Diffusion of rare earth elements in garnets and pyroxenes: Experiment, theory and applications

摘要: This thesis consists of three main chapters preceded by an introduction that dis­ cusses the importance diffusion in minerals to constrain geochemistry various magmatic processes. The first chapter deals with experimental technique and measurement tracer element data garnet clinopyroxene. Self-diffusion coefficients se­ lected REE have been measured as a function temperature (770''C-1050°) at 1 bar oxygen fugacity (/O-^) corresponding defined iron-wiistite buffer. results indicate small variations diffusivity for both gar­ net clinopyroxene activation energy which is similar major components. In second atomistic mechanism Nd investi­ gated molecular dynamics (MD) simulation. An optimization procedure based on genetic algorithm provides semi-empirical are used reproduce repulsive forces between atoms. Results from MD simulations high pressure show Schottky defect most favorable vacancy formation intrinsic region. preferred reaction incorporate neodymium dodecahedral site involves transferring iron atom octahedral af­ ter removing aluminum lattice site. A model extrinsic region prescribed fraction (10""*) also acceptable result. third considers some potential applications diffu­ sion patterns obtained