| Titre | U-Pb monazite SHRIMP geochronology of the northern Thelon Tectonic Zone - insights into the metamorphic and tectonic history of the of the Slave-Rae boundary zone |
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| Auteur | Mitchell, R K; Davis, W J ; Berman, R G; Carr, S D |
| Source | Margins through time: GAC-MAC 2016; Association géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 39, 2016 p. 65  Accès ouvert |
| Liens | Online - En ligne (complete volume - volume
complet, PDF, 1.3 MB)
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| Année | 2016 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190443 |
| Éditeur | Association géologique du Canada |
| Réunion | GAC-MAC 2016; Whitehorse, YK; CA; juin 1-3, 2016 |
| Document | publication en série |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Sujets | Zone de Thelon Tectonic ; Craton de Rae ; Craton de Slave ; géochronologie; tectonique; Sciences et technologie; Nature et environnement |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Chantrey-Thelon de la province de Rae |
| Diffusé | 2016 06 01 |
| Résumé | (disponible en anglais seulement)
The Thelon Tectonic Zone (TTZ) is a complex >500km long boundary zone between the Rae craton to the east and the Slave craton the west, located near Bathurst
Inlet, Nunavut. The TTZ has been interpreted as a ca. 2000 Ma continental arc on the western edge of the Rae craton, deformed during collision with, and indentation of the Slave craton ca. 1970 Ma. Alternative models propose that the TTZ represents
an interior mountain belt far removed from an active plate boundary, possibly following crustal thinning. The Thelon Tectonic Zone is composed of N-NNE striking domains with contrasting magnetic anomalies. Results of an ongoing GEM-2 project north of
65°N indicate the region comprises three belts of ca. 2.0 Ga plutonic rocks. An extensive ca. 1910 Ma leucogranite belt marks a major tectonic boundary within the zone. Other suites of syn- to post-tectonic 1940-1890 Ma plutons also occur. A
shortlived period of extension is marked by 1950 Ma ultramafic-mafic volcanic belt interlayered with psammitic metasedimentary rocks within the narrow Ellice River domain. Paleoproterozoic supracrustal rocks within this domain record deformation and
metamorphism at ca. 1814 Ma, and appear to have been structurally juxtaposed against higher grade domains. Metamorphism within the TTZ is upper amphibolite (migmatite) to granulite-facies, and reflects multiple high-grade events, including the ca.
2.35 Ga Arrowsmith orogeny documented in the western Rae. High-grade migmatitic paragneiss were chosen for U-Pb monazite SHRIMP geochronology to constrain the timing of metamorphism across geological domains. Garnet-bearing migmatitic paragneiss
assemblages are muscovite absent, and variably contain biotite, sillimanite, cordierite, spinel and orthopyroxene. Mineral assemblages, specifically spinel-quartz assemblages, are consistent with low pressure-high temperature conditions. Future work
will focus on constraining pressure-temperature-time paths for these samples. Matrix monazite grains in 5 samples yield mean 207Pb/206Pb ages ranging from 1914-1879 Ma. Monazites included in garnet porphyroblasts of 6 samples yield 207Pb/206Pb ages
of ca. 1955- 1904 Ma. These data indicate that the most widespread highgrade regional metamorphism occurred at ca. 1900-1910 Ma, was syntectonic in nature, and extending into the western Rae craton. An earlier ca. 1950 Ma metamorphic event, recorded
at two localities, is contemporaneous with extension-related volcanism in the Ellice River domain; however, the significance and extent of this event is not yet understood. |
| GEOSCAN ID | 321718 |
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