Rare-earth elements in matrix,inclusions, and chondrules of the Allende meteorite |
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| Authors: | Tsuyoshi Tanaka Akimasa Masuda |
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| Institution: | Geological Survey of Japan, Hisamoto, Takatsu-ku, Kawasaki, Japan;Department of Chemistry, Science University of Tokyo, Kagurazaka, Shinjuku-ku, Tokyo, Japan |
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| Abstract: | Rare-earth elements in a whole-rock sample and in major components of the Allende meteorite were investigated; for a few samples, abundances of Ba, Sr, Ca, and Al were also determined. Of the materials investigated in the present work, CaAl-rich inclusions G and O seem to be of the greatest significance. In spite of the minor difference in mineralogy between them, the apparent chondrite-normalized RE pattern is much different between these two inclusions. (Yb and Eu in inclusion G appear exceptionally irregular). This observation is inferred to reflect a rather subtle difference in condition of condensation. It is also worthwhile to note that, while two portions (pink and white) of the inclusion G show similar aspects in the abundances of lithophile trace elements investigated, they show a remarkable difference at the same time. The white portion (Gw) of inclusion G can be considered to be a mixture of chondritic material and highly fractionated material like the faintly pink portion (Gp) picked from the same inclusion. This would suggest the possibility that the Gp-like material was produced from chondritic dust.The “matrix” separated from Allende was found to be fractionated with respect to the RE abundances relative to representative chondrite. It has also a very high value for the Ba abundance. |
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