A lower crustal perspective on the stabilization and reactivation of continental lithosphere in the western Canadian shield

New geochronological, thermochronological, geological and isotopic data from an extensive (> 20,000 km²) exposure of high-pressure granulites (0.8 to > 1.5 GPa, >750 ⁰C) in the East Lake Athabasca region of the Snowbird tectonic zone provide important constraints on the stabilization, reactivation and exhumation of continental lithosphere in the western Canadian Shield. The exhumed lower crust of this craton comprises several disparate domains that preserve a complex record of tectonic, magmatic and metamorphic processes from formation to exhumation. U-Pb zircon geochronology documents two episodes of metamorphic zircon growth at 2.55 Ga and 1.9 Ga, linked with two high-pressure granulite facies assemblages preserved in Chipman domain mafic granulites. The intervening 650 m.y. of relative quiescence implies a period of lithospheric stability during which the granulites continued to reside in the deep crust. Disruption of the stable Archean craton at 1.9 Ga broadly coincides with the assembly of the Laurentian supercontinent. The correlation of 1.9 Ga mafic magmatism and metamorphism in the Chipman domain with contemporaneous mafic magmatism along > 1200 km strike-length of the Snowbird tectonic zone indicates that regional asthenospheric upwelling was an important aspect of this reactivation event.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Flowers, Rebecca Marie

Advisor dc:contributor.advisor

• Samuel A. Bowring.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/33944
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/33944

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33944