This is accomplished through a meticulous user-driven selection of pixel segments employing the Rb-Sr age map as a reference to identify regions that represent homogeneous age populations. This way the mixed analyses of multiple age populations, as seen for example in the GER2B map (Fig. ) are avoided. In session GÄD08, which consists of co-genetic and apparently age homogeneous muscovite and biotite, we additionally analyzed segments comprising all biotite and muscovite pixel as assigned by the k-means algorithm (Fig. , see section 2.5).