Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages
Secondary ion mass spectrometry (SIMS) U-Pb ages of Ca-phosphates from four texturally distinct breccia samples (72255, 76055, 76015, 76215) collected at the Apollo 17 landing site were obtained in an attempt to identify whether they represent a single or several impact event(s). The determined ages...
| Main Authors: | , , , , |
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| Format: | Journal Article |
| Published: |
John Wiley & Sons, Inc.
2017
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| Online Access: | http://hdl.handle.net/20.500.11937/53976 |
| _version_ | 1848759272769323008 |
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| author | Thiessen, F. Nemchin, Alexander Snape, J. Whitehouse, M. Bellucci, J. |
| author_facet | Thiessen, F. Nemchin, Alexander Snape, J. Whitehouse, M. Bellucci, J. |
| author_sort | Thiessen, F. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Secondary ion mass spectrometry (SIMS) U-Pb ages of Ca-phosphates from four texturally distinct breccia samples (72255, 76055, 76015, 76215) collected at the Apollo 17 landing site were obtained in an attempt to identify whether they represent a single or several impact event(s). The determined ages, combined with inferences from petrologic relationships, may indicate two or possibly three different impact events at 3920 ± 3 Ma, 3922 ± 5 Ma, and 3930 ± 5 Ma (all errors 2s). Searching for possible sources of the breccias by calculating the continuous ejecta radii of impact basins and large craters as well as their expected ejecta thicknesses, we conclude that Nectaris, Crisium, Serenitatis, and Imbrium are likely candidates. If the previous interpretation that the micropoikilitic breccias collected at the North Massif represent Serenitatis ejecta is correct, then the average 207Pb/206Pb age of 3930 ± 5 Ma (2s) dates the formation of the Serenitatis basin. The occurrence of zircon in the breccias sampled at the South Massif, which contain Ca-phosphates yielding an age of 3922 ± 5 Ma (2s), may indicate that the breccia originated from within the Procellarum KREEP terrane (PKT) and the Imbrium basin appears to be the only basin that could have sourced them. However, this interpretation implies that all basins suggested to fall stratigraphically between Serenitatis and Imbrium formed within a short (<11 Ma) time interval, highlighting serious contradictions between global stratigraphic constraints, sample interpretation, and chronological data. Alternatively, the slightly older age of the two micropoikilitic breccias may be a result of incomplete resetting of the U-Pb system preserved in some phosphate grains. Based on the currently available data set this possibility cannot be excluded. |
| first_indexed | 2025-11-14T09:57:15Z |
| format | Journal Article |
| id | curtin-20.500.11937-53976 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:57:15Z |
| publishDate | 2017 |
| publisher | John Wiley & Sons, Inc. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-539762017-10-17T00:37:51Z Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages Thiessen, F. Nemchin, Alexander Snape, J. Whitehouse, M. Bellucci, J. Secondary ion mass spectrometry (SIMS) U-Pb ages of Ca-phosphates from four texturally distinct breccia samples (72255, 76055, 76015, 76215) collected at the Apollo 17 landing site were obtained in an attempt to identify whether they represent a single or several impact event(s). The determined ages, combined with inferences from petrologic relationships, may indicate two or possibly three different impact events at 3920 ± 3 Ma, 3922 ± 5 Ma, and 3930 ± 5 Ma (all errors 2s). Searching for possible sources of the breccias by calculating the continuous ejecta radii of impact basins and large craters as well as their expected ejecta thicknesses, we conclude that Nectaris, Crisium, Serenitatis, and Imbrium are likely candidates. If the previous interpretation that the micropoikilitic breccias collected at the North Massif represent Serenitatis ejecta is correct, then the average 207Pb/206Pb age of 3930 ± 5 Ma (2s) dates the formation of the Serenitatis basin. The occurrence of zircon in the breccias sampled at the South Massif, which contain Ca-phosphates yielding an age of 3922 ± 5 Ma (2s), may indicate that the breccia originated from within the Procellarum KREEP terrane (PKT) and the Imbrium basin appears to be the only basin that could have sourced them. However, this interpretation implies that all basins suggested to fall stratigraphically between Serenitatis and Imbrium formed within a short (<11 Ma) time interval, highlighting serious contradictions between global stratigraphic constraints, sample interpretation, and chronological data. Alternatively, the slightly older age of the two micropoikilitic breccias may be a result of incomplete resetting of the U-Pb system preserved in some phosphate grains. Based on the currently available data set this possibility cannot be excluded. 2017 Journal Article http://hdl.handle.net/20.500.11937/53976 10.1111/maps.12814 John Wiley & Sons, Inc. restricted |
| spellingShingle | Thiessen, F. Nemchin, Alexander Snape, J. Whitehouse, M. Bellucci, J. Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title | Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title_full | Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title_fullStr | Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title_full_unstemmed | Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title_short | Impact history of the Apollo 17 landing site revealed by U-Pb SIMS ages |
| title_sort | impact history of the apollo 17 landing site revealed by u-pb sims ages |
| url | http://hdl.handle.net/20.500.11937/53976 |