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TitreMorphology of gossans in the Canadian Arctic Islands
AuteurPercival, J B; Williamson, M -C; McNeil, R J; Harris, J
SourceL'Association géologique du Canada-L'Association minéralogique du Canada, Réunion annuelle conjointe, Recueil des résumés vol. 37, 2014 p. 219
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130475
RéunionGeological Association of Canada - Mineralogical Association of Canada Joint Annual Meeting; Fredericton; CA; mai 21-23, 2014
Documentpublication en série
ProvinceNunavut; Territoires du Nord-Ouest
Sujetschapeaux ferrugineux; sulfures; gîtes sulfureux; altération; télédétection; géologie des dépôts meubles/géomorphologie; géophysique
Programmeadaptation et impacts sur l'environnement, environnement du nord, Géosciences environnementales
Résumé(disponible en anglais seulement)
Chemical and physical weathering of bedrock and surficial materials may produce secondary minerals that vector to buried ore deposits. For example, the classic gossan includes a sulphide - depleted and silica - enriched leach cap, underlain by the main gossan zone enriched in Fe - oxides, Fe - oxyhydroxides and other secondary minerals, overlying mineralized bedrock or surficial material containing primary sulphide minerals. Under certain conditions, some of these gossans react with permafrost and provide an analogue for mine wastes in the northern environment. The Arc tic Gossans Activity was supported by the Environmental Geoscience and Geo - Mapping for Energy and Minerals Programs between 2011 and 2014. Over the course of 2 field seasons on Victoria Island, NT, and Axel Heiberg Island, NU, several types of oxide - sulphide gossans were located and sampled. Remarkably, the morphology of these gossans is complex and in some cases, does not match the classic profile described above. The deposits are found within a variety of host rocks that include: volcanic successions, mafic sills, pyritic shale, evaporite diapirs and sulphide chimneys. In most cases, the gossans are associated with mafic intrusive rocks and local faulting. In other cases, there is no direct field evidence of an igneous protolith or nearby fault. In all cases, goethite, jarosite and gypsum predominate. Remote sensing technology has enabled detection of these alteration zones and identification of their inherent mineralogy, at various scales. Ground truthing during mapping, combined with analysis of materials (surficial and at depth) using field portable instruments such as reflectance spectroradiometer, allows rapid and precise detection of key alteration minerals. Follow - up laboratory mineral analysis (XRD/SEM) enabled detailed characterization of these deposits. This presentation will explore the similarities and differences in gossan development in the two study areas. It will demonstrate the need to be systematic with respect to (1) detection (2) classification (3) sampling (4) mineralogy and geo chemistry (5) and (6) integration with regional mapping.
Résumé(Résumé en langage clair et simple, non publié)
Ce résumé décrit les caractéristiques morphologiques (forme, taille, stratigraphie, composition) de chapeaux de fer situées dans la partie centrale de l'île Victoria, dans les Territoires du Nord-Ouest, et la partie ouest de l'île Axel Heiberg, au Nunavut. La présentation résumera les protocoles de terrain et en laboratoire qui ont permis de classifier plusieurs types de chapeaux de fer découverts dans les zones d'étude.