| Titre | Genesis of the Canadian Malartic, Côté Gold, and Musselwhite gold deposits: insights from LA-ICP-MS element mapping of pyrite |
| Télécharger | Téléchargement (publication entière) |
| |
| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Gao, J -F ;
Jackson, S E; Dubé, B; Kontak, D J; De Souza, S |
| Source | Targeted Geoscience Initiative 4: Contributions to the understanding of Precambrian lode gold deposits and implications for exploration; par Dubé, B (éd.); Mercier-Langevin, P (éd.); Commission géologique
du Canada, Dossier public 7852, 2015 p. 157-175, https://doi.org/10.4095/296636  Accès ouvert |
| Année | 2015 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/296636 |
| Media | en ligne; numérique |
| Référence reliée | Cette publication est contenue dans Targeted
Geoscience Initiative 4: Contributions to the understanding of Precambrian lode gold deposits and implications for exploration |
| Formats | pdf |
| Province | Ontario; Québec |
| SNRC | 32D/01; 32D/02; 32D/03; 32D/04; 32D/05; 32D/06; 32D/07; 32D/08; 41P/11; 41P/12; 41P/13; 41P/14; 41P/15; 41P/16; 42A; 53B/09; 53B/10; 53B/15; 53B/16 |
| Région | Kirkland Lake; Côté Lake; Rouyn Noranda; Lac Chassignolle; Malartic; North Caribou Lake |
| Lat/Long OENS | -82.0000 -78.0000 49.0000 47.5000 |
| Lat/Long OENS | -91.0000 -90.0000 53.0000 52.5000 |
| Sujets | Archéen; or; minéralisation; altération hydrothermale; gisements minéraux hydrothermaux; magmatisme; gîtes minéralogiques; gisements minéraux; potentiel minier; gîtes volcanogènes; sulfures; gîtes
sulfureux; genèse des gîtes minéraux; analyse par spectromètre de masse; pyrite; Ceinture de Swayze Greenstone ; Ceinture d'Abitibi Greenstone ; géologie économique; Précambrien; Protérozoïque |
| Illustrations | cartes de localisation; photomicrographies |
| Programme | Initiative géoscientifique ciblée (IGC-4) Étude des gîtes d'or |
| Diffusé | 2015 06 11 |
| Résumé | (disponible en anglais seulement)
Pyrite efficiently incorporates many key metals during progressive precipitation and thus records the chemical evolution of fluids from which it was deposited.
To reveal this information, a new LA-ICP-MS mapping procedure has been developed to allow generation of 2-D trace element concentration maps of minerals in petrographic section. The technique has been applied to pyrite-/pyrrhotite-bearing Au ores
from three major gold deposits.
Canadian Malartic is a low-grade bulk-tonnage deposit, which is located immediately south of the Larder Lake-Cadillac Fault Zone. It is hosted mainly by clastic metasedimentary rocks of the Pontiac Group, as well as
by porphyritic quartz monzodiorite and granodiorite. Textural evidence and elemental mapping have revealed five types of pyrite. The pre-mineralization pyrite (py1) is likely diagenetic pyrite, with high Co, As, and Se, and low Ni, Te, Sb, Bi, and
Pb. Gold-bearing pyrite 2, 3 and 4 (py2-py4) has covariant Co and Ni, high Au, Ag, Te, Bi, and Pb, and generally contains abundant potassic inclusions. Postmineralization pyrite (py5) has high Co and Ni but is low in other metals. Pyrite from the ore
zones distributed along the Sladen fault zone shows evidence of post-precipitation metal enrichment in fractures associated with Ca metasomatism. Though the elemental maps cannot unequivocally discriminate the deposit type, pyrite chemistry is
consistent with a two-stage model comprising early syn-pyrite Au mineralization associated with potassium alteration and a later post-pyrite upgrading associated with Ca metasomatism. The Côté Gold deposit is hosted by the Chester intrusive complex,
a high-level, multi-phase synvolcanic intrusion composed of tonalite and diorite. Nickel, As, Sb, and Pb are generally relatively depleted in the cores and enriched in the rims of the pyrite grains, whereas Te and Ag are relatively enriched in the
cores and depleted in the rims. Arsenopyrite grains have high Co, Ni, Se, Sb, and Te, but low Ag, Pb, and Bi. Gold is depleted both in pyrite and arsenopyrite, except locally in fractures, but is enriched in silicate minerals, possibly as
nanoparticles, suggesting that gold mineralization is related to a hydrothermal event post-dating pyrite precipitation.
The Musselwhite deposit is a banded iron formation-hosted lode gold deposit in a sequence of volcanic and sedimentary rocks
that include carbonaceous argillite locally hosting diagenetic pyrite nodules. Cobalt, Cu, Ni, Se, As, Ag, Sb, Te, Au, Tl, Pb, and Bi are enriched in the nodules but are depleted in recrystallized pyrite and pyrrhotite. Element and Pb-isotope maps
are consistent with a model whereby at least some of the ore gold was derived from fluids that garnered Au liberated via metamorphic recrystallization of auriferous diagenetic pyrite and, probably, carbonaceous material in local argillite. The
elemental maps show that gold has multiple sources. The Musselwhite deposit provides evidence for local pyritic carbonaceous sedimentary rocks as one of the possible sources of Au. The Canadian Malartic and Côté deposits have a strong association
with magmatic hydrothermal activity, although additional sources of Au may also have been important. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration dont le mandat consiste à fournir à
l'industrie la nouvelle génération de connaissances géoscientifiques et de techniques novatrices permettant de cibler plus efficacement les gîtes minéraux enfouis visant à réduire les risques associés à l'exploration minérale. Ce volume synthétise 18
activités de recherche complétées dans le cadre du projet sur les systèmes minéralisés or épigénétique de l'IGC-4. Ces activités portaient notamment sur les gisements d'or contenus dans les terrains anciens, déformés et métamorphisés principalement
localisés dans les provinces géologiques du Supérieur et la portion occidentale de celle de Churchill. |
| GEOSCAN ID | 296636 |
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