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Territory-wide mineral potential mapping in Yukon was last conducted 18 years ago. An updated suite of maps for land use planning is, therefore, necessary. The YGS has developed a new GIS-based mapping process for this purpose. Industry-based applications using the new method will be developed going forward. The approach makes use of mineral system components that potentially contribute to metal accumulations in an area. The method is a hybrid between a classic data-driven probabilistic approach and an expert-driven fuzzy logic approach. It is non-specific in terms of commodity and/or deposit type – however, the claim and assessment report footprint data that are integral to the mapping process capture these important components. The procedure makes use of block modeling techniques where each block is assigned a prospectivity and (bedrock mapping) confidence score. Calculations are based on the presence or absence of categorical features within unit cells, and the scores represent the posterior favourability of each cell. Evidential layers are weighted according to buffer distance and/or through the application of knowledge-based factors. Lithology classes are factored using a multiclass weights-of-evidence approach. Mineral potential and confidence scores are converted to either a 1, 2 or 3 according to a defined mathematical schema. The values are then combined – blocks with scores of 1:1 have the lowest mineral potential/lowest confidence whereas blocks with scores of 3:3 have the highest mineral potential/highest confidence. Nine possible combinations exist. Mineral potential maps containing measures of both potential and confidence are generated based on the cumulative contrast values. Areas cut by major structures along which significant displacement has occurred need to be evaluated separately, and then stitched back together at the end of the assessment process. Concurrently, the mineral potential data need to be leveled to account for prospectivity differences across the structure concerned.

The placer potential mapping process consisted of applying a classification rating of 1 to 5 (lowest to highest) for all streams within the planning area. Factors affecting a stream's potential included development history and hard rock mining potential (gold deposit potential). Terrain attributes such as potential overburden thichness, water flow, or local topography were not factored into the rating due to lack of knowledges for most unmined drainages.

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for a copy of this paper please contact the Yukon Geological Survey; geology@gov.yk.ca.

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