Slave Geological Province Road Corridor Study

An all-weather road through the Slave Geological Province (SGP) to tidewater in Nunavut has been intermittently considered by Government of the Northwest Territories (and/or Federal Government agencies) since the 1950s and by the private sector since at least the 1970s (Arthur Andersen LLP et al., 1999). The recently developed GNWT Mineral Development Strategy (GNWT, 2013) restated this commitment to invest in infrastructure to improve access to mineral potential. This study follows the 2014 GNWT Mineral Development Strategy Implementation Plan (GNWT, 2014) directive to undertake a resource access corridor study to help planning and prioritization of infrastructure to support resource development.

The Slave Geological Province Road Corridor Study (SGPRC) has at its core a series of maps illustrating the interpreted highest mineral potential in the study area. These maps are meant to be considered in concert with the results of other studies, to determine the best road routing. The data on which these maps are based are in a state of change, meaning that the results cannot be considered static or final.

The mineral potential maps make use of two major sets of data: the databases of known mineral occurrences throughout NWT and NU (the NORMIN and NUMIN databases, respectively), and geological map compilations of the SGP (Stubley, 2005) and surrounding areas (Wheeler et al., 1997). Along with mineral tenure and mapped fault locations, these data were evaluated by mainly subjective means, converted to numerical scores, and through Geographic Information System (GIS) analysis, represented on “heat maps”.

The mineral occurrence data were evaluated through partly objective but dominantly subjective criteria. The level of development associated with each occurrence, the commodities present, known resources or reserves, and current status of the more advanced projects were all considered. A numerical score was assigned to each of 2813 occurrences. Likewise, geological bedrock units (64 units) are converted to numerical scores based on their subjectively judged importance and/or favourability in mineral exploration.

The four variables (mineral occurrences, bedrock geology, mineral tenure and faults) were individually scored, and converted from a vector data format using GIS software into a raster data format based on 100m by 100m grid cells covering the study area. Raster maps of each variable were standardized to create criteria layers and displayed on a “blue to red” colour scale as thematic “heat maps”. Next, the four variables were rated against each other, using a pair-wise comparison matrix. Through the resulting matrix calculations, relative weightings were obtained for each variable. The scores for each variable were used in the GIS analysis with their relative weights, to evaluate every cell in the study area. The result is a “heat map” displaying interpreted mineral potential (Figure 1). Using additional GIS analysis functions with the mineral potential raster data it was possible to obtain a preferred route placement of an all-weather road through the areas of mineral potential (Figure 2).

The mineral potential map shows relatively thin, roughly north-trending belts through the western, central, and eastern SGP that correspond largely to the position of volcanic greenstone belts. In particular, the eastern belts, and northern part of the central belt are interpreted to have high potential. There are some broad areas of relatively high mineral potential at the northwest margin of SGP, in the northern Bear Province. These are at least partly an artefact of the lower resolution of digital geology available for this area.