Tectonic and chemical implications of cathodoluminescent microstructures in quartz, Parry Sound domain, Ontario, Canada

Cathodoluminescence (CL) imaging of quartz in orthogneiss of the Parry Sound domain, Grenville Province, Ontario, Canada, reveals four dark microstructures—medium-dark grains, mantles, sinuous lines, and straight lines. The Parry Sound domain experienced granulite-facies deformation and metamorphism followed by variable degrees of amphibolite-facies retrogression associated with the development of retrograde shear zones. We integrate our observations of CL-visible quartz microstructures with structures observable with optical and scanning transmission electron microscopy, analyses of water species concentration, and trace element distribution in quartz, as well as with microstructures in plagioclase, to determine their characteristics and elucidate their timing and mechanisms of formation relative to the deformational history. Medium-dark grains are primarily located in and near kilometer-scale shear zones at the margins of the Parry Sound domain, have notably darker cores than most samples in the interio...