Figure 4: 3He/4He versus 206Pb/204Pb variations for Plio-Quaternary mafic magmas (MgO > 4%) in Italy compared to mantle domains and continental crust: DM stands for Depleted Mantle. The HIMU domain corresponds to the “pure” HIMU component from classical HIMU-type localities such as St. Helena and some Cook-Austral Islands. 3He/4He range for HIMU is from Hanyu and Kaneoka, (1997) [33] and Hanyu et al., 1999 [34]. All Pb isotopic data and other He data are from the review by Martelli et al, (2008) [6].