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.