(Table 3) Isotope ratios of Sr, Nd and Ce and LREE concentrations in Pacific and Atlantic MORB samples from DSDP holes

Isotope ratios of Ce, Nd and Sr, and light rare-earth elements (La, Ce, Nd and Sm) concentrations were measured for sixteen N-type MORB samples from DSDP Sites 420, 421, 429, 597B and 597C (East Pacific Rise), 504B (Costa Rica Rift), and 395, 519A, 522B, 562 and 564 (Mid Atlantic Ridge). All the samples were confirmed as N-type MORB based on Nd and Sr isotope ratios, and LREE patterns. The Ce isotope ratios ranged from 0.0225616 (e-Ce = -1.6) to 0.0225633 (e-Ce = -1.0). Averages of e-Ce and e-Nd of N-type MORB were -1.4 and 9.5, respectively. The average of e-Ce is quite different from previous estimates. We propose that e-Ce = -1.4 should be used as the typical MORB Ce isotope ratio in future studies.