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TitreRecognizing optimum banded iron formation-hosted gold environments in ancient, deformed and metamorphosed terranes: preliminary results from the Meadowbank Deposit, Nunavut
AuteurCastonguay, S; Janvier, V; Mercier-Langevin, P; Dubé, B; McNicoll, V; Malo, M; Pehrsson, S; Bécu, V
SourceNorthwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume vol. 2012, 2012 p. 54-55
Année2012
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130045
ÉditeurNorthwest Territories Geoscience Office
Réunion40th Annual Yellowknife Geoscience Forum; Yellowknife, NT; CA; Novembre 13-15, 2012
Documentpublication en série
Lang.anglais
Mediapapier
Référence reliéeCette publication est reliée Janvier, V; Castonguay, S; Mercier-Langevin, P; Dubé, B; McNicoll, V; Malo, M; Pehrsson, S; Bécu, V; (2013). Recognizing optimum Banded-Iron Formation-hosted gold environments in ancient, deformed and metamorphosed terranes: Preliminary results from the Meadowbank deposit, Nunavut, Canada, Commission géologique du Canada, Dossier public 7407
Formatspdf; html
ProvinceNunavut
SNRC56D/13NW; 56E/04SW; 66A/16NE; 66H/01SE
Lat/Long OENS-96.2500 -95.7500 65.0833 64.9167
SujetsArchéen; formations ferrifères; gîtes minéralogiques; assemblages de minéraux; minéralisation; or; géologie du substratum rocheux; interpretations structurelles; caractéristiques structurales; failles; plis; lithologie; roches volcaniques; roches plutoniques; roches ignées; quartzites; roches volcaniques felsiques; roches ultramafiques; déformation; Groupe de Woodburn Lake ; géologie structurale; géologie économique; Précambrien; Protérozoïque
Illustrationslocation maps; photographs; cross-sections
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
LiensOnline - En Ligne
Résumé(disponible en anglais seulement)
The Meadowbank project is part of the Lode Gold Project of NRCan's TGI-4 Program that aims at improving geological exploration models where gaps exist in our understanding of Canada's major gold systems with respect to footprint, vectoring and fertility as indicators for hidden/buried deposits. The Lode Gold Project investigates a selected group of deposits in various settings, with some emphasis on underexplored styles/types of mineralization, including Banded Iron Formation (BIF)-hosted gold deposits, which represent prime exploration targets in northern Canada. The BIF-hosted gold deposits theme consists of a systematic investigation of the proximal and distal geological and hydrothermal signatures or footprints, structural controls and timing of the mineralization with respect to the overall geologic evolution of their host rocks and camp-scale settings. Such research is underway at the Musselwhite mine and Hardrock deposit in Ontario, and at the Meadowbank mine in Nunavut.
Agnico-Eagle Mines' Meadowbank mine is located in the Kavallik region of Nunavut, 70 km north of the community of Baker Lake. The deposit is hosted in the Neoarchean Woodburn Lake Group, in the Rae domain of the Western Churchill geological province. Ongoing research and data acquisition to date have mostly been concentrated on the Portage and Goose orebodies, which now represent a ca. 3 km-long open-pit operation. The lithologic sequence of the deposit consists of, from east to west, intermediate to felsic volcaniclastic rocks, banded iron formation, ultramafic rocks, locally interlayered with the BIF, and quartzite. The predominant gold mineralization found at the Portage and Goose orebodies is associated with pyrrhotite and pyrite, which have replaced magnetite or that occur as narrow stringers of disseminated sulphides. The ore zones are typically 6-7 m wide (5 up to 40 g/t) and hosted in the BIF, predominantly along the contacts with ultramafic rocks. Gold also is found in high-grade quartz veins (up to 300 g/t) crosscutting the BIF and adjacent volcaniclastic rocks. At least four phases of regional deformation affect the host rocks of the Meadowbank deposit, which have been metamorphosed to mid-greenschist through amphibolite facies. Regionally, the main phase of deformation (D2) consists of tight to isoclinal folds, axial planar foliation and shear zones, although mesoscopic F2 folds are rare in the mine area. Regional D3 (shallow-inclined open to closed folds and axial planar crenulation cleavage) and D4 (SW-plunging, steeply inclined cross-folds) deformation also affect the mine sequence and the mineralization. Although the geometry of the Portage orebodies is typically portrayed as an isoclinal F2 fold, preliminary new mapping suggests that mine sequence is also fault imbricated by two late-D2 shear zones preferentially developed within the ultramafic units. These shear zones appear to truncate the ore zones, and possibly control their distribution. Targeted geochronology, structural analysis, petrographic and geochemical analyses of roughly 400 samples along selected sections of the Portage and Goose orebodies are underway to characterize the proximal and distal alteration associated with the mineralization and ultimately establish its hydrothermal footprint, the timing of gold introduction and structural controls.
Résumé(Résumé en langage clair et simple, non publié)
L'étude du gisement Meadowbank fait partie du programme de l'Initiative Géoscientifique Ciblée 4 de RNCan qui vise a améliorer notre connaissance des systèmes minéraux majeurs du Canada. La mine Meadowbank appartenant à Agnico-Eagle est située dans la région de Kavallik au Nunavut. La recherche en cours s'est concentrée sur la cartographie géologique des gites de Portage et Goose. La séquence lithologique du gisement consiste de roches volcanoclastiques, de formations de fer rubanées (FFR), de roches ultramafiques et de quartzite. La minéralisation aurifère dominante est associée à de la pyrrhotite et de la pyrite yant remplacé la magnétite. Les zones minéralisées sont approximativement 7 m d'épaisseur (5 à jusqu'a 40 g/t) sont encaissées dans les FFR. L'or se retrouve également dans des veines de quartz de haute teneur au sein des roches volcanoclastiques. Quatre phases de déformation régionale affectent les roches hôtes, lesquelles ont été fortement métamorphisées. De la géochronologie et des analyses structural, pétrographique et géochimique ciblées sont en cours afin de caractériser le gisement et ultimement d'établir l'empreinte hydrothermal, la chronologie de l'introduction de l'or et les contrôles structuraux.
GEOSCAN ID292571