| Titre | The distinct metamorphic stages and structural styles of the 1.94-1.86 Ga Snowbird Orogen, Northwest Territories, Canada |
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| Auteur | Thiessen, E J; Gibson, H D; Regis, D; Pehrsson, S J; Ashley, K T; Smit, M A |
| Source | Journal of Metamorphic Geology vol. 38, issue 9, 2020 p. 963-992, https://doi.org/10.1111/jmg.12556  Accès ouvert |
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| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200303 |
| Éditeur | Blackwell Publishing Inc. |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1111/jmg.12556 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Territoires du Nord-Ouest; Alberta; Saskatchewan; Manitoba |
| SNRC | 64K; 64L; 64M; 64N; 65C; 65D; 65E; 65F; 65K; 65L; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P; 75A; 75B; 75C; 75D; 75E; 75F; 75G; 75H; 75I; 75J; 75K; 75L; 84I; 84P; 85A; 85H; 85I |
| Région | Lac Athabasca |
| Lat/Long OENS | -112.7078 -100.6586 62.4308 58.4936 |
| Sujets | évolution tectonique; métamorphisme; déformation; orogenèse; plissement; cisaillement; antecedents thermiques; géochimie des éléments en trace; géochimie des éléments majeurs; datation radiométrique;
datation au uranium-plomb; inclusions; conditions de pression-température; tendances structurelles; clivage; faciès métamorphiques; Archéen; Craton de Rae ; Orogène de Snowbird ; Paléoprotérozoïque; Laurentie; tectonique; géologie structurale;
pétrologie ignée et métamorphique; géochimie; géochronologie; Sciences et technologie; Nature et environnement; Précambrien; Protérozoïque |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; diagrammes stéréographiques tournant de wulff; photomicrographies; photographies; tableaux; profils; diagrammes de phases; cartes
géochronologiques; graphique à barres; diagrammes Concordia; graphiques; blocs-diagrammes |
| Diffusé | 2020 07 20 |
| Résumé | (disponible en anglais seulement)
Palaeoproterozoic orogenesis within the Archean southeastern Rae craton is related to the initial amalgamation of Laurentia. Characterizing the accompanying
tectonic processes during this time has been complicated due to polymetamorphism, which results in the obscuring of the age record of the terranes involved. To improve the knowledge of the tectonic evolution of the South Rae Craton, petrologic and
structural analyses are applied in conjunction with in situ trace element chemistry, inclusion barometry, U-Pb monazite and titanite, and Lu-Hf garnet chronology. The data robustly constrain Palaeoproterozoic pressure-temperature-time paths of major
deformational events along the southeastern Rae craton margin. D1 occurred between 1.94 and 1.93 Ga in the Dodge-Snowbird domain, which included prograde burial of metasedimentary rocks, deposited at 2.2-2.0 Ga, and the development of migmatitic
layering and east-southeast trending folds (S1, F1). Peak metamorphism is recorded in metasedimentary units at c. 1.93 Ga when rocks reached conditions of 9.0-10.5 kbar and 810-830°C. Within the Dodge-Snowbird domain, D2 imparted north-northeast
trending open folds and associated axial planar cleavage (S2, F2) between 1.93 and 1.90 Ga during east-west compression that appears to have been synchronous with cooling and exhumation. Later D2 deformation, localized within the Wholdaia Lake shear
zone (WLsz; ST1), developed in the footwall of this thrust-sense structure at 1,873 ± 5 Ma at conditions of 9.5-11.0 kbar and 820-850°C. The hangingwall Dodge-Snowbird domain had already cooled to below 300°C by then, indicating a significant
structural and metamorphic break across the domain's western boundary. A new phase of unroofing (D3) involved pervasive amphibolite- to greenschist facies extensional shearing (ST2) within the WLsz, which overprinted ST1 foliations between 1.87 and
1.86 Ga. Continued greenschist facies shearing younger than 1.86 Ga likely ended by c. 1.83 Ga when lamprophyre dykes cut the structure, which was followed by cooling until c. 1.80 Ga. This work highlights the utility and application of multiple
chronometers (zircon, monazite, titanite, garnet) along with structural and petrologic analysis that together can resolve precise orogenic cycles in polymetamorphic terranes that may otherwise be undetected. The time-resolved P-T-D histories derived
here enable more robust interpretations regarding the nature and evolution of 1.9 Ga tectonism along the southeast Rae craton margin, which may be used to refine models for Laurentian terrane amalgamation. |
| GEOSCAN ID | 326941 |
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