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Kovik AntiformTranslation of original French

 

 

First published: 15 May 2018
Last modified: 

 

 

Background

The term Kovik Antiform was introduced by Lamothe (2007), as suggested by Hocq (unpublished), in order to describe Archean rocks forming the internal northern basement within the Ungava Orogen (units AKOV1 to AKOV10; Lamothe, 2007). However, this nomenclature adopted for a formal lithodemic unit does not comply with the North American Stratigraphic Code (1983, 2005). The units were thus transferred to the Kovik Complex, Archean to Paleoproterozoic (Charette and Beaudette, 2018). The Kovik Antiform is the lithotectonic domain which contains rocks of the Kovik Complex. The Kovik Complex consists of ten units (Lamothe, 2007), which have been harmonized with the new nomenclature (ApPkvk1 to ApPkvk10).

Description

The Kovik Antiform is located in the central area of the Ungava Orogen and extends east to the New Quebec Orogen. This lithotectonic domain is bordered to the south by the Sud Domain. An axial trough zone in the centre of the antiform is occupied by rocks of the Narsajuaq Arc. The arc is interpreted as an allochtonous calc-alkaline magmatic terrane overthrusted on the parautochtonous bedrock and on rocks of the Nord Domain (Lucas and St-Onge, 1992), thus separating the northern bedrock into two blocks (east and west antiform). In the western part of the Kovik Antiform, the Sugluk Suture marks the boundary between the northern part of the domain and the Narsajuaq Arc.

Geology

The Kovik Antiform consists only of the Kovik Complex (ApPkvk). This complex is an Archean to Paleoproterozoic assemblage of orthogneiss, paragneiss and intrusive rocks. This assemblage mainly includes tonalite or biotite ± hornblende ± epidote ± titanite ± allanite granodiorite (ApPkvk4, ApPkvk5 and ApPkvk6 units) showing varying proportions of mafic and metasedimentary rock enclaves (Taylor, 1982; St-Onge and Lucas, 1990, 1992; St-Onge et al., 1992). In the western antiform, these lithologies are commonly migmatitized and intruded with white to pinkish granitoids. Rare klippes of highly deformed silicoclastic metasedimentary rock (ApPkvk3) and extrusive or intrusive mafic rock (Akvk1) are present in or near tonalitic intrusions. Late, metric to kilometric intrusions, ranging in composition from tonalitic to syenogranitic (ApPkvk7 to ApPkvk10), intrude into tonalites and granodiorites (St-Onge and Lucas, 1992).

Geological Evolution

The Kovik Antiform represents a window on the parautochnous Archaean basement, equivalent to Superior Craton rocks. This window is interpreted as the result of rock uplift during post-accretion crustal deformations D3 and D4 during the Ungava Orogenesis (Lucas and St-Onge, 1992).

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 de l’Énergie et des Ressources naturelles, Québec.2018Bulletin géologiQUE
LAMOTHE, D.Lexique stratigraphique de l’Orogène de l’Ungava. Ministère des Ressources naturelles, Québec; DV 2007-03, 62 pages.2007DV 2007-03
ST-ONGE, M.R. – LUCAS, S.B. – PARRISH, R.R.Terrane accretion in the internal zone of the Ungava orogen, northern Quebec. Part 1: Tectonostratigraphic assemblages and their tectonic implications. Canadian Journal of Earth Sciences; volume 29, pages 746-764.1992Source
LUCAS, S.B. – ST-ONGE, M.R.Terrane accretion in the internal zone of the Ungava orogen, northern Quebec. Part 2: Structural and metamorphic history. Revue canadienne des sciences de la Terre; 1992, volume 29, n°4, pages 765-782.1992Source
ST-ONGE, M.R. – LUCAS, S.B.Evolution of the Cape Smith belt: Early Proterozoic con­tinental underthrusting, ophiolite obduction and thick-skinned folding. In: The Early Proterozoic Trans-Hudson Orogen of North America (Lewry, J.F. and Stauffer, M.R.,editors). Geological Association of Canada; special paper 37, pages 313-351.1990
ST-ONGE, M.R. – LUCAS, S.B.New insight on the crustal structure and tectonic history of the Ungava Orogen, Kovik Bay and Cap Wolstenholme, Quebec. Geological Survey of Canada; Paper 92-1C, pages 31-41.1992Source
TAYLOR, F.C.Reconnaissance geology of a part of the Canadian Shield, northern Quebec and Northwest Territories. Commission géologique du Canada; Mémoire 399, 32 pages.1982Source
NORTH AMERICAN COMMISSION OF STRATIGRAPHIC NOMENCLATURE (NACSN)North American Stratigraphic Code. American Association of Petroleum Geologists Bulletin, volume 67, pages 841-875.1983Source
NORTH AMERICAN COMMISSION OF STRATIGRAPHIC NOMENCLATURE (NACSN)North American Stratigraphic Code. American Association of Petroleum Geologists Bulletin, volume 89, pages 1547-1591.2005Source
MINISTÈRE DE L’ÉNERGIE ET DES RESSOURCES DU QUÉBEC (MERQ)Code stratigraphique nord-américain (traduction of: North American Stratigraphic Code, NACSN, 1983). Ministère de l’Énergie et des Ressources du Québec; DV 86-02, 76 pages.1986DV 86-02

 

 

23 octobre 2018