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Laporte Supersuite
Stratigraphic label: [ppro]lpt
Map symbol: pPlpt

First published: 20 October 2016
Last modified: 24 July 2018

 

 

 

  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.
 
None
 
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: Metamorphosed volcano-sedimentary rocks
Category: Lithodemic
Rank: Supersuite
Status: Formal
Use: Active

Background

In the 1940s, geologists at Labrador Mining and Exploration introduced the term “Laporte Series” to describe schists, gneiss and amphibolites located NE of Schefferville, in the Laporte Lake area (Frarey and Duffell, 1964). Harrison (1952) formalized this unit as the Laporte Group. In the southern portion of the Quebec part of the New Quebec Orogen, Baragar (1967) designated metamorphosed rocks located east of the Labrador Trough as the Younger Complex, considering that metamorphism had obliterated primary structures of rocks and that the relative age of these units could not be established. However, this term was not used in subsequent work, as authors preferred the term “Laporte Group” (Frarey, 1967; Dimroth, 1978; Dressler, 1979; Girard, 1995). In the Kuujjuaq area (sheet 24K), Goulet (1995) assigned metamorphosed rocks equivalent to the Laporte Group to the Thévenet Formation (Sauvé and Bergeron, 1965), a term that was not used in subsequent work. In the Déborah Lake area, Girard (1995) reassigned some of Laporte Group rocks to the Deborah Formation, considering that in this area, paraschists have a mappable extent, consistency, internal homogeneity and established stratigraphic position. Metamorphosed rocks of the Laporte Group were considered by various authors to be equivalent to several units of the Kaniapiskau Supergroup (Labrador Trough). However, the metamorphic grade achieved in these rocks resulted in them losing their primary structures, which led Simard et al. (2013) to replace the term “Laporte Group” with “Laporte Supersuite”. This designation places this regional-scale unit among higher-ranking lithodemic units, equivalent to a supergroup, in accordance with the North American Stratigraphic Code (1983, 2005). The Laporte Supersuite thus combines all Paleoproterozoic metamorphosed supracrustal rocks of the Rachel-Laporte Lithotectonic Domain.

The New Quebec Orogen is divided into two large lithotectonic units: the Labrador Trough to the west and the Rachel-Laporte  lithotectonic domain to the east. Several names were used to designate the Rachel-Laporte Lithotectonic Domain. The term “Rachel Zone” was used in the northern portion (Wares and Goutier, 1989, 1990; Wardle et al., 1990; Hall et al., 2002) and the names “Laporte Terrane” (Wardle et al., 1990; Hall et al., 2002) and “Laporte Domain” (Van der Leeden et al., 1990) in the southern portion. Wardle and Van Kranendonk (1996), then Wardle et al. (2002) used the term “Rachel-Laporte Zone” to refer to the lithotectonic domain forming the eastern part of the New Quebec Orogen. This term has also been used by Hammouche et al. (2011) in the southern part of the Southeastern Churchill Province (SECP), and by Simard et al. (2013), Lafrance et al. (2014) and Charette et al. (2016), in the northern and central parts of the SECP. In 2018, Lafrance et al. proposed the new name “Rachel-Laporte Lithotectonic Domain” as part of the SECP regional synthesis. As mentioned above, Simard et al. (2013) assigned all Paleoproterozoic metamorphosed volcano-sedimentary rocks of the Rachel-Laporte Lithotectonic Domain to the Laporte Supersuite. The Rachel-Laporte Lithotectonic Domain also contains Archean structural complexes connected to thrust sheets in fault contact with Paleoproterozoic metamorphosed volcano-sedimentary rocks.

A regional compilation of the southern part of the SECP by the Ministère’s geologists in 2003 divided rocks of the Rachel-Laporte Lithotectonic Domain (pPLAP) into 14 informal units. In the Bonaventure Lake area, Hammouche et al. (2011) recognized units pPLAP1 and pPLAP5, and defined two new informal units (pPLAP15 and pPLAP16). As part of the SECP regional synthesis (Lafrance et al., 2018), these informal units were abandoned. They were reassigned to the Freneuse, Klein or Grand Rosoy suites, depending on their composition and origin.

In the Déborah Lake area, Girard (1995) divided the Laporte Group (now Laporte Supersuite) into four lithodemic packages: the Deborah Formation, Grand Rosoy Formation, De Jeu Gabbro and Manereuille Complex. With the exception of the Grand Rosoy Formation (now redefined as the Grand Rosoy Suite and reassigned to the Baleine Lithotectonic Domain), rocks of other units were also reassigned to the Freneuse and Klein suites, depending on their composition.

The Préville Suite was later introduced in the Jeannin Lake area (Charette et al., 2016).

 

Description

The Laporte Supersuite was divided into two suites by Simard et al. (2013): the Klein Suite, which includes all metamorphosed mafic and ultramafic rocks of effusive or intrusive origin, and the Freneuse Suite, which groups metasedimentary rocks. In the Jeannin Lake area, Charette et al. (2016) added a third suite, the Préville Suite, to group mafic calcosilicate rocks and carbonate gneiss. In the southern part of the SECP, the Grand Rosoy Suite, which consists of meta-arkoses and paraschists, was also included in the Laporte Supersuite.

