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Freneuse Suite
Stratigraphic label: [ppro]fru
Map symbol: pPfru

First published: 20 October 2016
Last modified: 12 February 2020

 

 

 

  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.
 
pPfru6 Quartzofeldspathic pebble or fragment conglomerate or breccia
pPfru5 Quartzite
pPfru4 Iron formation
pPfru4c Carbonate facies iron formation
pPfru4b Sulphide facies iron formation
pPfru4a Silicate ± oxide facies iron formation
pPfru3 Marble and calcosilicate rocks
pPfru3b Calcosilicate rocks
pPfru3a Marble, impure marble and dolomitic marble
pPfru2 Slightly metamorphosed mudrock and graphitic schist
pPfru1 Bitoite-muscovite metasedimentary rocks
pPfru1h Biotite-carbonate schist
pPfru1g Paraschist with some quartzite and marble
pPfru1f Garnet paraschist with abundant amphibolite
pPfru1e Paraschist and quartzitic paraschist with abundant amphibolite
pPfru1d Paraschist and garnet paragneiss
pPfru1c Paraschist and sillimanite paragneiss
pPfru1b Homogeneous metawacke and meta-arenite
pPfru1a Paraschist
 
Author: Simard et al., 2013
Age: Paleoproterozoic
Stratotype: None
Type area: Kuujjuaq and Ungava Bay area (NTS sheet 24K)
Geological province: Churchill Province
Geological subdivision: Rachel-Laporte Lithotectonic Domain
Lithology: Metasedimentary rocks
Category: Lithodemic
Rank: Suite
Status: Formal
Use: Active

Background

The Freneuse Suite was introduced by Simard et al. (2013) in the Kuujjuaq and Ungava Bay area to group all Laporte Supersuite metasedimentary rocks. The Laporte Supersuite includes Paleoproterozoic volcano-sedimentary rocks of the Rachel-Laporte Lithotectonic Domain, which represents the eastern part of the New Quebec Orogen in the Southeastern Churchill Province (SECP). The Freneuse Suite was continued southward in the Saffray Lake (Lafrance et al., 2014) and Jeannin Lake (Charette et al., 2016) areas.

Metasedimentary rocks now assigned to the Freneuse Suite were first mapped by Sauvé (1957, 1959), Gélinas (1958a, 1958b, 1959), Fahrig (1964), Dimroth (1966), Dressler (1974, 1979), Baragar (1967), Frarey (1967), Penrose (1978), Clark (1978, 1980) and Girard (1995). These observations were incorporated into the SIGÉOM compilation map by Thomas Clark between 2009 and 2016 and used to supplement the description of several units.

 

Description

The Freneuse Suite consists mainly of paraschists and various metasedimentary rocks (pPfru1) with lesser amounts of slightly metamorphosed mudstone, siltstone and mudslate (pPfru2), marble and calcosilicate rocks (pPfru3), iron formations (pPfru4), quartzite (pPfru5) and fragmented rocks interpreted as conglomerate or breccia (pPfru6).

 

Freneuse Suite 1 (pPfru1): Bitoite-Muscovite Metasedimentary Rocks

The metasedimentary rock unit of the Freneuse Suite (pPfru1) consists of homogeneous, granoblastic, and fine-grained rocks that usually display millimetric to centimetric banding. This banding, marked by variations in composition (proportion of micas) and grain size (finer in less micaceous bands) of the rock, may represent primary bedding. Compared to Core Zone metasedimentary rocks, Freneuse Suite metasedimentary rocks were not (or very little) affected by the migmatization phenomenon associated with a major regional melting event. Partial melting evidence is still recognized locally in thin sections. Unit pPfru1 is commonly cut by quartz veins subconformable to foliation. These veins are dismembered, boudinaged and folded. Metasedimentary rocks contain biotite and muscovite flakes that define primary foliation. The latter is often undulating and is affected by a second foliation (crenulation cleavage) marked by coarser mica flakes, indicating the existence of two generations of micas. In places, the foliation is at an angle with compositional banding. Chlorite, altering biotite, and garnet are frequently observed, whereas amphiboles are sparse and only present in certain beds.

