Metallic lead nanospheres discovered in ancient zircons
Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U–Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
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National Academy of Sciences
2015
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| Online Access: | http://hdl.handle.net/20.500.11937/36139 |
| _version_ | 1848754686621908992 |
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| author | Kusiak, M. Dunkley, Daniel Wirth, R. Whitehouse, M. Wilde, Simon Marquardt, K. |
| author_facet | Kusiak, M. Dunkley, Daniel Wirth, R. Whitehouse, M. Wilde, Simon Marquardt, K. |
| author_sort | Kusiak, M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U–Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where ion imaging has revealed submicrometer domains that are sufficiently heterogeneously distributed to severely perturb ages, in some cases yielding apparent Hadean (>4 Ga) ages from younger zircons. Documenting the composition and mineralogy of these Pb-enriched domains is essential for understanding the processes of Pb redistribution in zircon and its effects on geochronology. Using high-resolution scanning transmission electron microscopy, we show that Pb-rich domains previously identified in zircons from East Antarctic granulites are 5–30 nm nanospheres of metallic Pb. They are randomly distributed with respect to zircon crystallinity, and their association with a Ti- and Al-rich silica melt suggests that they represent melt inclusions generated during ultra-high temperature metamorphism. Metallic Pb is exceedingly rare in nature and previously has not been reported in association with high-grade metamorphism. Formation of these metallic nanospheres within annealed zircon effectively halts the loss of radiogenic Pb from zircon. Both the redistribution and phase separation of radiogenic Pb in this manner can compromise the precision and accuracy of U–Pb ages obtained by high spatial resolution methods. |
| first_indexed | 2025-11-14T08:44:21Z |
| format | Journal Article |
| id | curtin-20.500.11937-36139 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:44:21Z |
| publishDate | 2015 |
| publisher | National Academy of Sciences |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-361392017-09-13T15:18:39Z Metallic lead nanospheres discovered in ancient zircons Kusiak, M. Dunkley, Daniel Wirth, R. Whitehouse, M. Wilde, Simon Marquardt, K. Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U–Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced ultra-high temperature metamorphism, where ion imaging has revealed submicrometer domains that are sufficiently heterogeneously distributed to severely perturb ages, in some cases yielding apparent Hadean (>4 Ga) ages from younger zircons. Documenting the composition and mineralogy of these Pb-enriched domains is essential for understanding the processes of Pb redistribution in zircon and its effects on geochronology. Using high-resolution scanning transmission electron microscopy, we show that Pb-rich domains previously identified in zircons from East Antarctic granulites are 5–30 nm nanospheres of metallic Pb. They are randomly distributed with respect to zircon crystallinity, and their association with a Ti- and Al-rich silica melt suggests that they represent melt inclusions generated during ultra-high temperature metamorphism. Metallic Pb is exceedingly rare in nature and previously has not been reported in association with high-grade metamorphism. Formation of these metallic nanospheres within annealed zircon effectively halts the loss of radiogenic Pb from zircon. Both the redistribution and phase separation of radiogenic Pb in this manner can compromise the precision and accuracy of U–Pb ages obtained by high spatial resolution methods. 2015 Journal Article http://hdl.handle.net/20.500.11937/36139 10.1073/pnas.1415264112 National Academy of Sciences unknown |
| spellingShingle | Kusiak, M. Dunkley, Daniel Wirth, R. Whitehouse, M. Wilde, Simon Marquardt, K. Metallic lead nanospheres discovered in ancient zircons |
| title | Metallic lead nanospheres discovered in ancient zircons |
| title_full | Metallic lead nanospheres discovered in ancient zircons |
| title_fullStr | Metallic lead nanospheres discovered in ancient zircons |
| title_full_unstemmed | Metallic lead nanospheres discovered in ancient zircons |
| title_short | Metallic lead nanospheres discovered in ancient zircons |
| title_sort | metallic lead nanospheres discovered in ancient zircons |
| url | http://hdl.handle.net/20.500.11937/36139 |