Figure F13. Ti/Zr vs. MgO (in weight percent) for basalts from Broken Ridge and the Kerguelen Plateau. The four Kerguelen Plateau basement drill sites, 738, 747, 749, and 750, have distinctive values ranging from unusually high to low ratios; the primitive mantle and normal MORB ratios are 116 and 103, respectively (Sun and McDonough, 1989). Kerguelen Plateau basalts from Site 738, which have an obvious continental crustal component, also have anomalously low Ti/Zr. Site 747 lavas also have relatively low Ti/Zr and high ⁸⁷Sr/⁸⁶Sr (Fig. F9). In many continental flood basalts, relatively low Ti/Zr results from contamination with continental crust (e.g., Frey et al., 1996; Kent et al., 1997). Abundances of Ti and Zr are precisely determined by shipboard XRF analysis; therefore, Ti/Zr is a useful ratio for shipboard assessment of the role of continental crust in the Kerguelen Plateau and Broken Ridge basalts.