In thin sections, quartz and plagioclase have completely recrystallized. In some places, 5-25% K-feldspar is also observed as lenticular clusters or poikiloblasts. Garnet forms euhedral to subhedral millimetric poikiloblasts, locally elongated in foliation or deviant. These crystals show pressure shadows and generally aligned quartz, plagioclase and mica inclusions, indicating syn-kinematic to late kinematic growth. Garnet overlaps with biotite and also occurs as small skeletal crystals scattered in the matrix. The main accessory minerals observed in metasedimentary rocks are opaque minerals, apatite and tourmaline with, more locally, sillimanite (fibrolite), zircon (as inclusions in biotite and chlorite), epidote, calcite, dark green spinel and sphene.

Simard et al. (2013) divided unit pPfru1 into eight subunits, respecting informal lithological subdivisions proposed by Thomas Clark in SIGÉOM compilation maps. These subunits are based on structural, mineralogical or lithological characteristics and include: 1) biotite-muscovite ± garnet ± sillimanite ± kyanite ± staurolite paraschist (pPfru1a); 2) homogeneous biotite-muscovite ± garnet ± sillimanite metawacke and meta-arenite (pPfru1b); 3) biotite-sillimanite ± muscovite ± garnet paraschist and paragneiss (pPfru1c); 4) biotite-garnet ± muscovite paraschist and paragneiss (pPfru1d); 5) biotite-muscovite paraschist and quartzitic paraschist with abundant amphibolite (pPfru1e); 6) garnet-biotite paraschist with abundant amphibolite (pPfru1f); 7) biotite-muscovite paraschist with some quartzite and marble beds (pPfru1g); and 8) biotite-carbonate ± chlorite schist (pPfru1h). These different subunits are generally interstratified and have not always been able to be individualized during 1:250 000 scale mapping, particularly with respect to subunits pPfru1e to pPfru1h located primarily from previous work. Apart from the presence of secondary lithologies or specific minerals, metasedimentary rocks of subunits pPfru1c to pPfru1h are similar to those of subunits pPfru1a or pPfru1b described below.

 

Freneuse Suite 1a (pPfru1a): Paraschist

Paraschist of subunit pPfru1a is silver-grey or bluish grey in fresh exposure and beige or light grey in altered patina. It contains a significant amount of muscovite (15-35%) and brown biotite (10-25%) flakes. Locally, schist is characterized by varying amounts of garnet (2-40%), sillimanite, staurolite or kyanite.

When present, sillimanite forms whitish nodules 0.5-2 cm (Simard et al., 2013); this assemblage probably represents a retrogressive transformation of ancient andalusite porphyroblasts. Sillimanite also occurs as prismatic crystals aligned with the main foliation or crenulation cleavage. Staurolite forms poikiloblasts containing aligned quartz ± opaque mineral inclusions. Sparser, kyanite typically occurs as porphyroblasts fractured and elongated in foliation. It locally contains quartz inclusions. Chlorite is also observed as an alteration phase of staurolite, as well as at the edge of kyanite crystals.

 

Freneuse Suite 1b (pPfru1b): Homogeneous Metawacke and Meta-Arenite

Metasedimentary rocks of subunit pPfru1b are grey in fresh exposure and very light grey in altered surface. Protoliths are probably arkosic and lithic wackes. However, the presence of meta-arenite is also common. Micas, less abundant than in paraschist, consist of brown to reddish brown biotite (10-20%) and muscovite (2-10%) generally concentrated in millimetric laminae. In the Saffray Lake area (Lafrance et al., 2014), rocks are more deformed in the vicinity of the Lac Turcotte Fault and regularly display a mylonitic texture with quartz bands. In the Jeannin Lake area (Charette et al., 2016), 5-10 km north of Nachicapau Lake, laminated outcrops resembling intermediate tuffs were also assigned to subunit pPfru1b. Finally, this subunit also includes beds containing lenticular fragments of mafic or felsic rocks that could represent lapilli metatuffs or lithic metawackes.

