June 2003
 

New gold targets in the Chibougamau area

Patrick Houle
Géologie Québec

The Chibougamau mining district is known for its gold and copper potential. And yet, exploration in the western part of the Chibougamau Pluton (PDF Format, 64 kb) was mainly focussed on the search for copper, between 1935 and 1965. Then, investigations were for the most part concentrated along NNE to NE faults. Exploration has always been considerably limited in this area, given the presence of important water bodies. It does however host several NW to NNW ore-bearing structures (PDF Format, 553 kb) that most likely represent late orogenic subsidiary shears associated with major regional shear zones. This preferential NW to NNW orientation constitutes a new first-class gold target in the western part of the Chibougamau Pluton (NTS sheet 32G/15).

To date, most known mineral occurrences in the western part of the Chibougamau Pluton occur in sericitized shear zones; the latter still warrant much deeper exploration. The application of new high-resolution geophysical surveys in this part of the Chibougamau Pluton should allow explorationists to recognize or interpret the presence of NW-SE synvolcanic faults, and to generate very promising exploration targets.

Regional geology
Economic geology
Characterization of mineral occurrences
A porphyry-epithermal continuum

References

CARRIER, A.- JÉBRAK- M.- ANGELIER, J.- HOLYLAND, P., 2000 – The Silidor Deposit, Rouyn-Noranda District, Abitibi Belt: Geology, Structural Evolution, and Paleostress Modeling of an Au Quartz Vein-Type Deposit in an Archean Trondhjemite. Economic Geology; volume 95, pages 1049-1055.

CHOWN, E.H.- DAIGNEAULT, R. - MUELLER, W. - MORTENSEN, J.K., 1992 - Tectonic evolution of the Northern Volcanic zone, Abitibi Belt, Quebec. Canadian Journal of Earth Sciences; volume 29, pages 2211-2225.

DAIGNEAULT, R., 1998 – Une évolution tectonique métallogénique centrée sur le Pluton de Chibougamau. Dans : Géologie et métallogénie du district minier de Chapais-Chibougamau; Nouvelle vision du potentiel de découverte (éditeur : P. Pilote). Ministère des Ressources naturelles, Québec; DV 98-03, page 45-52.

GROVES, D.I. - GOLDFARB, R.J. - GEBRE-MARIAM, M. - HAGEMANN, S.G. - ROBERT, F., 1998 - Orogenic gold deposits: A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Ore Geology Reviews; volume 13, pages 7-27.

KIRKHAM, R.V. – PILOTE, P. – SINCLAIR, W.D. – ROBERT, F.- DAIGNEAULT, R., 1998 –Les veines de Cu-Au de l’île Merrill et le gîte porphyrique en Cu (-Mo) du lac Clark, camp minier du lac Doré, Chibougamau. Dans : Géologie et métallogénie du district minier de Chapais-Chibougamau, nouvelle vision du potentiel de découverte (éditeur : P. Pilote). Ministère des Ressources naturelles, Québec; DV 98-03, pages 97-106.

KROGH, T.E., 1982 – Improved accuracy of U-Pb zircon ages by the creation of more concordant systems using air abrasion technique. Geochemica and Cosmochimica Acta; volume 46, pages 637-649.

PILOTE, P. – JOANISSE, A. – DAIGNEAULT, R. – MAGNAN, M.- KIRKHAM, R.V.- ROBERT, F., 1998 – Les gisements de type Cu-Au porphyriques archéens du camp minier du lac Doré, Chibougamau : reconstruction géométrique et temporelle – potentiel du nord québécois. Association géologique du Canada –Association minéralogique du Canada; Congrès annuel, Québec 1998. Volume 23, page A-147.

PILOTE, P. – GUHA, J., 1998 – Métallogénie de l’extrémité est de la Sous-province de l’Abitibi. Dans : Géologie et métallogénie du district minier de Chapais-Chibougamau; Nouvelle vision du potentiel de découverte (éditeur : P. Pilote). Ministère des Ressources naturelles, Québec; DV 98-03, pages 29-43.







