Summary:
The mineralized zones on the La Loutre property belong to the crystalline flake graphite deposit type. Flake graphite can occur in marble, paragneiss, iron formation, quartzite, pegmatite, syenite and serpentinized ultramafics (Simandl et al., 1995). The most common hosts for economically significant crystalline flake deposits are paragneiss and marble that were subjected to upper amphibolite to granulite facies metamorphism. The highest graphite grades in paragneiss-hosted deposits tend to occur along or near paragneiss-marble contacts.
The La Loutre property is located within the Nominingue-Cheneville Deformation Zone (NCDZ), a 10 km wide ductile shear zone at amphibolite facies with lit-par-lit injections of monzonite and dioriteamong Mesoproterozoic porphyroclastic paragneiss.
The property consists of a unit of biotite gneiss (±diopside). Quartzite constitutes a significant part of outcrops on the property. Diopside-scapolite-bearing calc-silicate rocks, marbles and other lithological units of sillimanite-biotite gneiss and sillimanite-garnet gneiss are less abundant than biotite gneiss with which they generally alternate as lit-par-lit. The marbles are observed at only a few places on the property. Some outcrops of amphibolite were also observed. Orthogneiss is found along the edge of the eastern part of the property. Diabase dykes cut all previous units.
The paragneisses contain significant biotite and are generally oxidized to a grey-brown color, and are schistose, locally displaying ribboning. On fresh surface, the rock appears grey-black to brownish-gray. They contain biotite, phlogopite, quartz, feldspar, garnet and pyroxene (augite), with occasional sillimanite, 1% to 2% pyrrhotite and 1% to 10% graphite. The biotite content is variable and ranges from 10% to 30%.
Quartzites are generally quite massive, greyish and feature granoblastic texture. On fresh surface, the rock tends to be light grey to greyish white with a predominance of quartz and minor feldspar, pyroxene (augite) and carbonate. Others show quartz-feldspar or quartz-dominant compositions or median compositions between pelitic gneiss and pure quartzite. Generally, no graphite is observed within the quartzite, but in cases where graphite was observed, notably in drill core, it could represent remobilized graphite from adjacent paragneiss.
Marbles tend to be layered, greyish creamy color on outcrop and have a granoblastic texture. Fresh surfaces are more greyish white in color, consisting of carbonate (mostly calcite) with minor quartz, feldspar, phlogopite, pyrite and graphite. Locally they have a higher content of quartz, up to 70% pyroxene (augite) in places and are very coarse grained; they are termed calc-silicate rocks.
The sedimentary sequence consists principally of a thick paragneiss unit intercalated with thin units of quartzite and marble. Bedding has an orientation of N150° and a dip ranging from 30° to 50° in the Battery Zone. Quartzites reach up to 1,000 m in strike length continuity, and are generally thin (typically several meters thick, exceptionally to 100 m). Globally, the graphitic carbon grade (Cg) of the quartzite is below 1%, but in some cases, higher Cg grades occur in quartzite near its contact with paragneiss. Marble consists of thin units with lateral footprint of more than 1,000 m. Marble units do not contain significant Cg grades.
The mineralized zones were interpreted based on the graphite grade information from drill holes and guided by quartzite and marble distribution patterns. There are 22 high-grade (HG) zones and 5 low grade (LG) zones encompassing the HG zones interpreted in the Battery Zone. Mineralization in the Battery Zone strikes along an average trend of N150° and an average dip of 45° is generally stratigraphically concordant with quartzite and marble. Graphite flakes occur disseminated in the graphitic paragneiss, in variable concentration. LG zones are wide (10 to 150 m) and long (strike length up to 1,000 m) in the Battery Zone. The paragneiss associated with the LG zones contains more quartz than the paragneiss associated with the high-grade zones, and consequently have a paler colour.
The Electric Vehicle (EV) Zone was interpreted in section and in three dimensions using implicit modelling. Fifteen distinct domains have been interpreted with the graphite grades generally higher than at the Battery Zone. Mineralization strikes at about 155° with strike lengths up to 750 m and domains dipping 35° to 45°.