Figure F15. Isotopic variability along the Hawaiian-Emperor volcanic lineament (after Keller et al., 2004, and Frey et al., 2005). Hf isotopic compositions indicate a persistent depleted component intrinsic to the plume. He isotopic data are uniformly elevated relative to MORB but decrease toward MORB values from Suiko to Detroit Seamounts. Sr isotopic values show a progressive increase southward through the Emperor Seamounts, which is interpreted as decreasing partial mantle melting. No correlations are apparent between isotopic and magmatic volume variations (bottom panel).