radiometric surveys

Below is an example of some real data from the Corryong area. The ma
p shows potassium data; red areas have high gamma ray counts and the blue areas have low counts.


Another way to display radiometric data is to combine three datasets on the one picture using a red-green-blue ternary ratio. Each of the datasets are displayed using a different basic colour, which when combined make a colourful display with each shade representing different relative amounts of potassium, thorium and uranium. Usually the colours are displayed as follows:
Red = potassium
Green = thorium
Blue = uranium
I have read that the radiometric surveys were promising from erongo, however does the red in the pictures represent potassium or uranium?