title of the thesis - Department of Geology - Queen's University

similar crystallographic orientations were classified as individual grains; and a new data set was
created where each grain was represented as a single point (Fig. 2.9). This eliminated any bias
created by oversampling large grains and allowed for direct comparison with data derived from
the universal-stage (U-Stage) method. A summary of this post-acquisition data processing is
shown in Figure 2.9.
Quartz c-axis orientations were also measured for four samples via an optical microscope
mounted with a universal stage. A single c-axis measurement was taken for each individual grain
and attention was paid to not measure any grain more than once.
2.5.1.2 Descriptions of quartz CPO patterns
Quartz CPO patterns follow the definitions of Lister (1977), in which the plane normal to
the lineation (Y-Z plane) is defined as the symmetry plane. Fabrics that do not mirror themselves
across this plane are described as asymmetric. A summary of the orientation of principal strain
axes, active slip systems, fabric geometries in different strain fields, and evolution of CPO
patterns during non-coaxial strain at various temperatures is portrayed in Figure 2.10.
Photomicrographs of samples analyzed for quartz CPO patterns are seen in Figure 2.11. Quartz
CPO c- and a- axes are presented in Figure 2.12 as lower-hemisphere equal-area projections
oriented normal to the foliation and parallel to the lineation (see Appendix B for additional CPO
data).
Analyzed CPO fabrics were sampled from three domains: the ultra-high-strain zone
(domain III), the high-strain quartzite and pelitic GHS (domain IV), and the high-strain gneissic
GHS (domain V). CPO patterns from within each zone are described below.
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