Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Recent technical advances have made it possible to measure the abundance of boron in ultramafic xenoliths from alkali basalts thought to be representative of the upper mantle. Such data can provide information on the cosmochemistry of boron, particularly the temperature and mode of condensation of this element from the solar nebula. Analysis of xenoliths, selected by Jagoutz et al.1 to represent fertile unaltered mantle, shows that the mean boron abundance is more than three times that expected for the condensation temperature of 700 K calculated by Cameron et al.2. Our measurements, reported here, suggest that boron condensed at approximately 1,200 K as a solid solution in alkali feldspar or anorthite and not as an independent phase.