Diffusion, Atomic Ordering, and Mass Transport

One of the fundamental objectives of physical geochemistry is to understand the evolution of geochemical systems from microscopic to regional and global scales. At present there seems to be a general recognition of the fact that internal properties of minerals record important aspects of the evolutionary history of their host rocks which may be unraveled by very fine scale observations. A major focus in the development of geochemical research in the last thirty years has been the application of classical thermodynamics to reconstruct the conditions at which the states of quenched mineralogical properties of rocks have equilibrated during the course of their evolution. While these works have funda mentally influenced our understanding ofthe physico-chemical history ofrocks, in recent years petrologists, mineralogists, and geochemists have been making greater efforts towards the application of kinetic theories in order to develop a better appreciation of the temporal details of geochemical processes. The present volume brings together a variety of current research on transport in systems of geochemical interest from atomic to outcrop scales. A major theme is atomic migration or diffusion, and its various manifestations on microscopic and macroscopic scales. Transport in the solid state is controlled by diffusion and is responsible for the states of atomic ordering and relaxation of composi tional zoning in minerals, development of compositional zoning during cooling, exsolution lamellae, and creep.

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Transport phenomena in liquids and solids of geological significance are examined and their relationship to particular atomic structures is analyzed. Understanding of such processes as they occur today, e.g. in minerals, allows extrapolation to historic geological processes and design of new materials with defined properties. Diffusion, Atomic Ordering, and Mass Transport is especially appropriate for geophysicists, materials scientists and related researchers.

Contenu

1. Molecular Dynamics and Diffusion in Silicate Melts.- 2. Ising Models and Geological Applications.- 3. Electrostatic Properties of Minerals from X-Ray Diffraction Data: A Guide for Accurate Atomistic Models.- 4. Compositional Zoning and Cation Diffusion in Garnets.- 5. Ionic Diffusion in Olivine.- 6. Nuclear Microanalysis: A Powerful Tool for Measuring Low Atomic Diffusivity with Mineralogical Applications.- 7. Pressurer Enhanced Al/Si Diffusion and Oxygen Isotope Exchange.- 8. Some Experimental Constraints on the Role of Hydrogen in Oxygen and Hydrogen Diffusion and Al-Si Interdiffusion in Silicates.- 9. Strain Enhanced Diffusion in Feldspars.- 10. Mechanisms and Kinetics of Exsolution-Structural Control of Diffusion and Phase Behavior in Alkali Feldspars.- 11. Grain-Boundary Diffusion Kinetics in Silicate and Oxide Minerals.- 12. Thermal Diffusion in Petrology.- 13. The Quasi-Stationary State Approximation to Fluid/Rock Reaction: Local Equilibrium Revisited.