Methodology for Rare Earth Element Determinations of Uranium Oxides by Ion Microprobe

Abstract

A methodology for the determination of the rare earth elements in uranium oxides by ion microprobe has been set up on a Cameca ims‐3f instrument. An uranium oxide reference material from a syn‐metamorphic uranium deposit related to albitisation has also been developed for this type of analysis. Applications of the methodology are presented for a series of uranium oxides selected from some major uranium deposit types: from the world's highest grade unconformity‐related uranium deposit from the Athabasca Basin (Saskatchewan, Canada; the Shea Creek and the McArthur River examples), a perigranitic vein‐type deposit (Pen Ar Ran, Vendée, France) and a volcanic caldera‐related deposit (Streltsovkoye, Transbaikalia, Russia). Each type of uranium deposit appears to have a specific REE signature. All REE patterns from the Shea Creek and the McArthur deposits are characterised by bell‐shaped patterns centred on Tb‐Dy and similar to those already published for uranium oxides from unconformity‐related deposits from Australia. Such bell‐shaped REE patterns centred on Tb‐Dy may therefore be considered as a typical signature of uranium oxides from Mesoproterozoic unconformity‐related deposits. A smoother bell shape pattern centred on Eu characterises the syn‐metamorphic albitisation related deposit of Mistamisk selected for the reference material. The REE patterns from the Pen Ar Ran deposit show a fractionation from LREE to HREE with anomalously high abundances of Sm, Eu and Gd with respect to the other REEs, similar to the REE patterns of uranium oxides from the volcanic‐related deposits of Streltsovkoye.

Magmatic and Metamorphic Uraninite Mineralization in the Western Margin of the Trans-Hudson Orogen (Saskatchewan, Canada): A Uranium Source for Unconformity-Related Uranium Deposits?

“…Methodology for secondary ion mass spectrometry (SIMS) and LA-ICP-MS is described in Bonhoure et al (2007) and Mercadier et al (2011b), respectively.…”

Magmatic and hydrothermal behavior of uranium in syntectonic leucogranites: The uranium mineralization associated with the Hercynian Guérande granite (Armorican Massif, France)

“…The REE concentrations measured in the uranium oxides from the Pen Ar Ran deposit are typically low but the patterns show a significant fractionation from LREE to HREE with an enrichment in Sm, Eu and Gd (Bonhoure et al, 2007). Based on the comparison with some clearly volcanicrelated U deposits, these spectra have been interpreted as an indicator that the probable U source for the Pen Ar Ran deposit was the enclosing metavolcanic rocks (Bonhoure et al, 2007).…”

“…Based on the comparison with some clearly volcanicrelated U deposits, these spectra have been interpreted as an indicator that the probable U source for the Pen Ar Ran deposit was the enclosing metavolcanic rocks (Bonhoure et al, 2007). …”

“…Based on the REE patterns of uranium oxides from the Pen Ar Ran mineralization, Bonhoure et al (2007) proposed that the metavolcanics of the Piriac graben (Vendée porphyroids; Fig. 3) were the likely source for the uranium concentrated in this deposit.…”

“…Bonhoure et al (2007) proposed that the metavolcanic country rocks were the source for the U, based on the peculiar REE concentrations measured in the UO 2 oxides. However, another possibility is that at least some of the U was leached out from the Guérande leucogranite itself, which potentially represents a major source of available uranium because of the known existence of magmatic uranium oxides (Ouddou, 1984).…”