June 2003
 

New gold targets in the Chibougamau area
Regional geology

Patrick Houle
Géologie Québec

The Chibougamau mining camp is characterized by the presence of a vast layered intrusion, the Lac Doré Complex (DLC), cored by the Chibougamau Pluton (PDF Format, 64 kb). The importance of these two elements can be established at many different levels, whether as the main centre of volcanism, as the driving force behind the different types of ore deposits, and as a structural feature that governed response to deformation over a period of 30 Ma during the Archean (Daigneault, 1998). The crescent-shaped Chibougamau Pluton occupies the axial part of the Chibougamau anticline. It represents a multiphase synvolcanic intrusion (2718±2 Ma; Krogh, 1982) derived from the successive emplacement of magmas differentiated at shallow depths.

Consequently, substantial evidence suggests that porphyry-type and lode-type occurrences in the Lac Doré mining camp are products of a single but extensive pre-tectonic magmatic-hydrothermal ore-generating event, coeval with the emplacement of the Chibougamau Pluton and the construction of the second volcanic cycle in the Chibougamau area. The variety of ore deposit types observed in this mining district, which are particularly well developed along the northern and southern limbs of the Chibougamau Pluton, appears to be the result of normal or reverse movement along certain major faults, and of the local erosion level (Pilote et al., 1998).











June 2003
 

New gold targets in the Chibougamau area
Economic geology

Patrick Houle
Géologie Québec

Most Cu-Au deposits in the Chibougamau mining camp are hosted in NW-SE shear zones (mine shear) within the meta-anorthosite along the northern DLC. These zones are interpreted as synvolcanic structures that were reactivated by regional deformation (Kirkham et al., 1998). From 1954 to the end of 1997, eleven (11) ore deposits were mined in NW-SE shear zones, for a total production of 31.7 million short tons of ore at a grade of 1.76% Cu and 2.26 g/t Au. Historically, mines in the lac Doré and lac Chibougamau area have yielded a total production of 46.9 million short tons of ore at a grade of 1.74% Cu and 2.19 g/t Au, amounting to a little over 1.6 billion pounds of copper and 3.1 million ounces of gold (PDF Format, 65 kb).

Similarly, there are many other examples of gold deposits associated with granitoid intrusions in the Abitibi geological Subprovince. Among these, the Bourlamaque batholith in the Val-d’Or area hosts several gold deposits along its margins. Furthermore, the Belmoral mine (1,710,102 t at 6.46 g/t Au) is hosted in a shear zone within the Bourlamaque batholith, in a setting similar to what is observed in the western part of the Chibougamau Pluton.

In addition, late orogenic gold-bearing quartz veins in the Rouyn-Noranda mining district are largely hosted in Archean tonalitic plutons of the Blake River Group. For example, the Silidor mine (2.95 million tonnes at 5.1 g/t Au) is a 900-m-long ore zone oriented N330º/55ºE, with a vertical extension of 900 m and an average width of 3.5 m. It is enclosed in a strongly hematized trondhjemite of the Powell Pluton. The Silidor deposit is the result of several vein-filling episodes, which took place throughout the evolution of a fault network with normal or reverse movements (Carrier et al., 2000). NW to NNW-oriented lode gold deposits in the Powell Pluton therefore appear to be similar in many ways to NW to NNW structures in the western part of the Chibougamau Pluton.











June 2003
 

New gold targets in the Chibougamau area
Characterization of mineral occurrences

Patrick Houle
Géologie Québec

Most mineral occurrences in the western part of the Chibougamau Pluton are characterized by the presence of a shear zone, accompanied by strong sericitization. This sericite generally occurs as crystals aligned parallel to the shearing direction. Since known showings are currently found in all phases of the Chibougamau Pluton, and even in meladiorite and quartz diorite intrusive breccias, the type of host rock does not appear to be a determining criteria in the search for new mineral occurrences. Different types of veins were emplaced in the shear zones, as a result of several distinct phases of injection. Quartz remains the dominant mineral in these veins. In addition to quartz, the veins may contain the following minerals: carbonate, tourmaline, chlorite, sericite, fuchsite, epidote, albite, pyrite, chalcopyrite, sphalerite, magnetite, silver and gold. Native gold was observed in a few showings. Some showings exhibit weak hematization of plagioclase grains, possibly related to the presence of major NE faults, such as the Scott lake fault.

