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TitleThe Midcontinent Rift and its mineral systems: overview and temporal constraints of Ni-Cu-PGE mineralized intrusions
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorBleeker, WORCID logo; Smith, JORCID logo; Hamilton, M; Kamo, S; Liikane, D; Hollings, P; Cundari, R; Easton, M; Davis, D
SourceTargeted 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; by Bleeker, WORCID logo (ed.); Houlé, M G (ed.); Geological Survey of Canada, Open File 8722, 2020 p. 7-35, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in 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
File formatpdf
NTS41J; 41K; 41N; 41O; 42B; 42C; 42D; 42F; 42G; 42J; 42K; 42L; 52A; 52B; 52G; 52H; 52I; 52J
AreaLake Superior; Michigan; Wisconsin; Minnesota; Canada; United States of America
Lat/Long WENS -92.0000 -82.0000 51.0000 46.0000
Subjectseconomic geology; tectonics; geochronology; geophysics; Science and Technology; Nature and Environment; mineral deposits; nickel; copper; magmatic deposits; sulphide deposits; ore mineral genesis; mineralization; ore controls; modelling; radiometric dating; uranium lead dating; bedrock geology; lithology; igneous rocks; tholeiites; intrusive rocks; mafic rocks; ultramafic rocks; kimberlites; gabbros; carbonatites; tectonic setting; tectonic history; rifts; magmatism; intrusions; dykes; sills; provenance; mantle; drillholes; alkalinity; geophysical interpretations; magnetic interpretations; Midcontinent Rift; Superior Province; Crystal Lake Intrusion; Current Lake Intrusive Complex; Sunday Lake Intrusion; Tamarack Intrusive Complex; Bovine Igneous Complex; Duluth Complex; Pigeon River Dyke Swarm; Portage Lake Volcanic Group; Thunder Bay North Complex; Coldwell Complex; Eagle Intrusion; Eagle East Intrusion; Cloud River Dykes; Logan Sills; Mount Josephine Dyke; Mount Mollie Dyke; Echo Lake Intrusion; Mellen Complex; Beaver Bay Intrusion; Sonju Lake Intrusion; platinum group elements; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; tables; photographs; photomicrographs; Concordia diagrams; cross-sections
ProgramTargeted Geoscience Initiative (TGI-5) Nickel-copper-PGE-chromium systems
Released2020 09 08; 2023 03 17
AbstractIn an effort to better understand the spatial and temporal distributions of mineralized intrusions of the Midcontinent Rift (MCR), and what controls their style of magmatic Ni-Cu-PGE sulphide mineralization, we have compiled an overview of all known intrusions and their ages. We provide new U-Pb ages for more than ten such intrusions and/or their associated dyke systems. A number of these investigations are still in progress, and all ages should be treated as preliminary. Nevertheless, we discuss new results on the mineralized Current Lake, Sunday Lake, Tamarack, and Crystal Lake intrusions, as well as the Bovine Igneous Complex on the southern flank of the MCR. These new results, as well as improved ages for a number of the associated major dyke swarms and sill complexes (e.g. the Logan Sills), favour a relatively sharp onset of high-volume mafic-ultramafic magmatism in the MCR at ca. 1110 to 1106 Ma, although a few of the older age "outliers" remain to be tested. Mineralized intrusions are not confined to any specific magmatic pulse but are distributed through time, correlating with the major magmatic pulses at 1110-1106 Ma (e.g. Current Lake), 1104 Ma (Tamarack), of course at 1099 Ma (Duluth Complex), to as young as 1093 Ma (Crystal Lake). All these intrusions are dynamic, multi-phase, feeder-type systems. A major "post-Duluth Complex" reorganization in the magmatic plumbing system is identified starting at ca. 1097-1096 Ma, with magmatism contracting into a linear feeding zone along the northwestern shore of Lake Superior-the "north shore magmatic feeder zone" or NSMFZ-cored by the major Pigeon River dyke swarm. This feeder zone, a major magmatic fissure system, likely fed the entire lava flow field of the Portage Lake Volcanic Group, which extends to both sides of Lake Superior.
Summary(Plain Language Summary, not published)
Key objectives of Phase 5 (2015-2020) of the Targeted Geoscientific Initiative (TGI) program of Natural Resources Canada and the Geological Survey of Canada were to generate new knowledge, methodologies, and models to enhance the exploration industry's ability to detect buried ore deposits and extensions of existing ore systems, and to provide models for targeting new deposit areas. This synthesis volume contains nine individual papers that discuss deposit scale to magmatic system fundamentals from various Canadian examples pertaining to the TGI-5 Ni-Cu-PGE-Cr project.

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