GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreRegional glacial history, paleo-dynamics and dispersal patterns, South Rae craton, Northwest Territories
AuteurCampbell, J E; Lauzon, G; Dyke, A S; Roy, M
SourceGAC-MAC 2017; Association géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés .
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160446
ÉditeurAssociation géologique du Canada
ÉditeurAssociation minéralogique du Canada
RéunionGeological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2017; Kingston, ON; CA; mai 14-18, 2017
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
ProvinceTerritoires du Nord-Ouest
SNRC75A; 75B; 75G; 75H
Sujetslevés géologiques; prospection minière; dépôts de till; tills; analyses de till; antecedents glaciaires; dépôts glaciaires; déglaciation; directions des mouvements de la glace; éléments d'indice; Supergroupe de Dubawnt ; géologie économique; minéraux industriels; géologie régional
ProgrammeGéologie du substratum rocheux et des dépôts meubles du sud de la province de Rae, GEM2 : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
The southern Rae area in southwest Northwest Territories lies within one of the most poorly mapped and least understood regions of the Keewatin Sector of the Laurentide Ice Sheet (LIS). This region is heavily covered by glacial sediments, which impede both bedrock mapping and mineral exploration. To fill in this knowledge gap, recent regional-scale (1:250 000) mapping and till sampling in four NTS mapsheets (75A, B, G and H) has been undertaken, revealing complex surficial geology and glacial history in this region.
The glacial landscape records a complex history of changing glacial flow dynamics and subglacial conditions during deglaciation, as reflected by superimposed landforms, juxtaposed streamlined terrain (fast flow) and non-streamlined terrain (sticky spot/sluggish flow) and a network of WSW-SW trending subglacial meltwater corridors. Sediment/landform associations reflect variations in sediment transport distances, directions and degree of inheritance.
Field-based measurements of erosional ice-flow indicators (e.g. striations, roches moutonnées) and imagery mapping of streamlined landforms record at least five regional flow sets attributed to Wisconsinan glaciation. The oldest flow is recorded at a few sites as striations with unknown sense (SSE/NNW). Well-defined indicators reveal a clockwise rotation in regional ice-flow directions during the Late Wisconsin glacial/deglacial event, shifting from southward to southwestward flow. A late westward flow is recorded in the north half of the study area. The prevailing regional ice-flow direction is to the southwest.
Till composition data (clast lithology, indicator minerals, matrix geochemistry and texture) combined with ice-flow indicators are examined to establish sediment dispersal patterns as well as the varying degrees of till inheritance and hybridization. Preliminary results indicate that at the regional scale, till composition predominantly reflects the bedrock domains with sharp changes in lithological and geochemical constituents across domain boundaries. Distinctive erratics and exotic clast lithologies in the till are used as tracers for glacial dispersal patterns and compositional inheritance. Clasts, such as Dubawnt Supergroup lithologies, derived from sources located to the north-northeast of the study area, indicate sustained transport of glacial debris by the older southward flow.
This research will provide much needed input for the paleoglaciological reconstruction of the Keewatin Sector of the LIS, and a much needed Quaternary geological framework for mineral exploration and land resource management in the southwest region of the Rae geological province.
Résumé(Résumé en langage clair et simple, non publié)
Cette présentation présente l'interprétation préliminaire des données provenant du travail de cartographie des superficies et de l'échantillonnage du till réalisé dans les territoires du sud-est du Nord-Ouest, dans le cadre de la composante géologie superficielle de l'activité GEM-2 South Rae. La présentation se concentre sur les zones glaciaires, la reconstruction des glaces, les sédiments glaciaires et la composition du till. Les implications des résultats sont discutées.
GEOSCAN ID300220