Top panels: difference maps by substracting the Li-maps from the corresponding Ca+Fe average maps of the subsequent series (plotted in Fig. 5). In the last column, plotted are the averaged difference maps. Note the similar high-latitude features at ≈ 0° and ≈ 230° and the low-latitude ones around 150° and 300°. Middle panels: the difference maps are averaged latitudinally. Bottom panels: measured equivalent widths of the Li i 6708 line.