Host: Japan Association of Mineralogical Sciences
The isotope exchange between minerals and fluids is enhanced in the area swept by the migrating grain boundaries (GBs; Nakamura et al., 2005; McCaig et al., 2006). This "GB sweeping" mechanism may control the rate processes of chemical transport in the mantle metasomatism and partially molten rocks. To investigate the effect of GB migration on the compatible element exchange between rocks and fluids, we have carried out piston-cylinder experiments in the dunite-Ni system at the uppermost mantle condition. The volume swept by the GBs is at most 50%, and the maximum average concentration of NiO is 4 times as high as that calculated in a static GB diffusion model. In this paper, the experimental results will be presented with their analysis based on the 2-dimensional diffusion model.
