- 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 \((T_{zr})\) and titanium-in-zircon thermometry \((T_{(Ti–zr)})\) estimate magma temperatures of ~ 795 \(\pm\) 41 °C \((T_{zr})\) and ~ 845 \(\pm\) 46 °C \((T_{(Ti-zr)})\) in the deep crust, ~ 735 \(\pm\) 30 °C \((T_{zr})\) and ~ 785 \(\pm\) 30 °C \((T_{(Ti-zr)})\) in the middle crust, and ~ 796 \(\pm\) 45 °C \((T_{zr})\) and ~ 850 \(\pm\) 40 °C \((T_{(Ti–zr)})\) in the upper crust. The differing averages reflect ambient temperature conditions \((T_{zr})\) 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% \(H_{2}O\), whereas deeper melts contained 7 wt% \(H_{2}O\). Using these \(H_{2}O\) contents, monazite saturation temperature \((T_{mz})\) estimates agree with \(T_{zr}\) 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% \(SiO_{2}\)) melts. At inferred emplacement \(\textit {P–T}\) conditions of 5 kbar and 730 °C, additional \(H_{2}O\) 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-\(\it T\) 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.
MetadatenAuthor: | Silvia VolanteORCiDGND, William Joseph CollinsGND, Eleanore BlereauGND, Amaury PourteauGND, Christopher SpencerORCiDGND, Noreen EvansGND, Vito BarroteGND, A.R. Nordsvan, Zheng-Xiang LiGND, Jun LiGND |
---|
URN: | urn:nbn:de:hbz:294-95586 |
---|
DOI: | https://doi.org/10.1007/s00410-020-01752-7 |
---|
Parent Title (English): | Contributions to mineralogy and petrology |
---|
Subtitle (English): | insights from the Georgetown igneous complex, NE Australia |
---|
Publisher: | Springer |
---|
Place of publication: | Berlin |
---|
Document Type: | Article |
---|
Language: | English |
---|
Date of Publication (online): | 2023/01/04 |
---|
Date of first Publication: | 2020/11/05 |
---|
Publishing Institution: | Ruhr-Universität Bochum, Universitätsbibliothek |
---|
Tag: | Complete crustal section; Granitic melts; Phase equilibria diagrams; Water content; Zircon and monazite thermometry |
---|
Volume: | 175 |
---|
Issue: | Article 110 |
---|
First Page: | 110-1 |
---|
Last Page: | 110-22 |
---|
Note: | Dieser Beitrag ist auf Grund des DEAL-Springer-Vertrages frei zugänglich. |
---|
Institutes/Facilities: | Institut für Geologie, Mineralogie und Geophysik |
---|
Dewey Decimal Classification: | Naturwissenschaften und Mathematik / Geowissenschaften, Geologie |
---|
open_access (DINI-Set): | open_access |
---|
faculties: | Fakultät für Geowissenschaften |
---|
Licence (English): | Creative Commons - CC BY 4.0 - Attribution 4.0 International |
---|