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Cadieux Suite
Stratigraphic label: [narc]cad
Map symbol: nAcad

First published: 26 February 2018
Last modified: 6 November 2018

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Translation of original French

 

 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
 
None
 
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:Porphyraceous granodiorite
Unit type:Lithodemic
Rank:Suite
Status:Formal
Use:Active

 

 

Background

Hocq (1985) introduced the 485-km2 Lac Cadieux Massif between the Upper Eastmain Greenstone Belt (UEGB) and the Eastmain River to its work. This large felsic package is described as mostly granodioritic. In 1987, Roy clarified the nature of this massif and introduced the Lac Cadieux Granodiorite, which he described as banded and slightly porphyritic. Beauchamp and Massei (2018) refined the nomenclature of this unit and the name Cadieux Pluton. The Cadieux Pluton becomes the Cadieux Suite (Beauchamp and Massei, in preparation).

Description

The Cadieux Suite consists of granodiorite. The unit is very homogeneous and is easily distinguishable from other rocks in the area, particularly its porphyraceous texture from K-feldspar phenocrystals. These phenocrystals are 1 to 3 cm long and may represent 1 to 5% of the rock, with the remainder of the rock being medium-grained. This granodiorite is grey-white in altered surface and grey-pink in fresh exposure. Foliation is visible but light. The main ferromagnesian minerals are biotite (5-10%), amphibole (1-5%) and magnetite. Sphene is commonly observed. The magnetism of the rock moves from weak to moderate, but may be strong locally depending on the amount of magnetite present. The main alterations affecting the rock are mild chloritization and weak hematization. Under the microscope, sphene, epidote and allanite (locally zoned) are present. 

From a geochemical perspective, the Cadieux Suite rocks have a very strong calc-alkaline affinity (Ross and Bédard, 2009). They are peraluminous to metaluminous, but remain type I (Maniar and Picolli, 1989). They plot into the field of volcanic arc granites (Pearce et al., 1984). The rare earth profile does not have any particular anomaly and shows light rare earth enrichment relative to heavy rare earths.

  

 
 

Thickness and Distribution

There are three occurrences of the Cadieux Suite in NTS sheets 33A08 and 33A07. The first, in the northern portion, has the shape of an oval 8 km in the direction of the small axis and 15 km in the direction of the large axis, around which basalts of the Groupe de René mould themselves. The Lac Hécla Anticlinal crosses the heart of the pluton parallel to the main axis. The second occurrence runs south of the western branch of the UEGB along its entire length, from the south of Bohier Island in the east to sheet 33A07 in the west. 

Dating

None.

Stratigraphic Relationship(s)

The Cadieux Suite is in contact with rocks of the UEGB (René and Bohier groups), paragneiss of the Laguiche Complex and tonalite of the Misasque Suite. The suite is actually younger and less deformed than all the units it intrudes. 

Paleontology

Does not apply.

References

Author(s)TitleYear of PublicationHyperlink (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 Mistassini, municipalité Eeyou Istchee Baie-James, Québec, Canada. Ministère de l’Énergie et des Ressources naturelles, Québec.2018Bulletin géologiQUE
BEAUCHAMP, A.-M. – MASSEI, F.Géologie et potentiel minéral de la région du lac Cadieux, sous-provinces d’Opatica et d’Opinaca, région Eeyou Istchee Baie-James, Québec. Ministère de l’Énergie et des Ressources naturelles, Québec.In preparationBulletin géologiQUE
HOCQ, M.Géologie de la région des lacs Campan et Cadieux, Territoire-du-Nouveau-Québec. Ministère des Ressources naturelles, Québec; 188 pages.1985ET 83-05
MANIAR, P.D. – PICCOLI, P.M.Tectonic discrimination of granitoids. Geological Society of America Bulletin; volume 101, pages 635-643.1989Source
MCDONOUGH, W.F. – SUN, S.S.The composition of the earth. Chemical Geology; volume 120, pages 223-253.1995Source
PEARCE, J. A. – HARRIS, N. W. – TINDLE, A.G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology; volume 25, pages 956-983.1984Source
ROSS, P.-S. – BÉDARD, J.H.Magmatic affinity of modern and ancient subalkaline volcanic rocks determined from trace-element discriminant diagrams. Journal Canadien des Sciences de la Terre; volume 46, pages 823-839.2009Source
ROY, C.Géologie du secteur de l’île Bohier de la bande volcanosédimentaire de la rivière Eastmain supérieure. Ministère des Ressources naturelles; 115 pages.1988MB 88-16

 

6 novembre 2018