Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia
Accessory mineral thermometry and thermodynamic modelling are fundamental tools for constraining petrogenetic models of granite magmatism. U–Pb geochronology on zircon and monazite from S-type granites emplaced within a semi-continuous, whole-crust section in the Georgetown Inlier (GTI), NE Australi...
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| Format: | Journal Article |
| Language: | English |
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SPRINGER
2020
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| Online Access: | http://purl.org/au-research/grants/arc/FL150100133 http://hdl.handle.net/20.500.11937/90591 |
| _version_ | 1848765396619886592 |
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| author | Volante, Silvia Collins, Bill Blereau, E. Pourteau, Amaury Spencer, Christopher Evans, Noreen Barrote, Vitor Nordsvan, A.R. Li, Zheng-Xiang Li, J. |
| author_facet | Volante, Silvia Collins, Bill Blereau, E. Pourteau, Amaury Spencer, Christopher Evans, Noreen Barrote, Vitor Nordsvan, A.R. Li, Zheng-Xiang Li, J. |
| author_sort | Volante, Silvia |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Accessory mineral thermometry and thermodynamic modelling are fundamental tools for constraining petrogenetic models of granite magmatism. U–Pb geochronology on zircon and monazite from S-type granites emplaced within a semi-continuous, whole-crust section in the Georgetown Inlier (GTI), NE Australia, indicates synchronous crystallisation at 1550 Ma. Zircon saturation temperature (Tzr) and titanium-in-zircon thermometry (T(Ti–zr)) estimate magma temperatures of ~ 795 ± 41 °C (Tzr) and ~ 845 ± 46 °C (T(Ti-zr)) in the deep crust, ~ 735 ± 30 °C (Tzr) and ~ 785 ± 30 °C (T(Ti-zr)) in the middle crust, and ~ 796 ± 45 °C (Tzr) and ~ 850 ± 40 °C (T(Ti-zr)) in the upper crust. The differing averages reflect ambient temperature conditions (Tzr) within the magma chamber, whereas the higher T(Ti-zr) values represent peak conditions of hotter melt injections. Assuming thermal equilibrium through the crust and adiabatic ascent, shallower magmas contained 4 wt% H2O, whereas deeper melts contained 7 wt% H2O. Using these H2O contents, monazite saturation temperature (Tmz) estimates agree with Tzr values. Thermodynamic modelling indicates that plagioclase, garnet and biotite were restitic phases, and that compositional variation in the GTI suites resulted from entrainment of these minerals in silicic (74–76 wt% SiO2) melts. At inferred emplacement P–T conditions of 5 kbar and 730 °C, additional H2O is required to produce sufficient melt with compositions similar to the GTI granites. Drier and hotter magmas required additional heat to raise adiabatically to upper-crustal levels. S-type granites are low-T mushes of melt and residual phases that stall and equilibrate in the middle crust, suggesting that discussions on the unreliability of zircon-based thermometers should be modulated. |
| first_indexed | 2025-11-14T11:34:35Z |
| format | Journal Article |
| id | curtin-20.500.11937-90591 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:34:35Z |
| publishDate | 2020 |
| publisher | SPRINGER |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-905912023-03-24T04:27:04Z Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia Volante, Silvia Collins, Bill Blereau, E. Pourteau, Amaury Spencer, Christopher Evans, Noreen Barrote, Vitor Nordsvan, A.R. Li, Zheng-Xiang Li, J. Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon and monazite thermometry Water content Granitic melts Complete crustal section Phase equilibria diagrams LACHLAN FOLD BELT S-TYPE GRANITES TI-IN-ZIRCON U-PB PHASE-EQUILIBRIA WATER CONTENTS TEMPERATURE SATURATION BEARING INLIER Accessory mineral thermometry and thermodynamic modelling are fundamental tools for constraining petrogenetic models of granite magmatism. U–Pb geochronology on zircon and monazite from S-type granites emplaced within a semi-continuous, whole-crust section in the Georgetown Inlier (GTI), NE Australia, indicates synchronous crystallisation at 1550 Ma. Zircon saturation temperature (Tzr) and titanium-in-zircon thermometry (T(Ti–zr)) estimate magma temperatures of ~ 795 ± 41 °C (Tzr) and ~ 845 ± 46 °C (T(Ti-zr)) in the deep crust, ~ 735 ± 30 °C (Tzr) and ~ 785 ± 30 °C (T(Ti-zr)) in the middle crust, and ~ 796 ± 45 °C (Tzr) and ~ 850 ± 40 °C (T(Ti-zr)) in the upper crust. The differing averages reflect ambient temperature conditions (Tzr) within the magma chamber, whereas the higher T(Ti-zr) values represent peak conditions of hotter melt injections. Assuming thermal equilibrium through the crust and adiabatic ascent, shallower magmas contained 4 wt% H2O, whereas deeper melts contained 7 wt% H2O. Using these H2O contents, monazite saturation temperature (Tmz) estimates agree with Tzr values. Thermodynamic modelling indicates that plagioclase, garnet and biotite were restitic phases, and that compositional variation in the GTI suites resulted from entrainment of these minerals in silicic (74–76 wt% SiO2) melts. At inferred emplacement P–T conditions of 5 kbar and 730 °C, additional H2O is required to produce sufficient melt with compositions similar to the GTI granites. Drier and hotter magmas required additional heat to raise adiabatically to upper-crustal levels. S-type granites are low-T mushes of melt and residual phases that stall and equilibrate in the middle crust, suggesting that discussions on the unreliability of zircon-based thermometers should be modulated. 2020 Journal Article http://hdl.handle.net/20.500.11937/90591 10.1007/s00410-020-01752-7 English http://purl.org/au-research/grants/arc/FL150100133 http://creativecommons.org/licenses/by/4.0/ SPRINGER fulltext |
| spellingShingle | Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon and monazite thermometry Water content Granitic melts Complete crustal section Phase equilibria diagrams LACHLAN FOLD BELT S-TYPE GRANITES TI-IN-ZIRCON U-PB PHASE-EQUILIBRIA WATER CONTENTS TEMPERATURE SATURATION BEARING INLIER Volante, Silvia Collins, Bill Blereau, E. Pourteau, Amaury Spencer, Christopher Evans, Noreen Barrote, Vitor Nordsvan, A.R. Li, Zheng-Xiang Li, J. Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title | Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title_full | Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title_fullStr | Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title_full_unstemmed | Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title_short | Reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the Georgetown igneous complex, NE Australia |
| title_sort | reassessing zircon-monazite thermometry with thermodynamic modelling: insights from the georgetown igneous complex, ne australia |
| topic | Science & Technology Physical Sciences Geochemistry & Geophysics Mineralogy Zircon and monazite thermometry Water content Granitic melts Complete crustal section Phase equilibria diagrams LACHLAN FOLD BELT S-TYPE GRANITES TI-IN-ZIRCON U-PB PHASE-EQUILIBRIA WATER CONTENTS TEMPERATURE SATURATION BEARING INLIER |
| url | http://purl.org/au-research/grants/arc/FL150100133 http://hdl.handle.net/20.500.11937/90591 |