As an exploration guide, mineralized shear zones may be grouped into two preferential directions, namely NW to NNW (PDF Format, 84 kb) and NNE to NE (PDF Format, 85 kb).

A compilation of previous work conducted in the western part of the Chibougamau Pluton shows that most of this work was performed on mineral occurrences associated with NNE to NE-oriented shear zones. However, very little work has been conducted on showings hosted in NW to NNW shear zones. The Silver Tower showing (PDF Format, 84 kb) , associated with a NW to NNW shear, is an excellent example. It is defined by quartz veins with pyrite, sphalerite, chalcopyrite and gold mineralization (grab sample: 24.0 g/t Au, 0.80% Cu, 1.10% Zn and 9.4 g/t Ag). This mineralization, emplaced in the tonalite, is characterized by the presence of a shear zone (N330º) about 2 to 3 m wide. Previous work carried out on this showing includes EM geophysical surveys and surface sampling in a trench. Recently, in the fall 2002, in the vicinity of the showing, an induced polarization survey delineated a NW-trending conductor that extends for at least 1.8 km. The conductor is then disturbed by a series of late NNE to NE faults (C. Claveau, personal communication, 2003).









June 2003
 

New gold targets in the Chibougamau area
A porphyry-epithermal continuum

Patrick Houle
Géologie Québec

It has been shown that the discovery potential for porphyry gold and/or copper-gold deposits, and for lode-type or epithermal zinc-gold deposits is excellent in the Chibougamau area, since porphyry-type and epithermal deposits form a continuum derived from the same geological phenomenon (Groves et al., 1998).

Porphyry Cu-Au-Mo deposits

The Chibougamau mining camp hosts a few sub-economic to economic porphyry deposits (Île Merrill, Devlin, GrandRoy, Baie Hématite, Queylus, R2), which are spatially and genetically associated with the Chibougamau Pluton. Since these porphyry deposits were emplaced near surface, they were probably preserved as a result of tilting prior to erosion of the former geological system. The Chapais-Chibougamau area is interpreted as having been tilted early on (Chown et al., 1992), thus confirming the excellent preservation potential for this type of deposit.

The presence of porphyry Cu-Mo-Py occurrences is known southwest of the Chibougamau Pluton (near the Chapais-Chibougamau airport and Queylus); these occurrences may be related to NW-SE synvolcanic structures in the central part of the western Chibougamau Pluton.

Epithermal Zn-Au deposits

The potential of the Chibougamau area for epicrustal gold-rich polymetallic deposits is poorly understood and little explored. Recent investigations in the Chibougamau area outline a Zn-Au connection in certain areas where networks of locally brecciated quartz-carbonate-sphalerite veins and veinlets are found. This type of epithermal mineralization was identified at the Lac Berrigan deposit (PDF Format, 63,3 kb), namely polymetallic veins with Au-Ag-Cu-Pb-Zn-As (Pilote and Guha, 1998). The emplacement of these veins in ultramafic sills was ideally controlled by synvolcanic faults or associated subsidiary faults characterized by limited lateral movement. The latter faults may have served as conduits for mineralizing fluids or for the emplacement of intrusions. There exists a continuum, oriented NW-SE, between the Île Merrill porphyry deposits (9.4 Mt at 1.73% Cu, 0.72 g/t Au and 13.37 g/t Ag) at depth, and the Berrigan epithermal deposit (1.5 Mt at 3.31% Zn, 14 to 380 g/t Ag and 1.9 g/t Au), located in the upper part of the stratigraphic sequence.

In the western part of the Chibougamau Pluton, the Pointe showing (PDF Format, 84 kb) exhibits barite veins with traces of chalcopyrite. Fragments of quartz veins are present in the barite. These observations suggest that early quartz veins were emplaced and later brecciated, probably by shearing, then infilled with barite. Cavity infilling, to which quartz, calcite and barite are associated, may constitute the last hydrothermal phase in the formation of an epithermal zinc-gold deposit. The search for these epithermal-type veins (Au/Ag ratio < 1) in the western part of the Chibougamau Pluton may therefore represent another first-class exploration target.










