Refractory element fractionations among carbonaceous chondrite groups

Abstract

Chondritic meteorites consist of collections of grains formed in the solar nebula. Chondritic materials can often be resolved into components that formed in differing nebular conditions. Carbonaceous chondrites are often accorded special significance in planetary models, especially because abundances of most elements in the CI group are indistinguishable from those in the Sun. Abundances of refractory lithophiles are among the most useful parameters for the classification of chrondrites, because they systematically decrease through the sequence carbonaceous→ordinary→enstatite1,2. They are also the most general parameter linking groups of very similar chondrites into clans which consist of groups having certain common properties that may indicate formation within a narrow range of distances from the Sun3. We report here newly discovered differences in refractory abundances among the different groups of carbonaceous chondrites.