A PRIORI ESTIMATES OF ANOMALOUSLY HIGH 140, 142Ce AND 148, 152, 154Sm ABUNDANCES AND ANOMALOUSLY LOW 141Pr AND 151, 153Eu ABUNDANCES IN CHONDRITES

Abstract

It is known that the graphic presentation of lanthanide abundances in terrestrial rocks and ores in the nucleus charge versus the logarithm of abundance coordinates has a Z-shaped pattern with deep minimums and sharp maximums and a general tendency of decreasing abundances with increase in the nucleus charge. The difference between any neighboring maximum and minimum is substantially reduced in the case of chondrite normalization. This method implies that the abundances of lanthanides in chondrites are regarded as reference values. Lanthanides of constant valence contained in chondrites demonstrate a clear abundance reduction tendency with increasing nucleus charge. In contrast, the abundances of lanthanides of variable valence are anomalous because high abundances atypical of the general tendency are inherent to Ce, Sm, and Yb, whereas Pr, Eu, and Tb are also characterized by anomalously low abundances atypical of the general tendency. Therefore, such anomalous abundances could not be described and certainly not estimated a priori.