A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization
Hadean (≥4.0 Ga) zircon grains provide the only direct record of the first half-billion years of Earth’s history. Determining accurate and precise crystallization ages of these ancient zircons is a prerequisite for any interpretation of crustal evolution, surface environment, and geodynamics on the...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
| Published: |
Geological Society of America
2018
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| Online Access: | http://hdl.handle.net/20.500.11937/67678 |
| _version_ | 1848761629044375552 |
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| author | Ge, Rongfeng Wilde, Simon Nemchin, Alexander Whitehouse, M. Bellucci, J. Erickson, Timmons Frew, A. Thern, E. |
| author_facet | Ge, Rongfeng Wilde, Simon Nemchin, Alexander Whitehouse, M. Bellucci, J. Erickson, Timmons Frew, A. Thern, E. |
| author_sort | Ge, Rongfeng |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Hadean (≥4.0 Ga) zircon grains provide the only direct record of the first half-billion years of Earth’s history. Determining accurate and precise crystallization ages of these ancient zircons is a prerequisite for any interpretation of crustal evolution, surface environment, and geodynamics on the early Earth, but this may be compromised by mobilization of radiogenic Pb due to subsequent thermal overprinting. Here we report a detrital zircon from the Jack Hills (Western Australia) with 4486–4425 Ma concordant ion microprobe ages that yield a concordia age of 4463 ± 17 Ma (2σ), the oldest zircon age recorded from Earth. However, scanning ion imaging reveals that this >4.4 Ga apparent age resulted from incorporation of micrometer-scale patches of unsupported radiogenic Pb with extremely high 207Pb/206Pb ratios and >4.5 Ga 207Pb/206Pb ages. Isotopic modeling demonstrates that these patches likely resulted from redistribution of radiogenic Pb in a ca. 4.3 Ga zircon during a ca. 3.8 Ga or older event. This highlights that even a concordia age can be spurious and should be carefully evaluated before being interpreted as the crystallization age of ancient zircon. |
| first_indexed | 2025-11-14T10:34:42Z |
| format | Journal Article |
| id | curtin-20.500.11937-67678 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:34:42Z |
| publishDate | 2018 |
| publisher | Geological Society of America |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-676782018-09-19T01:33:58Z A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization Ge, Rongfeng Wilde, Simon Nemchin, Alexander Whitehouse, M. Bellucci, J. Erickson, Timmons Frew, A. Thern, E. Hadean (≥4.0 Ga) zircon grains provide the only direct record of the first half-billion years of Earth’s history. Determining accurate and precise crystallization ages of these ancient zircons is a prerequisite for any interpretation of crustal evolution, surface environment, and geodynamics on the early Earth, but this may be compromised by mobilization of radiogenic Pb due to subsequent thermal overprinting. Here we report a detrital zircon from the Jack Hills (Western Australia) with 4486–4425 Ma concordant ion microprobe ages that yield a concordia age of 4463 ± 17 Ma (2σ), the oldest zircon age recorded from Earth. However, scanning ion imaging reveals that this >4.4 Ga apparent age resulted from incorporation of micrometer-scale patches of unsupported radiogenic Pb with extremely high 207Pb/206Pb ratios and >4.5 Ga 207Pb/206Pb ages. Isotopic modeling demonstrates that these patches likely resulted from redistribution of radiogenic Pb in a ca. 4.3 Ga zircon during a ca. 3.8 Ga or older event. This highlights that even a concordia age can be spurious and should be carefully evaluated before being interpreted as the crystallization age of ancient zircon. 2018 Journal Article http://hdl.handle.net/20.500.11937/67678 10.1130/G39894.1 Geological Society of America restricted |
| spellingShingle | Ge, Rongfeng Wilde, Simon Nemchin, Alexander Whitehouse, M. Bellucci, J. Erickson, Timmons Frew, A. Thern, E. A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title | A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title_full | A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title_fullStr | A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title_full_unstemmed | A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title_short | A 4463 Ma apparent zircon age from the Jack Hills (Western Australia) resulting from ancient Pb mobilization |
| title_sort | 4463 ma apparent zircon age from the jack hills (western australia) resulting from ancient pb mobilization |
| url | http://hdl.handle.net/20.500.11937/67678 |