The Imaapik Complex comprises two units: 1) orthopyroxene intrusive and metamorphic rocks (ApPima1), and 2) massive purplish tonalite (ApPima2).

Rocks of this complex are characterized by orthopyroxene replaced to varying degrees by serpentine and fibrous amphiboles, locally leaving only preserved pyroxene cores. The Imaapik Complex is made up of little deformed intrusive rocks. It also includes orthogneiss and migmatites similar to those of the Kangiqsualujjuaq and Fougeraye complexes, except that those assigned to the Imaapik Complex contain orthopyroxene. The units surrounding the Imaapik Complex are also highly migmatized.

Gneissic and migmatitic rocks as well as diorites occur as enclaves within intrusive rocks and are in places highly assimilated. On some outcrops, intrusive rocks are dominant, particularly in the central part of the complex, but they mostly occur as diffuse intrusions (10-30%) within the other lithologies of the complex. These intrusions occur as dykes, clusters, but most often as bands parallel to gneissosity. Outcrops are complex and heterogeneous; the brown sugar to greenish colour and smoky quartz make it difficult to determine the composition of the rock. Contacts between the different lithologies are generally not very contrasted and may only be visible by a slightly different grain size.

Gneiss are even grained, fine to medium grained, well foliated and fairly well recrystallized. They contain 5 to 8% ferromagnesian minerals, mainly biotite with some hornblende and relics of orthopyroxene highly altered into a mixture of serpentine and fibrous amphiboles. They display banding formed by alternating tonalite and diorite bands or tonalite and granite bands. Diorite is fine grained and completely granoblastic. In several places, these lithologies are migmatitized and characterized by the presence of wavy and discontinuous banding and biotite schlierens. The mobilisate is granular, brownish to greenish and of variable composition.

Intrusive rocks are brown sugar coloured in fresh exposure and whitish to beige in altered surface. They are massive to very slightly foliated, homogeneous, even grained and medium grained. Their composition is mainly enderbitic but charnockitic phases are also present. These two compositions are impossible to differentiate on outcrops. The rocks are rich in quartz (30-40%), magnetic, and contain 5 to 10% ferromagnesian minerals commonly forming small millimetric to centimetric clusters. They consist of biotite and orthopyroxene with some magnetite and locally hornblende.

The massive purplish tonalite unit (ApPima2) is very homogeneous and limited to the eastern edge of the Imaapik Complex. It is similar to the intrusive phase observed in unit ApPima1 except that the rock, which is purplish grey, is invariably tonalitic in composition and does not contain orthopyroxene. Clinopyroxene was observed locally. Unit ApPima2 locally contains 5-10% enclaves of diorite and tonalitic gneiss.