The term “Flat Point Gneiss” was introduced in Labrador by James et al. (1996) to define a package of amphibolite facies dioritic to tonalitic gneiss. The term was retained by Hammouche et al. (2011) in the Bonaventure Lake area due to the continuity of these rocks in this area. As part of a synthesis of the Southeastern Churchill Province (SECP), Lafrance et al. (2018) identified new lithotectonic domains within the SECP. In the Baleine Lithotectonic Domain, Lafrance et al. (2020) reassigned Flat Point Gneiss units to the Knox Complex.

Field checks in the summers of 2015 and 2016, as well as new geochronological dating, have enabled Flat Point Gneiss units to be related to the Knox Complex. Both of these units include Archean felsic to intermediate gneiss, mafic rock layers and felsic intrusions; they are differentiated only by the presence or absence of orthopyroxene. However, altered orthopyroxene relics or cores in hornblende were locally observed in subunits considered to be orthopyroxene-free (formerly Flat Point Gneiss).

Previously grouped in an undifferentiated unit in the Flat Point Gneiss, different lithologies were associated with different units depending on their composition. For example, felsic to intermediate gneiss, amphibolized gabbro and diorite, and tonalite and granodiorite intrusions were assigned respectively to subunits ApPgkx1b, ApPgkx2b and ApPgkx3b of the Knox Complex.

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