A procedure for geochemical interpretation of terrestrial rare-earth abundance patterns

A procedure for geochemical interpretation of rare-earth abundances in rocks and minerals is presented. The ratio of each rare-earth abundance in the sample to the corresponding value in chondritic meteorites (on logarithmic scale) is plotted as a function of atomic number Z. Normalization to chondrites compensates for element-to-element irregularities and reveals small relative abundance variations among neighboring rare earths as a result of natural processes. It is shown that increased order occurs, permitting interpolations and extrapolations to be made with fair confidence, and systematic rare-earth abundance patterns are made apparent. The usefulness of the procedure is discussed using several examples from the existing literature.