Unravelling crustal melting processes through in-situ nanogranitoid analysis in monazite

• Applicant: Dr. Dominik Sorger
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 561221372

Understanding the mobilization and transport of critical chemical elements, including rare earth elements, yttrium, thorium, and uranium is crucial for advancing our knowledge of igneous and metamorphic petrogenesis. Monazite, a phosphate mineral with the general formula REE(PO4), serves as a key carrier of these elements in metamorphic as well as felsic igneous rocks. In metamorphosed pelitic rocks, monazite stability can extend from greenschist to granulite facies. Thus, it presents an ideal opportunity to investigate the behaviour of these elements during metamorphism and crustal melting processes. Previous studies have significantly advanced our understanding of monazite behaviour in melt-bearing systems and the partitioning of elements between these phases, through experimental studies, thermodynamic modelling of monazite growth and dissolution, and investigations of natural monazite in melt-bearing rocks. In this project, we seek to further explore these processes by analysing melt inclusions in monazite and garnet from granulite-facies rocks within the Bohemian Massif. This approach enables the direct study of both the melt and host phases in their natural contact within these samples. Furthermore, this research project will explore concentrations of volatile elements (H2O & CO2) and halogens (fluorine & chlorine) in the melt to understand their impacts on the fractionation of thorium and uranium. In conjunction with a geochronological investigation of monazite these data allow a correlation between melting events and the metamorphic evolution of the rock. To achieve these objectives, advanced analytical techniques will be utilized, including electron probe microanalyzer, laser ablation-inductively coupled plasma-mass spectrometry, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The data obtained will be correlated with existing pressure-temperature information to reconstruct the complex history of melt processes in high-grade metamorphic rocks. Special attention will be given to the element fractionation behaviour of monazite, garnet, and melt under varying conditions. The insights gained from this research project are anticipated to contribute significantly to our understanding of the complex melting processes in the Earth's crust. This knowledge has not only scientific value but can also contribute to sustainable resource management, ensuring responsible extraction and utilisation of these elements to meet current and future societal needs.

• DFG Programme: Research Grants
• International Connection: Austria, Italy
• Cooperation Partner: Professor Dr. Silvio Ferrero