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TitreEpidote-amphibole and accessory phase mineral chemistry as a vector to low-sulphide platinum group element mineralization, Sudbury: laser ablation ICP-MS trace element study of hydrothermal alteration
TéléchargerTéléchargement (publication entière)
AuteurAmes, D E; Tuba, G
SourceTargeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models; par Ames, D E (éd.); Houlé, M G (éd.); Commission géologique du Canada, Dossier public 7856, 2015 p. 269-286, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Ames, D E; Houlé, M G; (2015). Targeted Geoscience Initiative 4: Canadian nickel-copper-platinum group elements-chromium ore systems -- fertility, pathfinders, new and revised models, Commission géologique du Canada, Dossier public 7856
Lat/Long OENS -82.0000 -80.0000 47.0000 46.0000
Sujetsépidote; amphibole; platine; minéralisation; genèse des minerais; métallogénie; altération hydrothermale; analyse par spectromètre de masse; géochimie des éléments en trace; Province de Superior ; Complexe de Sudbury Igneous ; minéraux métalliques; pétrologie ignée et métamorphique; géochimie
ProgrammeÉtude des gîtes magmatiques de Ni-Cu-EPG, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 06 22
Résumé(disponible en anglais seulement)
In Sudbury, one of the world's largest Ni-Cu-Co mineral districts, geophysical methods have been successfully employed for detecting traditional contact and offset types of Ni-Cu-PGE ore for over a century. Recent discoveries of low- to no-sulphide, high-PGE tenor orebodies, defined in 2005 in the footwall environment to the Sudbury Igneous Complex (SIC), caused a shift in exploration focus to the detection of these precious metal-rich resources. These high-grade orebodies are hosted in randomly distributed impactderived breccia (Sudbury breccia) entirely within Archean and Proterozoic country rocks and comprise two footwall styles: a) high-sulphide vein-style Cu-PGE ores (i.e. Strathcona, McCreedy East 153 chalcopyrite veins) with a widely recognized magmatic-hydrothermal origin and b) low-sulphide disseminations, blebs and stringers with high PGE tenor and dominated by silicate assemblages of hydrothermal origin. This second, low- to no-sulphide, high-PGE footwall ore-style is a challenge to detect in the field with traditional geophysical methods used for magmatic deposits due to the absence of chalcopyrite or sulphide minerals, resulting in a need for development of non-conventional exploration techniques.
Proper classification is important for guiding future exploration for the low-sulphide metal-rich deposits in the footwall to the Sudbury Igneous Complex. Key hydrothermal alteration assemblages with distinct trace element signatures may aid the development of discriminant mineral chemistry diagrams to yield criteria that help find these high-grade PGE hydrothermal footwall ores. The aim of this study was to establish typical element-associations and behaviours for the paragenetically different hydrothermal assemblages produced during the diverse post-impact magmatic-hydrothermal history of the footwall and hanging-wall units of the Sudbury structure to detect a unique signature for alteration related to the high-tenor PGE mineralization. Factors affecting the trace element distribution patterns in epidote, amphibole, titanite, and allanite are examined, including the element partitioning between coeval minerals, the crystal structural control, and the effect of country rocks on the fluid-rock interaction, and detection of pathfinder elements. As and Zn in epidote and amphibole are host-rock dependant. The pathfinder elements Ni, Pb, Sn, and Co in epidote and amphibole are the most reliable elements to distinctly fingerprint the PGE mineralizing alteration in the footwall. However, mineral-pair partitioning of elements between epidote-amphibole-titanite and allanite indicate that single mineral phases or elements should not be used.