février 2003
 

Québec Exploration 2003
Claim your share of the action!
From November 24 to 27, 2003
Château Frontenac, Québec

Québec will host Québec Exploration 2003 in November. Jointly organized by the Ministère des Ressources naturelles du Québec and the Québec Mineral Exploration Association, Québec Exploration 2003 will offer high-quality programming to participants from the province of Québec, from elsewhere in Canada, and from other countries, and will constitute an exceptional tribune for the Québec mining sector.

Internationally acclaimed speakers will participate and numerous partners active in mining exploration in Québec will be in attendance. In addition, there will be presentations on the geological research work that will be undertaken in the summer of 2003 and the most recent discoveries made by the Québec mining industry.

You are invited to visit the event’s Internet site at the following address: www.QuebecExploration.qc.ca









février 2003
 

Ni–Cu–PGE Deposits in the Cape Smith Belt

Abdelali Moukhsil and Serge Perreault
Géologie Québec

EXPLORATION FOR Ni, Cu AND PGEs

Over the years, several showings of Ni–Cu mineralization have been discovered in the Cape Smith Belt (Ungava Trough). The earliest work that mentions such occurrences dates back to the end of the 19th century. The first copper–nickel showings in the Cape Smith–Wakeham Bay area were discovered by Murray Watts in 1937. These showings were developed by various companies in subsequent decades.

The Cape Smith Belt has unique mineral potential that is still largely undeveloped in Québec. During the 1950s, several companies became interested in this area, in conjunction with geological mapping undertaken by the gouvernement du Québec. Numerous showings and deposits were discovered at the time, including the Delta and Expo-Ungava deposits, as well as most of the Raglan mining camp deposits (Figure 1). Toward the mid-1980s, the belt was confirmed as a target area for platinum exploration.

In 1997, High North Resources, under Ungava Minerals Corporation's option, carried out a drilling program (1,038 m), mapping and airborne/ground-based geophysical surveys on the Expo-Ungava property. The program revealed that the Expo-Ungava deposit was formed of massive sulfide lenses at the base of ultramafic sills injected into the Povungnituk Group. The geochemical signature of these ultramafic sills is similar to ultramafic suites and cogenetic flows forming the Chukotat Group (Picard et al. 1995, MB 94-30). The geological model suggests that sulfides accumulated in troughs at the base of an ultramafic lava flow or sill that opens towards the west. The trough is truncated to the west by a thrust fault that juxtaposes sedimentary and volcanic rocks. A number of remobilized massive sulfide lenses occur within the sediment in the fault walls.

In 2001, Canadian Royalties Inc., under Ungava Minerals Corporation's option (Figure 1), discovered significant amounts of platinum and palladium as a result of new analyses of core samples taken during the 1997 drilling program conducted by High North Resources. During the initial program, drill cores were assayed for nickel, copper and cobalt but not for the platinum group elements (platinum, palladium, and rhodium). Other work carried out by the company in the summer of 2001 revealed mineralization along a length of 732 m in the east–west axis, with an average width of 107 m along the north–south axis.

During the same period, Canadian Royalties Inc. discovered significant amounts of platinum, palladium, nickel, and copper as the result of work done on a new showing (Phoenix), located on the TK property, 20 km south of the Raglan mining camp and 7 km northeast of Expo–Ungava. The mineralization comprises massive sulfides near the base of an ultramafic sill (TK sill) similar to the Raglan sill.

Prospects

The most recent results of the work carried out by Canadian Royalties reveals an outstanding potential for PGEs associated with ultramafic sills cogenetic to the Chukotat Group that are injected into the Povungnituk Group. The Povungnituk is currently one of the most promising sectors for mineral exploration in Québec due to the significant quantities of lava flows and mafic and ultramafic sills it contains. The task at hand is to find sufficient volume to make mining of these elements economically feasible. The prospects in this regard are excellent.

See also:

Geological overview
Ni-Cu dominant magmatic deposits
PGE dominant magmatic deposits









février 2003
 

Geological overview

The Cape Smith Belt in Nord-du-Québec, from the Lower PaleoProterozoic Era, is composed of a belt of volcano-sedimentary rocks extending over 370 km in an E–NE direction. The area is divided into four main tectonic units (Figure 1):

  1. the autochthonous Archean basement of the Superior Province;
  2. the allochthonous accretionary belt, or Ungava Trough s.s., made up of tectonic slices with south vergence;
  3. the Narsajuaq Terrane, from the PaleoProterozoic Era; and
  4. the parautochthonous Archean basement, locally separating the allochthonous accretionary belt and the Narsajuaq Terrane along the Kovik Antiform.

