Rare-earth, yttrium and scandium abundances in meteoritic and terrestrial matter—II

Abstract

Abundances and selected isotopic ratios of the 14 rare-earth elements (REE), yttrium, and scandium have been determined by neutron-activation analysis in 13 meteorites and 2 terrestrial specimens: 3 carbonaceous, 2 hypersthenic, and 1 bronzitic (troilite phase) chondrite; 2 calcium-rich and 2 nakhlitic achondrites; 1 mesosiderite; 2 pallasites; an Australian eclogite; and a Columbia Plateau basalt. This research is a continuation of recent REE work by Schmitt et al. (1963a). Absolute abundances of the REE and Sc in 2 Type I carbonaceous chondrites are about 33 per cent less compared with the Type II. Atomic ratios of Y 10 6 Si in carbonaceous chondrites remain approximately constant at 4.7 (Type I), 4.1 (Type II), and 4.8 (Type III), and ratios of the REE (La is representative) yielded La 10 6 Si at 0.36 (Type I), 0.53 (Type II), and 0.51 (Type III). The REE, Y, and Sc contents in the troilite-phase of a chondrite is ~0.3 of the content in the entire chondritic matrix. REE and Y abundances in Ca-rich achondrites and nakhlites are ~10 and ~5 times larger, respectively, than found in ordinary chondrites. No fractionation of the REE and Y distribution was observed in Ca-rich achondrites compared to chondritic REE and Y; fractionation in nakhlites is similar to terrestrial basalts. Fractionation of the REE and Y (Eu is enriched) in the mesosiderite Veramin and in two pallasites (Eu depleted in one pallasite) has been found. The observed fractionation of the REE and Y in Australian eclogite is opposite to fractionation in African eclogite, and fractionation in Columbia Plateau basalt was similar to Kilauea basalt.