Description
- Abstract:
- Geological materials in nature and in the lab are often subjected to intense driving forces created by large gradients in thermodynamic potentials. Under such conditions, analysis using equilibrium thermodynamics is not sufficient to explain the processes creating the intermediate and final reaction products. In this dissertation, I have used experimental and modeling techniques to explore the role of non-equilibrium thermodynamics in determining the textures, compositions and physical properties of glasses, rocks, and minerals. One study examines the magnetic response of submarine basaltic glass (SBG) during open-system dynamic oxidation. I demonstrate that the oxidation dynamics involves the outward motion of network-modifying cations, but below the glass transition temperature this reaction has no effect on the magnetic signature of the glass; the result speaks to the robustness of SBG to capture and retain (e.g., against alteration) thermal magnetic remanence. Further, quenched basaltic glass exhibits very fine scale metastable amorphous immiscibility that is the potential source for the nucleation of ferrites with a wide range of Ti contents. In a second study, I present new trace element data from olivine-hosted melt inclusions from Santiago and Fernandina Islands, Galápagos Archipelago, and use these data in a numerical model to explore possible origins of the “ghost plagioclase” signature recognized in some of the basaltic samples. By invoking variable extents of plagioclase dissolution and reprecipitation, as well as kinetic exchange between crystals and melt, I am able to recreate the trace element variation with minimal change to the major elements, as observed in the Fernandina melt inclusions. In the final study, I examine the formation of planar extended defects in olivine through the use of high-resolution transmission electron microscopy and energy-filtered imaging of experimental olivine-melt reaction samples. Defect nucleation and growth is driven by the large TiO2 chemical potential gradient across the olivine-glass phase boundary at the start of the experiments, which provides access to microstructures and thus diffusion kinetics not otherwise present (i.e., in those lacking the extreme driving force).
- Notes:
- Thesis (Ph.D. -- Brown University (2012)
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Citation
Burgess, Katherine D.,
"Diffusion, Dissolution and Defects: The Application of Non-Equilibrium Thermodynamics to Geological Materials"
(2012).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0Z60MC6
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....