Integrating Bedrock Geology with Stream-sediment Geochemistry in a Geographic Information System (gis): Case Study Nts 92h

Two data sets commonly used for geological resource assessment include bedrock geology and stream-sediment geochemistry. Traditional methods for determining relationships between these data include both qualitative and quantitative techniques. Qualitative interpretation and integration is generally based upon visual observations of spatial coincidence between the data. Quantitative results can be derived by summarising point values according to the dominant lithology of a sample’s drainage area, or according to the geological unit it coincides with. Qualitative methods lack numerical explicitness, reproducability and rigour. Quantitative methods struggle with the fact that streamsediment geochemistry sample points ax manipulated to represent areal distributions, where the area represented by each sample must somehow be inferred before quantitative analysis can take place. This study concerns quantitative techniques. Geographical infimnation systems (GIS) offer several methods for transforming geochemical points into areal coverage, allowing the resulting choropleth map to be integrated with maps depicting bedrock geology and used in the preparation of quantitative summaries or for further analysis. For example, points can be transformed into discrete homogeneous polygons (Thiessen polygons, drainage basins). or into continuous surfaces via interpolation (contouring, moving averages). This capability obviously hes tremendous potential for geological interpretation and mineral exploration. An ongoing research project at the University of Victoria, conducted in conjunction with the British Columbia Geological Survey Branch, is examining alternative methodologies for computationally integrating bedrock geology with stream-sediment geochemistry in GE, including comparing and contrasting different results obtained. This research note presents a cursory discussion of general methodologies for interpolating stream-sediment geochemical sample points for integration with bedrock geology within GIS. Preliminary results are discussed. Use of commercial names in this paper is for descriptive purposes only. It does not constitute endorsement by the University of Victoria or the British Columbia Geological SUWCY.