June 2003
 

Budget Flash

Jocelyne Lamothe
Direction du développement minéral

Adjustment of the tax credit relating to resources

In the June 12, 2003 Budget Speech, the gouvernement du Québec announced that all of the tax credits and tax holidays for businesses will be tightened. The refundable tax credit for resources announced in the March 2001 Budget Speech as well as the temporary improvement added in August 2002 are aimed at by these tightening measures.

In this way, the total credit of 60% that was available to eligible mining corporations has been reduced by 25% and is distributed in the following proportions:

 

Corporations not operating any mineral resource

Other corporations

 

Refundable portion

Non-refundable portion

Total

Refundable portion

Non-refundable portion

Total

Expenses relating to mineral resources

Near or Far North

Elsewhere in Québec

 

 

33.75

30

 

 

11.25

15

 

 

45

45

 

 

18.75

15

 

 

26.25

30

 

 

45

45

Expenses relating to other natural resources (cut stone)

 

 

15

 

 

n.a.

 

 

15

 

 

15

 

 

n.a.

 

 

15

In addition, this credit will henceforth be taxable under both the Taxation Act and the Mining Duties Act.

This rate reduction as well as the taxation of the tax credit relating to resources will be applied to eligible expenses incurred after June 12, 2003.

Modification of the tax benefits relating to flow-through shares

Even though Québec’s flow-through share system is maintained until the end of year 2004, it also undergoes reductions that are comparable to those applied to the refundable tax credit for resources.

In fact, the additional deductions of 25% and 50% that were admitted previously to the individual investor decrease to 10,42% and 20,83% respectively. The individual may claim, for example, a total deduction equal to 131,25%, instead of 175%, regarding surface exploration expenses incurred in Québec that have been foregone in his favour.

Moreover, deductions for flow-through share issue expenses may no longer be foregone in favour of an investor and the additional capital gains exemption for flow-through shares is abolished. These modifications apply to flow-through shares issued after the day of the Budget Speech. However, they do not apply to flow-through shares issued either following a private placement or following an application for receipt of the final prospectus or prospectus filing exemption, as the case may be, made no later than the day of the Budget Speech.

Over the coming months, the Québec ministère des Finances will review the efficiency and utility of these two measures and will decide whether or not to maintain them.







June 2003
 

2003-2004 Field Campaign
A new crop of data acquisition projects

Robert Marquis et Pierre Verpaelst
Géologie Québec

In order to promote the remarkable mineral potential of Québec, the Ministère des Ressources naturelles, through Géologie Québec, pursues with consistency and determination its efforts to acquire new geoscience data throughout Québec.

Field projects carried out by Géologie Québec were targeted in the wake of a vast client consultation conducted to help develop triennial plans for all of Québec’s territory. These plans are useful to constrain which geological settings are considered to be particularly prospective for new discoveries.

The results of fieldwork conducted by Géologie Québec crews during the summer 2003 throughout Québec will be exclusively unveiled next November, during the Québec Exploration 2003 event. Until then, here is a sneak preview of the new crop of data acquisition projects planned by Géologie Québec for the summer 2003.

Location of projects 2003-2004

Three-year plan for the Abitibi and the Baie-James region

Established in conjunction with the mining industry, Géologie Québec’s three-year plan for the Abitibi and the Baie-James region for the 2003-2006 period will cover all field projects carried out in the Abitibi region starting in the summer 2003. This work includes the Lac Olga project, in the Baie-James region. This project had initially been scheduled for the previous three-year plan covering the 2000-2003 period. The new plan also includes the Grenville Front project east of Chibougamau.

Baie-James region

In the Baie-James region, two inventory surveys will be conducted to link the geology of the Matagami and Chibougamau areas, and to better understand the Grenville Front east of Chibougamau. A metallogenic component is included in each of these projects. A "Quaternary" component is also planned to complement the Grenville Front project east of Chibougamau. Furthermore, a metallogenic study of the Mistassini basin, launched in 2002, will continue this year with the cooperation of the Institut national de la recherche scientifique (INRS) and the Mistissini Geological Resources Centre.

