Per Fidel Costa, Departament de Riscos Naturals, Institut de Ciències de la Terra "Jaume Almera", CSIC, Barcelona

Dimecres, 14 de març, sala de conferències de l'Institut J. Almera (CSIC), a les 12h

Comentaris:
Water has a strong influence on the physical and chemical properties of eart materials and processes. The meling point of rocks, the productivity of the mantle, or the transport rates of melts that fuel volcanoes are all influenced by water or protons. New experiments will be presented which show that small concentrations of water (i.e. several ppm) enhances the Si and O diffusion rates in olivine by more than an order of magnitude at upper mantle pressures. Such an increase in diffusion rates corresponds well with thee higher strain rates of olivine under water-bearing conditions (i.e the 'hydrolytic-weakening' effect). It will be discussed how such enhancement in the Si and O diffusion rates is related to the crystal structure. The findings that small amounts of H olivine through point and line defects in the crystal structure.