Nanoscale Isotopic Dating of Monazite
© 2020 The Authors. Geostandards and Geoanalytical Research © 2020 International Association of Geoanalysts Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation prec...
| Main Authors: | , , , , , , |
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| Format: | Journal Article |
| Published: |
2020
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| Online Access: | http://purl.org/au-research/grants/arc/DE190101307 http://hdl.handle.net/20.500.11937/80393 |
| _version_ | 1848764209516511232 |
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| author | Fougerouse, Denis Kirkland, Chris Saxey, David Seydoux-Guillaume, A.M. Rowles, Matthew Rickard, William Reddy, Steven |
| author_facet | Fougerouse, Denis Kirkland, Chris Saxey, David Seydoux-Guillaume, A.M. Rowles, Matthew Rickard, William Reddy, Steven |
| author_sort | Fougerouse, Denis |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | © 2020 The Authors. Geostandards and Geoanalytical Research
© 2020 International Association of Geoanalysts
Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation precludes the analysis of both micrometre-scale discrete monazite grains and fine textures within monazite crystals that are commonly found in geological specimens. Here, we analyse reference materials by atom probe tomography and develop a protocol for 208Pb/232Th dating of nanoscale domains of monazite (0.0007 μm3 analytical volume). The results indicate that the 208Pb2+/232ThO2+ ratios are higher than the true values. Such fractionation can be corrected using a linear regression between 208Pb2+/232ThO2+ and the M/ΔM10 peak shape parameter, where M is the position of the (Formula presented.) peak and ΔM10 the full-width-at-tenth-maximum for the same peak. This correction results in 15–20% analytical uncertainty on the corrected 208Pb/232Th age. Nonetheless, this approach opens the possibility of obtaining 208Pb/232Th ages with sufficient precision to address geological questions on an unprecedented small scale. To illustrate the approach, atom probe geochronology of a small monazite grain from the contact aureole of the Fanad pluton (Ireland) yielded a 208Pb/232Th atom probe age of 420 ± 60 Ma (2s) and is consistent with the known metamorphism in the region. |
| first_indexed | 2025-11-14T11:15:43Z |
| format | Journal Article |
| id | curtin-20.500.11937-80393 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:15:43Z |
| publishDate | 2020 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-803932021-05-28T02:44:55Z Nanoscale Isotopic Dating of Monazite Fougerouse, Denis Kirkland, Chris Saxey, David Seydoux-Guillaume, A.M. Rowles, Matthew Rickard, William Reddy, Steven © 2020 The Authors. Geostandards and Geoanalytical Research © 2020 International Association of Geoanalysts Monazite U-Th-Pb geochronology is widely used for dating geological processes, but current analytical techniques are limited to grains greater than 5 μm in diameter. This limitation precludes the analysis of both micrometre-scale discrete monazite grains and fine textures within monazite crystals that are commonly found in geological specimens. Here, we analyse reference materials by atom probe tomography and develop a protocol for 208Pb/232Th dating of nanoscale domains of monazite (0.0007 μm3 analytical volume). The results indicate that the 208Pb2+/232ThO2+ ratios are higher than the true values. Such fractionation can be corrected using a linear regression between 208Pb2+/232ThO2+ and the M/ΔM10 peak shape parameter, where M is the position of the (Formula presented.) peak and ΔM10 the full-width-at-tenth-maximum for the same peak. This correction results in 15–20% analytical uncertainty on the corrected 208Pb/232Th age. Nonetheless, this approach opens the possibility of obtaining 208Pb/232Th ages with sufficient precision to address geological questions on an unprecedented small scale. To illustrate the approach, atom probe geochronology of a small monazite grain from the contact aureole of the Fanad pluton (Ireland) yielded a 208Pb/232Th atom probe age of 420 ± 60 Ma (2s) and is consistent with the known metamorphism in the region. 2020 Journal Article http://hdl.handle.net/20.500.11937/80393 10.1111/ggr.12340 http://purl.org/au-research/grants/arc/DE190101307 fulltext |
| spellingShingle | Fougerouse, Denis Kirkland, Chris Saxey, David Seydoux-Guillaume, A.M. Rowles, Matthew Rickard, William Reddy, Steven Nanoscale Isotopic Dating of Monazite |
| title | Nanoscale Isotopic Dating of Monazite |
| title_full | Nanoscale Isotopic Dating of Monazite |
| title_fullStr | Nanoscale Isotopic Dating of Monazite |
| title_full_unstemmed | Nanoscale Isotopic Dating of Monazite |
| title_short | Nanoscale Isotopic Dating of Monazite |
| title_sort | nanoscale isotopic dating of monazite |
| url | http://purl.org/au-research/grants/arc/DE190101307 http://hdl.handle.net/20.500.11937/80393 |