Intrusive rocks of the Anville Pluton were originally mapped by Remick (1956, 1957) and Lyall (1959). They are included in the Lapparent Intrusive Suite, first named by Racicot et al. (1984). The Anville Pluton is described in the report of Midra et al. (1992).

Anville Pluton, Undivided (nAanv): Tonalite and Tonalite Containing Basalt and Gabbro Enclaves

According to Midra et al. (1992, p. 29): “The pluton consists generally of medium-grained grey tonalite, except in the western part, where its composition gradually changes to light pink porphyritic granodiorite.”

Tonalite is subhedral and displays a cataclastic to mylonitic texture in the southern part of the pluton.

According to the same author: “The main minerals encountered are: plagioclase, quartz, biotite, hornblende and microcline. Accessory minerals are epidote, allanite, sphene, chlorite, apatite, muscovite and opaque minerals. Plagioclase (An_25-28) forms euhedral to subhedral millimetric crystals. It is locally zoned and, in some cases, has myrmeckitic edges. The core of plagioclase is commonly altered to epidote and sericite. Quartz (0.05-1.5 mm) is interstitial to plagioclase and has undulatory extinction. In a few thin sections, grains have sutured edges. Tabular biotite (0.1-3.5 mm) highlights foliation of the rock. It is locally altered to chlorite or muscovite, and is commonly associated with sphene and epidote. Subhedral hornblende (0.1-3 mm) is restricted to a few samples. It is commonly surrounded by biotite. Microcline is in a minor phase in tonalite […].”

Granodiorite is composed of quartz (25%), albite or oligoclase (40-45%), K-feldspar (10-15%), green hornblende (10%), white mica (3-4%), epidote (4-5%) and accessory minerals such as ilmenite, apatite and zircon (Picard, 1985).

According to Midra et al. (1992, p. 29): “Foliation in granodiorite is marked by quartz stretching, the alignment of microcline phenocrystals and micaceous minerals. This foliation is locally accompanied by a slight subhorizontal mineralogical lineation. In places, quartz grains display crenulation at the outcrop scale.”

Thickness and distribution

The pluton has an ovoid shape with a long axis ~28.5 km parallel to regional foliation WNW-ESE. The short axis, oriented NNE-SSW, has a maximum length of 9.2 km.

Dating

A sample taken on outcrop 2012-YD-2676 yielded a crystallization age of 2714.8 ±0.6 Ma (Augland et al., 2016).