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DISTRIBUTION OF RARE EARTH ELEMENTS AND URANIUM IN VARIOUS COMPONENTS OF ORDINARY CHONDRITES |
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| Authors: | Mitsuru Ebihara Masatake Honda |
| Institution: | Institute for Solid State Physics University of Tokyo Roppongi, Minato-ku, Tokyo, Japan
Department of Chemistry, Faculty of General Studies. Gunma University, 4-2 Aramaki, Maebashi, Gunma 371, Japan Department of Chemistry, College of Humanities and Sciences. Nihon University, Sakura-josui, Setagaya-ku, Tokyo 156, Japan |
| Abstract: | Rare earth elements (REE) and uranium were studied for their distributions in various component phases of four ordinary chondrites, Kesen (H4), Richardton (H5), Bruderheim (L6), and Saint Séverin (LL6). A selective dissolution method was applied for the phase fractionation. The REE were analysed by neutron activation analysis, and U was determined by neutron-induced fission tracks. The present study revealed that both REE and U are highly enriched in the Ca-phosphate minerals with different enrichment factors, implying chemical fractionation between them. The phosphates seem to be responsible for more than 80% of the light REE in all chondrites. On the other hand, only 20–40% of the total U resides in the Ca-phosphates. This difference in enrichments might have been caused through the levels of metamorphic activity on the meteoritic parent bodies. |
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