Geology Of The Property

The western part of the property, belongs to the La Grande sub-province and is dominated by mafic volcanites sequences and by dioritic and granodioritic intrusions; the eastern part belongs to the Opinaca sub-province and is dominated by metasedimentary formations sequences..

M. Gauthier and L. Paquette (MB 97-02) describe one of the La Grande units as follows:

"One of the five large lithostratigraphical units of the La Grande and the Opinaca sub-provinces consists in an arenite, archean relic, in which are found sills and ultramafic lopolites (Roscoe and Donaldson, 1988) ".  This unit has been named the "Apple Formation".


              Part of the Matamec Sakami property is occupied by this formation.  The mafic volcanic rock consists in a massive basalt with a gabbroic texture or deformed pillowed textures.  These basalts are sometimes metamorphosed by leaching, involving an enrichment in aluminous minerals such as biotite and garnet.  These volcanites are sometimes strongly stretched as shown in the drill core.  Locally, lapilli and cinders tuffs have been observed with felsic dykes.  A few polygenic conglomerates and bedded iron formations (oxides, sulphides and silicates) have also been identified in the region.  Thin iron formations sequences with limited lateral extensions are intercalated with large volcanic sequences.  The basalts belong to the Yasinski group as defined by Goutier and al. (2000).  A few amphibolitic facies were also observed in the field, composed essentially of black and green probably ancient amphibole and of plagioclase.  These amphibolites are probably ancient metamorphosed basalts.

Intrusive units have also been observed in the field and in the drill core.  Granodiorite is the main constituent of the hill in the La Pointe sector.  This intrusion divides into three units.  The typical granodiorite is massive, usually whitish, coarse grained and is composed of quartz, feldspar, biotite and sometimes hornblende.  The second type is a quartzic porphyry grayish white, showing numerous rounded or sub-rounded quartz grains in a finer matrix composed of quartz and felspar with traces of biotite and amphibole.  The third sub-unit corresponds to the light grey aplite dykes.  Felsic dykes intrude the volcanic and sedimentary units.  They are generally silicified, light grey to weak bluish grey.  These dykes are fine grained and show some macroscopic biotite.  They have been observed along the lake shore between the zones 24 and 26, and also in the stripped area of the zone 23.

The metasediments of the Opinaca sub-province show two main facies : (1) an arenitic facies with arkose and sub-arkose and (2) apelitic facies with biotitic paragneiss.  Inside these facies, a few iron formation horizons have been observed, mainly on the Sakami property.  Those sedimentary units are generally metamorphosed into biotite and/or sillimanite paragneiss with some quartz.  These units indicate the contact between the volcanic and intrusive rocks of the La Grande sub-province and the sediments of the Opinaca sub-province.

               However, all the units show a well developed intimate regional schistosity at 234° azimuth.  This structural character is particularly developed in the sedimentary units and seems parallel with the stratigraphy.  In the region, the schistosity is marked by the orientation of mica flakes.  In the Sakami lake region, the regional schistosity is undulated by a very strong folding (P2).  The folds are orientated WSW-ENE and are open.


Summary of the works carried out








GÉOPHYSICS (line-km)



La Pointe

Traverses at 50m.

1.5 km²

32.6 km

41 holes (7889m)


24.6 km

32.6 km


Traverses at 100m.

12 km²

79.2 km

5 holes  (595 m)


50.4 km

79.2 km


Traverses at 100m.

10 km²

71.2 km

4 holes (644m)*


9.5 km

71.2 km


Traverses at 100m.

17 km²







Traverses at 100m.

18 km²








58.5 km²

183 km

50 holes


84.5 km

183 km




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