Major Building Blocks of Central Canada

University of Saskatchewan: Regional constraints on base metal, precious metal, and uranium mineral systems in the Trans-Hudson orogen, with a focus on Saskatchewan
Speaker: Kevin Ansdell

The Paleoproterozoic Trans-Hudson orogen, exposed in northern Manitoba and Saskatchewan, developed during the evolution and closure of the Manikewan Ocean resulting from intra-oceanic accretionary events, and complex collisions with the Archean Sask, Hearne, and Superior cratons. These rocks are host to hydrothermal base metal and precious metal systems, and the aim of this presentation will be to provide constraints on their regional and local characteristics, with a focus on examples in the western Reindeer Zone in Saskatchewan.

The oldest deposits are volcanic-hosted Cu-Zn deposits (e.g. McIlvenna Bay region, Brabant-McKenzie) that are considered to have formed synchronous with active arc and back-arc systems. These have been deformed and metamorphosed during later collisional events, destroying primary relationships. Fluids generated during prograde metamorphism may have interacted with the older deposits, and were, in places, auriferous. These fluids were focused into regional structures, leading to localized formation of orogenic gold deposits, such as those within the La Ronge, and Pine Lake greenstone belts.

The Paleoproterozoic rocks are unconformably overlain in the west by the uranium-rich Athabasca Basin. Reactivation of older structures, and interaction with rocks in the Reindeer Zone and the Archean Hearne/Rae cratons to the west, are important elements of the uranium system.

Province of Manitoba: Geology and mineral deposits of the Thompson Nickel Belt, central Manitoba 
Speaker: Chris Couëslan

The Thompson Nickel Belt forms a segment of the Superior Boundary Zone, along the northwestern margin of the Superior craton in Manitoba. The belt is host to one producing nickel mine, seven mines that are past-producing or on care and maintenance, and numerous deposits.  

The nickel deposits were generated when ca. 1.88 Ga ultramafic rocks intruded sulphide-rich sedimentary rocks of the Paleoproterozoic Ospwagan Group. Intense deformation and metamorphism during the ca. 1.80 Ga Trans-Hudson Orogen resulted in the local remobilization of nickel sulphides into regional fold noses and parasitic fold hinges.  

Conductors and ultramafic rocks associated with Ospwagan Group stratigraphy in regional fold hinges make prime exploration targets for nickel in the belt. A recent gold discovery in the northern portion of the belt suggests there may be a historically overlooked potential for precious metals in the Thompson Nickel Belt. 

Manitoba Geological Survey: Preliminary mapping results from Thompson Lake: Back to Basics with a Splash of New
Speaker: Kyle Reid

The structural complexity and felsic-dominated character of volcanic rocks in the Sourdough Bay block present challenges to understanding volcanic stratigraphy that is critical to effective volcanogenic massive sulphide exploration.

Mapping in 2026 capitalizes on recent forest fires that revealed large amounts of outcrop that had previously been heavily forested and covered with lichen. Initial reconnaissance was completed via a real-time kinematic position capable drone collecting detailed imagery, which was processed using photogrammetry to build a digital elevation model for the map area.

This imagery and elevation model were then used to assist bedrock geological mapping and structural interpretation as well as identify felsic volcaniclastic sequences that are bracketed by subordinate mafic flows that define a stratigraphy that can be traced from the centre of Thompson Lake (northern peninsula) through the North Star volcanogenic massive sulphide deposit to Murray Lake.

Geological Survey of Canada: Craton Reconstructions and Plume Tracks in Deep Time: Implications for the Geology of the NW Superior Craton
Speaker: Woulter Bleeker

Of the 35 preserved Archean cratons around the world, most if not all are fragments, or fragments of fragments, of late Archean “supercratons”, i.e. the larger landmasses to which these craton fragments trace their ancestry (Bleeker, 2003). At least two large independent supercratons, “Superia” and “Sclavia”, named after their well-preserved internal fragments, had formed by the late Archean and underwent progressive breakup during the early Paleoproterozoic, from ca. 2.2 Ga to 1.9 Ga. Based on well-populated apparent polar wander paths, these supercratons moved independently, and, hence, the notion of a single, long-lived, late Archean supercontinent “Kenorland” cannot be correct, aside from being hard to test.

Craton fragments can be correlated and put back together again by matching distinctive basement geology, by correlating pre-breakup epicontinental basin remnants, and by correlating pre- to syn-breakup large igneous provinces, particularly their dyke swarms. Large dyke swarms, being vertical and intruding far back into cratonic hinterlands, are relatively insensitive to uplift and erosion. They provide robust piercing points, can be precisely dated, and can yield high-quality paleopoles. Of all the dispersed Archean cratons, more than 10 trace their origin back to supercraton Superia, representing “nearest neighbour” fragments to the large Superior craton: Karelia and Kola, Wyoming, Hearne, Kaapvaal and Pilbara, Yilgarn, Zimbabwe, Sask, North Atlantic craton, and possibly Dharwar. Kaapvaal-Pilbara, as part of a large ancient superterrane that also included Wyoming, joined a growing Superia late in the game at ca. 2660 Ma, and separating again ~700 Myr later, leaving the ancient Minnesota River Valley terrane behind—one of the earliest examples of “terrane swap”. Also “greater Karelia” may have been part of this ancient superterrane. Yilgarn is best matched, belt-by-belt, to the western margin of the Superior, with major implications for Manitoba mineral potential. Wyoming and Hearne broke off Superia as one piece and likely represent a single craton.

 With a robust reconstruction of Superia, many other important new insights follow, including on ancient mantle plume tracks. Here we present evidence for two major plume tracks, both starting within Superia’s core, one at 2480 Ma (the “Matachewan track”), the other at 2125 Ma (the “Marathon track”). The Matachewan plume track is particularly relevant to the position of Karelia within supercraton Superia (Davey et al., 2020) and spawned some of Europe’s largest mafic layered intrusions. The Marathon plume track, after crossing over into then-contiguous Kaapvaal, first spawned 2060 Ma carbonatites (e.g., Phalaborwa), before culminating with the emplacement of the Bushveld Complex at 2056 Ma (Bleeker et al., 2025).