Detailed abundances of rare earth elements, thorium and uranium in chondritic meteorites: An ICP‐MS study

Abstract

Abstract— Inductively coupled plasma mass spectrometry (ICP‐MS) was successfully applied to bulk samples of Allende, Jilin, Modoc, Saint‐Séverin and Atlanta for the determination of rare earth elements (REE) (Y and 14 lanthanoids), Th and U. The results of ICP‐MS showed good agreement with recommended values, and their reproducibilities were high enough to discuss the detailed abundances of lanthanoids and actinoids in chondritic meteorites. For the Allende reference sample issued by the Smithsonian Institution, a positive anomaly of Tm, a fractionation between light REE and heavy REE and a high Th/U ratio were observed in the CI‐normalized abundances of REE, Th and U. These features are common for group II inclusions in Allende, suggesting that the abundances of refractory lithophiles in Allende are somewhat influenced by those in a specific constituent. For the other chondritic meteorites, a zigzag alteration was commonly observed in the heavy‐REE region of their CI‐normalized abundance patterns. It is suggested that such a zigzag pattern is attributable to erratically high abundances of monoisotopic REE (Tb, Ho and Tm) in the CI values. Abundances of REE, Th and U in the bulk samples are also discussed separately in detail.