Fractionation of rare earth elements in refractory inclusions from the Ningqiang meteorite: Origin of positive anomalies in Ce, Eu, and Yb
文献类型：期刊论文
| 作者 | Hiyagon, H.1; Yamakawa, A.2; Ushikubo, T.3; Lin, Y.4; Kimura, M.5 |
| 刊名 | GEOCHIMICA ET COSMOCHIMICA ACTA
 |
| 出版日期 | 2011-06-15 |
| 卷号 | 75期号:12页码:3358-3384 |
| ISSN号 | 0016-7037 |
| DOI | 10.1016/j.gca.2011.03.029 |
| 文献子类 | Article |
| 英文摘要 | Ion microprobe analyses of rare earth elements (REEs), Ba, and Hf were performed for various types of refractory inclusions including amoeboid olivine aggregates (AOAs) from the Ningqiang ungrouped carbonaceous chondrite to search for possible relationships between REE abundance patterns and bulk chemical compositions of the inclusions. Four types of CI-normalized REE patterns were recognized: (1) nearly flat (unfractionated) pattern with or without Eu (and Yb) anomalies (Groups I, III, or V), (2) depletions of ultrarefractory heavy REEs (HREEs) relative to light REEs (LREEs), and depletions of Eu and Yb (Group II, but without depletion of Yb in some cases), (3) depletions of ultrarefractory HREEs with positive anomalies in Ce, (Eu), and Yb (Modified Group II), and (4) nearly flat pattern with positive anomalies in Ce, (Eu), and Yb (Modified Group I). No systematic correlation was found between bulk chemical compositions and REE patterns of the inclusions. This suggests that the observed REE fractionations occurred prior to condensation of major elements (e. g., Mg and Si) which defined bulk chemical compositions of the inclusions. It is remarkable that 7 out of 19 inclusions show positive anomalies in Ce, Yb, and in some cases, Eu as well (Modified Group I and Modified Group II), suggesting that such anomalies are rather common among inclusions in the Ningqiang and possibly in other primitive meteorites. Two possible mechanisms are considered for the formation of Modified Group II and Modified Group I patterns. In Model 1, Modified Group II is formed by a process similar to that produced Group II but removal of ultrarefractory dust occurred at slightly lower temperatures, where not only ultrarefractory HREEs but some fraction of LREEs had been condensed and removed from the system. Modified Group I may be explained by addition of an unfractionated component to the Modified Group II component, or alternatively, by partial removal of ultrarefractory dust from the system. In Model 2, Modified Group II is formed by later addition of Ce, (Eu), and Yb onto fine-grained dust or inclusions having HREE-depleted, Group II-like REE patterns. Similarly, Modified Group I is explained by later addition of Ce, (Eu), and Yb onto those with almost unfractionated REE patterns. The observed REE data show that both the degree of HREE-depletion (e. g., Er-depletion) and that of fractionation among HREEs (e. g., depletion in the Er/Gd ratio) for Modified Group II are very similar to those for Group II. Model 1 predicts almost complete removal of ultrarefractory HREEs from the system, resulting in much higher HREE-depletion for Modified Group II, which is not consistent with the present observations. Addition of an unfractionated component may explain moderate depletion of HREEs in Modified Group II, but it will diminish fractionation among HREEs, which is not consistent with the present observations. In contrast, Model 2 predicts no correlations between Ce-(Eu)-Yb-enrichment and HREE-depletion or between Ce-(Eu)-Yb-enrichment and fractionation among HREEs, consistent with the present observations. Hence, Model 2 seems more likely. If this is the case, at least two distinct regions with different REE characteristics are required for the formation of Modified Group II inclusions: one is a high temperature region where Group II-like (HREE-depleted) inclusions or their precursors are formed by condensation from a fractionated gas after removal of ultrarefractory dust, and another is a low temperature region enriched in Ce, Eu, and Yb in the gas phase. |
| WOS关键词 | MURCHISON CARBONACEOUS CHONDRITE ; SPINEL-RICH INCLUSIONS ; ISOTOPIC COMPOSITIONS ; ALLENDE METEORITE ; SOLAR NEBULA ; ABUNDANCES ; CONDENSATION ; PETROLOGY ; CALCIUM ; CLASSIFICATION |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:000293088500004 |
| 出版者 | PERGAMON-ELSEVIER SCIENCE LTD |
| 资助机构 | Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; 19540500 ; 19540500 ; 22540488) ; 22540488) ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; 19540500 ; 19540500 ; 22540488) ; 22540488) ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; 19540500 ; 19540500 ; 22540488) ; 22540488) ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Ministry of Education, Science, Sport, and Culture of Japanese government(12440153 ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; Chinese Academy of Sciences(kzcx2-yw-Q08) ; 19540500 ; 19540500 ; 22540488) ; 22540488) |
| 源URL | [http://ir.iggcas.ac.cn/handle/132A11/73712]  |
| 专题 | 中国科学院地质与地球物理研究所 |
| 通讯作者 | Hiyagon, H. |
| 作者单位 | 1.Univ Tokyo, Grad Sch Sci, Dept Earth & Planetary Sci, Tokyo 1130033, Japan 2.Okayama Univ, Inst Study Earths Interior, Tottori 6820193, Japan 3.Univ Wisconsin Madison, Dept Geosci, Madison, WI 53706 USA 4.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earths Deep Interior, Beijing 100029, Peoples R China 5.Ibaraki Univ, Fac Sci, Mito, Ibaraki 310, Japan |
| 推荐引用方式 GB/T 7714 | Hiyagon, H.,Yamakawa, A.,Ushikubo, T.,et al. Fractionation of rare earth elements in refractory inclusions from the Ningqiang meteorite: Origin of positive anomalies in Ce, Eu, and Yb[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2011,75(12):3358-3384. |
| APA | Hiyagon, H.,Yamakawa, A.,Ushikubo, T.,Lin, Y.,&Kimura, M..(2011).Fractionation of rare earth elements in refractory inclusions from the Ningqiang meteorite: Origin of positive anomalies in Ce, Eu, and Yb.GEOCHIMICA ET COSMOCHIMICA ACTA,75(12),3358-3384. |
| MLA | Hiyagon, H.,et al."Fractionation of rare earth elements in refractory inclusions from the Ningqiang meteorite: Origin of positive anomalies in Ce, Eu, and Yb".GEOCHIMICA ET COSMOCHIMICA ACTA 75.12(2011):3358-3384. |
入库方式： OAI收割
来源：地质与地球物理研究所
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