RELATIONSHIP AMONG O, MG ISOTOPES AND THE PETROGRAPHY OF TWO SPINEL-BEARING COMPOUND CHONDRULES
- DSpace Home
- →
- Геология России
- →
- ELibrary
- →
- View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.
dc.contributor.author | Maruyama S. | |
dc.contributor.author | Yurimoto H. | |
dc.date.accessioned | 2021-12-29T04:38:04Z | |
dc.date.available | 2021-12-29T04:38:04Z | |
dc.date.issued | 2003 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=5070787 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2003, 67, 20, 3943-3957 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/33926 | |
dc.description.abstract | The petrological properties, and O and Al-Mg isotopic compositions of two spinel-bearing chondrules from the Allende CV chondrite were investigated using scanning electron microscopy and secondary ion mass spectrometry. A coarse spinel grain in a barred-olivine (BO) chondrule is less enriched in 16O (Δ17O ~ -5%%; Δ17O = δ17O - 0.52 δ18O), whereas smaller spinel grains in a plagioclase-rich chondrule member of a compound chondrule are extremely 16O-rich (Δ17O ~ -17%%) and the spinels have a strongly serrated character. The petrological features and 16O-enrichments of the spinels in the plagioclase-rich chondrule indicate that spinels originating in coarse-grained Ca-Al-rich Inclusions (CAIs) were incorporated into chondrule precursors and survived the chondrule-forming event. The degree of 16O-excesses among minerals within each chondrule is correlated to the crystallization sequences. This evidence suggests that the O isotopic variation among minerals may have resulted from incomplete exchange of O isotopes between 16O-rich chondrule melt and 16O-poor nebular gas. Aqueous alteration also has changed the O-isotope compositions in the mesostasis. The feldspathic mesostasis in the BO chondrule shows a disturbed Mg-Al isochron indicating that the BO chondrule experienced secondary alteration. While plagioclase in the plagioclase-rich chondrule member of the compound chondrule shows slight 26Mg-excesses corresponding to (26Al/27Al)0 = [4.6+/-4.0(2σ)] x 10-6, nepheline formed by secondary alteration shows no detectable excess. The Al-Mg isotopic system of these chondrules was disturbed by aqueous alteration and thermal metamorphism on the Allende parent body. | |
dc.title | RELATIONSHIP AMONG O, MG ISOTOPES AND THE PETROGRAPHY OF TWO SPINEL-BEARING COMPOUND CHONDRULES | |
dc.type | Статья |
Files in this item
This item appears in the following Collection(s)
-
ELibrary
Метаданные публикаций с сайта https://www.elibrary.ru