Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia
Dating multiple geological events in single samples using thermochronology and geochronology is relatively common, but it is only with the recent advent of triple quadrupole laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that in situ rubidium-strontium (Rb-Sr) dating has bec...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
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2020
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| Online Access: | http://purl.org/au-research/grants/arc/LE140100150 http://hdl.handle.net/20.500.11937/90952 |
| _version_ | 1848765470303322112 |
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| author | Olierook, Hugo Rankenburg, Kai Ulrich, Stanislav Kirkland, Christopher Evans, Noreen Brown, Stephen McInnes, Brent Prent, Alexander Gillespie, Jack McDonald, Bradley Darragh, Miles |
| author_facet | Olierook, Hugo Rankenburg, Kai Ulrich, Stanislav Kirkland, Christopher Evans, Noreen Brown, Stephen McInnes, Brent Prent, Alexander Gillespie, Jack McDonald, Bradley Darragh, Miles |
| author_sort | Olierook, Hugo |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Dating multiple geological events in single samples using thermochronology and geochronology is relatively common, but it is only with the recent advent of triple quadrupole laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that in situ rubidium-strontium (Rb-Sr) dating has become a more commonly applied and powerful tool to date K-rich or Rb-bearing minerals. Here, we date two generations of mineral assemblages in individual thin sections using the in situ Rb-Sr method. Two distinct mineral assemblages, both probably associated with Au mineralization, are identified in samples from the Tropicana gold mine in the Albany-Fraser Orogen, Western Australia. For Rb-Sr purposes, the key dateable minerals are two generations of biotite as well as additional phengite associated with the younger assemblage. Our results reveal that the first, coarse-grained generation of biotite grains records a minimum age of 2535±18 Ma, coeval with previous 40Ar/39Ar biotite, rhenium-osmium (Re-Os) pyrite and uranium-lead (U-Pb) rutile results. The second, fine-grained and recrystallized generation of biotite grains record an age of 1207±12 Ma across all samples. Phengite and muscovite yielded broadly similar results at ca. 1.2 Ga, but data are overdispersed for a single coeval population of phengite and show elevated age uncertainties for muscovite. We propose that the ca. 2530 Ma age recorded by various geochronometers represents cooling and exhumation and that the age of ca. 1210 Ma is related to major shearing associated with the regional deformation as part of Stage II of the Albany-Fraser Orogeny. This is the first time that an age of ca. 1210 Ma has been identified in the Tropicana Zone, which may have ramifications for constraining the timing of mineralization in the region. The in situ Rb-Sr technique is currently the only tool capable of resolving both geological events in these rocks. |
| first_indexed | 2025-11-14T11:35:46Z |
| format | Journal Article |
| id | curtin-20.500.11937-90952 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T11:35:46Z |
| publishDate | 2020 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-909522023-05-08T07:23:48Z Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia Olierook, Hugo Rankenburg, Kai Ulrich, Stanislav Kirkland, Christopher Evans, Noreen Brown, Stephen McInnes, Brent Prent, Alexander Gillespie, Jack McDonald, Bradley Darragh, Miles Dating multiple geological events in single samples using thermochronology and geochronology is relatively common, but it is only with the recent advent of triple quadrupole laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that in situ rubidium-strontium (Rb-Sr) dating has become a more commonly applied and powerful tool to date K-rich or Rb-bearing minerals. Here, we date two generations of mineral assemblages in individual thin sections using the in situ Rb-Sr method. Two distinct mineral assemblages, both probably associated with Au mineralization, are identified in samples from the Tropicana gold mine in the Albany-Fraser Orogen, Western Australia. For Rb-Sr purposes, the key dateable minerals are two generations of biotite as well as additional phengite associated with the younger assemblage. Our results reveal that the first, coarse-grained generation of biotite grains records a minimum age of 2535±18 Ma, coeval with previous 40Ar/39Ar biotite, rhenium-osmium (Re-Os) pyrite and uranium-lead (U-Pb) rutile results. The second, fine-grained and recrystallized generation of biotite grains record an age of 1207±12 Ma across all samples. Phengite and muscovite yielded broadly similar results at ca. 1.2 Ga, but data are overdispersed for a single coeval population of phengite and show elevated age uncertainties for muscovite. We propose that the ca. 2530 Ma age recorded by various geochronometers represents cooling and exhumation and that the age of ca. 1210 Ma is related to major shearing associated with the regional deformation as part of Stage II of the Albany-Fraser Orogeny. This is the first time that an age of ca. 1210 Ma has been identified in the Tropicana Zone, which may have ramifications for constraining the timing of mineralization in the region. The in situ Rb-Sr technique is currently the only tool capable of resolving both geological events in these rocks. 2020 Journal Article http://hdl.handle.net/20.500.11937/90952 10.5194/gchron-2-283-2020 http://purl.org/au-research/grants/arc/LE140100150 http://creativecommons.org/licenses/by/4.0/ fulltext |
| spellingShingle | Olierook, Hugo Rankenburg, Kai Ulrich, Stanislav Kirkland, Christopher Evans, Noreen Brown, Stephen McInnes, Brent Prent, Alexander Gillespie, Jack McDonald, Bradley Darragh, Miles Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title | Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title_full | Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title_fullStr | Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title_full_unstemmed | Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title_short | Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia |
| title_sort | resolving multiple geological events using in situ rb–sr geochronology: implications for metallogenesis at tropicana, western australia |
| url | http://purl.org/au-research/grants/arc/LE140100150 http://hdl.handle.net/20.500.11937/90952 |