The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia
Zircon and phosphate grains from matrix and quartz-monzodiorite (QMD) clasts in two thin sections of Apollo 15 impact melt breccia 15405 were investigated using optical microscopy, scanning electron microscopy, Raman spectroscopy, and ion microprobe U-Pb analyses. U-Pb results for zircon grains with...
| Main Authors: | , , |
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| Format: | Journal Article |
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Wiley-Blackwell Publishing Inc.
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/29067 |
| _version_ | 1848752704084508672 |
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| author | Grange, Marion Nemchin, Alexander Pidgeon, Robert |
| author_facet | Grange, Marion Nemchin, Alexander Pidgeon, Robert |
| author_sort | Grange, Marion |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Zircon and phosphate grains from matrix and quartz-monzodiorite (QMD) clasts in two thin sections of Apollo 15 impact melt breccia 15405 were investigated using optical microscopy, scanning electron microscopy, Raman spectroscopy, and ion microprobe U-Pb analyses. U-Pb results for zircon grains with well-defined cathodoluminescence zoning define the primary (i.e., magmatic) crystallization age as 4330 ± 6Ma (2σ). One zircon consists of a preserved inner part surrounded by a porous polycrystalline (“granular”) mixture of zircon and baddeleyite, indicating incomplete reaction of the zircon with melt. Previous work showed that this microstructure could form at pressures above 60GPa and a temperature close to ~1700°C and is evidence of an impact-related melting event. The U-Pb system of this grain indicates a resetting event at 1940 ± 10Ma, interpreted as the age of this impact (impact #1). Other zircon and phosphate grains also have disturbed U-Pb systems, showing an even younger reset event (impact #2) at 1407 ± 57 Ma. Evidence of impact is supported by microstructures of zircon and baddeleyite such as secondary rims. These impacts are tentatively identified as those having formed Autolycus and Aristillius craters. |
| first_indexed | 2025-11-14T08:12:51Z |
| format | Journal Article |
| id | curtin-20.500.11937-29067 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:12:51Z |
| publishDate | 2013 |
| publisher | Wiley-Blackwell Publishing Inc. |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-290672017-09-13T15:23:30Z The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia Grange, Marion Nemchin, Alexander Pidgeon, Robert Zircon and phosphate grains from matrix and quartz-monzodiorite (QMD) clasts in two thin sections of Apollo 15 impact melt breccia 15405 were investigated using optical microscopy, scanning electron microscopy, Raman spectroscopy, and ion microprobe U-Pb analyses. U-Pb results for zircon grains with well-defined cathodoluminescence zoning define the primary (i.e., magmatic) crystallization age as 4330 ± 6Ma (2σ). One zircon consists of a preserved inner part surrounded by a porous polycrystalline (“granular”) mixture of zircon and baddeleyite, indicating incomplete reaction of the zircon with melt. Previous work showed that this microstructure could form at pressures above 60GPa and a temperature close to ~1700°C and is evidence of an impact-related melting event. The U-Pb system of this grain indicates a resetting event at 1940 ± 10Ma, interpreted as the age of this impact (impact #1). Other zircon and phosphate grains also have disturbed U-Pb systems, showing an even younger reset event (impact #2) at 1407 ± 57 Ma. Evidence of impact is supported by microstructures of zircon and baddeleyite such as secondary rims. These impacts are tentatively identified as those having formed Autolycus and Aristillius craters. 2013 Journal Article http://hdl.handle.net/20.500.11937/29067 10.1002/jgre.20167 Wiley-Blackwell Publishing Inc. unknown |
| spellingShingle | Grange, Marion Nemchin, Alexander Pidgeon, Robert The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title | The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title_full | The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title_fullStr | The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title_full_unstemmed | The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title_short | The effect of 1.9 and 1.4 Ga impact events on 4.3 Ga zircon and phosphate from an Apollo 15 melt breccia |
| title_sort | effect of 1.9 and 1.4 ga impact events on 4.3 ga zircon and phosphate from an apollo 15 melt breccia |
| url | http://hdl.handle.net/20.500.11937/29067 |