pre-compaction exposure ages of CAIs in primitive meteorites: clarification of mechanisms of transportation and circulation of materials in the solar nebula

2014 Fiscal Year Final Research Report

• Project/Area Number: 23684046
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Geochemistry/Astrochemistry
• Research Institution: Kyushu University
• Principal Investigator: OKAZAKI Ryuji 九州大学, 理学(系)研究科(研究院), 助教 (40372750)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: 難揮発性包有物 / 原始太陽系星雲 / 物質輸送 / 照射年代 / 浮遊年代 / コンドライト / CAI / 希ガス

Outline of Final Research Achievements

Five CAIs were found in polished sections prepared from the Allende CV chondrite. Their textural features and chemical compositions were determined by FESEM and EPMA, respectively. Stepped heating noble gas analyses were performed for two large CAIs.
One CAI has concordant exposure ages based on Ne and Kr stable isotopes (T21 and T83, respectively). An apparent age based on 81Kr is consistent with T21 and T83 within experimental uncertainties, suggesting that the pre-compaction exposure is shorter than 5 Ma. However, the further discussion is difficult due to the large experimental uncertainties. Another CAI shows excesses in 80Kr and 82 Kr that are derived from epi-thermal neutron capture of Br. In addition, 129Xe excess due to radiogenic 129I is observed. These excesses indicate this CAI is enriched in halogens.

Free Research Field

地球外物質科学