| Titre | Structural-stratigraphic setting and U-Pb geochronology of Ni-Cu-Co-PGE ore environments in the central Cape Smith Belt, Circum-Superior Belt |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Bleeker, W ; Kamo,
S L |
| Source | Targeted Geoscience Initiative 5: Advances in the understanding of Canadian Ni-Cu-PGE and Cr ore systems - Examples from the Midcontinent Rift, the Circum-Superior Belt, the Archean Superior Province, and
Cordilleran Alaskan-type intrusions; par Bleeker, W (éd.);
Houlé, M G (éd.); Commission géologique du Canada, Dossier public 8722, 2020 p. 65-98, https://doi.org/10.4095/326882  Accès ouvert |
| Image |  |
| Année | 2020 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/326882 |
| Media | en ligne; numérique |
| Référence reliée | Cette publication est contenue dans Targeted
Geoscience Initiative 5: Advances in the understanding of Canadian Ni-Cu-PGE and Cr ore systems - Examples from the Midcontinent Rift, the Circum-Superior Belt, the Archean Superior Province, and Cordilleran Alaskan-type intrusions |
| Formats | pdf |
| Province | Québec; Nunavut |
| SNRC | 24M; 24N; 25C/04; 25C/05; 25C/12; 25C/13; 25C/14; 25D; 25E; 25F; 35A/13; 35A/14; 35A/15; 35A/16; 35B/13; 35B/14; 35B/15; 35B/16; 35C/13; 35C/14; 35C/15; 35C/16; 35D; 35E/16; 35F; 35G; 35H; 35I; 35J; 35K;
35L/01; 35L/08; 35L/09 |
| Région | Nunavik; Ungava Peninsula |
| Lat/Long OENS | -79.0000 -69.0000 63.0000 59.0000 |
| Sujets | gisements minéraux; nickel; cuivre; cobalt; gîtes magmatiques; gîtes sulfureux; genèse des minerais; minéralisation; contrôles des minerais; établissement de modèles; géologie du substratum rocheux;
lithologie; roches sédimentaires; turbidites; mudstones; conglomérats; grès; roches ignées; roches ultramafiques; roches mafiques; komatiites; roches volcaniques; coulées de lave; basaltes; roches intrusives; gabbros; caractéristiques structurales;
failles; failles, chevauchement; plis; synclinaux; structures anticlinale; antécédents géologiques; développement du bassin; antécédents tectoniques; cadre tectonique; métamorphisme; déformation; magmatisme; volcanisme; intrusions; filons-couches;
filons rocheux; érosion; manteau terrestre; crevasses; décollement; orogenèse; travaux de prospection; échantillons carrotés; datation radiométrique; datation au uranium-plomb; datations au zircon; roches hôtes; fluage; structures flui dales;
analyses géométriques; trajectoires d'écoulement; analyses structurales; analyses stratigraphiques; lithostratigraphie; corrélations stratigraphiques; craton; interprétations géophysiques; interprétations magnétiques; Paléoprotérozoïque; Ceinture de
Circum-Superior ; Ceinture de Cape Smith ; Craton de Supérieur; Faille de Cross Lake ; Dépôt de Donaldson ; Terrane de Narsajuaq ; Groupe de Chukotat ; Groupe de Povungnituk ; Groupe de Parent ; Groupe de Spartan ; Groupe de Watts ; éléments du
groupe de platine; géologie économique; géochronologie; géologie structurale; stratigraphie; géophysique; Sciences et technologie; Nature et environnement; Précambrien; Protérozoïque |
| Illustrations | cartes géolscientiques généralisées; coupes schématiques transversales; échelles stratigraphiques; diagrammes Concordia; photomicrographies; histogrammes; cartes géochronologiques; modèles;
photographies; représentations schématiques |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes de nickel-cuivre-EGP-chrome |
| Diffusé | 2020 09 08; 2023 03 17 |
| Résumé | (disponible en anglais seulement)
The economically important Cape Smith Belt of northern Quebec represents a key segment of the "Circum- Superior Belt", preserving a ~12-15 km thick record of
Paleoproterozoic stratigraphy in a south-vergent, mostly north-dipping fold-thrust belt. The central part of this belt is only moderately deformed and experienced merely sub-biotite grade metamorphism. It hosts world-class Ni-Cu-Co-PGE mineralization
in both extrusive and intrusive settings that, at present, form the basis for two integrated mining operations. Collectively, these attributes make this belt unique in Canada and the world. A detailed, holistic understanding of this belt has been
hampered, however, by conflicting interpretations on the degree of thrust stacking, and a lack of accurate and precise ages for critical elements of the stratigraphy. Here we report on new fieldwork and drill core observations-collected over several
