GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreDefinition of magnetic domains within the Rae Craton, mainland Canadian Shield, Nunavut, Northwest Territories, Saskatchewan, and Alberta: their magnetic signatures and relationship to geology
TéléchargerTéléchargements
AuteurThomas, M D
SourceCommission géologique du Canada, Dossier public 8343, 2018, 100 pages, https://doi.org/10.4095/306561
Année2018
ÉditeurRessources naturelles Canada
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/306561
Mediaen ligne; numérique
Formatspdf
ProvinceNunavut; Territoires du Nord-Ouest; Saskatchewan; Alberta
SNRC45P; 46; 47A; 47B; 47C; 47D; 47E; 47F; 55; 56; 57A; 57B; 57C; 57D; 57E; 57F; 64I; 64P; 65; 66; 67A; 67B; 67C; 67D; 67E; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P; 75; 76; 84I; 84P; 85A; 85H
Lat/Long OENS-113.0000 -80.0000 71.0000 58.0000
Sujetsinterprétations géophysiques; interprétations géophysiques; interprétations magnétiques; levés géophysiques; levés magnétiques; levés aéromagnétiques; anomalies magnétiques; magnétisme du champ complet; domaines structuraux; analyses du comportement des surfaces; caractéristiques structurales; zones de failles; failles; zones de cisaillement; intrusions; géologie du substratum rocheux; lithologie; roches métamorphiques; gneiss; roches granitiques; roches sédimentaires; formations ferrifères; roches ignées; roches intrusives; evolution de la croûte; évolution tectonique; accretion; Archéen; Bouclier Canadien; Province de Churchill ; Craton de Rae ; Orogène d'Arrowsmith ; Bloc de Chesterfield ; Orogenèse de Macquoid ; Bassin de Thelon ; Zone de cisaillement de Wager Bay ; Zone de Snowbird Tectonic ; Zone de Thelon Tectonic ; Faille de Mcdonald ; Bassin d'Athabasca ; Zone de cisaillement de Grease River ; Zone de cisaillement de Big Lake ; Zone de cisaillement d'Hanbury Island ; géophysique; géologie structurale; stratigraphie; Précambrien
Illustrationsgeoscientific sketch maps; index maps
Consultation
Endroit
 
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
 
ProgrammeGéologie du substratum rocheux et des dépôts meubles du sud de la province de Rae, GEM2 : La géocartographie de l'énergie et des minéraux
Diffusé2018 03 06
Résumé(disponible en anglais seulement)
The Archean Rae craton, western Churchill Province, occupies a huge area within the northwestern mainland Canadian Shield. It extends >1600 km from the Talston magmatic zone northeastward to the east coast of Melville Peninsula, ranging in width from roughly 300 km to 900 km. The craton is covered by aeromagnetic data collected over many decades by Canada's National Aeromagnetic Survey Program, typically along lines 805 m apart at a flight elevation of 305 m. Additionally, many higher resolution aeromagnetic surveys have been completed during the last decade or so. The craton is geologically mapped at various scales, but most geological coverage is at a relatively large scale. For this reason magnetic data provided by the national program are considered to be of sufficient resolution to investigate relationships with geology.
Here, seventy-five magnetic domains are defined using textures, fabrics, patterns, orientations and intensities of residual total magnetic field anomalies and their derivative equivalents (first vertical derivative, tilt angle). Given that patterns and orientations of narrow derivative magnetic anomalies reflect closely geological structure, the magnetic domains can be viewed essentially as representative of structural domains. The maximum dimension of most domains is >100 km, but many attain dimensions of several 100 km. Although the Rae craton has an overall northeastward trend, a strong pattern of linear magnetic domains running parallel to this trend along the length of the craton is not apparent. A few generally relatively broad and parallel domains do run northeastward along the spine of the craton between roughly the Talston magmatic zone and Aberdeen sub-basin. Several narrower and typically less extensive domains also trend northeast within the Chesterfield block along the southeast margin of the craton southeast of the sub-basin. Where the southern part of the craton, south of the roughly east- trending Amer and Wager Bay shear zones, swings into a more eastward trend, linearity is lost and domains become smaller and more irregular in shape, with some trending across the craton.
The best developed linear pattern of domains probably lies between the Thelon magmatic zone and Chantrey fault zone, where several narrow to moderately wide, sub-parallel domains extend between the McDonald fault (and its northeastward projection) and Queen Maud Gulf. Eastward they change orientation progressively from northward to roughly N30°E towards the fault zone. A sense of a linear arrangement of domains is observed also on the Boothia and Melville peninsulas, with trends varying between approximately east-northeast and northeast. A broad area east of the Chantrey fault zone, north of the Amer and Wager Bay shear zones, south of the Boothia Peninsula and including the southern part of the Melville Peninsula contains some linear domains trending approximately northeast, but there are also sizable domains of irregular shape lacking an internal magnetic fabric characterized by prominent northeast trends.
Many close correlations between magnetic anomalies and mapped lithological units exist, but there are numerous examples where anomalies transect unit boundaries thus questioning boundary positions. Magnetic anomalies indicate probable lithological/compositional changes within many large gneissic units pointing to a need for more detailed mapping. Many examples of exceptionally strong magnetic highs are associated with mapped iron formations. Such highs in areas apparently lacking iron formations signify their potential presence. Magnetic patterns and signatures outline locations of small circular to roughly oval, unmapped igneous intrusions, and many faults not displayed on geological maps.
Résumé(Résumé en langage clair et simple, non publié)
Les cartes magnétiques du craton de Rae précambrien dans la partie nord-ouest du bouclier canadien continental sont utilisées pour définir les domaines magnétiques. Les principales cartes magnétiques sont le champ magnétique total résiduel et la dérivée première verticale du champ total et le tilt du champ total. Les deux dernières cartes magnétiques fournissent des images des domaines structuraux associées aux domaines magnétiques. À l'échelle du craton, la définition des domaines fournit une perspective différente pour l'évaluation des relations structurelles et du développement tectonique. À des échelles plus locales, les relations entre les signatures magnétiques et la géologie cartographiée supportent parfois la cartographie et, dans d'autres cas, remettent en question l'attribution d'un certain type de roche ou le positionnement d'un contact. Les cartes magnétiques indiquent également les zones désignées comme une seule unité sachant qu'elles sont géologiquement beaucoup plus complexes. Ce qui est normal étant donné que la cartographie géologique dans de nombreuses régions est en grande partie de nature de reconnaissance.
GEOSCAN ID306561