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

Résumé

Alpha-track images (ATI) of B and Li in ordinary and carbonaceous chondrites were prepared from polished thin sections. The first sections examined gave ATIs showing much petrographic detail, but terrestrial contamination was suspected. The contamination was confirmed and comes from B, chiefly but not only in diamond polishing paste used in section preparation. In addition to enhancing textural detail, the contamination is also revealed by spots ofhigh track density unrelated to petrography. Specially prepared (uncontaminated) sections of Murchison and Antarctic météorites gave ATIs of weaker intensity but which still distinguish chondrules, rims, clasts, and matrix. The Antarctic samples also show B and/or Li to be localized in red-brown alteratron. ATIs can give valuable information on B and Li distribution within meteorites, but contamination must be excluded during section preparation. Polished sections for ionmicroprobe study require similar care.