Noble gas and chronological study of Asuka eucrites: A-880761 and A-881388 are paired, but A-880702 is not
Noble gas isotopic and elemental compositions of three Antarctic eucrites Asuka-880702, Asuka-880761 and Asuka-881388 have been measured by two steps of heating temperatures (400 and 1750°C ). Cosmic-ray exposure ages calculated from cosmogenic ^(21)Ne were 20.5, 32.3 and 29.7m.y. for A-880702, A-88...
| Main Authors: | , |
|---|---|
| Format: | Report |
| Language: | English |
| Published: |
Laboratory for Earthquake Chemistry, Graduate School of Science, University of Tokyo/Laboratory for Earthquake Chemistry, Graduate School of Science, University of Tokyo
2005
|
| Subjects: | |
| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=6074 http://id.nii.ac.jp/1291/00006074/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=6074&item_no=1&attribute_id=18&file_no=1 |
| Summary: | Noble gas isotopic and elemental compositions of three Antarctic eucrites Asuka-880702, Asuka-880761 and Asuka-881388 have been measured by two steps of heating temperatures (400 and 1750°C ). Cosmic-ray exposure ages calculated from cosmogenic ^(21)Ne were 20.5, 32.3 and 29.7m.y. for A-880702, A-880761 and A-881388, respectively. Combining the exposure ages with ^(81)Kr-Kr apparent exposure ages, terrestrial ages of 0.20, 0.22 and 0.23m.y. were derived for A-880702, A-880761 and A-881388, respectively. ^(244)Pu-Xe ages based on fissiogenic Xe isotopes showed that the Asuka eucrites began Xe retention at around the crystallization age of Angra dos Reis. Among the Asuka eucrites, A-880702 is about 20m.y. older than the others. From the noble gas and age data described above, we conclude that A-880761 and A-881388 are paired, but A-880702 is not. |
|---|