The composition and abundance of the volcanic gases has strongly influenced the habitability of our planet over time. The Earth's mantle represents the largest reservoir of elements like carbon, hydrogen, boron, nitrogen and sulfur, but their residence time in depth and their release to the atmosphere strongly depend on pressure (P), temperature (T) and oxygen fugacity (fo2) at which they are transferred from host minerals to magmas affecting, in turn, their viscosity, density and eruptive styles at the surface. Only once magmas rise up to the surface, volatile elements become less soluble and start to degas to the atmosphere or transferred to shallow waters, e.g. oceans and groundwaters. To be able to model the cycle of volatile elements from the mantle to the atmosphere, we need to know the ascent rate of magmas as function of their composition, pressure and temperature; this links with the rheological properties of magmas, i.e. viscosity and melt structure. In addition, elements like C, H2O and B are all soluble into terrestrial magmas and might affect the physical properties of melts. However, as these elements are incorporated in minerals (C in diamonds, graphite and carbonates; H2O and B in tourmaline, H2O in amphiboles but also nominally anhydrous minerals), it is necessary to understand what mechanism controls their partition to melts (e.g. redox reactions, decomposition, dissolution).
Therefore, the aim of this project is,
1) To investigate the pressure, temperature and oxygen fugacity at which C, H and B are transferred from typical host minerals of the Earth' s interior to coexisting magmas;
2) to determine the physical properties (viscosity and melt structure) of C-, H2O- and B-rich liquids representative of terrestrial magmas and (metasomatic) fluids at pressures and temperatures of the Earth' s upper mantle;
3) to measure the dissolution rate of minerals and melts when in contact with water with particular focus for the partition of C and B.
