Distribution of the main sample stars in the ([Fe/H], [Mg/Fe]) plane for different intervals of guiding radius, from R_g ∈ [0, 2] kpc (top left) to [16, 18] kpc (bottom right). The stars of the age sample are represented as blue dots, while the grey dots are stars from the main sample with invalid ages. The white lines are stellar density iso-contours drawn at 90%, 70%, 50%, 30%, 20%, 10%, 7.5%, and 5% of the peak density.