Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses
© 2015 Elsevier Ltd. The U-Pb systems of apatite and merrillite grains within four separate Apollo 14 impact melt breccia samples were analysed by secondary ion mass spectrometry. No systematic difference was identified between the 207Pb/206Pb ages of the apatites and merrillites. A combined 207Pb/2...
| Main Authors: | , , , , , |
|---|---|
| Format: | Journal Article |
| Published: |
2016
|
| Online Access: | http://hdl.handle.net/20.500.11937/16630 |
| _version_ | 1848749231520612352 |
|---|---|
| author | Snape, J. Nemchin, Alexander Grange, Marion Bellucci, J. Thiessen, F. Whitehouse, M. |
| author_facet | Snape, J. Nemchin, Alexander Grange, Marion Bellucci, J. Thiessen, F. Whitehouse, M. |
| author_sort | Snape, J. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2015 Elsevier Ltd. The U-Pb systems of apatite and merrillite grains within four separate Apollo 14 impact melt breccia samples were analysed by secondary ion mass spectrometry. No systematic difference was identified between the 207Pb/206Pb ages of the apatites and merrillites. A combined 207Pb/206Pb age of 3927±2Ma (95% conf.) is determined for three of these samples (14305,103: 3926±4Ma; 14306,150: 3926±6Ma; 14314,13: 3929±4Ma). By combining these data with the ages previously obtained for zircons in Apollo 12 impact melt breccia fragments and the lunar meteorite SaU 169, a weighted average age of 3926±2Ma (95% conf.) is obtained, which is attributed to the formation of the Imbrium basin. An age of 3943±5Ma is determined for the fourth breccia (14321,134), which is similar to ages of 3946±15Ma and 3958±19Ma, obtained from several older phosphates in 14305,103 and 14314,13. The weighted average of these three older ages is 3944±4Ma (95% conf.). This is indistinguishable to the age (3938±4Ma; 2s) obtained for a different Apollo 14 impact melt breccia in a previous study. After investigating likely sources for this older ~3940Ma age, we conclude that the Humorum or Serenitatis basin forming events are likely candidates. The potential identification of two large impact events within ~15Myrs has important implications for the rate of lunar bombardment around 3.95-3.92Ga. This study demonstrates the importance of high-precision age determinations for interpreting the impact record of the Moon, as documented in lunar samples. |
| first_indexed | 2025-11-14T07:17:39Z |
| format | Journal Article |
| id | curtin-20.500.11937-16630 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:17:39Z |
| publishDate | 2016 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-166302018-03-29T09:07:22Z Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses Snape, J. Nemchin, Alexander Grange, Marion Bellucci, J. Thiessen, F. Whitehouse, M. © 2015 Elsevier Ltd. The U-Pb systems of apatite and merrillite grains within four separate Apollo 14 impact melt breccia samples were analysed by secondary ion mass spectrometry. No systematic difference was identified between the 207Pb/206Pb ages of the apatites and merrillites. A combined 207Pb/206Pb age of 3927±2Ma (95% conf.) is determined for three of these samples (14305,103: 3926±4Ma; 14306,150: 3926±6Ma; 14314,13: 3929±4Ma). By combining these data with the ages previously obtained for zircons in Apollo 12 impact melt breccia fragments and the lunar meteorite SaU 169, a weighted average age of 3926±2Ma (95% conf.) is obtained, which is attributed to the formation of the Imbrium basin. An age of 3943±5Ma is determined for the fourth breccia (14321,134), which is similar to ages of 3946±15Ma and 3958±19Ma, obtained from several older phosphates in 14305,103 and 14314,13. The weighted average of these three older ages is 3944±4Ma (95% conf.). This is indistinguishable to the age (3938±4Ma; 2s) obtained for a different Apollo 14 impact melt breccia in a previous study. After investigating likely sources for this older ~3940Ma age, we conclude that the Humorum or Serenitatis basin forming events are likely candidates. The potential identification of two large impact events within ~15Myrs has important implications for the rate of lunar bombardment around 3.95-3.92Ga. This study demonstrates the importance of high-precision age determinations for interpreting the impact record of the Moon, as documented in lunar samples. 2016 Journal Article http://hdl.handle.net/20.500.11937/16630 10.1016/j.gca.2015.11.005 restricted |
| spellingShingle | Snape, J. Nemchin, Alexander Grange, Marion Bellucci, J. Thiessen, F. Whitehouse, M. Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title | Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title_full | Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title_fullStr | Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title_full_unstemmed | Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title_short | Phosphate ages in Apollo 14 breccias: Resolving multiple impact events with high precision U-Pb SIMS analyses |
| title_sort | phosphate ages in apollo 14 breccias: resolving multiple impact events with high precision u-pb sims analyses |
| url | http://hdl.handle.net/20.500.11937/16630 |