 

Freneuse Suite 2 (pPfru2): Slightly Metamorphosed Mudrock and Graphitic Schist

In addition to klippes drawn on the map, unit pPfru2 also forms non-mappable decimetric beds interstratified with metasedimentary rocks of unit pPfru1. The rock is weakly metamorphosed, aphanitic and dark grey to black, locally bluish. It consists of a very finely recrystallized feldspar-quartz-mica matrix containing coarser crystals of biotite, garnet and opaque minerals, mainly graphite and sulphides. Chlorite, apatite and zircon are accessory phases observed in thin sections.

 

Freneuse Suite 3 (pPfru3): Marble and Calcosilicate Rocks

Unit pPfru3 consists of marble (pPfru3a) and calcosilicate rocks (pPfru3b) which typically occur in discontinuous beds a few hundred metres thick. These beds are mainly located near large thrust faults, as well as near faulted contacts of the Boulder and Rénia complexes in the Kuujjuaq area (Simard et al., 2013). They could represent decollement surfaces that would have facilitated movement along these faults. These lithologies also form centimetric to decimetric beds and boudins in metasedimentary rocks of unit pPfru1, as well as in mafic rocks of the Klein Suite. On outcrops, unit pPfru3 rocks show a characteristic surface marked by millimetric to centimetric ridges and furrows due to differential erosion of beds more or less rich in carbonates or silicates.

 

Freneuse Suite 3a (pPfru3a): Impure Marble and Dolomitic Marble

Marble of subunit pPfru3a is homogeneous, fine to coarse grained and whitish grey with a light, beige or orange grey altered surface. It is generally quite pure and composed of completely recrystallized carbonate with a few quartz lenses and phlogopite layers, possibly representing primary bedding. In other areas, marble is impure and contains some tremolite, diopside or wollastonite (Gélinas, 1958a, b). Accessory minerals are sphene, zircon and apatite. High magnesium contents indicate that marble is composed of a mixture of dolomite and calcite.

 

Freneuse Suite 3b (pPfru3b): Calcosilicate Rocks

Calcosilicate rocks of subunit pPfru3b are more heterogeneous, white, grey or green, and show significant variations in composition. They are mainly composed of feldspar, diopside, carbonate, amphibole (tremolite or hornblende) and quartz. The quartzofeldspathic matrix is granoblastic or as anhedral clusters surrounding ferromagnesian minerals. These frequently occur as large poikilitic crystals. Diopside is replaced by amphiboles. Calcosilicate rocks contain phlogopite (<8%), sphene (<4%) and, in smaller amounts, apatite, zircon, garnet and opaque minerals. Alteration minerals, such as zoisite, scapolite and chlorite, have been observed in places.

 

Freneuse Suite 4 (pPfru4): Iron Formation

Iron formations consist of three generally interstratified facies: 1) silicate facies iron formations (pPfru4a); 2) sulphide facies iron formations (pPfru4b); and 3) carbonate facies iron formations (pPfru4c). The silicate facies is the most common. All silicate and carbonate facies iron formation klippes were observed in the Kuujuaq area (Simard et al., 2013), whereas the two occurrences of sulphide facies iron formation are in the Jeannin Lake area (Charette et al., 2016).

Sauvé and Bergeron (1965) describe ferriferous units in the Thévenet Lake area (sheet 24K03) as rocks composed of quartz, magnetite, garnet, Fe-amphibole and Fe-carbonate. This latter phase is only abundant in two carbonate facies iron formation klippes (pPfru1c) located NE of Rachel Lake.