Abitibi

Southeast of Lebel-sur-Quévillon, an inventory survey along the Grenville Front will be completed by a metallogenic study in the adjacent Urban-Barry area. As in the Chibougamau area, a Quaternary component is also planned to round off this project. In the Rouyn-Noranda area, two complementary metallogenic studies will detail the mineral potential of the Blake River Group. Finally, a metallogenic study undertaken last year along the Destor-Porcupine fault in the Duparquet area will be completed.

From now on, 3D modelling of geoscience data will be systematically integrated to regional metallogenic syntheses in the Abitibi region. In partnership with the Unité de recherche et de service en technologie minérale (URSTM) of the Université du Québec en Abitibi-Témiscamingue and Mira Geoscience, two new digital products at the leading edge of technology will be developed this year. The first concerns a particularly prospective segment of the Destor-Porcupine fault for gold deposits, in the Duparquet area. The second will present the unified geology of the main mining camp in Québec, the Doyon-Bousquet-LaRonde district.

Far North

This year, Géologie Québec will complete the mapping coverage at 1:250,000 scale of the Far North west of Ungava Bay and the Labrador Trough. Two geological surveys will be conducted in the Kogaluk Bay (34N) and Lac Minto (34F and 34G) areas, along the eastern shore of Hudson Bay. The MRN will also continue its cooperative effort with the Geological Survey of Canada, in the search for kimberlite indicator minerals. This search was very successful over the last two years, and has renewed interest for diamond exploration in the Far North.

Based on consultations conducted with our clientele, we have also developed a three-year data acquisition plan for 2003-2006. This plan provides for synthesis work covering stratigraphy, geochemistry, structure, metamorphism, and mineral deposits for this vast area, as well as mapping of the area located between the 54th and 55th parallels in 2004 and 2005.

Grenville

This year, geoscience work in the Grenville basically involves the completion of a mapping project in the area north of Mont-Laurier (31O/02), within the scope of a synthesis of the Central Metasedimentary Belt, and the conclusion of a study of tectonic nappes in the Pontiac area. A study of the nickel, copper and platinum group element potential is also planned for the Mauricie region. Finally, a lake sediment survey is planned in the Côte-Nord area north of Baie-Comeau (22F-K-N). The latter will be conducted in partnership with mining companies and regional agencies, as a preliminary phase leading to regional mapping to be conducted over the next few years.

Consultations were conducted over the past year, in order to develop a three-year action plan for the Grenville. We are currently conducting a comprehensive review of previous work, in order to pinpoint gaps in our knowledge of the Grenville. We will then be able to define priorities to address over the coming years. This plan will be submitted in the fall 2003, for application in 2004-2007.

Appalachians

Géologie Québec continues to implement its three-year action plan for the Appalachians. We will begin phase 2 of the plan this year, with two projects to update the geology in the southern (22B/01 and 08) and central (22B/16) Gaspe region and with a metallogenic study in the central Gaspe. These studies are specifically focussed on base and precious metal deposits in sedimentary settings in the south, and in a volcanic environment in the central part. We will also complete a ground gravity survey of the Gaspésie region this year, launched in 2002 in partnership with SOQUEM and Hydro-Québec.

Industrial minerals

A survey of sand and gravel resources in the Saguenay–Lac-Saint-Jean region will begin this season. This project should last from three to six years, according to the human and financial resources allocated for the project. A two-year survey of the peat resources in the Bas-Saint-Laurent region will also be launched this year. A number of visits of peatlands throughout the province will complete the ice peat study. A few industrial mineral deposits, namely slate and limestone occurrences, will be examined within the scope of a synthesis study conducted in Southern Québec. To complete the rare metals project, potential assessments of a few areas of interest will be conducted. Finally, the gravity survey undertaken last year in the Gaspésie region will be completed.

 






June 2003
 

Québec Exploration 2003
The preliminary program has been released

November 24 to 27, 2003
Château Frontenac - Québec

With more than 100 exhibitors, six speaker sessions and over 1,200 participants expected to attend, Québec Exploration 2003 promises to be the most important mining event in Québec and Eastern Canada. The event will take place under the Honorary Chair of Mr. Pierre Lassonde, president and director of Newmont Mining Corporation and a highly acclaimed leader in the mining industry.

The preliminary program is now available on the event’s website, at the following address: www.QuebecExploration.qc.ca.