Techniques for analysis and visualization of lithogeochemical data with applications to the Swayze greenstone belt, Ontario

In January 1993, the Geological Survey of Canada, in conjunction with the O ntario Geological Survey, initiated a three-year project involving the comp ilation and analysis of a wide range of digital data over the Swayze greens tone belt using GIS technology. As part of the geochemical compilation proc ess, a large lithogeochemical database was assembled which included proprie tary (provided by Falconbridge Ltd.) and non-proprietary (provided by Ontar io Geological Survey and Geological Survey of Canada) geochemical data. Thi s paper presents results from the development and comparison of methodologi es for detecting altered Versus un-altered lithogeochemical samples, and re sults from the identification of anomalous lithogeochemical populations (se lected oxides) from background. Out of a total of 3395 samples, 1606 were f lagged as altered, representing approximately 47% of the total number of sa mples. Trends between the altered and non-altered samples include elevated SiO2, K2O and MgO values, and lowered CaO, FeO and TiO2 values for altered samples. SiO2, K2O and MgO enrichment reflects silicic, potassic, and chlor itic alteration. Zones of intense alteration, representing potential areas of mineralization, have been identified using a variety of univariate and m ultivariate techniques. Based on these analyses, several key alteration zon es have been identified that are worthy of exploration follow-up. (C) 1999 Elsevier Science B.V. All rights reserved.