Interpretation of Drill-Hole Geochemical Data from the Volcanic Rocks of the Hanson Lake Mine, Saskatchewan

CIM Bulletin, Vol. 71, No. 793, 1978

J. S. Fox, Research Scientist, Geology Division, Saskatchewan Research Council, Saskatoon, Sask.

It is generally recognized that the interpretation of bedrock geochemical data in volcanic terrains can be improved by adjusting for rock-type. Various chemical attributes of volcanic rocks have been put forward in the literature as rapid indicators of rock-type, but there is some question as to which of these is the most reliable. Only one such attribute, total iron, seems to have seen systematic use in geochemical mapping in the Flin Flon region. Discriminant analysis of 500 basalts, andesites, dacites and rhyolites suggests that SiO2 is the most important rock-discriminating variable and that MgO, CaO, TiO2, AI2O3 and FeOtot are successively poorer discriminators. Lithological normalization in the sub-alkaline volcanic environment should therefore be made over ranges of this variable. Trace-metal data from drill core through the sulphide orebody at Hanson Lake, Saskatchewan are used to demonstrate various approaches to lithological correction, including silica normalization, factor analysis and trend analysis. All of these extract economically important information from the core that is not apparent in the raw data logs. However, silica normalization does not seem to be subject to as many serious limitations as factor and trend analysis in this case, and therefore seems to provide the most reliable basis for the interpretation of subsurface exploration geochemical data.
Keywords: Exploration, Geochemical exploration, Drill-hole geochemistry, Trace metals, Rock-type correction, Factor analysis, Trend analysis, Silica normalization, Volcanic rocks, Hanson Lake mine.