The Chibougamau-Chapais mining camp is located in the northeast corner of the Matagami-
Chibougamau Greenstone Belt (MCGB) of the Abitibi Subprovince of the Archean Superior Province. It is
bordered either to the north and south by poorly known Archean granite and gneissic terrains, and to
the east by the Grenville Province, wherein the east-west stratigraphy of the belt abruptly terminates
along the Grenville Front (Figure 3).
The geology of the Chibougamau-Chapais district consists of two Archean age mafic to felsic volcanic
cycles (Roy Group) unconformably overlain by the Opémisca Group volcano-sedimentary sequence
(Figure 4). The volcanics and associated sediments are intruded by a series of large granitoid plutons and
septa of probable basement which influence the prevailing tectonic fabric of the district, typified by
alternating greenstone belts and aligned granitic plutons.
During the Archean period, extensional tectonics within the Matagami-Chibougamau Greenstone Belt
initially produced an extensive volcanic submarine pile of pillowed basalts and minor felsic pyroclastics
surmounted by large shield volcanoes (Obatogamau Formation), upon which a large number of small
intrusive felsic eruptive centres developed (Waconichi Formation). These rocks were broadly folded
during an initial phase of deformation (D1). During this initial extensional regime a number of early
plutons were also emplaced giving rise to local domes in the district. Normal faulting associated with
emplacement of the plutons produced a series of flanking grabens which were subsequently filled by
sediments. The surrounding volcanic highlands and emerging plutons were eroded, producing graben
filling sediments of the Opémisca Group. North-south horizontal shortening (D2 deformation) followed the initial phase of extensional tectonics in the belt resulting in the dominant regional east-west
foliation throughout the district.
As the major tectonic event in the Chibougamau-Chapais district, D2 deformation is characterized by a
well-developed east-west axial planar schistosity and is responsible for most of the isoclinal folds in the
region. The Kenoran age deformation is seen to consist of two distinct events: folding and ductile
faulting, either of which, are seen to have evolved progressively over time in the district and is
responsible for the development of the Faribault and Gwillim faults that exert regional structural
controls on the localization of several zones of east-west shear zones of variable thickness (2- 20m)
accompanied by strong ferrocarbonate alteration on the Croteau Est property.
A third regional deformation event (D3) in the Chibougamau-Chapais district has resulted in two sets of
brittle faults: one set oriented northeast, and one set oriented north-northeasterly. These brittle faults
demonstrate both oblique dextral and sinistral movement that form secondary dilatant zones with
respect to the existing east-west shears in the district.
The current understanding of the property geology is summarized, Figure 5. The geology presented is
the culmination of several prospecting, bedrock mapping, geophysical interpretation, reverse circulation
drilling, core drilling programs and integration of all publicly available data.
The Croteau and Waconichi properties are underlain by a mafic dominated volcanic package that
corresponds to the Bruneau Member of the upper part of the Gilman Formation. On the Waconichi
property, the Bruneau Member is separated from volcaniclastic and sedimentary rocks of the Blondeau
Formation by the regional east-west trending Faribault Fault.
The Bruneau Member largely consists of massive to pillowed, hyaloclastic and brecciated basalts that
have been intruded by co-magmatic gabbroic sills and/or massive flows. Within the mafic volcanic
sequence, narrow intervals of intermediate to felsic volcaniclastics also occur locally, as well as several
crosscutting quartz-porphyry and quartz-feldspar porphyry dykes. The northwest portion of the Croteau
property investigated by trenching and diamond drilling undertaken by Northern Superior Resources
since 2011 is also seen to contain a 400m wide belt of volcano- sedimentary rocks (intermediate tuff,
argillite and siltstone) that are seen to be intruded by a series of synvolcanic felsic, intermediate, and
quartz-feldspar porphyry dykes. The south dipping, east-west contact between mafic volcanics and
volcano- sedimentary rocks provides the locus for shearing and mineralization within the CBSZ on the
Within the CBSZ, strongly developed carbonate-ankerite-sericite alteration accompanied by localized
fuchsite alteration is observed across decametre-wide intervals. The alteration zones which vary 20-
120m in width, are characterized by variable quantities of quartz vein development, of which three sets
are recognized in various trench exposures. Pyrite and lesser trace quantities of chalcopyrite are also
observed as coarse to fine disseminations spatially associated with quartz veins hosted by strongly
ferrocarbonate (ankerite) and sericite altered wallrocks.
