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Kuujjuaq Pluton
Stratigraphic label: [ppro]kuu
Map symbol: pPkuu

First published: 6 August 2019
Last modified:

 

 

 

  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: Perreault and Hynes, 1990
Age: Paleoproterozoic
Stratotype: None
Type area: Kuujjuaq area (NTS sheet 24K)
Geological province: Churchill Province
Geological subdivision: Baleine Lithotectonic Domain
Lithology: Gneissic felsic intrusions
Category: Lithodemic
Rank: Lithodeme
Status: Formal
Use: Active
Related unit(s)

None

Background

Gélinas (1959) used the term « Stewart Dome » to describe a unit of quartzofeldspathic gneiss sourrounded by biotite-rich and locally garnet-rich gneiss. Perreault and Hynes (1990) later used the term “Kuujjuaq Batholith” to describe this unit. Reinterpretation of this area by Simard et al. (2013) using field descriptions by Serge Perreault (unpublished data) has linked rocks assigned to the Kuujjuaq Batholith to a single intrusion corresponding to a geophysical anomaly of very clear oval shape. Consequently, the name « Kuujjuaq Batholith » was replaced by the more appropriate name « Kuujjuaq Pluton ». To the east of the Pingiajjulik Fault, banded gneissic rocks originally assigned to the Kuujjuaq Batholith were reassigned to the Ungava Complex. Intrusive rocks on the west side of this fault were associated with the Kaslac Complex or Tasialuk Suite, depending on their composition.

 

Description

Orthogneiss of the Kuujjuaq Pluton varies in composition from tonalitic to granodioritic, with locally dioritic and granitic phases. They are also strongly injected by pegmatites. Orthogneiss are whitish grey or pink. Gélinas (1959) mentions that gneiss in the Stewart Lake area is rarely banded, but it is well foliated. Thus, they appear to be deformed intrusive rocks with a gneissic appearance rather than ancient gneiss. Kuujjuaq Pluton rocks contain 40-70% quartz and 20-40% feldspatr, with oligoclase more abundant than microcline. Ferromagnesian minerals are sparse (5%) and include biotite and locally hornblende. Accessory minerals are sphene, allanite, zircon, apatite and magnetite.

 

Thickness and distribution

The Kuujjuaq Pluton forms an elliptical intrusion oriented NW-SE, 11 km long by 6 km wide, in the NW portion of the Baleine Lithotectonic Domain. It covers an area of ~53 km2 and is located just east of the Pingiajjulik Fault.

 

Dating

U-Pb dating on zircons of the Kuujjuaq Pluton has given crystallisation ages between 1869 Ma and 1833 Ma, and metamorphic ages around 1830 Ma. This confirms the hypothesis of Gélinas (1959) which proposed that this unit consist of deformed intrusive rocks rather than ancient gneiss. The sample from Perreault and Hynes (1990) was taken in the SE portion of the pluton, while that of Corrigan (personal communication, 2018) was sampled in the central portion. These ages are contemporaneous to the emplacement of other intrusive units within the Baleine Domain, namely the Champdoré Suite (1859-1837 Ma), Kaslac Complex (1835-1828 Ma), De Pas Supersuite (1862-1805 Ma), Lhande Suite (1834 Ma), as well as crystallization of diatexites of the Winnie Suite (1839-1838 Ma).

Unit Isotopic System Mineral Crystallization Age (Ma) (+) (-) Metamorphic Age (Ma) Reference(s)
pPkuu U-Pb Zircon 1869 4 4   David Corrigan, personal communication, 2018
pPkuu U-Pb Zircon 1845-1833     1830 Perreault and Hynes, 1990

Stratigraphic Relationship(s)

The Kuujjuaq Pluton is surrounded by biotite-rich paragneiss, locally garnet-bearing, of the False Suite. It is cut by late intrusionsl of the Dancelou (pPdac) and Aveneau (pPavn) suites.

Paleontology

Does not apply.

References

Author(s) Title Year of Publication Hyperlink (EXAMINE or Other)
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
PERREAULT, S. –  HYNES, A. Tectonic evolution of the Kuujjuaq terrane, New Québec Orogen. Geosciences Canada; volume 17, pages 238-240. 1990
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

 

 

5 février 2020