 

Thickness and distribution

The Laporte Supersuite is the dominant unit of the Rachel-Laporte Lithotectonic Domain that represents the eastern part of New Quebec Orogen. It is ~550 km long and 20-35 km wide, along general NW-SE orientation, and is adjacent to the eastern limit of the Labrador Trough.

 

Dating

Protoliths of Laporte Supersuite metamorphic rocks have not been dated. It is possible that Laporte Supersuite rocks are largely equivalent to rocks of the Kaniapiskau Supergroup (Simard et al., 2013), located in the Labrador Trough just to the west. However, recent mapping indicates that the metasedimentary rocks of the Laporte Supersuite (Freneuse Suite) differ from those of the Labrador Trough by a greater apparent thickness and a more homogeneous composition.

The Labrador Trough consists of a Paleoproterozoic volcano-sedimentary sequence deposited at the margin of the Archean Superior Craton between 2.2 Ga and 1.87 Ga (Clark and Wares, 2004). This sequence was folded, overthrusted and metamorphosed during collision between the Superior and the Core Zone during the New Quebec Orogenesis (1.82-1.77 Ga).

Stratigraphic Relationship(s)

The Laporte Supersuite covers the entire Rachel-Laporte Lithotectonic Domain, which forms the eastern part of the New Quebec Orogen. It is limited to the west and east by thrust faults. It is also in fault contact with various Archean or Proterozoic structural complexes that are, north to south: the Boulder, Rénia, Highfall, Boullé, Wheeler and Giton complexes (Simard et al., 2013; Lafrance et al., 2014; Charette et al., 2016). These complexes correspond to thrust sheets that overthrusted Paleoproterozoic rocks during the New Quebec Orogenesis.

Volcano-sedimentary units of the Laporte Supersuite are locally intruded by dykes or sills of granite and pegmatitic granite 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
LAFRANCE, I. – CHARETTE, B. – VANIER, M.A. Sud-est de la Province de Churchill, Nunavik, Québec, Canada : synthèse de la géologie. Ministère de l’Énergie et des Ressources naturelles, Québec. 2018 Preliminary BG
CHARETTE, B. – LAFRANCE, I. – MATHIEU, G. Géologie de la région du lac Jeannin (SNRC 24B). Ministère de l’Énergie et des Ressources naturelles, Québec. 2016 Electronic geological report
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. Région de la fosse du Labrador (54°30′-56°30′). Ministère des Richesses naturelles, Québec; RG 193, 396 pages. 1978 RG 193
DRESSLER, B. Région de la Fosse du Labrador (56°30′-57°15′). Ministère des Richesses naturelles, Québec; RG-195, 117 pages. 1979 RG 195
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
FRAREY, M.J. – DUFFELL, S. Revised stratigraphic nomenclature for the central part of the Labrador Trough. Geological Survey of Canada; Paper 64-25, 13 pages. 1964 Source
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
GOULET, N. Étude structurale, stratigraphique et géochronologique de la partie nord de la Fosse du Labrador. Ministère des Ressources naturelles, Québec; MB 95-36, 39 pages, 1 plan. 1995 MB 95-36
HALL, J. – LOUDEN, K.E. – FUNCK, T. – DEEMER, S. Geophysical characteristics of the continental crust along the Lithoprobe ECSOOT transect: a review. Canadian Journal of Earth Sciences; Volume 39, pages 569-587. 2002 Source
HAMMOUCHE, H. – LEGOUIX, C. – GOUTIER, J. – DION, C. – PETRELLA, L. Géologie de la région du lac Bonaventure. Ministère des Ressources naturelles et de la Faune, Québec; RG 2011-03, 37 pages, 1 plan. 2011 RG 2011-03
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
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
VAN DER LEEDEN, J. – BELANGER, M. – DANIS, D. – GIRARD, R. – MARTELAIN, J. Lithotectonic domains in the high-grade terrain east of the Labrador Trough (Quebec). In : The Early Proterozoic Trans-Hudson Orogen (Lewry, J.F. and Stauffer, M.R., editors). Geological Association of Canada; Special Paper 37, pages 371-386. 1990 Source
WARDLE, R.J. – RYAN, B. – ERMANOVICS, I. The eastern Churchill Province, Torngat and New Québec orogens : an overview. Geoscience Canada; volume 17, pages 217-222. 1990 Source
WARDLE, R.J. – VAN KRANENDONK, M.J. The Paleoproterozoic Southeastern Churchill Province of Labrador-Quebec, Canada: orogenic development as a consequence of oblique collision and indentation. In: Precambrian Crustal Evolution in the North Atlantic Region (Brewer, T.S., editor). Geological Society; Special Publication, volume 112, pages 137-154. 1996 Source
WARDLE, R. J. – JAMES, D.T – SCOTT, D.J. – HALL, J. The southeastern Churchill Province : synthesis of a Paleoproterozoic transpressional orogen. Canadian Journal of Earth Science; Volume 39, pages 639-663. 2002 Source
WARES, R. – GOUTIER, J. Synthèse métallogénique des indices de sulfures au nord du 57e parallèle, Fosse du Labrador : Étape II. Ministère de l’Énergie et des Ressources, Québec; MB 89-38, 114 pages. 1989 MB 89-38
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

 

 

 

10 février 2020