants mineral belt the rare-earth elements and thorium commonly are enriched in the ore zones as well as the Mo-Se-V-As suite. Further, thorium and the rare earth elements are greatly enriched in the authigenic fraction of ore and ore gangue; these data may suggest local provenance for uranium in the Morrison Formation of the Grants mineral belt. Although this observation is of extreme interest, so, too, is the fact that these elements, because of their different behavior under oxidizing conditions relative to uranium, may serve as pathfinder elements for mapping uranium movement. Such a treatment, although admittedly cumbersome owing to the analytic time involved in present technology, offers great promise for future uranium exploration.

AAPG Search and Discovery Article #90969©1977 AAPG-SEPM Rocky Mountain Sections Meeting, Denver, Colorado