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TitleRecognizing optimum banded iron formation-hosted gold environments in ancient, deformed and metamorphosed terranes: preliminary results from the Meadowbank Deposit, Nunavut
AuthorCastonguay, 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
Year2012
Alt SeriesEarth Sciences Sector, Contribution Series 20130045
PublisherNorthwest Territories Geoscience Office
Meeting40th Annual Yellowknife Geoscience Forum; Yellowknife, NT; CA; November 13-15, 2012
Documentserial
Lang.English
Mediapaper
RelatedThis publication is related to 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, Geological Survey of Canada, Open File 7407
File formatpdf; html
ProvinceNunavut
NTS56D/13NW; 56E/04SW; 66A/16NE; 66H/01SE
AreaKavallik; Goose Island; Third Portage Lake; Second Portage Lake
Lat/Long WENS-96.2500 -95.7500 65.0833 64.9167
Subjectsstructural geology; economic geology; Archean; iron formations; mineral occurrences; mineral assemblages; mineralization; gold; bedrock geology; structural interpretations; structural features; faults; folds; lithology; volcanic rocks; plutonic rocks; igneous rocks; quartzites; felsic volcanic rocks; ultramafic rocks; deformation; Meadowbank mine; Woodburn Lake Group; Precambrian; Proterozoic
Illustrationslocation maps; photographs; cross-sections
ProgramGold Ore Systems, Targeted Geoscience Initiative (TGI-4)
LinksOnline - En Ligne
AbstractThe 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.
Summary(Plain Language Summary, not published)
The study of the Meadowbank deposit is part of NRCan's Targeted Geoscience Iinitiative-4 Program that aims at improving our understanding of Canada's major mineral systems. Agnico-Eagle Mines¿ Meadowbank mine is located in the Kavallik region of Nunavut. Research to date has mostly been concentrated on the geological mapping of the Portage and Goose orebodies. The lithologic sequence of the deposit consists of volcaniclastic rocks, banded iron formation (BIF), ultramafic rocks and quartzite. The predominant gold mineralization is associated with pyrrhotite and pyrite, which have replaced magnetite. The ore zones are approximately 7 m wide (5 up to 40 g/t) and hosted in the BIF. Gold also is found in high-grade quartz veins in volcaniclastic rocks. Four phases of regional deformation affect the host rocks, which have been strongly metamorphosed. Targeted geochronology, structural, petrographic and geochemical analyses are underway to characterize the deposit and ultimately establish the hydrothermal footprint, timing of gold introduction and structural controls.
GEOSCAN ID292571