UBC Theses and Dissertations
Diffusion in Fe-Mg olivine at elevated temperatures Misener, Donald James
In the process of deformation of a solid at low strain rates, the rate of atomic migration in the crystal lattice is a critical factor. Experiments designed to measure the diffusion coefficient of Fe in olivine were unsuccessful. It is theoretically shown that at temperatures greater than one-half of the melting temperature the diffusion coefficient of Mg in olivine silicate is an exponential function of temperature and pressure. [formula omitted] The results also indicate that at T > .5Tm and at nonhydrostatic stresses <500 bars the experimentally determined steady state creep of the upper mantle rocks dunite and peridotite may be governed by movement of dislocations. It is shown that the rate limiting parameter in the creep-equation is probably the ionic diffusion coefficient in the olivine silicate structure.
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