Ralph Dohmen, Institut fur Geologie, Mineralogie und Geophysik, Ruhr-Universitat Bochum, Alemanya

Divendres, 23 de març de 2007, Sala de conferències de l'Institut Jaume Almera (CSIC), a les 12h.

Element or isotopic exchange between minerals in a rock often has to be mediated by transport through a rock matrix. The bulk exchange is a process, which in principle depends on many subprocesses such as volume diffusion, interface reactions (solution/precipitation) as well as grain boundary transport. A thermodynamic-kinetic model has been developed, which explicitly considers all of these subprocesses. From the modeling a reaction mechanism map can be constructed, where the reaction behavior of such reaction systems is subdivided into six different kinetic regimes. In this presentation the application of the model will be shown for three different situations: (1) Modeling of the Fe-Mg exchange between garnet and biotite in a metamorphic rock (2) Design of nano-scale experiments two extract transport properties of a fine grained polycrystalline matrix (3) Experimental study of an exchange reaction mediated by a gas phase and its direct application for processes in the ea