| タイトル | Petrography, mineralogy, and Mg isotope composition of VICTA: A vigarano CaAl4O7-bearing type A inclusion |
| 本文（外部サイト） | http://hdl.handle.net/2060/19940011730 |
| 著者（英） | Long, J. V. P.; Morse, A.; Greenwood, R. C. |
| 著者所属（英） | Museum of Natural History |
| 発行日 | 1993-01-01 |
| 言語 | eng |
| 内容記述 | Thermodynamic calculations predict that Ca-dialuminate (CaAl4O7) condenses from a cooling gas of solar composition after hibonite and before melilite. Although Ca-dialuminate has now been recorded from Ca Al-rich inclusions (CAI's) in at least 9 meteorites, compared to hibonite it is a relatively rare phase. As pointed out by Michel-Levy et al., the absence of Ca-dialuminate from most hibonite-bearing inclusions poses a serious problem for the condensation model of CAI formation. Here we describe an inclusion which contains abundant CA-dialuminate partially altered to a hercynite-rich (FeAl2O4) assemblage. The evidence from VICTA indicates that compared to all other phases in type A inclusions, Ca-dialuminate is the most susceptible to secondary alteration; a feature which may explain its restricted occurrence. Unaltered Ca-dialuminate and melilite in VICTA display excess Mg-26 indicative of in situ decay of Al-26. |
| NASA分類 | GEOPHYSICS |
| レポートNO | 94N16203 |
| 権利 | No Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/115989 |
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