Although gold was first discovered in the Chapais-Chibougamau district as early as 1903, no permanent
development took place until 1949 when economic copper deposits were discovered near Chapais. And
although having begun as a copper mining camp, the Chibougamau-Chapais district has also been a
major past producer of gold. Since its beginning, this camp was produced some 1,050Mt of gold at an
average grade of 1.85 g/t Au.
Within the Chapais-Chibougamau camp there is a distinct variation in the average gold, silver and
copper grades between various types of deposits in the district, which is a product of the various ore
generating systems that have evolved over time.
The most important gold mineralizing event in the camp coincides with the onset of the Kenoran
Orogeny (ca. 2700Ma) which resulted in a major series of east-west trending faults and shear zones that
acted as a precursor for a major gold mineralizing episode. A number of deposits in the region (e.g.
Cooke, Norbeau, Gwillim, Joe Mann) are hosted by such east-west structures. The spatial relationship
between east-west trending shear zones and northeast trending fault systems has also been shown to
be a possible mechanism for generating added dilatancy during a late Kenoran gold mineralizing phase.
These are typically lode gold deposits associated with shear zones showing characteristic advanced
argillic (carbonate-ankerite-sericite-pyrite) alteration with the major gold mineralizing episode occurring
late in the deformation sequence. The deposits bear a strong resemblance to other Archean lode gold
hosted deposits elsewhere in the Abitibi Subprovince. The veins are mostly auriferous with, or without
economic grades of copper. Gold occurs as a visible phase or as microscopic grains associated with
pyrite and chalcopyrite. Most of these deposits are hosted within mafic sills.
A later, post-Kenoran shear system controlled the emplacement of the last major phase of gold
mineralization in the district characterized by stratiform ultramafic intrusions of the Lac Doré Complex.
Shear zones associated with the post-Kenoran Grenville Orogeny consist of southwest trending,
northerly dipping, left lateral oblique dip slip shears that host numerous copper-gold deposits in the
National Instrument 43- 101 Standards of Disclosure for Mineral Projects (NI 43-101) Technical Report
On January 14th, 2016, the Company announced that it had received a National Instrument 43-101 –
Standards of Disclosure for Mineral Projects (“NI 43-101”) Technical Report (dated September 28, 2015)
prepared by Optiro Pty Limited (the "Optiro Report", 2015), which includes an Inferred Mineral
Resource estimates (see Table 1) for the central part of the CBSZ.
Table 1.Croteau Est September 2015 Mineral Resource appropriate for public reporting
at 1.0ppm gold cut-off.
||Gold grade (Au g/t)
||Gold ounces (Koz)
|Inferred Mineral Resource
Due to the inherent sample support issues associated with including channel sample assay data into
resource models, previously reported high grade assay values from several trench exposures across the
central CBSZ were excluded from the Optiro Report and model (see press releases: October 12, 2011;
November 12, 2013; November 3, 2014).
Northern Superior management believes that the Inferred Mineral Resource estimates presented by the
Optiro Report represent a great start to understanding the gold potential of the CBSZ specifically, and
the Croteau Est property as a whole. Keep in mind that the inferred resource reported here is based only
on 64 core drill holes or 20,643m of core drilling (Figure 6). On the CBSZ alone, a tremendous
opportunity exists to expand the number of gold ounces within the CBSZ based on the premise that
additional exploration may:
- upgrade some of the exploration potential/target of the CBSZ (Figure 7);
- convert part of the Inferred Mineral Resource to Indicated Mineral Resource category by infill
drilling of core drill holes, from 50m x 50m to 25m x 25m;
- add additional gold ounces by inclusion of the high grade gold values previously reported from
channel samples cut in several trenches at surface within the central part of the CBSZ in future
- identify potential high grade rods or shoots within the CBSZ (see Northern Superior Resources
press release, November 3, 2014) with tighter collar spacing; and
- identify additional gold ounces along strike (east and west) of the central CBSZ and at depth, as
the system is open in those directions.
Management at Northern Superior has always maintained that the CBSZ is a small component of a much
larger gold mineralized system on the property, based not only on management’s observations, but also
from those recommendations made from several qualified consultants who have worked on the project.
Optiro Report Recommendations Include:
- Infill drilling of the central section of the CBSZ deposit to 25 x 25m drill hole spacing to
potentially upgrade the classification of this area to Indicated Mineral Resource category; and
- Exploration drilling to test along strike extensions of the central CBSZ deposit, in particular on
the eastern end of the deposit, where there are three drill holes that have mineralised intervals
consistent with the projection of the CBSZ. These intersections may suggest either an isolated
zone of mineralisation, or continuation of mineralisation of an unknown extent along the CBSZ.