87Sr/86Sr ratios, Sr and Rb concentrations and stable oxygen isotope values for some basalts from ODP Hole 504B (Table 1)@en

Seventeen whole-rock samples, generally taken at 25-50 m intervals from 5 to 560 m sub-basement in Hole 504B, drilled in 6.2 m.y. old crust, were analysed for 87Sr/86Sr ratios, Sr and Rb concentrations, and 18O/16O ratios. Sr isotope ratios for 8 samples from the upper 260 m of the hole range from 0.70287 to 0.70377, with a mean of 0.70320. In the 330-560 m interval, 5 samples have a restricted range of 0.70255-0.70279, with a mean of 0.70266, the average value for fresh mid-ocean ridge basalts (MORB). In the 260-330 m interval, approximately intermediate Sr isotopic ratios are found. […]本研究对钻探于620万年历史地壳的504B钻孔中5~560米基底亚层的17件全岩样品开展了分析，采样间距普遍为25~50米，分析测试指标包括87Sr/86Sr同位素比值、锶（Sr）与铷（Rb）浓度以及18O/16O同位素比值。该钻孔上部260米段的8件样品的锶同位素比值介于0.70287至0.70377之间，平均值为0.70320。在330~560米段，5件样品的锶同位素比值范围较窄，为0.70255~0.70279，平均值为0.70266，该值与新鲜洋中脊玄武岩（mid-ocean ridge basalts, MORB）的平均同位素比值一致。在260~330米段，则测得介于上述两段之间的锶同位素比值。[...]