1999 Fiscal Year Final Research Report Summary
Meteorite research based on microanalysis of oxygen isotopes using SIMS
| Project/Area Number |
09440183
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HIYAGON Hajime Graduate School of Science, The University of Tokyo, Associate Professor, 大学院・理学系研究科, 助教授 (70192292)
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| Project Period (FY) |
1997 – 1999
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| Keywords | SIMS / carbonaceous chondrites / refractory inclusions / isotopic anomaly / oxygen isotopes / magnesium isotopes / potassium isotopes |
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| Research Abstract |
I have improved the technique of microanalysis of oxygen isotopes using SIMS (secondary ion mass spectrometry). Precision of the analysis for the oxygen 17/16 and 18/16 ratios for a 10 μm spot is about ±2‰, which is excellent when compared with other laboratories in the world. Using this technique, micro-distribution of oxygen isotopes were intensively studied for inclusions and chondrules in different types of chondrites. It has been well known that refractory inclusions, or CAIs, have 4-5% excess in 0-16, and an important aim of this study was to understand their origin. During the course of the study, I and Dr. Hashimoto discovered olivine-rich inclusions which also have large O-isotopic anomalies similar to those found in CAIs, and the results were published in Science The results are very important in considering the origin of the O-isotopic anomalies, because olivine is a mineral less refractory than CAI-minerals and much abundant in chondrites. We also found that various types of inclusions in different carbonaceous chondrite groups have very similar O-isotopic anomalies. This suggests a common source or a common process for the formation of these inclusions. The results of this study suggests a possibility that some kind of chemical processes in the early solar system may be responsible for the observed O-isotopic anomalies. Also some important results were obtained for Mg and K isotopic compositions in some selected inclusions. Most of the results obtained in the present study were presented at international conferences as well as domestic ones.
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