The Cape Smith Belt is composed of seven tectonostratigraphic units divided into north and south lithotectonic domains separated by the Bergeron Fault (Figure 1). The South Domain contains three groups. From south to north these are: the Lamarche Group, composed of a proximal to distal sediment assemblage, is cut by several gabbro sills; the Povungnituk Group, composed of tholeiitic flows, lies in angular unconformity over the Archean basement; and the Chukotat Group, made up primarily of basalts, komatiites and tholeiites. The North Domain is composed of:

  1. the Chassé Formation (parautochthonous detrital unit);
  2. the Watts Group (sedimentary and metavolcanic rocks), cut by mafic (peridotite, pyroxenite and gabbro) to felsic intrusions, overlaps the Chukotat along the Bergeron Fault in the south and is separated from the Archean basement by a décollement zone (Deception Complex) in the north;
  3. the Parent Group, made up of a tuff and tholeiite-flow assemblage associated with felsic tuffs and dacitic and rhyolitic domes;
  4. the Spartan Group, composed of psammites, pelites, semipelites, sandstones, felsic tuffs locally, and thick layers of mudstone; and
  5. the Perreault Group, composed of a detrital assemblage consisting of wacke, conglomerate, sandstone (feldspathic) and mudstone.

Several subdivisions for deposits containing Ni, Cu and/or PGE mineralization have been suggested. The subdivision proposed by Thériault et al. (2002) for the Ni–Cu–PGE mineralization map of Québec has been adopted here.









February 2003
 

Ni-Cu dominant magmatic deposits

The Raglan Mining Company, a wholly owned subsidiary of Falconbridge Ltd., began open-pit and underground production in 1998, after an initial investment of $500 million in the mine, concentrator and infrastructures. The mineralization is composed of several massive sulfide lenses associated with Proterozoic ultramafic flows that extend along the contact between tholeiites and sediments of the Povungnituk Group and komatiites of the Chukotat Group. The average grades from 23 samples taken at the Raglan mine were 4.49% Ni, 1.22% Cu, 2.9 g/t Pd, and 1.3 g/t Pt. Reserves at the mine are 9.0 Mt of ore at 3.06% Ni and 0.89% Cu. Nine zones are recognized over a distance of 55 km in the area of the mine (Donaldson, Boundary, West Boundary, 13–15, 5–8, Katinniq, 2–3, East Lake, and Cross), as shown in Figure 1. The sulfides are associated with pentlandite and pyrrhotite. Chalcopyrite, magnetite and pyrite are also associated with Cu and PGEs.








février 2003
 

PGE dominant magmatic deposits

Fifteen kilometres south of the Raglan Mine in Nunavik, Canadian Royalties Inc. completed over one hundred drillholes on its property in the summer of 2002. The objective of the drilling program, which was conducted near the Mesamax and TK Raglan-type sill occurrences, was to test approximately ten targets located along more than 50 km of ultramafic rocks conducive to mineralization (Ni, Cu, Co, Au, Pt, and Pd). The ore consists of irregular lenses with varied mineralization (finely granulated or massive disseminated sulfides containing pyrrhotite, pentlandite and chalcopyrite) that is hosted by peridotite- and/or pyroxenite sills. These sills are probably cogenetic with a magmatic phase related to the emplacement of the Chukotat Group units and are injected into the volcano-sedimentary units of the Povungnituk Group (Figure 1).

During the month of November 2002, the Cape Smith Belt was the scene of intense map-designation activity following publication of various press releases by Canadian Royalties Inc. Significant PGE results originating from the Mesamax (NW) showing were reported. This showing is located in the extension of the Expo–Ungava property.

The latest drilling results by Canadian Royalties Inc. can be consulted at the following address: www.canadianroyalties.com








février 2003
 

The Porcupine–Destor Fault
Significant gold potential

Marc Legault and Jean Goutier
Géologie Québec

Since the first discovery of gold by John Beattie on an island in Duparquet Lake in 1910, the Porcupine–Destor Fault has continued to attract gold seekers. Although the area was the site of gold mining from 1933 to 1956 (Beattie, Donchester, Central Duparquet, and Duquesne mines) and from 1983 to 1990 (Duquesne and Yvan Vezina–Davangus mines [eastern sector]), little gold was extracted on the Québec side (~ 55 t Au – production + resources) compared to the Ontario side (~ 2300 t Au – production + resources).