summers-that resolve many of the outstanding questions and provide a more detailed stratigraphic framework for the mineralization and the belt as a whole. We integrate these data and observations with new high-precision U-Pb ages for ~10 critical
rock units, from the Cape Smith Belt and other parts of Circum-Superior Belt, as well as relevant parts of the overall craton-scale ore system. We briefly describe the different ore settings of the Cape Smith Belt and place these in the
structuralstratigraphic framework. We show that the central part of the Cape Smith Belt is more coherent and less imbricated by thrusts than previously interpreted. The important Nuvilik Formation of thinly bedded distal turbidites and sulphidic
mudstones forms a stratigraphic unit at the top of the Povungnituk Group, reflecting a phase of basin formation and deepening following volcanism of the ca. 1959 Ma Cecilia Formation. Neither the lower contact nor the upper contact of the Nuvilik
Formation is a regional thrust. At 1883-1882 Ma, the Nuvilik sulphidic mudstones formed the ambient seafloor across which high-volume, hot, Mg-rich lavas of the Chukotat Group were emplaced, which included high-flow rate, turbulent, channelized
komatiite flows, thus bringing into direct contact the most dynamic magma system of the belt with a ubiquitous, prolific sulphur source. Although Chukotat magmas may have been at sulphur saturation on final ascent, thermo-mechanical erosion of the
lava channels into underlying Nuvilik mudstones, and mixing and melting of sulphidic sediments into the channels, led to massive sulphur oversaturation and accumulation of net-textured and massive sulphides. Our ages show that all of this happened
during the onset and climax phase of the Chukotat magmatic event, which lasted ~2 Myr and occurred at the same time as similar events more than 1500 km away, in Thompson, Manitoba. At Raglan, we describe one well preserved lava and ore channel where,
in present coordinates, flow was demonstrably down-dip and to the north-northeast. This is the first observation of flow polarity. We prefer an overall model of several anastomosing, subparallel lava channels presently plunging down to the
north-northeast, not a single, giant, meandering lava channel subparallel to the trace of the basal Chukotat lavas on the present erosion surface. The observed flow direction makes it feasible, if not likely, that the channelized komatiite flows were
fed from an eruptive fissure system ~25 km to the south, which would suggest a "processing length" of ~25 km to achieve optimal mixing, sulphide saturation, and segregation at high R-factors. At the craton scale, the overall model that best explains
the rich spectrum of phenomena is that of a hot mantle upwelling ascending from a deep thermal boundary layer to impinge on the base of the lithosphere of the Superior craton, or rather its ancestral supercraton Superia, prior to final breakup. Rapid
lateral flow of hot buoyant mantle to lithospheric "thin spots", such as active or pre-existing rifts or delamination scars, caused nearly synchronous, high-volume, ultramafic-mafic magmatism around what ultimately became the margins of a fully
separated Superior craton. Although the overall magmatic event has a younger tail, to as young as 1878 Ma, and also a distinct younger pulse at ca. 1870 Ma, the early onset and climax phase of high-volume ultramafic-mafic magmatism is most
prospective for economic Ni-Cu-Co-PGE mineralization. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Les principaux objectifs de la phase 5 (2015-2020) du programme de l'Initiative géoscientifique ciblée (IGC) de Ressources naturelles Canada et
de la Commission géologique du Canada étaient de générer de nouvelles connaissances, méthodologies et modèles afin d'améliorer la capacité de l'industrie de l'exploration à détecter les gisements de minerai enfouis et les extensions des systèmes de
minerai existants, et de fournir des modèles pour cibler de nouvelles zones de gisement. Ce volume synthèse contient neuf articles individuels qui traitent des principales caractéristiques des gisements magmatiques, de l'échelle du dépôt à celui du
système magmatique, à partir de divers exemples canadiens reliés au projet Ni-Cu-PGE-Cr de l'IGC-5. |
| GEOSCAN ID | 326882 |
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