Building an atlas of epitaxy in metamorphic rocks

Epitaxy is a crystal nucleation pathway that involves daughter nuclei templating upon a surface of a preexisting parent crystal, leading to an inheritance of the daughter lattice orientation from the parent phase. Numerous examples of epitaxy have been identified in rocks formed under a range of igneous and metamorphic conditions, yet most studies are focused on one or two mineral-pairs and so it is not known how prevalent epitaxy is as a nucleation pathway in nature. Here, I take a broader approach by analyzing nine mineral-pairs in eight rock samples, all from a range of crustal environments. Using electron backscatter diffraction data and a post-processing routine in MTEX crystal orientation toolbox for MATLAB I identify, for each mineral-pair, the preferred nucleation orientation relationships. By reconstructing these orientation relationships in the lattice visualization program CrystalMaker, I develop an understanding of how lattice structure and atomic arrangement influence the location and orientation of daughter phase nucleation. The workflow developed for this thesis proves to be a useful tool for rapidly determining the presence of epitaxial nucleation in thin section and grain mount. The results of this thesis support the notion that epitaxy is the default nucleation pathway in metamorphic rocks, which has implications for kinetics of metamorphic reactions and the rheology of metamorphic crust.