Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination
The recognition of lithospheric delamination as a mechanism for magmatism and uplift is under-recognized in the geological record. A pertinent example is the terminal phase of the New England Orogen in eastern Australia, where current explanations of slab roll-back-driven extension are incompatible...
| Main Authors: | , , , , , , , , , , , , , |
|---|---|
| Format: | Journal Article |
| Language: | English |
| Published: |
ELSEVIER
2022
|
| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/LE130100053 http://hdl.handle.net/20.500.11937/91507 |
| _version_ | 1848765533139238912 |
|---|---|
| author | Olierook, Hugo Gale, J. Pirajno, F. Jourdan, Fred Kirkland, Chris Evans, Noreen McDonald, B.J. Krejci, M. Jiang, Q. Shantha Kumara, A. Mayers, C. Frew, R.A. Kaag, H. McInnes, Brent |
| author_facet | Olierook, Hugo Gale, J. Pirajno, F. Jourdan, Fred Kirkland, Chris Evans, Noreen McDonald, B.J. Krejci, M. Jiang, Q. Shantha Kumara, A. Mayers, C. Frew, R.A. Kaag, H. McInnes, Brent |
| author_sort | Olierook, Hugo |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The recognition of lithospheric delamination as a mechanism for magmatism and uplift is under-recognized in the geological record. A pertinent example is the terminal phase of the New England Orogen in eastern Australia, where current explanations of slab roll-back-driven extension are incompatible with plate motions in the Late Triassic. Although abundant mafic rocks are present, almost all Late Triassic temporal information is from felsic rocks. To investigate potential Late Triassic mafic magmatism in the New England Orogen, we date a series of tholeiitic and alkaline mafic products in its back-arc (Sydney Basin) using plagioclase 40Ar/39Ar and apatite U-Pb geochronology. We obtained a plagioclase 40Ar/39Ar plateau age of 202.77 ± 0.68 Ma (2σ) from tholeiitic magmatic products and an apatite U-Pb age of 202 ± 7 Ma (2σ) from a proximal alkaline sill some 70 m deeper, both of which overlap within uncertainty. Complementary trace element geochemistry shows that the tholeiitic and alkaline magmatic products were derived from a similar deep, garnet-bearing source, which we attribute to upwelling asthenosphere underneath a thickened lithosphere. Our data suggest that extension occurred ∼10 m.y. later in the back-arc basin than along its arc, further supporting the notion that slab roll-back could not have caused this terminal phase of Late Triassic extension in the New England Orogen. The Late Triassic magmatism in the New England Orogen is best explained by lithospheric delamination as it accounts for the orogenic architecture, chemical signature of the ca. 200 Ma products and spatio-temporal distribution of Late Triassic magmatic products. |
| first_indexed | 2025-11-14T11:36:45Z |
| format | Journal Article |
| id | curtin-20.500.11937-91507 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:36:45Z |
| publishDate | 2022 |
| publisher | ELSEVIER |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-915072024-01-24T00:13:26Z Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination Olierook, Hugo Gale, J. Pirajno, F. Jourdan, Fred Kirkland, Chris Evans, Noreen McDonald, B.J. Krejci, M. Jiang, Q. Shantha Kumara, A. Mayers, C. Frew, R.A. Kaag, H. McInnes, Brent Science & Technology Physical Sciences Geosciences, Multidisciplinary Geology 40Ar/39Ar U-Pb Sydney Basin Bowen basin Slab roll-back EASTERN AUSTRALIA SYDNEY BASIN VOLCANIC-ROCKS TASMAN SEA CONTINENTAL LITHOSPHERE PARTITION-COEFFICIENTS GEODYNAMIC EVOLUTION INTRAPLATE VOLCANISM ISOTOPE GEOCHEMISTRY THOLEIITIC BASALTS The recognition of lithospheric delamination as a mechanism for magmatism and uplift is under-recognized in the geological record. A pertinent example is the terminal phase of the New England Orogen in eastern Australia, where current explanations of slab roll-back-driven extension are incompatible with plate motions in the Late Triassic. Although abundant mafic rocks are present, almost all Late Triassic temporal information is from felsic rocks. To investigate potential Late Triassic mafic magmatism in the New England Orogen, we date a series of tholeiitic and alkaline mafic products in its back-arc (Sydney Basin) using plagioclase 40Ar/39Ar and apatite U-Pb geochronology. We obtained a plagioclase 40Ar/39Ar plateau age of 202.77 ± 0.68 Ma (2σ) from tholeiitic magmatic products and an apatite U-Pb age of 202 ± 7 Ma (2σ) from a proximal alkaline sill some 70 m deeper, both of which overlap within uncertainty. Complementary trace element geochemistry shows that the tholeiitic and alkaline magmatic products were derived from a similar deep, garnet-bearing source, which we attribute to upwelling asthenosphere underneath a thickened lithosphere. Our data suggest that extension occurred ∼10 m.y. later in the back-arc basin than along its arc, further supporting the notion that slab roll-back could not have caused this terminal phase of Late Triassic extension in the New England Orogen. The Late Triassic magmatism in the New England Orogen is best explained by lithospheric delamination as it accounts for the orogenic architecture, chemical signature of the ca. 200 Ma products and spatio-temporal distribution of Late Triassic magmatic products. 2022 Journal Article http://hdl.handle.net/20.500.11937/91507 10.1016/j.gr.2022.01.002 English http://purl.org/au-research/grants/arc/LE130100053 http://purl.org/au-research/grants/arc/LE140100150 http://purl.org/au-research/grants/arc/LE130100219 http://creativecommons.org/licenses/by-nc-nd/4.0/ ELSEVIER fulltext |
| spellingShingle | Science & Technology Physical Sciences Geosciences, Multidisciplinary Geology 40Ar/39Ar U-Pb Sydney Basin Bowen basin Slab roll-back EASTERN AUSTRALIA SYDNEY BASIN VOLCANIC-ROCKS TASMAN SEA CONTINENTAL LITHOSPHERE PARTITION-COEFFICIENTS GEODYNAMIC EVOLUTION INTRAPLATE VOLCANISM ISOTOPE GEOCHEMISTRY THOLEIITIC BASALTS Olierook, Hugo Gale, J. Pirajno, F. Jourdan, Fred Kirkland, Chris Evans, Noreen McDonald, B.J. Krejci, M. Jiang, Q. Shantha Kumara, A. Mayers, C. Frew, R.A. Kaag, H. McInnes, Brent Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title | Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title_full | Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title_fullStr | Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title_full_unstemmed | Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title_short | Terminal tectono-magmatic phase of the New England Orogen driven by lithospheric delamination |
| title_sort | terminal tectono-magmatic phase of the new england orogen driven by lithospheric delamination |
| topic | Science & Technology Physical Sciences Geosciences, Multidisciplinary Geology 40Ar/39Ar U-Pb Sydney Basin Bowen basin Slab roll-back EASTERN AUSTRALIA SYDNEY BASIN VOLCANIC-ROCKS TASMAN SEA CONTINENTAL LITHOSPHERE PARTITION-COEFFICIENTS GEODYNAMIC EVOLUTION INTRAPLATE VOLCANISM ISOTOPE GEOCHEMISTRY THOLEIITIC BASALTS |
| url | http://purl.org/au-research/grants/arc/LE130100053 http://purl.org/au-research/grants/arc/LE130100053 http://purl.org/au-research/grants/arc/LE130100053 http://hdl.handle.net/20.500.11937/91507 |