The Champdoré Suite was first named “Lac Champdoré Granodiorite” following the work of Bourque in the Mina Lake area during the summer of 1985 (Bourque, 1986, 1991). This unit was extended southward in the Recouet Lake area by Danis (1988). In the Jeannin Lake area, Charette et al. (2016) formally renamed it “Champdoré Suite” to comply with the North American Stratigraphic Code. The unit was also extended southward in the Résolution Lake area as part of the Southeastern Churchill Province synthesis (Lafrance et al., 2020).

The Champdoré Suite consists of two units: granodiorite, monzogranite and quartz monzodiorite (pPchm1), and fine-grained pink granite (pPchm2).

According to Bourque (1991), the development of gneissosity is more important at the edge of the unit, which is closer to contact with diatexites and migmatized paragneiss of the Winnie and False suites. Locally, the different facies of unit pPchm1 develop a protomylonitic texture with the formation of quartz bands, feldspar porphyroclasts and recrystallization tails. These rocks also contain small amounts of stretched enclaves or boudinaged layers of diorite and granoblastic gabbro and ultramafic rocks. These enclaves are small (<1 m) and have sharp contacts, with no reaction rims with the intermediate to felsic host rock. Rocks of unit pPchm1 are commonly cut by intrusions of pegmatitic granite and, in some areas, by decimetric to metric dykes unit pPchm2 granite.

Champdoré Suite 1a (pPchm1a): K-Feldspar Porphyroclastic Granodiorite, Quartz Monzodiorite and Monzogranite

A fairly common last facies is characterized by the presence of 10-25% microcline phenocrystals or porphyroclasts, and light pink orthose 0.5-4 cm long. It is generally impossible to separate the different facies observed because of their close association at the outcrop scale. However, it has been possible in some places to group the porphyritic facies in informal subunit pPchm1a, which forms decametric to kilometric plutons. Based on the close association between well-foliated or gneissic granoblastic rocks and less-deformed facies showing well-preserved igneous textures, Charette et al. (2016) were able to group these different facies into a single unit. This hypothesis was confirmed by the ages obtained in the different facies of the unit.

Champdoré Suite 2 (pPchm2): Fine-Grained Pink Granite

Unit pPchm2 granite is non-magnetic and brownish pink to orange in fresh exposure and white to pinkish in altered surface. It is homogeneous, massive or slightly foliated, even grained and fine to very fine grained (aplite). Igneous textures are well preserved, although there is slight recrystallization locally. Granite contains 2-10% ferromagnesian minerals, mainly dark brown to green biotite and green to blue-green hornblende. The main accessory minerals are epidote, chlorite, muscovite, garnet, allanite, sphene, apatite and zircon. Myrmekitic textures are commonly observed in thin sections.

Thickness and distribution

The Champdoré Suite is located in the SW portion of the Baleine Lithotectonic Domain and covers an area of ~1500 km². In terms of area, unit pPchm1 is the largest (1454 km²) while subunit pPchm1a (67 km²) is much smaller. Unit pPchm2 (4 km²) forms only six plutons a few hundred metres wide.

Dating

Paleoproterozoic crystallization ages (1859-1837 Ma) were obtained in both porphyritic and granoblastic facies of the Champdoré Suite. These ages are contemporaneous to the emplacement of other intrusive units within the Baleine Domain, namely the Lhande Suite (1834 Ma), the Kaslac Complex (1835-1828 Ma), the De Pas Supersuite (1862-1805 Ma), the Kuujjuaq Pluton (1869-1833 Ma), as well as crystallization of diatexites of the Winnie Suite (1839-1838 Ma).