| Title | Neoarchean convergent margin-related Ni-Cu mineralization? Axis Lake and Nickel King Ni-Cu deposits in the south Rae craton of the Canadian Shield |
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| Author | Acosta-Góngora, P; Pehrsson, S J; Knox, B; Regis, D; Hulbert, L J; Creaser, R; Ashton, K |
| Source | Precambrian Research 316, 2018 p. 305-323, https://doi.org/10.1016/j.precamres.2018.07.016 |
| Image |  |
| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20180090 |
| Publisher | Elsevier |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Canada |
| Area | Axis Lake; Nickel King |
| Lat/Long WENS | -96.0000 -72.0000 67.6667 66.3333 |
| Subjects | general geology; mineralogy; Nature and Environment; Science and Technology; structural geology; nickel; copper; mineral deposits; intrusions; mafic intrusive rocks; ultramafic rocks; Churchill
Province; Rae Craton; Neoarchean; Canadian Shield; Precambrian |
| Illustrations | location maps; cross-sections; photographs; tables; plots; AFM diagrams |
| Program | GEM2: Geo-mapping for Energy and Minerals South Rae Province Bedrock/Surficial geology |
| Released | 2018 10 01 |
| Abstract | The southern portion of the Rae craton in the Canadian Shield is host to multiple ca. 2.63 Ga Ni-Cu-rich metamorphosed mafic intrusions with noritic, noritic-anorthositic and pyroxenitic compositions,
including those hosting the undeveloped Axis Lake and Nickel King deposits found in northern Saskatchewan and southeast Northwest Territories. In order to understand the setting of these intrusions, and their concomitant mineralization, we
investigated their geochemical and isotopic characteristics. Mineralized intrusions at Axis Lake and Nickel King are metamorphosed up to granulite facies, with local partial melting. The intrusions preserve whole-rock major element geochemistry
consistent with a sub-alkaline basaltic composition (e.g., SiO2=46-54 wt%; TiO2 < 0.5 wt%). In terms of their trace elements, these intrusions have: LREE to HREE enrichments (La/YbPM=2-16), low HREE fractionation (Gd/YbPM=1.0-2.6), well defined
negative Nb (Nb/Nb?=0.06-0.31) and Zr (Zr/ Zr?=0.24-0.41) and variable negative to positive Ti anomalies (Ti/Ti?=0.25-1.38), and Th/Yb versus Nb/Yb distributions consistent with formation in an arc-like setting. The Nd isotope values of the Axis Lake
intrusion (?Ndt2630=+0.3 to +2.1) are more juvenile and closer to the depleted mantle value, relative to those of the Nickel King deposit (?Ndt2630=?2.4 to ?0.4). This agrees with their also distinctive Th/Yb and Nb/Yb distributions suggesting
oceanic and continental arc-like settings, respectively. The Axis Lake and Nickel King Nd isotope compositions are indistinguishable from other arc-like 2.61 to 2.58 Ga mafic to felsic intrusions and volcanic rocks recognized in the Rae craton and
the neighboring Chesterfield block. The age, spatial distribution and geochemistry of the studied intrusions coincide with the initial stages of a recently defined 2.63-2.60 Ga continental arc, the roots of which are found in the south Rae craton.
Our data indicate that Neoarchean intrusions with an arc-like geochemistry may be a significant exploration target in the Rae craton. This broadens possible host suites beyond the established Paleoproterozoic rift-related rocks most commonly
considered as the prime target for Ni-Cu-PGE mineralization. |
| Summary | (Plain Language Summary, not published)
The South Rae craton of the southeastern Northwest Territories and northern Saskatchewan is host to multiple Neoarchean Ni-Cu-rich prospects and
undeveloped deposits contained in magmatic intrusions emplaced along the the Snowbird Tectonic Zone. In general, magmatic derived Ni-Cu deposits are constrain to crustal boundaries where the continental crust is rifted apart, but less often, this
type of ore is found in convergent boundaries somewhat equivalent to that hosting the Andean volcanic range in South America. In this study we characterize the geochemistry of mafic intrusions hosting the South Rae's Nickel King and Axis Lake
deposits, and suggest that these were formed in a convergent margin, distinct from previous rift-related exploration models commonly used in the Canadian shield. This has important implications for future mineral exploration in the area, and also
provides new insights on the Neoarchean tectonic history of the south Rae craton. |
| GEOSCAN ID | 308316 |
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