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Aveneau Suite
Stratigraphic label: [ppro]avn
Map symbol: pPavn

First published: 25 October 2016
Last modified: 6 August 2019

 

 

 

  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.
 
pPavn1 White tonalite and granite
pPavn1a Heterogeneous white tonalite and granite containing biotite schlierens and various enclaves
 
Author: Simard et al., 2013
Age: Paleoproterozoic
Stratotype: None
Type area: Kuujjuaq area (NTS sheet 24K)
Geological province: Churchill Province
Geological subdivision: Baleine Lithotectonic Domain
Lithology: Felsic intrusions
Category: Lithodemic
Rank: Suite
Status: Formal
Use: Active
Related unit(s)

None

Background

The Aveneau Suite was defined in the Kuujjuaq and Ungava Bay areas by Simard et al. (2013) to group whitish intrusive rocks similar in appearance to the Qurlutuq Complex migmatite leucosome. The unit was continued southward in the Saffray Lake (Lafrance et al., 2014) and Jeannin Lake (Charette et al., 2016) areas, and SE in the Henrietta Lake and Brisson Lake areas (Lafrance et al., 2015, 2016). As a result the Southeastern Churchill Province (SECP) division into lithotectonic domains (Lafrance et al., 2018), the definition of the Aveneau Suite has been revised to include only outcrops located within the Baleine Lithotectonic Domain (Lafrance et al., in preparation). In the George and Falcoz lithotectonic domains, similar white tonalites and granites were assigned to the Guesnier and Fougeraye complexes respectively. The Aveneau Suite used to have two informal units, and since outcrops of this second unit were located exclusively in the George Domain, they were reassigned to the Guesnier Complex.

Description

Aveneau Suite 1 (pPavn1): White Tonalite and Granite

The Aveneau Suite consists of whitish tonalite and granite with significant grain size variation, containing fine to coarse-grained rock piles. These rocks are massive to foliated by the alignment of biotite schlierens. They also contain irregular pegmatite clusters and pockets, decimetric to decametric, in diffuse contact. Ferromagnesian minerals are sparse (1-8%) and consist of brown biotite commonly concentrated in schlierens. Reaction textures on grain contact, as well as antiperthitic and myrmekitic textures are common in thin sections. Quartz is anhedral and displays marked undulatory extinction. Muscovite is ubiquitous (1-5%) and, although not abundant, accessory minerals observed are opaque minerals, sphene, epidote and zircon with, more locally, garnet, sericite and carbonate.

 

Aveneau Suite 1a (pPavn1a): Heterogeneous White Tonalite and Granite Containing Biotite Schlierens and Various Enclaves

 Subunit pPavn1a corresponds to areas where whitish intrusions of the Aveneau Suite are more heterogeneous, mainly due to many partially assimilated enclaves and 10-30% biotite schlierens in the rock. Enclaves are mostly composed of diorite, gneiss (e.g. paragneiss) and migmatite. In these areas where geology is heterogeneous, samples of the suite resemble migmatitic rocks of the Qurlutuq Complex (ApPqur); however, continuous banding is neither observed on outcrops nor in fresh exposure. Biotite schlierens are commonly aligned with foliation.

Thickness and distribution

With an area of ~4486 km2, the Aveneau Suite represents a significant proportion of the Baleine Lithotectonic Domain. The area of unit pPavn1 (3083 km2) is roughly twice that of subunit pPavn1a (1403 km2).

Dating

The two crystallization ages of the Aveneau Suite are Paleoproterozoic and contemporaneous to the crystallization period of the Winnie Suite anatectic liquid (1838-1807 Ma) derived from melting of False Suite paragneiss. The dating also gave ancient inherited ages indicating that the Aveneau Suite originated from melting of Archean rocks. The Aveneau Suite has been interpreted as the final melting product of Ungava Complex gneiss (Simard et al., 2013). However, geochronological results from migmatites of the Qurlutuq Complex, which are derived from partial melting of gneiss, do not adequately limit partial melting age to the Paleoproterozoic (Lafrance et al., in preparation).

ID-TIMS analyses of three Proterozoic zircon groups that are representative of a distinct population, with no evidence of Archean nuclei, yielded very precise and consistent results, but have a significant value range of 40 Ma, i.e. between 1832 Ma and 1792 Ma (Davis et al., 2015). According to Davis et al. (2015), tonalite would result from either remobilization of slightly older Proterozoic rocks in association with an Archean component, or from crystallization that has stretched over a long period of time, possibly in the deep crust, during a period of metamorphism. The presence of monazite in one of the samples could also indicate a sedimentary component in the source (Davis et al., 2014).

Unit Sample Number Isotopic System Mineral Crystallization Age (Ma) (+) (-) Inherited Age (Ma) (+) (-) Reference(s)
pPavn1 2011-IL-3141A U-Pb Zircon 1817 10 10 2697 18 18 Davis et al., 2014
Monazite 1848 13 13      
pPavn1a 2012-IL-3176A U-Pb Zircon 1811 12 12 2718 17 17 Davis et al., 2015

Stratigraphic Relationship(s)

Rocks of the Aveneau Suite contain up to 15% centimetric to decimetric enclaves from other units in the area, particularly diorite and gabbro of the Ralleau Suite, gneiss of the Ungava Complex, migmatite of the Qurlutuq Complex and paragneiss of the False Suite. Most of these enclaves show deformation prior to the Aveneau Suite’s emplacement. In several places, whitish intrusions of the Aveneau Suite are emplaced into older rocks as decimetric to decametric sills.

Paleontology

Does not apply.

References

Author(s) Title Year of Publication Hyperlink (EXAMINE or Other)
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
DAVIS, D W. MOUKHSIL, A. LAFRANCE, I. HAMMOUCHE, H. GOUTIER, J. PILOTE, P. TALLA TAKAM, F. Datations U-Pb dans les provinces de Churchill et du Supérieur effectuées au Géotop en 2012-2013. Ministère de l’Énergie et des Ressources naturelles; RP 2014-071, 56 pages. 2015 RP 2014-07
DAVIS, D W. SIMARD, M. HAMMOUCHE, H. BANDYAYERA, D. GOUTIER, J. PILOTE, P. LECLERC, F. DION, C. Datations U-Pb effectuées dans les provinces du supérieur et de Churchill en 2011-2012. Ministère de l’Énergie et des Ressources naturelles; RP 2014-05, 62 pages. 2014 RP 2014-05
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
LAFRANCE, I. – VANIER, M.-A. – CHARETTE, B.  Domaine lithotectonique de Baleine, sud-est de la Province de Churchill, Nunavik, Québec, Canada : synthèse de la géologie. Ministère de l’Énergie et des Ressources naturelles, Québec. In preparation Bulletin géologiQUE
LAFRANCE, I. BANDYAYERA, D. BILODEAU, C. Géologie de la région du lac Henrietta (SNRC 24H). Ministère des Ressources naturelles, Québec; RG 2015-01, 62 pages. 2015 RG 2015-01
LAFRANCE, I. BANDYAYERA, D. CHARETTE, B. BILODEAU, C. DAVID., J. Géologie de la région du lac Brisson (SNRC 24A). Ministère de l’Énergie et des Ressources naturelles, Québec; RG 2015-05, 61 pages. 2016 RG 2015-05
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
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