The Ouescapis Pluton appears for the first time on the map accompanying the report of Ahmedali and Remick (1974). It is part of a suite of monozodiorite-granodiorite-tonalite-diorite plutons that have developed at the boundary of the Abitibi and Opatica subprovinces (e.g., Barlow, Canet and Ouescapis; Sawyer et al., 1993; Davis et al., 1995).

The Ouescapis Pluton is essentially composed of diorite more or less deformed. Generally massive, it develops a gneissic to migmatitic structure in the area south of Ouescapis Lake. Light gray diorite is composed of hornblende (up to 30%), plagioclase (65 to 80%) and minor amounts of biotite and quartz. Hornblende gives a bird’s eye appearance to massive diorite and defines the foliation of gneissic to migmatitic diorite. In migmatitic diorite, the foliated medium-grained monzonitic to monzodioritic leucosome contains phenocrysts of potassium feldspar, hornblende and biotite. It regularly contains diorite xenoliths 15 to 20 cm in size. The melanosome forms poorly defined centimetric bands of melanocratic hornblende-rich diorite. Restite is a medium-grained, foliated diorite composed of hornblende, biotite and, locally, magnetite. This facies is particularly well developed at the eastern edge of the pluton, on outcrops located in the southern part of Poncheville Lake (NTS sheet 32K02).