In 2002, Géologie Québec undertook a metallogenic study along the Porcupine–Destor Fault in order to complete the regional mapping work begun in the early 1990s. The objective of this project is to develop new tools for gold exploration through a regional metallogenic study and 3D modelling. The purpose of the metallogenic study is to characterize the various gold occurrences in order to define the chronology, mineralization controls and regional alteration patterns. This study should explain the enormous variation in gold concentrations on either side of the border.

Regional geology

The Porcupine–Destor Fault region has been divided into three sectors: eastern, western and central. Only the western and central sectors have been examined to date. The western sector generally exhibits simple geology (basalt, gabbro) with a few felsic and ultramafic intrusions. Ultramafic volcanic rocks of the Kinojévis Group and wackes of the Kewagama Group are commonly found pinched inside the Porcupine–Destor Fault. The central sector features a shallower structural level, thereby preserving calc-alkalic (2,689 Ma) to alkalic (2,682 Ma) porphyry intrusions and a significant unconformable accumulation of Timiskaming-type conglomerate (Duparquet Formation).

Economic geology

Over 70 gold showings (> 1g/t Au) are present in the area studied along the Porcupine–Destor Fault. The gold mineralizations in the western and central sectors have different characteristics. In the western sector, there is a close spatial relationship between the location of the gold-bearing zones, the carbonate alteration and the Porcupine–Destor Fault. The mineralizations exhibit several characteristics that are typical of orogenic deposits, including a ratio of Au/Ag>>1, carbonate–quartz veins, a high iron-carbonate alteration, and structural control. Just one deposit has been defined to date in the western sector (Structure 71 (Cambior) - 195,000 t at 5.2 g/t Au). The central sector (Duparquet Basin) is distinguished by the fact that several ore-bearing zones are located far from the Porcupine–Destor Fault, being associated with subsidiary structures or porphyry intrusions. The carbonate alteration is associated with the Porcupine–Destor Fault as well as with the subsidiary structures. Several old mines and deposits are known in the central sector, including the Beattie (resources > 2.6 Mt at 3.8 g/t Au) and Duquesne (resources of 0.22 Mt at 7.8 g/t Au) mines. The ore in the Duparquet Basin is generally associated with fine-grained disseminated pyrite with few quartz–carbonate veins, as well as sericite alteration. It appears to be somewhat rheologically and/or chemically controlled and exhibits metal contents typical of epithermal deposits (Au/Ag<1, up to 50 ppm Hg, 0.34% Sb, 0.61% Zn, 0.19% Pb). However, orogenic-type mineralization has been noted in the central sector. This mineralization is generally found peripheral to the Duparquet Basin and is associated with an iron-carbonate alteration. Hence, two types of alteration (carbonates±sericite and sericite) in association with the gold mineralization are present in the central sector. This suggests the superposition of at least two separate mineralization episodes for this sector or a variation in the hydrothermal-fluid composition due to the various depths of the mineralization emplacement.

Exploration

The recent exploration work conducted by Cambior and the Globex/Kinross partnership reaffirms the gold potential along the Porcupine–Destor Fault. The presence of the Holloway and Holt–McDermott mines approximately 17 km west of the Ontario border has strongly influenced the approach of exploration in the western sector. At these two deposits, high albitization is spatially associated with the best gold values, and it is located in the centre of sericitization and carbonatization halos. However, such an alteration is rarely observed in the western sector. At the Holloway deposit, albitization and economic gold values begin at a depth of approximately 300 m. At shallower depths, only sericitization and carbonatization are present, suggesting that the highly sericitized structures must be explored at greater depths. Structure 71 exhibits high carbonate and sericite alteration but has not been explored at depths of more than 180 m. In addition, the Holt–McDermott deposit is associated with an ENE subsidiary structure south of the Porcupine–Destor Fault. Certain structures having a similar orientation are also present on the Québec side but have been only slightly explored.

