Journal
EARTH AND PLANETARY SCIENCE LETTERS
Volume 422, Issue -, Pages 18-27Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.epsl.2015.04.008
Keywords
R chondrites; rare earth elements; uranium; thorium; phosphorus
Categories
Funding
- Tokyo Metropolitan Government
- Ministry of Education, Culture, Sports, Science, and Technology, Japan (MEXT) [25246038]
- Grants-in-Aid for Scientific Research [25246038] Funding Source: KAKEN
Ask authors/readers for more resources
Rare earth elements (REEs), Th, U and P were determined in 15 Rumuruti (R)-type chondrites and the Allende CV chondrite. Repeated analyses of Allende for REEs, Th and U by ICP-MS and P by ICP-AES, and comparisons of these data with literature values ensure high reproducibility (precision) and reliability (accuracy) of acquired data. Cl-normalized REE abundances in R chondrites are slightly enriched in heavy REEs with a small, positive Ce anomaly, in contrast to Allende. Cl-normalized Pr/Tm and Nd/Yb ratios show a positive correlation, suggesting the heterogeneous mixing of two components (CI-like and refractory-dch materials) during the accretion of the R chondrite parent body. A Ce anomaly, however, was likely homogeneously present in the nebula. A mean Th/U ratio of R chondrites is 3.81 +/- 0.13 (1 sigma), which is 5.1% higher than the Cl ratio. Probably, the Th-U fractionation was inherited from the nebula from which the R chondrite parent body formed. Besides the Th-U fractionation, REEs and Th-U are heterogeneously fractionated in R chondrites, for which parent body processing is assumed to be the cause. A mean P content of R chondrites (1254 mu g/g) is higher than for any ordinary chondrite and is close to the EL mean. There appears to be a negative correlation between P and REEs contents in R chondrites. It is probable that REEs were diluted by extraneously supplied, REEs-depleted and P-containing materials (schreibersite or metal). This process must have occurred heterogeneously during accretion so that the heterogeneity of P-containing materials was preserved in the R chondrite parent body and individual R chondrites. (C) 2015 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available