|Author:||Madore et al., 2001|
|Type area:||Klotz Lake and New Quebec Crater regions (NTS sheets 35A and 35H)|
|Geological province:||Superior Province|
|Geological subdivision:||Minto Subprovince / Rivière Arnaud Terrane / Douglas-Harbour Domain|
|Lithology:||Biotite-hornblende granodiorite and granite|
Table des matières
The Leridon Suite was introduced by Madore et al. (2001) to group large granodioritic and granitic intrusions of the Klotz Lake and New Quebec Crater regions. The Leridon Suite later inherited other subunits of granitic and granodioritic intrusions from the Faribault-Thury Suite and the Qimussinguat Complex (Madore et al., 1999; Madore and Larbi, 2000). Simard et al. (2008) then assigned to it some of the Faribault-Thury’s monzonite and porphyritic quartz monzonite intrusions (Madore and Larbi, 2000).
The Leridon Suite consists of intrusive granitic, granodioritic and monzonitic rocks. These rocks are homogeneous with a massive, foliated or porphyraceous texture.
Unit nAlrd1 is composed of homogeneous granodiorite and granite, massive to foliated. These rocks contain few felsic injections and generally less than 5% mafic enclaves. They have average grain size ranging from 2 to 4 mm. Under the microscope, a coarse-grained igneous texture partially obliterated by metamorphic recrystallization. When deformed, rocks have a lepidoblastic texture with foliation defined by the orientation of biotite crystals. Granoblastic texture and quartz band relics are observed in the most deformed areas. Granite and granodiorite contain between 3 and 15% ferromagnesian minerals represented by biotite, hornblende and rarely orthopyroxene and clinopyroxene. Allanite, apatite and zircon are in traces. Plagioclase is partially sericitized and epidotitized. Other granite intrusions, which are too small to be mapped, contain biotite, muscovite, some garnet and no oxide (Madore et al., 1999, 2001; Madore and Larbi, 2000).
Porphyraceous granite appears homogeneous in outcrop. It is massive or foliated and contains very little felsic mobilisate. Granite contains local mafic enclaves. In microscopy, there is a porphyraceous igneous texture partially obliterated by metamorphic recrystallization around the feldspar phenocrystals’ rims (Madore et al., 2001). Porphyraceous granite contains about 10% ferromagnesian minerals, the most common of which are hornblende and biotite. In places, clinopyroxene is observed. Trace minerals are allanite, apatite, zircon and sphene.
Leridon Suite 2a (nAlrd2a): Porphyraceous monzonite, quartz monzonite
Subunit nAlrd2a includes monzonite and quartz monzonite with a porphyraceous texture. They are generally deformed, marked by foliation defined by the alignment of feldspar phenocrystals and ferromagnesian minerals. These rocks can be massive in places (Madore and Larbi, 2000). In microscopy, they are affected by preferentially localized recrystallization along the rims of feldspar phenocrystals as well as in the quartzofeldspathic matrix. Preferential orientation of quartz neoblasts indicates a recrystallization that occurred during a dynamic ductile deformation episode. Euhedral feldspar phenocrystals are preferentially oriented, which is typical of syntectonic intrusions. Monzonitic rocks contain between 25 and 50% orthose and microcline euhedral phenocrystals (1-5 cm). They also contain 20 to 35% smaller plagioclase phenocrystals that are generally sericitized. Phenocrystals are in a matrix consisting of 5-20% quartz, as well as 5-15% biotite and <1-10% green hornblende, which are locally chloritized. Accessory minerals are apatite, sphene, epidote and zircon. Rocks contain between 1 and 3% of small grains of magnetite and ilmenite (Madore and Larbi, 2000).
The Leridon Suite occurs as dispersed intrusions in the Faribault-Thury Suite and the Qimussinguat Complex. Intrusions are generally elongated in parallel with regional foliation and follow major regional structures. They 1 to 8 km wide and 5 to 35 km long.
The Leridon Suite has not been dated, but relationships observed in the field make it possible to estimate intrusion between 2735 and 2720 Ma (Simard et al., 2008).
The Leridon Suite is intrusive into “TTG” type rocks of the Faribault-Thury Suite and the Qimussinguat Complex. It consists of lithological assemblages quite similar to those found in the La Chevrotière and Pinguq suites further west. Simard et al. (2008) consider these three units equivalent and associated with a major potassic magmatic event that affected the Minto Subprovince’s northern part between 2735 and 2720 Ma.
Does not apply.