In the central sector, the epithermal-type mineralization in the interior of the Duparquet Basin is possibly associated with a mineralization event prior to the Porcupine–Destor Fault and related to the development of this basin. The orogenic-type mineralization peripheral to the basin possibly represents the deep extension of the epithermal mineralization discovered during late vertical movements along the faults bordering the Duparquet Basin. It is also possible that this orogenic mineralization is associated with the Porcupine–Destor Fault and that it is not associated with the epithermal mineralization. In the central sector, exploration work is concentrated near the Porcupine–Destor Fault and some of the subsidiary structures, such as the Duquesne Fault. Little exploration work has been done on the subsidiary faults bordering the northeastern part of the basin, such as the Ottman and Lépine faults, despite their significant alteration zones (carbonate and sericite maps). In addition, except in a few sectors (Beattie, Shaft, Patino), little exploration work has been done at depths greater than 500 m.

Deep gold potential

The environment of the eastern part of the Porcupine–Destor Fault differs from that of the western part (Timmins sector) by exhibiting a lower metamorphic facies and hence a shallower structure. The lack of gold on the Québec side is therefore possibly associated with its epizonal position, as illustrated by the presence of epithermal mineralization. Therefore, the potential of the Porcupine–Destor Fault is at depth, a dimension that has been, to date, underexplored.






février 2003
 

3D Common-Earth Model
New Exploration Tool Applied
to the Joutel and the Duparquet Mining Camps, Abitibi (Québec)

Francine Fallara (URSTM-UQAT), Marc Legault (Géologie Québec) and Gervais Perron (Mira Geoscience)

In mature mining camps, the comprehensive integration of geoscientific data into a unique three-dimensional model represents a significant technological breakthrough. This approach, associated with the completion of a regional metallogenic synthesis, is likely to result in new discoveries. 3D modelling requires a structured quantitative approach. For this purpose, it is necessary to have adequate quality multidisciplinary data having a relatively uniform distribution over the entire study area. This necessitates the cooperation of the mining industry at all stages, particularly during the data compilation phase.

Since 2000, to stimulate exploration within the Abitibi Subprovince, Géologie Québec, in close collaboration with URSTM, used two mining camps, Joutel and Duparquet, to construct 3D common-earth models to define base metals and gold exploration targets.:. These projects follow the current trend in mineral exploration, which searches for more and more deep-seated deposits. Like many major mining companies (Noranda, Barrick Gold, Placer Dome, Falconbridge, Inco, Aur Resources, Cambior, etc.), we used the gOcad® technology to produce these new 3D geological models. The Joutel and Duparquet models also illustrate the advantages of the gOcad® software over 2D GIS software in that it can delineate areas of high potential in 3D.

Both common-earth models produces a new dynamic exploration tool used to define targets which can be queried using significant geological criteria based on specific user's needs, such as alteration patterns, drill hole densities, geophysical anomalies, etc. Models themselves can be modified and improved continuously by adding geophysical, geochemical and geological data from new drilling or field cartography.

Hence, 3D geo-modelling represents a new dynamic tool that can be adapted to specific needs exploration companies using data such as geophysical anomalies and alteration indexes to discover mineral deposits. It also enables Géologie Québec to deliver new standardized products for the mining industry using all of the digital geoscientific data available in the SIGÉOM public database. In addition, these models can be modified and improved at all times by adding new geological, geochemical and geophysical data provided by drilling and mapping programs. The main advantages of such a tool are database homogenization and geological interpretation validation that also take into consideration geophysical and geochemical data.

Definition of 3D common earth models
Use of 3D common-earth modelling as an exploration tool
 






février 2003
 

Definition of 3D common earth models:

Géologie Québec proposes to produce 3D common-earth modelling with quantitative geological interpretations of Abitibi Subprovince mining camps. This approach is based on shared physical properties that permits the formation of a quantitative geoscientific link integrated into the 3D common-earth model. Consequently, it is possible to juxtapose the geological and geophysical models, particularly when physical properties (density and magnetic susceptibility measurements) are available for rock outcrops. A similar approach can be used to integrate geological interpretations and the lithogeochemical data. 3D common-earth models aim to fit the criteria defined by each of the disciplines involved within the project and support quantitative-geology applications. Therefore, the principal stakeholders involved in a project make reference to a single model using the same platform (Figure 1). A regional 3D common-earth model therefore acts as an integration and a processing platform for all available geoscientific data on a quantitative basis.

