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TitleTargeting Ni-Cu mineralization in the Canadian High Arctic large igneous province: integrating geochemistry, magmatic architecture and structure
AuthorSaumur, B M; Williamson, M -CORCID logo; Bédard, J H
SourceMineralium Deposita 2021 p. 1-37,
Alt SeriesNatural Resources Canada, Contribution Series 20200796
Mediapaper; on-line; digital
File formatpdf; html
AreaEllesmere Island; Canada
Lat/Long WENS-114.0000 -59.0000 83.0000 76.0000
Subjectsgeochemistry; Science and Technology; metallogeny; Canadian Arctic; Structural geology
Illustrationslocation maps; satellite imagery; photographs; diagrams; tables; cross-plots
Released2021 05 12
AbstractMafic-ultramafic subvolcanic intrusive complexes, at the 1-10-km scale, constitute favorable environments for the formation of orthomagmatic Ni-Cu-PGE sulfide deposits. Within 100-1000-km scale large igneous provinces (LIPs), the most favorable economic target areas may be difficult to identify using a traditional regional exploration approach. We report results of field and laboratory studies focused on an integrated geochemical-architectural model for the Ni-Cu-PGE sulfide potential of the High Arctic large igneous province (HALIP) of Canada, the largest and best-exposed portion of this circum-arctic LIP. Previous lithogeochemical studies of the Canadian HALIP (130–80 Ma) concluded that subalkaline mafic units located on Axel Heiberg Island were more prospective than younger, alkalic igneous rocks (alkaline basalts to basanites) exposed on northern Ellesmere Island. Mapping carried out for this study revealed the presence of abundant subalkaline igneous rocks on western Ellesmere Island. We interpret these units as an extension of the Schei Sills, a stratigraphically bound sequence of intrusions exposed along a~N-S belt on eastern Axel Heiberg Island. Samples from the Schei Sills and from the Middle Fiord Intrusive Complex (~ 20 km2, central Axel Heiberg Island) show Cu/Zr values above and below unity, consistent with complementary sulfide enrichment and removal, respectively, within these intrusive systems. The spatial association of the Schei Sills with the post-emplacement Eocene Stolz Thrust is noteworthy, as later thrusting associated with the Paleogene Eurekan Orogeny caused the uplift of deeper parts of the HALIP subvolcanic feeder system and associated wall-rock stratigraphy. Absolute Ir-group PGE contents are low throughout the HALIP; however, Pt-group PGE contents range widely among analyzed tholeiitic intrusive rocks. For example, relatively elevated Pt+Pd values of 10-30 ppb in samples from the Middle Fiord Intrusive Complex and the Schei Sills suggest heightened prospectivity in these two areas. In contrast, tholeiitic flood basalts in the Strand Fiord Formation and associated intrusions exposed in western Axel Heiberg Island (~ 95 Ma) exhibit Cu/Zr<1 and low Pt+Pd contents (below 10 ppb). The ca. 120 Ma magmatic event associated with the Schei Sills and Middle Fiord Intrusive Complex appears to have generated magmas that are more prospective than those of the younger (ca. 95 Ma) magmatic pulse associated with the flood basalts of the Strand Fiord Formation. This work demonstrates that not all architectural elements of a LIP are equal in terms of metallogenic potential, and that nested zones of higher prospectivity can be identified through the integration of several geological constraints.
Summary(Plain Language Summary, not published)
In this paper, we highlight the results of geochemical and structural studies carried out under the Geo-mapping for Energy & Minerals Program (GEM-2). The objective of the study was to re-examine the Ni-Cu-PGE potential of the High Arctic Large Igneous Province (HALIP) with a focus on regional mapping and sampling on Axel Heiberg Island and Northern Ellesmere Island. Our data suggest that the Middle Fiord volcanic-intrusive complex and the Schei Sills emplaced during the initial pulse of the HALIP (120 Ma) constitute the most prospective areas.

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