1,2,2,3- 1NAWI Graz Geocenter, Department of Earth Sciences, University of Graz, Graz, Austria
- 2Geoscience Center, Department of Mineralogy & Petrology, University of Göttingen, Germany
- 3Department of Chemical and Geological Sciences, University of Cagliari, Monserrato, Italy
Melt inclusions in minerals provide key insight into mineralisation and petrogenesis in the lithosphere. For decades research commonly focused on glassy inclusions hosted in igneous minerals, helping to characterise a variety of magmatic processes. More recently, inclusions of anatectic melt in high grade metamorphic rocks increasingly gained more interest, providing a direct snapshot of crustal melting processes. In most cases they occur as polyphase crystalline inclusions in metamorphic minerals, consisting of quartz (or quartz polymorphs), mica and feldspar polymorphs, referred to as nanogranitoid. Nanogranitoids must be re-melted to a homogenous glass by recreating their original confinement conditions with subsequent quenching for a complete geochemical analysis.
In this project we analyse nanogranitoid-inclusion (NI) hosted in monazite and garnet from granulite facies gneisses with differing P-T-t paths of the southern Moldanubian Bohemian Massif. Distinct zonation in monazite and garnet were used to reveal this multiple complex metamorphic evolution from ca. 370 Ma to 312 Ma (Sorger et al. 2020). NI within these distinct mineral generations enable us to correlate metamorphic conditions during anatexis. For successful re-homogenisation of NI while ensuring individual grain recovery, we apply a modified established experimental routine with a piston cylinder apparatus (Bartoli et al. 2013). NI identification, textural and geochemical analysis are carried out by Raman and infrared spectroscopy, electron microscopy and laser ablation inductively coupled plasma mass spectrometry. Monazite as an important reservoir for LREE, Th, U and Y, paired with nanogranitoids provides an ideal toolset for studying partitioning mechanisms under variable conditions in natural systems. Geochemical analysis of the hosted melt inclusions could help us to further enhance our understanding of the dynamics and timing of crustal melting during orogeny, the fluids involved and the conditions of melt-host stability.
References
Bartoli et al. (2013). Geofluids 13 (4), 405-420
Sorger et al. (2020). Gondwana Research 85, S. 124–148
How to cite: Günzler, D., Sorger, D., Müller, T., Willbold, M., and Ferrero, S.: In-situ analysis of nanogranitoids in monazite opens up new paths for understanding crustal melting, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9568, https://doi.org/10.5194/egusphere-egu26-9568, 2026.
