DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
|Author:||Simard et al., 2013|
|Type area:||Kuujjuaq area (NTS sheet 24K)|
|Geological province:||Churchill Province|
|Geological subdivision:||Rachel-Laporte Lithotectonic Domain|
The Mercier Suite was defined in the Kuujjuak and Ungava Bay areas (Simard et al., 2013) to group all granitic intrusions of the Rachel-Laporte Lithotectonic Domain. Most of these intrusions were described by Gélinas (1958, 1965) and were not revisited during the Ministère’s 1:250 000 mapping work between 2011 and 2016. The Mercier Suite was continued southward in the Saffray Lake (Lafrance et al., 2014), Jeannin Lake (Charette et al., 2016) and Résolution Lake areas.
The Mercier Suite consists of two units: pegmatitic muscovite granite (pPmrc1), and medium-grained pink granite (pPmrc2).
Pegmatitic granite of unit pPmrc1 occurs as decimetric to decametric intrusions oriented parallel to foliation in metasedimentary rocks and amphibolites of the Laporte Supersuite (Freneuse and Klein suites). It is poor in ferromagnesian minerals and commonly displays a well-developed graphic texture at the megascopic scale. Its colour can vary rapidly from white to pink on the same outcrop. Granite is composed of plagioclase, quartz (25-35%), muscovite clusters (10-20%), varying amounts of K-feldspar (3-20%), and small chloritized biotite flakes (1-3%). It also contains 1-15% millimetric to centimetric crystals of accessory minerals such as tourmaline, garnet, apatite and hematite.
In the Kuujjuaq area, Gélinas (1965) states that the amount of pegmatitic granite dykes and sills increases from west to east.
The Mercier Suite also includes a major intrusion (25 km x 5 km) of biotite pink granite in the Saffray Lake area (Lafrance et al., 2014). Granite is pink, very homogeneous, massive, medium to coarse grained and contains <5% biotite. It contains in places some decimetric amphibolite enclaves. Granite of unit pPmrc2 resembles that of the Dancelou Suite in the Baleine Lithotectonic Domain.
Unit pPmrc1 forms small intrusions <1 km wide in the Rachel-Laporte Lithotectonic Domain, with a greater concentration in the northern part of the area. Unit pPmrc2 consists of a large-scale granitic intrusion (25 km x 5 km) that cuts Archean rocks of the Rénia and Highfall complexes, on the edge of the Lac Turcotte Fault, in the Saffray Lake area (Lafrance et al., 2014).
Intrusive rocks of the Mercier Suite cut metamorphosed volcano-sedimentary rocks of the Rachel-Laporte Lithotectonic Domain, namely the Freneuse and Klein suites. The Rachel-Laporte Domain corresponds to the eastern part of the New Quebec Orogen.
Does not apply.