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TitleLithological and tectonic controls on banded iron formation-associated gold at the Amaruq deposit, Churchill Province, Nunavut, and implications for exploration
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorValette, M; De Souza, S; Mercier-Langevin, P; Côté-Mantha, O; Simard, M; Wodicka, NORCID logo; McNicoll, V J; Barbe, P
SourceTargeted Geoscience Initiative 5: contributions to the understanding of Canadian gold systems; by Mercier-Langevin, P (ed.); Lawley, C J MORCID logo (ed.); Castonguay, SORCID logo (ed.); Geological Survey of Canada, Open File 8712, 2020 p. 251-266, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 5: contributions to the understanding of Canadian gold systems
RelatedThis publication is related to Geological setting of the 5.2 Moz Au Amaruq banded iron formation-hosted gold deposit, Churchill Province, Nunavut
File formatpdf
AreaWhale Lake; Mammoth Lake; Kivalliq Region
Lat/Long WENS -96.7500 -96.6667 65.4333 65.3833
Subjectseconomic geology; tectonics; structural geology; igneous and metamorphic petrology; geochemistry; Science and Technology; Nature and Environment; mineral deposits; gold; strata-bound deposits; replacement deposits; ore mineral genesis; mineralization; ore controls; modelling; mineral exploration; exploration guidelines; tectonic setting; tectonic history; deformation; folding; metamorphism; greenschist facies; orogenesis; shearing; strain; fabric analyses; veins; sulphides; hydrothermal systems; hydrothermal alteration; intrusions; bedrock geology; lithology; volcano-sedimentary strata; sedimentary rocks; iron formations; cherts; greywackes; argillites; pelites; igneous rocks; volcanic rocks; basalts; komatiites; intrusive rocks; diorites; ultramafic rocks; mafic rocks; metamorphic rocks; structural features; folds; shear zones; faults; faults, normal; structural analyses; structural trends; fold geometry; structural domains; mineral assemblages; petrographic analyses; host rocks; whole rock geochemistry; x-ray diffraction analyses; core samples; graphite; silicates; Archean; Canadian Shield; Churchill Province; Rae Craton; Amaruq Deposit; Woodburn Lake Group; Rumble Assemblage; Whale Tail Zone; IVR Zone; Snow Island Suite; Woodburn Lake Greenstone Belt; Rae Domain; Neoarchean; Paleoproterozoic; Precambrian; Proterozoic
Illustrationslocation maps; geoscientific sketch maps; stratigraphic columns; geochemical plots; ternary diagrams; tables; photographs; photomicrographs; cross-sections
ProgramTargeted Geoscience Initiative (TGI-5) Gold ore systems
Released2020 06 11; 2023 03 17
AbstractThe Amaruq gold deposit in Nunavut is underlain by the Neoarchean (ca. 2.73-2.63 Ga) supracrustal rocks of the Woodburn Lake group, within the Rae Craton of the Churchill Province. The mineralized zones are hosted in polydeformed, upper greenschist-facies banded iron formation and volcanic and sedimentary rocks of the Rumble assemblage. The assemblage includes rocks of contrasting rheology and geochemistry, such as greywacke, chert, graphitic argillite, komatiite, and komatiitic basalt, which have been deformed and metamorphosed in the Archean and during subsequent Paleoproterozoic orogenesis. In the Amaruq area, several generations of structures are recognized: 1) tight and isoclinal F1 folds and D1 shear zones; and 2) upright and isoclinal northeast-plunging F2 folds and associated D2 shear zones that host the bulk of gold mineralization. Progressive strain accommodation during D2 deformation led to the development of northwest-verging overthrust and recumbent F2 folds. Subsequent deformation consists of open to chevron-style, northeast- and southwest-plunging F3 folds, and north- and east-striking D4 and D5 normal faults and shear zones, respectively. The two principal mineralized areas of the Amaruq deposit, the Whale Tail and IVR, comprise contrasting styles, geometry, and distribution of ore zones in distinct structural domains. The Whale Tail area is primarily characterized by stratabound and locally discordant disseminated to semi-massive pyrrhotite-arsenopyrite-gersdorffite replacement-style orebodies in chert-poor silicate-facies iron formation, and by 'silica flooding' zones associated with arsenopyrite-löllingite-pyrrhotite in chert-rich silicate-facies iron formation. The IVR area occurs in an overturned F2 fold-hinge zone and consists predominantly of shallowly southeast-dipping quartz±carbonate veins that cut the host volcano-sedimentary sequence. Proximal alteration is characterized by variable amounts of Ca-amphibole-feldspar-epidote-muscovite-biotite-carbonate. Petrographic relationships of metamorphic and auriferous sulphide minerals indicate that prograde upper greenschist metamorphism is coeval with D2 deformation. Native gold was in part exsolved from prograde löllingite during retrograde metamorphism to lower greenschist facies associated with D3 deformation. The crosscutting relationships between the contrasting ore styles suggest a protracted, multiphase hydrothermal history. The age and relative timing of the gold mineralization represent key issues that are being addressed to help in the development of improved exploration models for banded iron formation-hosted/associated gold deposits in the Churchill Province and other Archean terranes.
Summary(Plain Language Summary, not published)
The main objective of phase 5 (2015-2020) of Natural Resources Canada and Geological Survey of Canada's Targeted Geoscientific Initiative (TGI) program was to generate new knowledge, methodologies and models to enhance the exploration industry's ability to detect buried ore deposits. This synthesis volume contains 20 individual papers that discuss craton to deposit-scale characteristics of auriferous deposits, plus some support material pertaining to the TGI-5 Gold project.

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