Generation and Interpretation of Ternary Images of the Aerial Gamma-Ray Spectrometric Survey Data, Egyptian Desert. PDF

Keywords

Geology, ternary images, aerial-ray spectrometric survey data, Eastern Desert, Egypt

Abstract

High-sensitivity multi-channel aerial gamma ray spectrometric survey conducted over the studied Abu-Had area, Central Eastern Desert, Egypt (Lat. 26°:20' and 26°: 35' North, long. 32° 40' and 33°:20' East) provides reliable measurements of the apparent surface lithologic concentrations of potassium (K), equivalent uranium (eU), and equivalent thorium (eTh). These data can be expressed in the form of nine radio spectrometric parameters of absolute, ratio and reverse ratio values: K, eU, eTh, eU/eTh, eU/K, eTh/K, eTh/eU, K/eU and K/eTh. Because the nine parameters taken three at a time result in a total of 84 combinations, the choice of which combination to use should include consideration of the purpose of the aerial geophysical survey and geochemical models of interest to the interpreter. In the present research, the ternary images were produced from the four following combinations: eU, eTh and K (three radioelement composite colour image), eU, eU/eTh and eU/K (uranium composite colour image), eTh, eTh/eU and eTh/K (thorium composite colour image) and K, K/eU and K/eTh (potassium composite colour image). The ternary (three- component) image method is an effective method for displaying in a single image any three radio spectrometric parameters. Since a distinct colour hue is used to represent each ternary ratio on the map, zones with similar temary ratios will be represented by a unique colour. This distinct relationship between colour hue and ternary ratio allows the map to represent the surface lithologic radioelement distributions better than any one alone of the nine radio spectrometric parameters. The generated four temary radioelement maps provide a partial synthesis of the radio spectrometric data that can be used as an aid to lithologic discrimination based on colour differences. Furthermore, they highlight zones of preferential radioelement enrichment and potassic alteration zones. Consequently, they enabled narrowing down favourable target areas for detailed ground geological, geophysical and geochemical follow up for mineral exploration purposes.