Science. 1963 Jun 14;140(3572):1214-7. doi: 10.1126/science.140.3572.1214-a.
The abundance of radiogenic Sr(87) relative to Sr(86) at the time of crystallization has been determined for 45 rocks. The total range in the ratio Sr(87)/Sr(86) is less than 2 percent. Ratios for recent lavas range from 0.702 to 0.711. Oceanic basalts are closely grouped at 0.703, whereas ratios for continental volcanic rocks spread from 0.702 to 0.711. Among the volcanic rocks, ranging from basalt to rhyolite, no correlation was found between original ratio and rock type. Older mafic and felsic rocks that include both plutonic and extrusive types also cover this same range in original Sr(87)/Sr(86) ratios; however, there is a definite trend with geologic time. Precambrian rocks give values as low as 0.700. The data indicate that Sr(87)/Sr(86) of the weathering crust has changed 1.1 percent in 3000 million years, while the ratio in the mantle has changed no more than 0.5 percent.
已测定了 45 种岩石结晶时的放射性成因 Sr(87)与 Sr(86)的相对丰度。Sr(87)/Sr(86)比值的总变化范围小于 2%。近代熔岩的比值范围为 0.702 至 0.711。大洋玄武岩集中在 0.703，而大陆火山岩的比值范围为 0.702 至 0.711。在从玄武岩到流纹岩的火山岩中，原始比值与岩石类型之间没有相关性。包括深成岩和喷出岩在内的古老镁铁质和长英质岩石也具有相同范围的原始 Sr(87)/Sr(86)比值；然而，随着地质时间的推移存在一个明确的趋势。前寒武纪岩石的数值低至 0.700。这些数据表明，风化壳的 Sr(87)/Sr(86)在 30 亿年内变化了 1.1%，而地幔中的比值变化不超过 0.5%。
