Title: Great Slave Lake Shear Zone, Canadian Shield: reconstructed vertical profile of a crustal-scale fault zone
Abstract: The Great Slave Lake Shear Zone (GSLSZ) of the northwestern Canadian Shield, a 25 km wide, early Proterozoic, transcurrent, dextral, mylonite zone, is a type example of a crustal-scale fault zone profile. With time: (1) the metamorphic grade decreased from granulite to greenschist facies; (2) the locus of high strain narrowed and jumped laterally, abandoning relatively older mylonites. Progressively younger mylonites represent both cooler temperatures and lower pressures; thus the sequence of narrowing mylonite belts represents a series of progressively shallower seated sections through the GSLSZ; (3) deformation evolved through the brittle-ductile transition, initially producing non-dilational penetrative breccias, followed first by discrete non-dilational faulting and subsequently by dilational, quartz "stockworks". Developing crustal-scale shear zones grow to an optimum width dictated by the requirement of minimum geologically reasonable strain rates for given conditions of wall rock rheology and displacement rate. Independent of variations in relative plate motion, mature shear zones change width and migrate laterally as a function of inferred thermally activated rheological changes within the wall rocks.
Publication Year: 1988
Publication Date: 1988-06-01
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 131
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot