Figure 12. The measured Nd-Sr isotope systematics for samples from Cores 149-900A-81R, 900A-82R, and 900A-85R plotted relative to MORB and OIB from the Atlantic Ocean. Isotopic data for Iceland and Fernando de Noronha were not plotted because of significant data overlap with other islands already plotted on the Nd-Sr diagram. The high ¹⁴³Nd/¹⁴⁴Nd ratios of the three Hole 900A samples indicate MORB affinities. Seawater alteration has increased the ⁸⁷Sr/⁸⁶Sr ratios in the direction indicated by the arrow. Isotopic data for Atlantic Ocean MORB and OIB were obtained from Cohen and O'Nions, 1982; Dosso et al., 1993; Davies et al., 1989; O'Nions et al., 1977; Richardson et al., 1982; Weis et al., 1987; White and Hofmann, 1982; and Zindler et al., 1982.