In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny
Antarctica contains continental fragments of Australian, Indian and African affinities, and is one of the key elements in the reconstruction of Nuna, Rodinia and Gondwana. The Bunger Hills region in East Antarctica is widely interpreted as a remnant of the Mesoproterozoic Albany–Fraser Orogen, which...
| Main Authors: | , , , , , , , , |
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| Format: | Journal Article |
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Elsevier BV
2018
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| Online Access: | http://purl.org/au-research/grants/arc/FT140100826 http://hdl.handle.net/20.500.11937/67350 |
| _version_ | 1848761543323287552 |
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| author | Stark, J. Camilla Wang, Xuan-Ce Li, Zheng-Xiang Rasmussen, Birger Sheppard, Steve Zi, Jianwei Clark, Christopher Hand, M. Li, W. |
| author_facet | Stark, J. Camilla Wang, Xuan-Ce Li, Zheng-Xiang Rasmussen, Birger Sheppard, Steve Zi, Jianwei Clark, Christopher Hand, M. Li, W. |
| author_sort | Stark, J. Camilla |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Antarctica contains continental fragments of Australian, Indian and African affinities, and is one of the key elements in the reconstruction of Nuna, Rodinia and Gondwana. The Bunger Hills region in East Antarctica is widely interpreted as a remnant of the Mesoproterozoic Albany–Fraser Orogen, which formed during collision between the West Australian and Mawson cratons and is linked with the assembly of Rodinia. Previous studies have suggested that several generations of mafic dyke suites are present at Bunger Hills but an understanding of their origin and tectonic context is limited by the lack of precise age constraints. New in situ SHRIMP U-Pb zircon and baddeleyite dates of, respectively, 1134 ± 9 Ma and 1131 ± 16 Ma confirm an earlier Rb-Sr whole-rock age estimate of ca. 1140 Ma for emplacement of a major mafic dyke suite in the area. Existing and new geochemical data suggest that the source of the dyke involved an EMORB-like source reservoir that was contaminated by a lower crust-like component. The new age constraint indicates that the dykes post-date the last known phase of plutonism at Bunger Hills by ca. 20 million years and were emplaced at the end of Stage 2 of the Albany-Fraser Orogeny. In current models, post-orogenic uplift and progressive tectonic thinning of the lithosphere were associated with melting and reworking of lower and middle crust that produced abundant plutonic rocks at Bunger Hills. A major episode of mafic dyke emplacement following uplift, cooling, and plutonic activity with increasing mantle input, suggests that the dykes mark the end of a prolonged interval of thermal weakening of the lithosphere that may have been associated with continued mafic underplating during orogenic collapse. If the undated olivine gabbro dykes with similar trend, geochemistry and petrology at Windmill Islands are coeval with the ca. 1134 Ma dyke at Bunger Hills, this would suggest the presence of a major dyke swarm at least 400 km in extent. In such case, the dykes could have been emplaced laterally from a much more distant mantle source, possibly a plume, and interacted with the locally heterogeneous and variably metasomatised lithosphere. |
| first_indexed | 2025-11-14T10:33:20Z |
| format | Journal Article |
| id | curtin-20.500.11937-67350 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:33:20Z |
| publishDate | 2018 |
| publisher | Elsevier BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-673502023-01-25T06:58:18Z In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny Stark, J. Camilla Wang, Xuan-Ce Li, Zheng-Xiang Rasmussen, Birger Sheppard, Steve Zi, Jianwei Clark, Christopher Hand, M. Li, W. Antarctica contains continental fragments of Australian, Indian and African affinities, and is one of the key elements in the reconstruction of Nuna, Rodinia and Gondwana. The Bunger Hills region in East Antarctica is widely interpreted as a remnant of the Mesoproterozoic Albany–Fraser Orogen, which formed during collision between the West Australian and Mawson cratons and is linked with the assembly of Rodinia. Previous studies have suggested that several generations of mafic dyke suites are present at Bunger Hills but an understanding of their origin and tectonic context is limited by the lack of precise age constraints. New in situ SHRIMP U-Pb zircon and baddeleyite dates of, respectively, 1134 ± 9 Ma and 1131 ± 16 Ma confirm an earlier Rb-Sr whole-rock age estimate of ca. 1140 Ma for emplacement of a major mafic dyke suite in the area. Existing and new geochemical data suggest that the source of the dyke involved an EMORB-like source reservoir that was contaminated by a lower crust-like component. The new age constraint indicates that the dykes post-date the last known phase of plutonism at Bunger Hills by ca. 20 million years and were emplaced at the end of Stage 2 of the Albany-Fraser Orogeny. In current models, post-orogenic uplift and progressive tectonic thinning of the lithosphere were associated with melting and reworking of lower and middle crust that produced abundant plutonic rocks at Bunger Hills. A major episode of mafic dyke emplacement following uplift, cooling, and plutonic activity with increasing mantle input, suggests that the dykes mark the end of a prolonged interval of thermal weakening of the lithosphere that may have been associated with continued mafic underplating during orogenic collapse. If the undated olivine gabbro dykes with similar trend, geochemistry and petrology at Windmill Islands are coeval with the ca. 1134 Ma dyke at Bunger Hills, this would suggest the presence of a major dyke swarm at least 400 km in extent. In such case, the dykes could have been emplaced laterally from a much more distant mantle source, possibly a plume, and interacted with the locally heterogeneous and variably metasomatised lithosphere. 2018 Journal Article http://hdl.handle.net/20.500.11937/67350 10.1016/j.precamres.2018.02.023 http://purl.org/au-research/grants/arc/FT140100826 http://purl.org/au-research/grants/arc/FL150100133 Elsevier BV restricted |
| spellingShingle | Stark, J. Camilla Wang, Xuan-Ce Li, Zheng-Xiang Rasmussen, Birger Sheppard, Steve Zi, Jianwei Clark, Christopher Hand, M. Li, W. In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title | In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title_full | In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title_fullStr | In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title_full_unstemmed | In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title_short | In situ U-Pb geochronology and geochemistry of a 1.13 Ga mafic dyke suite at Bunger Hills, East Antarctica: The end of the Albany-Fraser Orogeny |
| title_sort | in situ u-pb geochronology and geochemistry of a 1.13 ga mafic dyke suite at bunger hills, east antarctica: the end of the albany-fraser orogeny |
| url | http://purl.org/au-research/grants/arc/FT140100826 http://purl.org/au-research/grants/arc/FT140100826 http://hdl.handle.net/20.500.11937/67350 |