The Sanningajualuk Suite, whose namesake hill is located south of the Inuit community of Ivujivik, was introduced by Charette and Beaudette (2018) to describe late potassic intrusions of the Narsajuac Lithotectonic Domain (formely the Narsajuaq Arc). These intrusive rocks were previously described by St-Onge and Lucas (1992) and St-Onge et al. (1992) as included in the younger plutonic suite of the Narsajuaq Arc, specifically in unit pPNAR4. Dunphy and Ludden (1998) described this suite as an “anatectic suite”. Charette and Beaudette (2018) preferred to distinguish late-orogenic to postorogenic intrusions into different formal units, including the Sanningajualuk Suite, in order to highlight their variable textures, their different intrusion (cross-cutting) and to comply with the North American Statigraphic Code (1983, 2005). This suite has been extended in the Sirmiq Lake area (Vanier and Lafrance, 2020).

The Sanningajualuk Suite is the main unit of late-orogenic to postorogenic intrusions of the Narsajuaq Domain by its volume and distribution over the entire arc’s N-S axis. It is divided into two informal units: the main unit of foliated to massive syenogranite and monzogranite (pPsnn1) and the secondary unit of graphic-textured granite (pPsnn1a).

Unit pPsnn1 consists mostly of syenogranite, which is characterized by its pink to reddish pink colour and its low content in ferromagnesian minerals (<10%). This unit includes, in a lesser proportion, a pinkish beige monzogranite with a coarser-grained syenogranitic pinkish phase in bands or diffuse clusters. Syenogranite and monzogranite share the same structural and textural characteristics. At the outcrop scale, both are characterized by fine to coarse grain variation and, in general, traces of hematite. These granitoids usually show weakly-developed foliation, marked by discontinuous millimetric biotite laminae. In close proximity to regional deformation zones, potassic intrusions of the pPsnn1 unit have strong foliation, contain K-feldspar porphyroclasts a few millimetres to one centimetre and, in places, quartz bands or stretch lineation marked by quartz rods.

Petrographic study of the granite indicates that these rocks are formed by several phases in diffuse contact. A coarse-grained phase, usually richer in K-feldspar and with a smaller proportion of ferromagnesian minerals, occurs as diffuse clusters or bands in a main rock, fine to medium-grained. Biotite is the dominant ferromagnesian mineral and is partially chloritized. Hornblende occurs in ferromagnesian clusters in some samples. It is commonly matted and is partially replaced by biotite. Euhedral allanite crystals are generally observed in association with ferromagnesian laminae or clusters. Few accessory minerals, such as apatite, muscovite, epidote and zircon, are observed in thin sections. In deformed zones, the quartzofeldspathic matrix is oriented and has numerous microfractures. Quartz is characterized by subgrain extinction.