![]() ![]() The melt itself is thought by many to be in disequilibrium with the host rock due to its rapid nature, but during cooling equilibrium is probably reached at small scales. The frictional melts that quench into PST may reach >1400 Â☌, but are extremely localized and cool to country rock temperatures within minutes, resulting in glass and/or microlitic mineral growths. ![]() ![]() Some but not all PST veins have been overprinted with the Cora Lake shear zone foliation, and undeformed PST locally bears microlitic garnet. Pseudotachylyte, a glassy vein-filling substance that results from frictional melting during seismic slip, is common in ultramylonitic strands of the shear zone, where veins run for tens of meters subparallel to foliation. The terrane hosts the 1.88 Ga Cora Lake shear zone, a 3-5 km wide sinistral and extensional oblique-slip system that was active at high-pressure granulite-grade conditions ( ~1.0 GPa, >800Â☌ to ~0.8 GPa and 700 Â☌). The Athabasca Granulite Terrane is an exhumed section of deep continental crust exposed in the western Canadian shield. Pseudotachylytes of the Deep Crust: Examples from a Granulite- Facies Shear Zone ![]()
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