| Titre | Timing and controls on Ni-Cu-PGE mineralization within the Crystal Lake Intrusion, 1.1 Ga Midcontinent Rift |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Smith, J W; Bleeker, W ; Hamilton, M; Petts, D; Kamo, S L; Rossell, D |
| 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. 37-63, https://doi.org/10.4095/326881  Accès ouvert |
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| Année | 2020 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/326881 |
| 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 | Ontario |
| SNRC | 52A/03; 52A/04 |
| Région | Pardee Township; Crook Township; Lac Supérieur |
| Lat/Long OENS | -89.7000 -89.2333 48.1583 48.0000 |
| Sujets | gisements minéraux; nickel; cuivre; palladium; platine; gîtes magmatiques; gîtes sulfureux; genèse des minerais; minéralisation; contrôles des minerais; datation radiométrique; datation au uranium-plomb;
datations au zircon; cadre tectonique; antécédents tectoniques; crevasses; magmatisme; intrusions; filons rocheux; filons-couches; mise en place; xénolites; dynamique des fluides; cristallisation fractionnée; altération; remobilisation; géologie du
substratum rocheux; lithologie; roches ignées; roches intrusives; roches mafiques; roches ultramafiques; gabbros; troctolites; diabases; porphyres; granophyres; roches sédimentaires; grauwackes; mudstones; formations ferrifères; chailles;
associations de minéraux; assemblages de minéraux; analyse par spectromètre de masse; géochimie du soufre; interprétations géophysiques; interprétations magnétiques; analyses des éléments en trace; analyses pétrographiques; distribution des éléments;
Province de Superior ; Intrusion de Crystal Lake ; Formation de Rove ; Formation de Gunflint ; éléments du groupe de platine; Méthodologie; géologie économique; tectonique; géochronologie; pétrologie ignée et métamorphique; minéralogie; géochimie;
géophysique; Sciences et technologie; Nature et environnement; Précambrien; Protérozoïque |
| Illustrations | cartes géolscientiques généralisées; coupes transversales; coupes stratigraphiques; profils; photographies; photomicrographies; tableaux; diagrammes Concordia; graphique à barres;
graphiques |
| Programme | Initiative géoscientifique ciblée (IGC-5) Systèmes de nickel-cuivre-EGP-chrome |
| Diffusé | 2020 09 08; 2023 03 17 |
| Résumé | (disponible en anglais seulement)
North America's 1.1 Ga Midcontinent Rift (MCR) hosts a diverse range of ultramafic and mafic intrusions, many of which contain Ni-Cu-PGE mineralization. The
gabbroic, sulphide-bearing Crystal Lake Intrusion was emplaced between 1095-1091 Ma during the 'main-stage' of rift evolution. The Ni-Cu-PGE mineralization shows a close spatial association with contaminated, Cr-spinel-bearing, vari-textured gabbros.
Despite the MCR having a rich legacy of research, the temporal and spatial controls on ore formation, in addition to the processes critical for ore genesis, remain poorly constrained. Here we present new field, petrographic, and mineralogical
observations, with preliminary U-Pb zircon and baddeleyite isotope dilutionthermal ionization mass spectrometry (ID-TIMS) results for various phases of the Crystal Lake Intrusion to resolve questions regarding the timing of emplacement and its
relationship to other MCR magmatic events, such as the Mount Mollie dyke, the Pigeon River dykes, and the Cu-Ni-bearing Duluth Complex. Results suggest that the sulphide ores at Crystal Lake were formed under low confining pressures from a magma
saturated in volatiles through contamination. The addition of crustal S prior to emplacement, by assimilation and melting of wall rocks and xenoliths entrained in the magma, is considered critical for the genesis of the ores. The local addition of S
in situ, as indicated by S/Se ratios, likely contributed only minor S into the system and is not considered essential for S saturation. Reworking of the magmatic system is indicated within the taxitic units by local brecciation, 'ripped' sulphide
clasts and large (>1 cm) globular sulphides, which may indicate minimal transportation of the ores and the potential of a deeper sulphide pool/source. The pronounced magnetic anomaly of the southern limb may suggest the presence of a feeder dyke in
the south. Palladium (91-99%) and Pt (>99%) reside primarily as platinum group minerals (PGMs) in association with sulphides. The PGM assemblage, which is largely controlled by the availability of semi-metals through contamination, is dominated by Pt
arsenides, Pd-Bi-Sb}Te phases, Pd-Sn}Sb phases, Pd bismuthides, and Pd antimonides. The similarity of the PGM assemblage throughout the Crystal Lake Intrusion indicates crystallization from compositionally similar magmas. The distribution of elements
is consistent with the fractionation of a sulphide liquid, with later low-temperature alteration locally remobilizing elements at the micro-scale. The preferential partitioning of Mo, As, Bi, Re, and Pd into discrete parallel linear features and the
development of a micro-fabric within unaltered sulphide globules suggests localized remobilization of select elements post-sulphide fractionation. |
| 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 | 326881 |
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