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La Tuque Anorthosite
Stratigraphic label: [mpro]tuq
Map symbol: mPtuq

First published: 17 January 2018
Last modified:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Translation of original French

 

 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
None
 
Author:Klugman, 1976
Age:Mesoproterozoic
Reference section:Anorthosite outcrop 17-MR-4064
Type area:Haut-Saint-Maurice (NTS sheet 31P10)
Geological province:Grenville Province
Geological subdivision:Allochton
Lithology:Mafic intrusive rocks
Type:Lithodemic
Rank:Lithodeme
Status:Formal
Use:Active

 

 

Background

The La Tuque Anorthosite was introduced by Klugman (1976). Then Rondot (1978) described it as an intrusive body resembling the Langelier Anorthosite. Summer 2017 fieldwork (Moukhsil and Côté, 2018) observed it on the southern edge of NTS sheet 31P10. This intrusion consists of anorthosite and minor amounts of gabbronorite.

 

Description

The La Tuque Anorthosite forms an orthopyroxene mafic intrusion with local iron oxides.

 

 

Anorthosite is white and weakly deformed. It is composed of biotite, clinopyroxene, orthopyroxene, amphibole, opaque minerals and accessory quartz. Amphibole is biotitized and plagioclase is slightly sericitized.

 

Gabbronorite is greyish in fresh exposure and is composed of amphibole, clinopyroxene, orthopyroxene, plagioclase, pyrrhotite, magnetite and biotite. Accessory minerals are apatite and zircon.

From a geochemical perspective, SiO2 contents range from 49.5% to 52.6% and the rare earth element (REE) diagram is more or less flat, with a slight enrichment of light REE compared to heavy REE. There is a positive europium (Eu) anomaly due to high plagioclase content. Plagioclase is of labradorite type.

 

 

 

 

 

Thickness and Distribution

The La Tuque Anorthosite forms a small mass (12 km2) located on the boundary between sheets 31P10 and 31P07.

 

Dating

None.

Stratigraphic Relationship(s)

The unit intrudes into the Vermillon Plutonic Suite. 

Paleontology

Does not apply.

References

Author(s)TitleYear of PublicationHyperlink (EXAMINE or Other)
KLUGMAN, M.A. La Tuque Area: West half (Comte de Laviolette). Ministère des Richesses naturelles, Québec, 49 pages.1976DPV 370
RONDOT, J.Géologie de la région du Saint-Maurice. Ministère des Richesses naturelles, Québec, 91 pages, 2 cartes.1978DPV 594
MOUKHSIL, A. – CÔTÉ, G.

Levé géologique dans la Province de Grenville, au nord de La Tuque, régions de la Mauricie et du Saguenay-Lac-Saint-Jean (région du lac Borgia). Ministère de l’Énergie et des Ressources naturelles, Québec.

2018Bulletin géologiQUE

 

29 octobre 2018