 

Freneuse Suite 4a (pPfru4a): Silicate ± Oxide Facies Iron Formation

Silicate facies iron formations are generally well banded and consist of alternating light (quartz) and dark (quartz-magnetite or garnet-amphibole ± magnetite) bands. Amphiboles occur in large grains and radial aggregates. Sauvé and Bergeron (1965) describe two types of amphiboles, one resembling hornblende and another resembling grunerite. The two amphiboles appear to be stable in the presence of each other and are occasionally intergrown. Accessory minerals are biotite, chlorite, apatite and tourmaline. Beds of grunerite schist, oxide facies iron formation and metachert are interstratified with the silicate facies.

 

Freneuse Suite 4b (pPfru4b): Sulphide Facies Iron Formation

Sulphide facies iron formations, including beds interstratified with the silicate facies, are characterized by a brecciated texture consisting of 15-35% millimetric to centimetric subrounded to subangular fragments of quartzofeldspathic rocks, chert and quartz in a very fine-grained and highly magnetic dark matrix. The matrix is mainly composed of pyrrhotite with lower amounts of graphite and pyrite. The latter occurs as subhedral crystals (1-4 mm).

 

Freneuse Suite 5 (pPfru5): Quartzite

In addition to klippes of unit pPfru5 drawn on the map, small quartzite beds were observed within other units of the Laporte Supersuite. Quartzite is a finely recrystallized holohyaline rock, whitish, greenish or pinkish, which contains some muscovite or chlorite. It displays millimetric to centimetric bedding marked by muscovite laminae or small hematitized beds. It is cut by 2-10% millimetre to decimetre-wide quartz veins, often boudinaged. Some impure quartzite beds contain millimetric to decimetric biotite-muscovite schist beds.

 

Freneuse Suite 6 (pPfru6): Quartzofeldspathic Pebble and Fragment Conglomerate or Breccia

Unit pPfru6 is located between the Boulder and Rénia complexes in the Kuujjuaq area (Simard et al., 2013). The rock is highly deformed and contains very stretched fragments 5-30 cm long by 1-8 cm wide. Gélinas (1958a) describes this unit as conglomerate or breccia with quartz and feldspar pebbles and fragments in a matrix rich in amphibole and epidote.

 

Thickness and distribution

The Freneuse Suite is the main unit of the Laporte Supersuite in the Rachel-Laporte Lithotectonic Domain. It is generally 25-40 km wide and oriented NW-SE. This unit thins in the extreme north of the SECP (~3 km), as well as in the vicinity of the Archean Rénia, Highfall and Wheeler complexes. Subunits pPfru1a and pPfru1b are the main units of the Freneuse Suite. Paraschists of subunit pPfru1a dominate in the northern part of the Rachel-Laporte Domain, in the Kuujjuaq area (Simard et al., 2013) and northern Saffray Lake area (Lafrance et al., 2014), where they form a metasedimentary sequence ~12 km wide by 170 km long. Another large sequence, ~10 km wide by 70 km long, was recognized farther south in the Jeannin Lake area (Charette et al., 2016). Smaller strips were also observed between the two sequences. Subunit pPfru1b mainly outcrops in the south-central part of the Rachel-Laporte Domain where it forms a sequence of more than 250 km long by 30 km wide. This subunit thins on the edge of the Wheeler Complex like the rest of the Freneuse Suite.

Subunit pPfru1c was observed in the Kuujjuaq area (Simard et al., 2013) and the northern Saffray Lake area (Lafrance et al., 2014). It is located primarily near the eastern edge of the Rachel-Laporte Domain where it forms a strip ~85 km long by 0.5-3 km wide. Subunit pPfru1d also forms a few hectometric to kilometric strips in the Kuujjuaq and Saffray Lake areas, while subunit pPfru1e forms two strips 15-20 km long and <1 km wide in the central part of the Kuujuaq area. Subunit pPfru1f forms two hectometric klippes in the Boulder Complex area (Simard et al., 2013). Subunit pPfru1g is observed exclusively in the Ballantyne Lake area (sheet 24K11; Sauvé, 1959), where it forms strips a few kilometres wide within paraschist sequences (pPfru1a). Finally, subunit pPfru1h was mapped by Dressler (1974) in the Marcel Lake area (sheet 24C16), near the Lemoyne Complex carbonatite.

