Various combinations of the gammaray data channels can be classified using an unsupervised classification algorithm to produce a thematic map of radioelement domains (classes) that show a distinct statistical separation (Fig.
Ratio maps, including ternary K-U-Th colour presentations, are useful but, in the absence of corresponding radioelement concentration maps, are ambiguous.
1987, A modified ternary radioelement mapping technique and its application to the south coast of Newfoundland: Geological Survey of Canada, Paper 87-14, scale 1:100 000.
International Atomic Energy Agency, 2003, Guidelines for radioelement mapping using gamma ray spectrometry data: International Atomic Energy Agency, TECDOC-1363, 173 p.
Radioelement concentrations in different classes of rocks (Killeen 1979).