Hocq (1985) introduced the 485 km² Lac Cadieux Massif between the Upper Eastmain Greenstone Belt (UEGB) and the Eastmain River during its work. This large felsic to intermediate package is described as mostly granodioritic. Later, Roy (1988) clarified the nature of this massif and introduced the Lac Cadieux Granodiorite, described as banded and slightly porphyritic. Beauchamp et al. (2018) refined the nomenclature of this unit and renamed it the Cadieux Pluton. Since two additional intrusive masses were identified in sheets 33A08, 33A07 and 33A02, the Cadieux Pluton became the Cadieux Suite (Beauchamp, 2020).

The Cadieux Suite consists mainly of quartz monzodiorite and granodiorite. The unit is very homogeneous and is easily distinguishable from other rocks in the area, particularly by its K-feldspar porphyraceous texture. Zoned phenocrystals are 1 to 3 cm long and may represent 1 to 20% of the rock, with the remainder of the rock being medium grained. The rock is grey-white in altered surface and grey-pink in fresh exposure. The S_n foliation is prominent and marked by the alignment of ferromagnesian minerals along flattening planes. The main ferromagnesian minerals are biotite (1-15%), hornblende (1-10%) and magnetite. Sphene is commonly observed (1-3%). In thin section, epidote and allanite (locally zoned) are present. The rock’s magnetism varies from moderate to strong depending on the amount of magnetite present. The main alterations affecting the rock are mild chloritization and weak hematization.

From a lithogeochemical perspective (Beauchamp, 2020), the Cadieux Suite rocks are of calc-alkaline affinity (Frost et al., 2001). They are generally metaluminous and type I (Maniar and Picolli, 1989). They plot into the field of volcanic arc granites (Pearce et al., 1984). The rare earth profile does not have any particular anomaly and shows light rare earth enrichment relative to heavy rare earths. Rocks of the Cadieux Suite are less magnesian and slightly richer in light rare earths than those of the Macleod Batholith and the Lépante Suite. The spider diagram nomalized to the CI chondrite (McDonough and Sun, 1995) shows negative anomalies in Nb, Ta, P and Ti, and positive anomalies in La, Ce and Nd.