|Author:||Charette and Beaudette, 2018|
|Stratotype:||Kuugaq River, NTS sheet 35L01 (type locality)|
|Geological province:||Churchill Province|
|Geological subdivision:||Ungava Orogen / Narsajuaq Lithotectonic Domain|
|Lithology:||Potassic intrusive igneous rock|
Table des matières
The Kuugaq Suite was introduced by Charette and Beaudette (2018) to distinguish intrusions of the Narsajuaq Lithotectonic Domain: 1) well-foliated, even-grained and partially recrystallized, and 2) porassic, late, slightly foliated to massive. The unit’s name is taken from the Kuugaq River located in sheet 35L01. The unit was extended east to Hudson Strait by Vanier and Lafrance (2020).
The composition of the Kuugaq Suite varies from monzogranitic to syenogranitic, or even locally granodioritic. The quartz content is generally 25% and 35%, but in places <20%. These rocks are then quartzo-monzodioritic. Unit pPkug1 has a low content of ferromagnesian minerals (4-15%), mainly bitotite with minor amounts of hornblende and magnetite. Foliation is highlighted by biotite, which forms thin millimetric layers. Granite also includes 10-20% medium-grained, pinkish or pinkish beige discontinuous diffuse bands. Hematitization is commonly observed and gives outcrops a pinkish colour.
Regardless of composition, two main phases were identified. The dominant phase is characterized by fine grain size, well-developed foliation (commonly gneissic in appearance), and an even-grained, fine and medium-grained texture, locally granoblastic. The secondary phase is distinguished by a coarser size and lack of gneissic structure. Accessory minerals are apatite, epidote, zircon and sphene. In thin sections, trace amounts of retrograde chlorite are observed locally replacing biotite.
Outcrops of the Kuugaq Suite commonly contain 2-5% diorite or gabbro, which form dislocated and boudinaged bands or enclaves.
The Kuugaq Suite forms kilometric zones scattered throughout the Narsajuaq Domain. These zones are elongated following the E-W regional foliation and locally folded.
The Kuugaq Suite granite is cut by granitoid intrusions and plutons of the Sanningajualuk Suite. It locally occurs as enclaves within them. It is generally close to large masses of foliated charnockite of the Siurartuuq Suite. However, the contact between these two units was not observed in the field. The contact is sharp with mesocratic hypersthene gabbronorite and diorite of the Pingasualuit Complex.
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CHARETTE, B., BEAUDETTE, M. 2018. Geology of the Cape Wolstenholme Area, Ungava Orogen, Churchill Province, Southeast Ivujivik, Quebec, Canada. MERN. BG 2018-03, 1 plan.
VANIER, M.-A., LAFRANCE, I. 2020. Geology of the Sirmiq Lake Area, Ungava Orogen, Nunavik, Quebec, Canada. MERN. BG 2020-02, 1 plan.
Ministère de l’Énergie et des Ressources naturelles (MERN). Kuugaq Suite. Quebec Stratigraphic Lexicon. http://gq.mines.gouv.qc.ca/lexique-stratigraphique/province-de-churchill/suite-de-kuugaq_en [accessed on Day Month Year].
Mehdi A. Guemache, P. Geo., Ph.D. (coordination); Mélina Langevin, GIT, B.Sc. (critical review); Simon Auclair, P. Geo., M.Sc. (editing); Céline Dupuis, P. Geo., Ph.D. (English version); Ricardo Escobar Moran (HTML editing).
Isabelle Lafrance, P. Geo., Ph.D. firstname.lastname@example.org (redaction)
Mehdi A. Guemache, P. Geo., Ph.D. (coordination); Benoit Charette, P. Geo., Ph.D. (critical review); Simon Auclair, P. Geo., M.Sc. (editing); Céline Dupuis, P. Geo., Ph.D. (English version); Ricardo Escobar Moran (HTML editing).