Petrology

Rare metals are essential ingredients to power the technological transition to a green, low-energy, low-carbon-based society. The rising global demand for these elements cannot be met by recycling alone and requires a mining inventory of existing assets and the discovery of economic ore bodies. Ore deposit formation results from the conjunction of a wide range of processes and intensive parameters and from the relative involvement of different media (melt, minerals, fluids). This complexity is reflected in natural rocks, where the reconstruction of the evolution of a single deposit can be challenging. As a support to field-based studies, experimental petrology allows to simulate natural processes at conditions relevant for natural systems. In addition, the role of a single parameter (e.g. P, T, fO2, t) or process (e.g. melting, crystallization, fluid circulation) can be quantified precisely allowing the production of important datasets (e.g. partition coefficients, solubility data, factors of enrichment) to better understand ore deposits and possibly predict their occurrences in natural settings. Ongoing research projects focus on understanding metal enrichment processes in: (i) layered intrusions (e.g. Fe, V, PGEs) and (ii) magmatic-hydrothermal deposits (e.g. Li-Sn-Nb-Ta-W).

Our working group actively contributes to the study of drill core samples obtained through the International Ocean Discovery Program (IODP) and the International Continental Scientific Drilling Program (ICDP). These internationally coordinated drilling projects provide unique access to deep-seated geological records, enabling high-resolution investigations of magmatic, metamorphic, and sedimentary processes. In collaboration with international research teams, we have explored various geological settings ranging from oceanic plateaus and massifs (e.g. Shatsky Rise and Atlantis Massif, mid-ocean ridges (e.g. Southwest Indian Ridge and East Pacific Rise), ophiolites (e.g. Oman), large igneous complexes (e.g. Bushveld), volcanic arcs (Izu-Bonin-Mariana) and continental hotspots (e.g. Yellowstone). To unravel the mineralogical and geochemical complexities of core samples from such localities, we employ cutting-edge analytical techniques, such as EPMA, FTIR or Raman spectroscopy, and combine these with experimental investigations and geochemical modelling. This approach ultimately allows us to provide a comprehensive understanding of the processes shaping Earth's lithosphere.

A detailed investigation of the processes that lead to the generation and development of magmas is essential to better understand active volcanoes. High-pressure experiments (in combination with high-resolution analysis) can provide valuable data for this purpose and enable the further development of existing petrological tools used for the reconstruction of magmatic processes (e.g. geothermobarometry, geochronometry, or thermodynamic models). In several research projects, we are experimentally investigating the systematic influences of various chemical and physical parameters (e.g. temperature, pressure, water content, and chemical composition) on phase relations and mineral stability fields for different magmatic systems (e.g. ranging from submarine mid-ocean ridges to subduction zone volcanoes). Furthermore, several ongoing research projects are dealing in detail with individual active volcanoes (e.g. located in Kamchatka, Chile, or the Eifel) in order to better understand pre-eruptive magma storage conditions and, potentially, be able to make any statements regarding their (future) eruption dynamics.

In our research, we focus on developing and improving innovative analytical and experimental methods for petrological and mineralogical investigations. Analytical techniques we are primarily working on include electron probe microanalysis (EPMA), Fourier Transform Infrared Spectroscopy (FTIR), micro-Raman spectroscopy, as well as wet chemistry colorimetric and titration methods. In one of our current projects, we are further improving the EPMA "flank method" allowing us to obtain high-resolution and high-quality data of ferric-ferrous ratios in mineral and glass samples. Moreover, we are continuously working on refurbishing our experimental facilities, for example to improve the control and monitoring of run conditions and develop new ground-breaking experimental approaches. Our experimental lab plays a crucial role for the synthesis of various glass and mineral standards for use in Raman and EPMA analysis. Additionally, we are integrating deep learning techniques in our approaches to enhance the processing of large datasets obtained with our analytical and experimental facilities.