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TitleRegional lithogeochemical synthesis of mafic-ultramafic volcanic and intrusive rocks in the Cape Smith Belt, Nunavik, northern Quebec
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorMcKevitt, D J; Lesher, C M; Houlé, M G
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. 99-115, 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
NTS35G/08; 35G/09; 35G/16; 35H/05; 35H/06; 35H/11; 35H/12; 35H/13; 35H/14
AreaNunavik; Ungava Peninsula
Lat/Long WENS -74.3667 -73.0833 61.8000 61.4500
Subjectseconomic geology; geochemistry; stratigraphy; Science and Technology; Nature and Environment; lithogeochemistry; mineral exploration; exploration guidelines; mineral deposits; nickel; copper; cobalt; magmatic deposits; sulphide deposits; ore mineral genesis; mineralization; ore controls; modelling; bedrock geology; lithology; igneous rocks; ultramafic rocks; mafic rocks; komatiites; volcanic rocks; lava flows; basalts; intrusive rocks; gabbros; pyroxenites; peridotites; volcano-sedimentary strata; sedimentary rocks; carbonates; iron formations; structural features; faults; folds; whole rock geochemistry; trace element geochemistry; major element geochemistry; magmatism; volcanism; intrusions; petrogenesis; lithostratigraphy; metallogeny; flow structures; tectonic history; geodynamics; Paleoproterozoic; Circum-Superior Belt; Cape Smith Belt; Katinniq Deposit; Raglan Mining Camp; Kikialik Deposit; Donaldson Deposit; Chukotat Group; Esker Lake Subgroup; Nuvilik Formation; Cécilia Formation; Povungnituk Group; Lamarche Subgroup; Beauparlant Subgroup; Beauparlant Formation; Cross Lake Syncline; Cross Lake Fault; Bergeron Fault; Lac Bélanger Suite; Nituk Formation; platinum group elements; Metadata; Methodology; Precambrian; Proterozoic
Illustrationslocation maps; geoscientific sketch maps; tables; geochemical plots; schematic models
ProgramTargeted Geoscience Initiative (TGI-5) Nickel-copper-PGE-chromium systems
Released2020 09 08
AbstractMore than a century of geological reconnaissance, mapping, and mineral exploration across the Cape Smith Belt has yielded a wealth of geochemical data. However, as is the case with much "big data" that span many years, sources, methodologies, and file types, the data have not been compiled in their entirety in a common format. This research component of the TGI-5 Ni-Cu-PGE-Cr Project was to compile, harmonize, and interpret publicly available lithogeochemical data for volcanic and associated intrusive rocks in the Cape Smith Belt. The current data set includes ~18,800 unique whole-rock analyses from the Cape Smith Belt (87%) and surrounding domains in Nunavik (13%) with major ± trace elements and accompanying metadata (drillhole collars and depths, sample locations, rock descriptions, and references) from 130 sources. Duplications of records from different sources allowed cross-validation and identification of transcription errors, and preliminary QA-QC of data generated for the same rock units using multiple methods revealed differences in sample preparation and analytical methods employed at various laboratories. Analysis of the collated data reveals significant differences in lithogeochemistry, and therefore petrogenesis, of several lithostratigraphic units. In the Southern Domain of the Cape Smith Belt, major and trace element contents can be used to readily distinguish between the major volcanic events; for example, the Povungnituk Group volcanic rocks have higher incompatible (e.g. Th, Nb, LREE, Zr, Ti) and lower compatible (e.g. Mg, Cr, Ni) element contents than those of the Chukotat Group, which have generally lower incompatible and higher compatible element contents. Fractionations in Th/Nb/Yb suggest that the Povungnituk Group formed from magmas derived by low-moderate degree partial melting of a depleted mantle source, whereas the Chukotat Group formed from magmas derived by higher degrees of partial melting of a depleted mantle source with variable degrees of contamination by crustally-derived sediments. Within the Povungnituk Group, coarser grained mafic (gabbroic) rocks of the Lac Bélanger Suite are geochemically indistinguishable from the surrounding finer grained mafic (basaltic) rocks of the Beauparlant Formation, consistent with the coarser grained Lac Bélanger units being thick flows or high-level synvolcanic sills that are geochemically related to but cooled more slowly than the finer grained Beauparlant volcanic rocks. Similarly, thicker and coarser grained olivine orthocumulate-mesocumulate units of the Lac Esker Suite are geochemically related to thinner olivine- and pyroxene-phyric mafic (komatiitic basaltic) volcanic rocks of the Chukotat Group. The units of the Lac Esker Suite can be subdivided into an upper Raglan Trend, comprising poorly differentiated lava channels/invasive channels (Ni-Cu-PGE mineralized) and well differentiated sheet flows/sills (unmineralized), and a lower Expo Trend that includes poorly differentiated bladeshaped dykes (Cu-Ni-PGE mineralized) and well to poorly differentiated sills (unmineralized). Raglan units are characterized by higher Mg, Cr, and Th contents, higher La/Sm ratios, and generally higher Ni/Cu ratios than Expo units. Contrary to some previous interpretations, these geochemical differences suggest that the pyroxene peridotite/melagabbro blade-shaped dykes in the Expo Trend did not feed the peridotite/pyroxenite lava channels in the Raglan Trend. These lithogeochemical characteristics of the stratigraphic units provide important constraints on petrogenetic and metallogenic relationships and therefore the nature of the volcanic-subvolcanic-intrusive plumbing system, and should aid in categorizing potentially prospective units in areas along strike from known sulphide deposits.
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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