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

Quartz grains are dynamically recrystallized and intensely attenuated into elongate
ribbons (Fig. 2.5e,f). Relict grains show subgrain extinction, bulges, and recrystallized subgrains
and bulges (Fig. 2.5f). These textures suggest deformation temperatures approximating the
transition from bulging to subgrain rotation recrystallization at ~400°C (Stipp et al., 2002).
Feldspar grains exhibit bent twins, patchy undulose extinction, and abundant grain-scale
fractures, including antithetic micro-faulting (Fig. 2.5d). Brittle deformation within the feldspar
suggests a temperature of deformation below ~400°C (Tullis and Yund, 1991). Coeval dynamic
recrystallization of quartz and brittle deformation of feldspar constrain deformation temperatures
to 280 -400°C within the ultra-high-strain zone (Stipp et al., 2002; Tullis and Yund, 1991).
Asymmetric fabric elements observed within the ultra-high-strain zone include delta-type
rotated feldspar porphyroclasts and mica fish (Fig. 2.5d,e). Shear sense indicators show a near
even distribution of dextral and sinistral senses of motion. Within the leucogranite dyke,
numerous conjugate shear bands are observed. Additional microscale observations include garnet
and tourmaline grains that are fractured, boudinaged, and pulled apart parallel to the dominant
mineral elongation lineation.
2.4.2.4 Domain IV – High-strain quartzite and pelitic GHS
Highly strained quartzite and pelitic schist of the GHS are found ~1 km structurally
underlying the GHS-TSS interface (Figs. 2.3, 2.6). The mineralogy of the quartzite and pelitic
schist (Qtz ± Fsp ± Ms ± Bt ± Grt) is similar to the overlying ultra-high-strain GHS rocks;
however, this domain has been subjected to lower deformation at higher temperatures. Mylonitic
fabrics and mineral lineations defined by alignment and elongation of quartz, feldspar, and mica
define a pervasive south-dipping foliation and shallowly to moderately plunging ESE-WNW
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