Shawville Intrusive Suite
Stratigraphic label: [mpro]shv
Map symbol: mPshv

First published: 16 June 2023
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):Bilodeau, 2022
Stratotype:Reference outcrops 2021-CB-1198 and 2021-CB-1200
Type area:Municipalities of Clarendon and Shawville, Île-du-Grand-Calumet (NTS sheet 31F10)
Geological province:Grenville Province
Geological subdivision:Allochton
Lithology:Felsic intrusive rocks


The Shawville Intrusive Suite was introduced by Bilodeau (2022) after geological mapping works in the Île-du-Grand-Calumet area in 2021. Similar granite and granitic gneiss units were been described in the surroundings of the Bristol municipality and the locality of Onslow Corner, east of this study area (Sabourin, 1954).



The Shawville Intrusive Suite consists of three small calc-alkaline intrusions, granitic to granodioritic in composition, located in the southern part of the Île-du-Grand-Calumet area. The rocks are leucocratic, fine to medium grained, homogeneous in outcrops and highly foliated. Their alteration patina is light grey with a beige or pinkish tinge. The fresh fracture is pinkish grey. They are composed of quartz, K-feldspar, slightly damouritized plagioclase and minor amounts of biotite and clinopyroxene partially replaced by hornblende. Samples of granodioritic composition contain up to 5% of small plagioclase phenocrysts a few millimetres in size. Some samples are hololeucocratic and highly siliceous. The unit is characterized by a very low opaque mineral content and very weak magnetic susceptibility. Outcrops of greyish granodiorite systematically display small pink felsic bands of millimetric to centimetric thickness. These small bands are perfectly concordant with foliation, and can be distinguished from a family of small, later, subconcordant, white planar injections that have been observed in only a few outcrops.


Thickness and Distribution

The Shawville Intrusive Suite comprises small, elongated plutons of modest dimensions, oriented along the regional NE-SW structural grain. The low concentration of outcrops in the area and the low resolution of geophysical maps make it impossible to estimate the true size of the intrusions. Continuous outcrops on Île Boom suggest a minimum thickness of 550 m for one of the intrusions.



Stratigraphic Relationship(s)

Intrusions of the Shawville Suite are in intrusive contact with a single unit, the calcitic marble of the Outaouais Supracrustal Sequence. No contact has been observed in the field. The stratigraphic position of the suite in relation to the other intrusive units is not known, as there are no geochronological data on this unit.


Does not apply.


Publications available through SIGÉOM Examine

BILODEAU, C. 2022. Géologie de la région de l’Île-du-Grand-Calumet, Province de Grenville, Outaouais, Québec, Canada. MERN; BG 2022-07, 1 plan.

SABOURIN, R.J.E. 1954. Rapport préliminaire sur la région de Bristol, comté de Pontiac. RP 307, 9 pages et 1 plan.  


Suggested Citation

Ministère des Ressources naturelles et des Forêts (MRNF). Shawville Intrusive Suite. Quebec Stratigraphic Lexicon. [accessed on Day Month Year].


First publication

Carl Bilodeau, P.Geo., M.Sc. (redaction)

Céline Dupuis, P.Geo., Ph.D. (coordination); Abdelali Moukhsil, P.Geo., Ph.D. (critical review); Simon Auclair, P.Geo., M.Sc. (editing); Catherine Tremblay (English version); André Tremblay (HTML editing). 

7 février 2024