The fundamental goals of my Earth science research are to gain detailed insights into dynamic differentiation processes of the Earth’s lithosphere and upper mantle that have led to the present shape of the Earth and that still have effects on our habitat. Modern experimental mineralogy provides several powerful tools for investigating composition, structure and dynamic processes of the Earth’s interior at high temperatures and pressures. My research is motivated by a desire to promote the fundamental understanding of the interaction of volatiles (H2O, CO2, SO2/H2S, Cl, noble gases) with the geosphere.
These investigations are not only of local interest, e. g. estimation of endangering potential of population living nearby active volcanoes, they are also of global importance, e. g. to understand the climatic eruption of Mount Pinatubo in 1991. Investigation of fluid-rock interaction is also important for the knowledge on physical properties of the earth’s crust and mantle, e. g. rheology, thermal and electrical conductivity and propagation of sonic waves. Furthermore, experimentally extracted physicochemical data can be applied for a more detailed knowledge on our terrestrial neighbor planets
Fluid-Melt-Rock interactions: From micrometer to global scale
Fluid-rock interactions on a micrometer scale trigger macroscopic metamorphic processes and, at sufficiently high temperatures, intense magma formation in the Earth’s crust and upper mantle. Fluid-mineral-melt interactions have significant effects on plutonic processes and control volcanic eruptions at the surface of the Earth to a great extent. However, the basic parameters that control reaction of minerals, devolatilization, melt formation, fluid dissolution and volatile degassing in dynamic systems like subduction zones or large igneous provinces, which are important parts of geochemical cycles, are still missing. Thus, it is challenging to link fluid-mineral-melt interactions on the microscale that can be studied with experimental techniques to large scale geologic processes.
For given pressure, temperature, and composition conditions, thermodynamics predict the macroscopic state of an equilibrated system. However, regardless of scale (e. g. regional or microscopic), fluid-melt-rock interactions are controlled by a number of dynamic nano- and microscale processes, including (1) solution/precipitation, (2) recrystallisation, (3) surface and grain boundary diffusion, and (4) volume diffusion. Time and geometry have to be considered to investigate the reaction kinetics of fluid-melt-rock interaction processes. Chemical (and isotopic) heterogeneities are a powerful source of information on the conditions and temporal history of fluid-melt-rock interaction, providing crucial evidence of processes and rates that impact mass transfer up to the global scale. However, to properly interpret this information, we must understand the complex interactions among the different processes, mechanisms and rates. Despite significant effort during the last decade, the understanding of the interaction among fluids, melts, and minerals on a micro-scale is still at the beginning. Experimental and theoretical mineralogic methods have the potential to solve many questions and problems of kinetics of fluid-melt-rock interactions. This field of research offers besides the geosciences links to material sciences. Furthermore, the investigation of physical properties, e. g. rheology of partially molten rocks with low proportions of volatile bearing melts at pressures and temperatures of the Earth’s crust and mantle is essential for the understanding and modelling of geodynamic processes.