Data integration within 3D models depends on data availability, density and distribution, as well as the project objectives sought. To ensure the success of 3D common-earth modelling, the following data must be available:

  1. Surface data (2D):
  • Topographic elements (digital elevation points, hydrography)
  • Mining and road infrastructures
  • Main lithological and stratigraphical contacts (key horizons marker)
  • Faults and folds traces, planar and linear structural measurements
  • Systematic sections covering the entire study area
  • Lithogeochemical analyses, alteration indexes and economic assays
  • Geophysical survey data
  • Physical rock properties (magnetic susceptibility measures, density)
  1. Drilling information available in 3D:
  • All available drilling data (collar, deviation, geology, mineralized intersections, alteration indexes, magnetic susceptibility measures, densities, etc.)
  1. Ground-based, drilling-related and airborne geophysical surveys:
  • Seismic data
  • Magnetic data
  • Gravimetric data
  • Electric methods (DC, IP)

The 3D common-earth model of the Joutel mining camp (Figure 2) was used as an initial project for this new type of dynamic, queryable, and upgradable product. Production of this model required an optimal use of public digital database as well as the recovery of major databases from mining companies. Also, validation exercises (ex: poll survey) done on the Joutel 3D common-earth model were used to define the mining exploration industry’s needs in regard to 3D products. Finally, the multidisciplinary approach used in the 3D geological modelling for the Joutel mining camp demonstrates that this new digital regional product (1/20 000) can also be used as an exploration tool.

A second project is currently under way in the Destor-Porcupine region (Figure 3). The main objectives of this 3D common-earth modelling were to:

  1. Produce a regional 3D common-earth model (11.4 X 4.0 X 1.0 km) integrating all of the geoscientific data (geology, geophysics, lithogeochemistry, drilling, mineralization, alteration index, etc.) available in this mining camp;
  2. Define the 3D gold distribution in function of the diamond drill hole data available;
  3. Establish queries on the basis of geological, geophysical and geochemical data in order to establish new exploration targets.

The compilation of multidisciplinary data for the 3D modelling of Destor-Porcupine took place during the summer of 2002. Data integrated within the gOcad® modules was primarily acquired from exploration companies currently active within the Duparquet mining camp, from the SIGÉOM and from a purchased lithogeochemical database from Jean Descarreaux. A total of 1,746 drillholes, including 50,348 economic assays and 3,638 lithochemical analyses, were imported into the 3D model.

Inversion of the magnetic data indicates that the Duparquet Formation is locally shallow and that certain geological contacts must be reverified. In addition, integration of the drillholes gave us a better idea of the geology as well as the gold distribution and alteration.






février 2003
 

Use of 3D common-earth modelling as an exploration tool:

Example applied to the Joutel VMS mining camp

Queries performed on the 3D geochemical data interpolation:

The gOcad® technology incorporates modules which facilitate automatic predefined calculation commands, hence performing user-defined queries. For the Joutel VMS mining camp, the interpolation type and queries performed on the geochemical data was pre-established to fit metallogenic criteria proposed by Piché (2000) to define VMS targets. Therefore, the emphasis was placed on certain alteration indexes defined specifically for VMS deposits (query A). In order to refine logically query A in 3D and to define new VMS exploration targets within the Joutel mature mining camp, other constraints were added to this first query. These constraints represent the distance between voxet cells and, respectively, diamond drill holes (query B), synvolcanic faults (query C) and synvolcanic plutons (query D). These queries were computed within the gOcad® software in the following manner:

  • Query A: Reproduction of 2D VMS targets defined by Piché (2000) in 3D (figure 4);
  • Query B: 250 m < distance between voxet cells and diamond drill holes < 400 m (figure 5);
  • Query C: 1 km < distance between voxet cells and synvolcanic faults < 1,5 km (figure 6);
  • Query D: 4 km < distance between voxet cells and synvolcanic plutons < 5 km (figure 7).

The Joutel 3D common-earth model described in this paper represents a dynamic exploration tool since it allows the use of multidisciplinary criteria or constraints in order to refine our exploration target query definition. For example, other geophysical or geochemical anomalies can be added to our queries for other specific exploration criteria for other metals, based on the user’s requirements or interests.

The continuance of 3D common-earth-modelling associated to regional metallogenic syntheses of mature mining camps within the Abitibi Subprovince will allow Géologie-Québec to:

  1. Develop a solid expertise in quantitative geology in Québec’s principal mining region (Abitibi) forming a strong partnership with major exploration companies;
  2. Continuously validate and upgrade SIGEOM’s database and produce regional syntheses integrating geological, geophysical and geochemical models in a single technological platform linked to SIGEOM; and
  3. Position Québec towards international competition by delivering refined technological geological syntheses likely to attract significant investments from mining companies, especially for deep exploration programs.