Unit pPfru2 is mostly in contact with units of the Labrador Trough, where it forms strips several tens of kilometres long and a few kilometres wide. Units pPfru4 and pPfru5 generally form small hectometric klippes continuous over a few kilometres in the Rachel-Laporte Domain. However, larger quartzite sequences (pPfru5) were observed in the southern portion of the Jeannin Lake area (40 km x 3 km), near the SW edge of the Rénia Complex (10 km x 3 km), and immediately south of Horseshoe Lake (8 km x 1.5 km). Finally, unit pPfru6 consists of two close klippes, 5-10 km long and <500 m wide, located between the Rénia and Boulder complexes, in the Thévenet Lake area (Gélinas, 1958a).

Dating

None.

Stratigraphic Relationship(s)

Several authors have proposed that Freneuse Suite metasedimentary rocks mostly represent equivalents of Kaniapiskau Supergroup metasedimentary rocks located in the Labrador Trough just to the west. (Harrison, 1952; Gélinas, 1958a, b; Sauvé and Bergeron, 1965; Simard et al., 2013). However, mapping work by Charette et al. (2016) indicates that metasedimentary rocks of the Laporte Supersuite are distinguishable from those of the Labrador Trough by a greater apparent thickness and a more homogeneous composition.

In the Thévenet and Gabriel lakes areas, Gélinas (1958a, b) mentioned that the paraschist subunit (pPfru1a) might correspond in part to the Thévenet Formation of the Labrador Trough. In the area adjacent to the west, Sauvé and Bergeron (1965) propose that most of metasedimentary rocks now assigned to the Freneuse Suite are equivalent to the Baby Formation, consisting of pellitic rocks, quartzite and ferriferous rocks. The Baby Formation was assigned to the Koksoak Group (Wares and Goutier, 1990), associated with the second deposition cycle of the Kaniapiskau Supergroup, which was between 1884 Ma and 1870 Ma (Clark and Wares, 2004). Carbonate rocks of the Freneuse Suite (pPfru3) could be equivalent to older dolomitic rocks of the Denault Formation (Harrison, 1952), which is the lower part of the Attikamagen Group (Clark & Wares, 2004) associated with the end of the Labrador Trough’s first cycle.

Rocks of the Freneuse Suite are commonly interstratified with amphibolites and mafic and ultramafic intrusions of the Klein Suite. The Freneuse Suite is in fault contact with various Archean or Proterozoic complexes (thrust sheets) of the Rachel-Laporte Domain, namely the Boulder, Rénia, Highfall, Boullé, Wheeler and Giton complexes. (Simard et al., 2013; Lafrance et al., 2014; Charette et al., 2016). The various Klein units are also locally intruded by granite and pegmatitic granite dykes or sills of the Mercier Suite.

Paleontology

Does not apply.

References

Author(s) Title Year of Publication Hyperlink (EXAMINE or Other)
BARAGAR, W.R.A. Wakuach Lake map-area, Quebec-Labarador (23 O). Geological Survey of Canada; Memoir 344, 174 pages. 1967 Source
CHARETTE, B. LAFRANCE, I. MATHIEU, G. Géologie de la région du lac Jeannin (SNRC 24B). Ministère de l’Énergie et des Ressources naturelles. 2016

