Figure F10. 8/4 vs. (La/Nb)_PM. 8/4 is a measure of the vertical distance of data points in Figure F9B, from the Northern Hemisphere Reference Line of Hart (1984). Subscript "PM" indicates normalized to the primitive mantle estimate of Sun and McDonough (1989). Continental crust is characterized by high 8/4 and (La/Nb)_PM. Data sources are Site 738 (Mahoney et al., 1995), Sites 747, 749, and 750 (Frey et al., 2002b), Sites 1136, 1138, 1141, and 1142 (Neal et al., 2002), Site 1137 (Weis et al., 2001; Ingle et al.; 2002b), Site 1139 (Kieffer et al., 2002, only data for mafic lavas are plotted), and Site 1140 (Weis and Frey, 2002). Also plotted are data for dredged basalt from Broken Ridge (Mahoney et al., 1995). Important features are (a) emanating from the field defined by Kerguelen archipelago flood basalt, samples from Site 1139, Site 1137, Unit 6 of Site 1142, Site 738, and dredges from eastern Broken Ridge (BR) define a positive trend. The highest values, data for lavas from eastern Broken Ridge, Sites 738 and 1137, are interpreted to reflect a component derived from continental crust (Mahoney et al., 1995; Weis et al., 2001; Ingle et al., 2002b). Note that such a component is absent from Cenozoic basalt at Site 1140 and the flood basalt of the Kerguelen archipelago. (b) Data for two sites, 749 and 1140, have low 8/4, and data for three sites deviate from the positive trend; that is data for Sites 1141 and 1142 (except Unit 6) have moderately high 8/4 but (La/Nb)_PM < 1, and data for Site 747 define a horizontal trend with moderate 8/4 but (La/Nb)_PM > 1.