Geological Setting

The Project is situated within the Paleoproterozoic Huronian Supergroup of the Southern Province, which extends approximately 450 km from Sault Ste. Marie, Ontario, into western Quebec (Bennett et al. 1991; Figure 5). The Huronian Supergroup comprises a series of steeply dipping metasedimentary rocks with subordinate metavolcanic rocks which were deposited from 2.45-2.02 Ga in a transform rift basin (Hill, 2019; Krough et al., 1984).  The Huronian group sediments were regionally folded during the 2.4-2.2 Ga Blezardian Orogeny (Riller et al., 1999). Several intrusive events occurred contemporaneously with deposition of the Huronian, including the 2.22-2.02 Ga emplacement of the Nipissing Sills (Corfu and Andrews, 1984). The Blezardian Orogeny occurred prior to the intrusion of the Nipissing Sills, which can be observed as the sills intrude across the axial plane of regional folds (Jackson, 1997). The older East Bull Lake intrusions were emplaced from 2.49-2.47 Ga (James et al., 2002). 

An impact at 1.85 Ga formed the Sudbury Igneous Complex (SIC) and an impact structure over 200 km in diameter (Spray et al., 2003; Krough et al., 1984). The SIC includes the richly endowed Ni-Cu-PGE deposits for which Sudbury is famous. Although Penokean-age deformation has been dated within the SIC, the intensity of deformation imposed on the SIC by Penokean compression is still debated (Bleeker et al., 2015; Mukwakwami et al., 2014).

The Penokean Orogeny occurred from 1.86-1.82 Ga and was originally interpreted and inferred to have deformed Huronian Sediments in a north-vergent fold-and-thrust belt (Craddock et al., 2018; Piercey et al., 2007). Penokean deformation is well constrained in the Lake Superior region, but its effects elsewhere are not as well understood (Schulz and Cannon, 2007). A period of felsic magmatism occurred from 1.77-1.69 Ga. This period includes the intrusions of the Killarney granitic suite, the Eden Lake Pluton, the Cutler Batholith, the Gronodine Complex, and the Fox Island Granite (Piercey et al., 2007; Schandl and Gorton, 1994; Davidson et al., 1992). This is coeval with the Yavapai Orogeny, which occurred from 1.77-1.7 Ga. The Yapavai Orogeny is also associated with a regional albitization event in the Southern Province that is documented over a strike length of at least 340km. This event was dated at 1.7 Ga with a possible component at 1.74 Ga at the Scadding Mine Site (Schandl and Gorton, 1994), indicating that albitization is associated temporally with the Yapavai Orogeny and the emplacement of the Killarney granites.

MacDonald’s observation on the SPJ project indicate that the albitites resulting from regional sodic alteration in the Southern Province are folded, brecciated and deformed. These observations indicate that the Penokean Orogeny probably is not associated with significant deformation on the SPJ project, but instead that the Yavapai Orogeny represent peak deformation in the Sudbury region. This is supported by regional structural work in the Sudbury area that indicates that the Sudbury region was considerably reworked during the Yavapai Orogeny (Papapavlou et al., 2018).