Adélard Plutonic Suite
Stratigraphic label: [mpro]ade
Map symbol: mPade

First published: 4 October 2022
Last modified:




  DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail. 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
Author(s):El Bourki and Moukhsil, 2021
Stratotype:Reference outcrops 2021-ME-1008 and 2021-ME-1012
Type area:Area south and west of Adélard Lake (NW corner of sheet 32H07)
Geological province:Grenville Province
Geological subdivision:Allochton
Lithology:Felsic, intermediate and mafic intrusive rocks


The Adélard Plutonic Suite was defined by El Bourki and Moukhsil (2021) during mapping work in the areas north of Dolbeau-Mistassini (sheet 32H01), Girardville and Blondelas Lake (sheet 32H07), in the Saguenay–Lac-Saint-Jean region.


The Adélard Plutonic Suite consists of a polyphase intrusion composed of charnockite, granite injected gabbronorite, quartz monzonite, alkali feldspar granite and lesser proportions of mangerite and quartz syenite. The lithologies of this intrusion are magnetic to very magnetic, which allows them to be easily identified from aeromagnetic maps and delineated (Intissar and Benahmed, 2015).

Charnockite (hypersthene granite) is pink-brown to pink-grey in alteration patina and pink-grey in fresh surface. The rock is fine to medium grained and foliated to gneissic. It contains quartz, plagioclase, potassium feldspar, biotite, orthopyroxene and magnetite. Under the microscope, orthopyroxene is partially to completely uralitized into greenish amphibole, potassium feldspar is perthitic, quartz is in large patches of undulating extinction and, in places, the plagioclase is sericitized. The charnockite is locally mylonitic, notably in an outcrop near the border of the intrusion with its host rock, which corresponds to a certain fault of unknown movement (e.g., outcrop 2021-FS-4100). This charnockite is characterized by a proportion of 1-2% red garnet and an intense deformation. The proportion of orthopyroxene is variable in outcrop; above 1-2%, the rock changes to a fine to medium-grained, foliated to gneissic syenogranite, grey to brownish in alteration patina and pink-grey in fresh surface (e.g., outcrop 2021-ME-1003). Under the microscope, it contains quartz with undulatory extinction, perthitic and non-perthitic potassium feldspar, locally sericitized plagioclase, magnetite, biotite, and traces of allanite and zircon.


Gabbronorite is black-green in alteration patina and fresh surface (e.g., outcrop 2021-FS-4062). It has a medium to coarse grain size and a subophitic structure, with no significant deformation in the solid state. It consists of plagioclase with polysynthetic twins parallel among themselves, amphibole, pyroxenes (clinopyroxene and orthopyroxene), biotite, magnetite and garnet. Ferromagnesian minerals (biotite, pyroxene, amphibole) and magnetite are concentrated in clusters here and there in the rock. Accessory minerals are apatite and epidote. The gabbronorite is cut by veins and dykes of charnockite and quartz syenite (1 to 10 cm thick).


Quartz monzonite has a grey-black alteration patina and a pink-grey fresh surface. The rock is fine, medium to coarse grained, granoblastic and foliated. It is magnetic with low deformation. It contains quartz, potassium feldspar, plagioclase, biotite, magnetite and traces of orthopyroxene. In general, outcrops of this lithology are cut by injections a few millimetres to a few centimetres thick in the form of pinkish veins of alkali feldspar granite.


The alkali feldspar granite is pink to grey in alteration patina and pinkish-white in fresh surface (e.g., outcrop 2021-FT-3151). The rock is fine to medium grained and foliated. The granite consists of quartz, potassium feldspar, plagioclase, biotite, clinopyroxene and magnetite. It is also injected by massive medium to coarse-grained granite and magnetite. The alkali feldspar granite contains centimetric enclaves of gabbronorite and is also cut by dykes of medium to coarse-grained pinkish syenite and of pegmatite of granitic composition with magnetite.


Mangerite (hypersthene monzonite) is whitish in alteration patina and green in fresh surface, fine to medium grained and foliated. It contains quartz, potassium feldspar, orthopyroxene, biotite and hornblende.


The quartz syenite is mainly mapped as injections into the other lithologies of this suite. Outcrops of this syenite show a variation in the proportions of quartz and potassium feldspar, with the composition of the rock approaching the limit of alkali feldspar granite (e.g., outcrop 2021-ME-1000 with 5.99% K2O). It is pinkish in alteration patina and fresh surface. The rock is fine to coarse grained and magnetic. Microscopically, the rock contains the following minerals: perthitic potassium feldspar, quartz in a large patch with undulatory extinction, plagioclase, biotite, amphibole, magnetite, allanite, myrmekite and zircon. In places, ferromagnesian minerals and magnetite form millimetre-sized clusters in the rock.

Thickness and distribution

The Adélard Plutonic Suite consists of a polyphase intrusion mapped in the NE corner of sheet 32H07. Interpretation of the aeromagnetic maps extends this suite further north (sheet 32H10) and west (corners of sheets 32H06 and 32H11). This interpretation gives it an area of ~144 km².



Stratigraphic Relationship(s)

The Adélard Plutonic Suite is cut by the Vertu Plutonic Suite and the Crevier Alkaline Intrusion.


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Publications available through SIGÉOM Examine


El BOURKI, M., MOUKHSIL. A., 2021. Géologie de la région de Dolbeau-Blondelas, Province de Grenville, région du Saguenay–Lac-Saint-Jean, Québec, Canada. MERN; BG 2022-02, 1 plan.

INTISSAR, R., BENAHMED, S., 2015. Levé magnétique aéroporté dans le secteur ouest du Lac-St-Jean, Province de Grenville. MERN, GOLDAK AIRBORNE SURVEYS; DP 2015-06, 7 pages, 2 plans.


Suggested Citation

Ministère de l’Énergie et des Ressources naturelles (MERN). Adélard Plutonic Suite. Quebec Stratigraphic Lexicon. [accessed on Day Month Year].


First publication

Abdelali Moukhsil, P.Geo., Ph.D.; Mhamed El Bourki, GIT, M.Sc.A. (redaction)

Mehdi A. Guemache, P.Geo., Ph.D. (coordination); Fabien Solgadi, P.Geo., Ph.D. (critical review); Simon Auclair, P.Geo., M.Sc. (editing); Catherine Tremblay (English version). 

12 décembre 2023