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Frichet Suite
Stratigraphic label: [ppro]fri
Map symbol: pPfri

First published: 26 April 2018
Last modified:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Translation of original French

 

 

Informal subdivision(s)
Numbering does not necessarily reflect the stratigraphic position.
 
pPfri1 Porphyraceous hypersthene jotunite and diorite and leucogabbronorite
 
Author:Charette and Beaudette, 2018
Age:Paleoproterozoic
Reference section: 
Type area:Frichet River (NTS sheet 35F13)
Geological province:Churchill Province
Geological subdivision:Ungava Orogen / Narsajuaq Arc
Lithology:Mafic intrusive rock
Type:Lithodemic
Rank:Suite
Status:Formal
Use:Active

 

 

Background

The Frichet Suite was introduced by Charette and Beaudette (2018) to describe the coarse-grained, locally porphyraceous and recrystallized mafic intrusions of the Narsajuaq Arc. The name of this suite comes from the river of the same name near the largest intrusion of hypersthene jotunite and diorite.

 

Description

 

Frichet Suite 1 (pPfri1): Porphyraceous Hypersthene Jotunite and Diorite and Leucogabbronorite

The majority of the Frichet Suite consists of orthopyroxene-clinopyroxene jotunite and diorite. These lithologies, usually coarse-grained, are white and black in altered surface and have a characteristic granoblastic speckled appearance. This appearance is produced by centimetric clusters of greenish and brownish mafic minerals and, in places, by a porphyraceous texture. These 0.5 to 2 cm porphyroids are formed by recrystallization of plagioclase phenocrystals. Jotunite varies from a foliated appearance to a massive one in the core of larger intrusions. When the rock is deformed, mafic mineral clusters and plagioclase phenocrystals form lenses stretched in foliation. Mafic minerals make up between 20 and 45% of the rock and sometimes have a heterogeneous distribution. Orthopyroxene is commonly fractured and partially replaced by biotite or iddingsite. Orthopyroxene and clinopyroxene are found in the core of recrystallized hornblende crystal clusters. Hornblende is the main mafic mineral and is locally replaced by biotite. Few accessory minerals are observed in this lithology (e.g., magnetite, pyrite, apatite, chlorite, carbonate and zircon). In the matrix, plagioclase crystals are well recrystallized and are moderate to strongly saussuritized.

On some outcrops, other intrusive lithologies associated with jotunite are observed. The first is a coarse-grained leucogabbronorite, less rich than jotunite in mafic minerals (5-25%) and including, like jotunite, centimetric clusters of mafic minerals giving a speckled appearance to the rock. The second, of gabbroic composition, contains up to 60% mafic minerals, is homogeneous, varies from medium to coarse grained and distinguished from other lithologies by the absence of the porphyraceous and speckled textures. Jotunite also contains ultramafic horizons (websterite, olivine websterite locally) and garnet gabbronorite enclaves.

 

Thickness and Distribution

The Frichet Suite appears as a large sigmoid mass in NTS sheet 35F13 (>35 km by 3 km) as well as small plutons stretched along the regional foliation (approximately 5 km by 1 km). These plutons concentrate within or near the Sugluk Suture. At the contact with the latter, the jotunite forms an elongated mass oriented east-west and is in contact with the granulitic gneiss of uncertain origin of the Pingasualuit Complex (pPpgs2a).

 

Dating

None.

Stratigraphic Relationship(s)

This unit is generally spatially associated with porphyraceous or porphyroclastic felsic-intermediate units of the Suluraaq Suite (pPslq). Intrusive rocks of the Frichet and Suluraaq suites both forms competent masses in the vicinity of the Sugluk Suture deformation zone. Both of these could be cogenetic. The Frichet Suite intrusions cut gabbronorite, gabbro and diorite of the Pingasualuit Complex (pPpgs1a). These are also observed as enclaves in the mafic intrusions.

Paleontology

Does not apply.

References

Author(s)TitleYear of PublicationHyperlink (EXAMINE or Other)
CHARETTE, B. – BEAUDETTE, M.Géologie de la région du cap Wolstenholme, Orogène de l’Ungava, Province de Churchill, sud-est d’Ivujivik, Québec, Canada. Ministère des Ressources naturelles, Québec.2018Bulletin géologiQUE
9 novembre 2018