Percival and Card (1994) defined, in the Minto Lake and Feuilles River area (sheet 34G), a homogeneous unit of hornblende biotite ± horblende granite and leucogranite with a lower amount of pegmatite, which included the Morrice and Dufreboy suites. The Morrice Suite was introduced in the Nedlouc Lake area (sheet 34H; Parent et al., 2000, 2001) to describe homogeneous granite, as well as three small late tonalite intrusions. Later, Morrice granites were recognized in the Aigneau Lake (sheet 24E; Berclaz et al., 2001, 2002), La Potherie Lake (sheet 34I; Leclair et al., 2001, 2002) and Vernon Lake (sheet 34J; Parent et al., 2002, 2003) areas (Simard, 2008). Simard et al. (2008) consider the Morrice Suite to consist exclusively of granite; association with tonalite has not been demonstrated. The authors therefore grouped the three tonalitic intrusions described by Parent et al. (2000, 2001) into a new unit, the Rivière Qijuttuuq Suite. In the Vernon Lake area, Simard et al. (2008) also assigned to the Morrice Suite granites that once belonged to the Le Roy Complex (redefined as a unit composed exclusively of diatexite), based on lithological characteristics and regional distribution of these granites.

The Morrice Suite consists of homogeneous biotite granite, massive to foliated, medium to coarse-grained, locally porphyritic, pinkish in fresh exposure and reddish pink in altered surface (Parent et al., 2000, 2001; Berclaz et al., 2001, 2002; Leclair et al., 2001, 2002; Parent et al., 2002, 2003; MNRF, 2001; Boily et al., 2004; Simard et al., 2005; Simard et al., 2008; Simard, 2008; MNRF, 2010a-f). Granite is leucocratic to locally hololeucocratic and contains 2-15% ferromagnesian minerals. The main mineral phases are quartz, microcline, plagioclase, green biotite and, in smaller amounts, magnetite and hornblende. Biotite is finely disseminated in the rock or as clusters a few millimetres in diameter. The rock commonly contains 1-5% K-feldspar phenocrystals 1-2 cm long, locally microperthitic. Clinopyroxene, muscovite, epidote, titanite, allanite, apatite, sphene and zircon are also present in places as accessory minerals. Along fault corridors, the rock is usually hematitized; this alteration is also accompanied by chloritization and epidotization of ferromagnesian minerals, as well as sericitization of feldspars. Foliation, when present, is generally undulating and marked by biotite alignment, preferential orientation of quartz lenses and a mortar texture (Leclair et al., 2001, 2002).

Pegmatitic phases are commonly associated with granite (Berclaz et al., 2001, 2002; Boily et al., 2004; Simard et al., 2008; Simard, 2008; MNRF, 2010b, d). Granite and pegmatites intrude into the majority of Archean host units and contain enclaves of the latter, reflecting the late character of granitic rocks (Parent et al., 2002, 2003; Simard et al., 2005; Simard et al., 2008; Simard, 2008; MNRF, 2010a, e). Enclaves observed in granite are of various composition: diorite, amphibolite, foliated tonalite, granodiorite, diatexite, garnet paragneiss and mafic gneiss. In the Sulluppagalik Lake area (sheets 34H25 and 34H16), some uranium and thorium mineralized zones were identified. Mineralization is associated with K-feldspar porphyritic granites; it is disseminated in feldspar-fragment biotite-matrix breccias, as well as in hematitized and epidotized pegmatites cutting granite.

Thickness and distribution

The Morrice Suite covers a significant area in the central part of the Minto Subprovince and is distributed over seven sheets (24E, 34G, 34H, 34I, 34J, 34O and 34P). Overall, intrusions follow a general NW-SE direction.

Dating

A granite from the Nedlouc Lake area yielded different Pb-Pb ages on zircon (David et al., 2009). Analysis of three unique crystalline terminations (brownish prisms) yielded a crystallization age of 2684 ±6 Ma, while laser ablation analysis of ten crystals resulted in a crystallization age of 2679 ± 2 Ma and an inherited age of 2708 ±7 Ma. Moreover, two monazite crystals yielded ages of 2669 ±2 Ma and 2674 ±2 Ma. These ages on monazite indicate that intrusive suites of the area were affected by metamorphism contemporaneous to the development of diatexites of the Rivière aux Mélèzes Suite (2668 ±11 Ma; David et al., 2009).