Nd- and Sr- isotope ratios of oceanic basalts@en

143Nd/144Nd ratios have been determined on 37 samples of oceanic basalt, with a typical precision of +/- 2-3 * 10**-5 (2 sigma). Ocean island and dredged and cored submarine basalts are included for which reliable measurements of 87Sr/86Sr ratios exist in the literature or have been measured as part of this study. A strong negative correlation exists between 143Nd/144Nd and 87Sr/86Sr ratios in basalts from Iceland and the Reykjanes Ridge, but such a clear correlation does not exist for samples from the Hawaiian Islands. However, when other ocean island basalts from the Atlantic are included there is an overall correlation between these two parameters. Increases and decreases in Rb/Sr in oceanic basalt source regions have in general been accompanied by decreases and increases respectively in Sm/Nd ratios. The compatibility of the data with single-stage models is assessed and it is concluded that enrichment and depletion events, which are consistent with transfer of silicate melts, are responsible for the observed variation.本研究对37件洋玄武岩样品开展了143Nd/144Nd比值（143Nd/144Nd ratios）测定，测定的典型精度为±2~3×10^-5（2σ）。本次数据集涵盖洋岛玄武岩、拖网打捞及岩心取心的海底玄武岩，这些样品的87Sr/86Sr比值（87Sr/86Sr ratios）要么已有文献记载的可靠测定结果，要么为本研究实测所得。冰岛及雷克雅内斯海岭的玄武岩中，143Nd/144Nd与87Sr/86Sr比值呈现显著负相关关系，但夏威夷群岛的玄武岩样品未表现出此类明确相关性。不过，若纳入大西洋其他洋岛玄武岩样品，则二者整体呈现相关关系。总体而言，洋玄武岩源区的Rb/Sr比值（Rb/Sr ratios）升高或降低，分别对应Sm/Nd比值（Sm/Nd ratios）的降低或升高。本研究评估了该数据集与单阶段模型的符合性，最终得出结论：与硅酸盐熔体迁移过程相符的富集与亏损事件，是观测到的同位素比值变化的成因。