Electronic geological report

CLARK, T. Région du lac Hérodier, Nouveau-Québec. Ministère des Richesses naturelles; DPV 568, 48 pages. 1978 DPV 568
CLARK, T. Région de la rivière Koksoak. Ministère de l’Énergie et des Ressources, Québec; DPV 781, 24 pages. 1980 DPV 781
CLARK, T. – WARES, R. Synthèse lithotectonique et métallogénique de l’Orogène du Nouveau-Québec (Fosse du Labrador). Ministère des Ressources naturelles, de la Faune et des Parcs, Québec; MM 2004-01, 182 pages, 1 plan. 2004 MM 2004-01
DIMROTH, E. Géologie de la région du lac Dunphy, Territoire du Nouveau-Québec. Ministère des Richesses naturelles, Québec; RP 557, 24 pages. 1966 RP 557
DRESSLER, B. Geology of the Nachicapau, Horseshoe (1/6 SW), Marcel, Buteux and Jogues (East half) Lakes areas, New Quebec Territory. Ministère des Richesses naturelles, Québec; DP 269, 17 pages. 1974 DP 269
DRESSLER, B. Région de la Fosse du Labrador (56°30′-57°15′). Ministère des Richesses naturelles, Québec; RG-195, 117 pages. 1979 RG 195
FAHRIG, W. F. Lac Hérodier, Québec. Geological Survey of Canada; map 1146A (annotated map). 1965 Source
FRAREY, M.J. Willbob Lake and Thompson Lake map-areas, Quebec and Newfoundland (23 0/1 and 23 O/8). Geological Survey of Canada; Memoir 348, 73 pages. 1967 Source
GÉLINAS, L.
Région du lac Thévenet (moitié est), Nouveau-Québec. Ministère des Mines, Québec; RP 363, 9 pages, 1 plan.
1958a RP 363

GÉLINAS, L.

Région du lac Gabriel (partie ouest), Nouveau-Québec. Ministère des Mines, Québec; RP 373, 11 pages, 1 plan. 1958b RP 373
GÉLINAS, L. Région du lac Gabriel (partie est), et la région de Fort Chimo (partie ouest), Nouveau-Québec. Ministère des Mines, Québec; RP 407, 11 pages, 1 plan. 1959 RP 407
GIRARD, R. Géologie de la région du lac Déborah, territoire du Nouveau-Québec. Ministère des Ressources naturelles, Québec; MB 95-20, 185 pages, 2 cartes. 1995 MB 95-20
HARRISON, J.M. The Quebec-Labrador iron belt, Quebec and Newfoundland. Geological Survey of Canada; Paper 52-20, 21 pages. 1952 Source
LAFRANCE, I. SIMARD, M. BANDYAYERA, D. Géologie de la région du lac Saffray (SNRC 24G-24F). Ministère des Ressources naturelles, Québec; RG 2014-02, 49 pages. 2014 RG 2014-02
PENROSE, B. Géologie de la région du lac Horseshoe, Territoire du Nouveau-Québec. Ministère des Richesses naturelles, DPV 573, 39 pages. 1978 DPV 573
SAUVÉ, P. Région du lac de Freneuse (moitié est), Nouveau-Québec. Ministère des Mines, Québec; RP 358, 8 pages, 1 plan. 1957 RP 358
SAUVÉ, P. Région de la baie aux Feuilles, Nouveau-Québec. Ministère des Mines, Québec; RP 399, 13 pages, 1 plan. 1959 RP 399
SAUVÉ, P. BERGERON, R. Région des lacs Gerido et Thévenet, Nouveau-Québec. Ministère des Richesses naturelles, Québec; RG 104, 124 pages, 3 plans. 1965 RG 104
SIMARD, M. LAFRANCE, I. HAMMOUCHE, H. LEGOUIX, C. Géologie de la région de Kuujjuaq et de la Baie d’Ungava (SNRC 24J et 24K). Ministère des Ressources naturelles, Québec; RG 2013-04, 60 pages. 2013 RG 2013-04
WARES, R. – GOUTIER, J. Synthèse métallogénique des indices de sulfures au nord du 57e parallèle, Fosse du Labrador : Étape III. Ministère de l’Énergie et des Ressources, Québec; MB 90-25, 103 pages, 2 plans. 1990 MB 90-25

 

 

 

12 février 2020