Current Research Focus



Hueco Tanks State Historic Park, TX

I have several projects that I am currently working on, all very different, but all focusing on the kinetics and non-equilibrium thermodynamics of diffusion and/or dissolution in ultramafic and mafic materials.

One project explores the presence of small titanomagnetite grains in basalitc glass, and I did experiments with quenched and reheated glasses. An oxygen chemical potential gradient applied at various temperatures to glasses originally equilibrated at FMQ causes the diffusion toward the surface of network-modifying cations, enriching the near surface in cations such as Fe, Mg and Ca while depleting a layer further from the surface. The project also involved recognizing the presence of spinodal decomposition in the glass when viewed at very high magnification in the TEM. It is likely that this metastable immsicibility in the glass leads to the formation of the low-Ti magnetite found in the natural glasses. I am interested in exploring further the effect metastable immiscibility in glass and undercooled liquids could have on crystallization and the composition of near-liquidus phases.

I am also currently working to model possible melt/rock interactions that could lead to the presence of a 'ghost plagioclase' signature in certain lavas and melt inclusions. The data I am working with comes from the Galapagos, where several olivine-hosted melt inclusion from Fernandina show anomalously enriched Sr contents while not showing the trends in major elements expected for plagioclase dissolution. I am using a model to look at the effect of synchronous dissolution of low-An plagioclase and crystallization of high-An plagioclase.

A new project is exploring the impact that extended defects in olivine could have on diffusion (e.g., of REEs). "Fast path" diffusion could have large effects on the fidelity of melt inclusions. I am using TEM to look for disslocations and other defects both in natural samples that host melt inclusions, and in olivine+basalt experimental charges.