|Author:||Bandyayera and Daoudene, 2018|
|Type area:||Champion Lake area (NTS sheet 32N09)|
|Geological province:||Superior Province|
|Geological subdivision:||La Grande Subprovince|
|Lithology:||Granitic intrusive rocks|
Table des matières
The Valiquette Pluton is a lithodeme (Bandyayera and Daoudene, 2018) describing a large intrusive mass located north of Valiquette Lake, which occupies the northern half of the Champion Lake region (sheet 32N09), where large, representative outcrops are located.. It was a former member of the Champion Complex, assigned by Card and Ciesielski (1986) to the La Grande Subprovince. The Rivière Rupert Shear Zone marks the contact between the Valiquette Pluton and the Nemiscau Subprovince (Bandyayera and Daoudene, 2018).
The unit consists of locally pegmatitic, medium to coarse-grained biotite granite. It is homogeneous, massive to very weakly foliated. The rock, which is locally hematitized, is typically pink to pale pink in fresh exposure and altered surface. It generally contains 1-5% biotite, 2% hornblende and 2% magnetite. Biotite is partially chloritized and locally epidotitized. It shows in places biotite schlierens (concentrated in more magnetic levels) that are likely the result of the assimilation of supracrustal rocks. The Valiquette Pluton contains metric enclaves of gneissic tonalite, amphibolite, diorite and porphyritic granodiorite.
From a geochemical perspective, biotite granite is type I, peraluminous, calc-alkaline to shoshonitic, potassium-rich (K2O >4 wt.%) and characterized by negative europium (Eu) anomalies. A dozen lithogeochemical analyses show that the granite is syncollisional (Pearce et al., 1984).
The Valiquette Pluton extends from east to west over a length of more than 50 km and a width of 15 km. The magnetic susceptibility of the rock is low and homogeneous, which allows its extent to be clearly defined on geophysical maps (D’Amours, 2011).
The Valiquette Pluton cuts the tonalitic gneiss, tonalite and granodiorite units of the Champion Complex. At its southern limit, the Valiquette Pluton cuts volcanic mafic rocks of the Lac des Montagnes Group of the Nemiscau Subprovince. This contact is also evidenced by the presence of shear zones of the Nemiscau and Rupert rivers. The Valiquette Pluton also contains amphibolitized, weakly migmatitized volcano-sedimentary rock enclaves, which were assigned to the Anatacau-Pivert Formation further north and described by Moukhsil (2000).
Does not apply.