Gaël Intrusive Suite
Stratigraphic label: [narc]gae
Map symbol: nAgae

First published: 1 May 2018
Last modified: 14 May 2018








Translation of original French




Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
Author: Beauchamp and Massei, 2018
Age: Neoarchean
Reference section:  
Type area: Bohier Island area (NTS sheet 33A08)
Geological province: Superior Province
Geological subdivision: Opatica Subprovince
Lithology: Diorite
Type: Lithodemic
Rank: Suite
Status: Formal
Use: Active




The Gaël Intrusive Suite was introduced by Beauchamp and Massei (2018) following mapping work conducted by MERN in 2017. The suite consists of a series of dioritic plutons observed on outcrop or described by Eastmain Resources as “felsic intrusive” in its campaign reports (Gerber and Robinson, 2012).



In the literature, rocks belonging to the Gaël Intrusive Suite are poorly documented. They are described as a fine to medium-grained diorite containing hornblende and feldspar (Drouin and Thiboutot 1983; Knowler and Thiboutot 1988).

In outcrop, it is a medium grey diorite, locally brownish and slightly lighter in fresh exposure. It is fine to medium-grained and foliated. Some outcrops show a L-tectonite. The unit has up to 15-20% biotite-epidote clusters and clusters and veins of chloritic alteration that show intense chloritization. In addition to biotite, the rock contains 10% amphibole, 10% epidote, 5% carbonate and opaque minerals often associated with ferromagnesian clusters. Sphene and apatite are accessories. Alterations that affect the rock are intense chloritization, weak to moderate carbonatation with disseminated carbonates and moderate to strong sericitization of plagioclases.

The mineralogical assemblage, the disposition of biotite grains in clusters, and the presence of disseminated carbonates are reminiscent of certain characteristics of the Île Bohier Pluton, which is located a few kilometres north.







Thickness and Distribution

The Gaël Intrusive Suite consists of 8 mapped plutons, the smallest being 130 m x 160 m and the largest being 2 km x 0.8 km. They are located between Érasme and Gaël lakes at distances between 1 and 4 km west of the Eastmain mine. 



Stratigraphic Relationship(s)

The Gaël Invasive Suite cuts the Érasme Formation and the Roman Formation, both members of the René Group. In the event that the Gaël Intrusive Suite is affiliated with the Île Bohier Pluton, it would be contemporaneous to the Roman Formation. 


Does not apply.


Author(s) Title Year of Publication Hyperlink (EXAMINE or Other)
BEAUCHAMP, A.-M. – MASSEI, F. Géologie de la région de l’île Bohier, au contact entre les sous-provinces d’Opatica, d’Opinaca et le bassin d’Otish, au nord de Mistissini, municipalité Eeyou Istchee Baie-James, Québec, Canada. Ministère de l’Énergie et des Ressources naturelles, Québec. 2018 Bulletin géologiQUE
DROUIN, M. – THIBOUTOT, H. Drilling and geological report, Eastmain river project. Placer Development, rapport statutaire déposé au ministère de l’Énergie et des Ressources naturelles, Québec; GM 41013, 165 pages, 29 plans. 1983 GM 41013
GERBER, W. – ROBINSON, D.J. Report on 2010 drilling and mapping programs, Eastmain mine project. Eastmain Resources, rapport statutaire déposé au ministère de l’Énergie et des Ressources naturelles, Québec; GM 66611, 3242 pages, 83 plans. 2012 GM 66611
KNOWLES, R.J. – THIBOUTOT, H. Geological report, F grid extensions 1, 2, 3 – 87, Eastmain river project. Milner Consolid Silver Mines L, Placer Dome, rapport statutaire déposé au ministère de l’Énergie et des Ressources naturelles, Québec; GM 47887, 38 pages, 8 plans. 1988 GM 47887



7 novembre 2018