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TitreAge and geological setting of the Rankin Inlet greenstone belt and its relationship to the gold endowment of the Meliadine gold district, Nunavut, Canada
AuteurLawley, C J M; McNicoll, V; Sandeman, H; Pehrsson, S; Simard, M; Castonguay, S; Mercier-Langevin, P; Dubé, B
SourcePrecambrian Research vol. 275, 2016 p. 471-495, https://doi.org/10.1016/j.precamres.2016.01.008
Année2016
Séries alt.Secteur des sciences de la Terre, Contribution externe 20150301
ÉditeurPrecambrian Research
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1016/j.precamres.2016.01.008
Mediapapier; en ligne; numérique
Formatspdf; html
ProvinceNunavut
SNRC45D; 45E; 45L; 45M; 46D; 46E; 46L; 46M; 47B/03; 47B/04; 47B/05; 47B/06; 47B/11; 47B/12; 47B/13; 47B/14; 47C/03; 47C/04; 47C/05; 47C/06; 47C/11; 47C/12; 47C/13; 47C/14; 55; 56; 57A; 57B; 57C; 57D; 65; 66; 67A; 67B; 67C; 67D
Lat/Long OENS-104.0000 -86.0000 70.0000 60.0000
Sujetsor; Archéen; ceintures de roche verte; lithogéochimie; datations au uranium-plomb; lithostratigraphie; gisements minéraux; datations au zircon; roches volcaniques; turbidites; filons rocheux; tonalites; granodiorites; conglomérats; roches volcaniques; pétrogenèse; Province de Churchill ; géochimie; géochronologie; Précambrien; Protérozoïque
Illustrationslocation maps; lithographic cross-section; core logs; photographs; schematic cross-section; tables; stereonets; geochemistry charts; geochronology charts; photomicrographs; bargraphs
ProgrammeÉtude des gîtes d'or, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
Archean greenstone belts host a significant proportion of the world's gold, typically in deposits that formed late during greenstone belt formation and cratonization. However, this is not always the case and, in the multiply reworked western Churchill Province (wCP), orogenic lode gold deposition post-dates greenstone belt formation by nearly one billion years. The spatial link between Proterozoic gold and Archean greenstone belts in the wCP is thus particularly striking although its significance is still not fully understood. The Meliadine gold district (2.8 Moz contained Au in reserves, plus an indicated and inferred resources of 5.8 Moz Au) represents an important example of this deposit style and is hosted within the Rankin Inlet greenstone belt (RIGB), which occupies a critical, but controversial position along the largely inferred boundary between the Hearne craton and the Chesterfield block. RIGB felsic volcanic rocks (ca. 2.66 Ga) are structurally intercalated, and broadly coeval, with mafic volcanic and volcaniclastic rocks (2.66-2.64 Ga), turbidite (=2.66-2.64 Ga), argillite, auriferous banded iron formation successions and syn-volcanic granodioritic to tonalitic intrusions (2.67-2.64 Ga). Neoarchean basaltic to andesitic volcanic rocks possess calc-alkaline to primitive arc-like tholeiitic magmatic affinities along with lesser MORB-like basaltic compositions. Geochemically evolved lavas yield depleted 144Nd/143Nd ratios (epsilon-Nd 2.66 Ga = -1.1 to +1.6) that reflect variable interaction with an evolved and hitherto undocumented Meso- to Neoarchean basement underlying the RIGB, whereas transitional, arc-like primitive tholeiitic and MORB-like basaltic samples overlap with the Nd isotopic composition of depleted mantle at ca. 2.66 Ga (epsilon-Nd 2.66 Ga = +1.6 to +2.7). These Neoarchean volcano-sedimentary panels represent the main auriferous rock package within the Meliadine gold district and are intercalated with deformed Paleoproterozoic conglomerate (=2.50 and =2.155 Ga). The latter are, in turn, unconformably overlain by a geochemically distinct pillowed-basalt sequence and a unique carbonate-siliciclastic package that presumably represent the remnants of Paleoproterozoic basins and are not known to host gold. The geological setting of gold deposits thus likely reflects this favourable Neoarchean lithostratigraphy in addition to metamorphism and fluid focusing along the reactivated faults during the collision of the Hearne and combined Chesterfield block-Rae craton at 1.90-1.85 Ga.
Résumé(Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC) est un programme géoscientifique fédéral de collaboration qui fournit à l'industrie les connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. Les roches volcaniques métamorphisées sont des hôtes de première importance pour certaines des plus grandes concentrations d'or au monde. L'IGC-4 se concentre sur l'amélioration des modèles et le ciblage de ces dépôts métamorphisés. Dans la présente, nous présentons de nouveaux résultats découlant de nos travaux sur le terrain et d'analyses géochimiques en ce qui a trait à un assemblage de roches métamorphisées situé près de Rankin Inlet, l'un des plus vastes districts aurifères émergents du Canada (Meliadine). Ces résultats nous permettent d'évaluer les principaux facteurs influant sur la répartition de l'or et de formuler des hypothèses sur la continuité possible de cet assemblage de roches prometteur dans les régions avoisinantes.
GEOSCAN ID297310