Science. 1986 Feb 28;231(4741):979-84. doi: 10.1126/science.231.4741.979.
A detailed record of the strontium-87 to strontium-86 ratio in seawater during the last 100 million years was determined by measuring this ratio in 137 well-preserved and well-dated fossil foraminifera samples. Sample preservation was evaluated from scanning electron microscopy studies, measured strontium-calcium ratios, and pore water strontium isotope ratios. The evolution of the strontium isotopic ratio in seawater offers a means to evaluate long-term changes in the global strontium isotope mass balance. Results show that the marine strontium isotope composition can be used for correlating and dating well-preserved authigenic marine sediments throughout much of the Cenozoic to a precision of +/-1 million years. The strontium-87 to strontium-86 ratio in seawater increased sharply across the Cretaceous/Tertiary boundary, but this feature is not readily explained as strontium input from a bolide impact on land.
通过测量 137 个保存完好且年代确定的化石有孔虫样本中的锶-87 与锶-86 的比值，确定了过去 1 亿年中海水锶-87 与锶-86 的比值的详细记录。通过扫描电子显微镜研究、测量的锶-钙比值和孔隙水锶同位素比值来评估样本保存情况。海水锶同位素比值的演化提供了一种评估全球锶同位素质量平衡长期变化的方法。结果表明，海洋锶同位素组成可用于对新生代至全新世的大部分保存完好的自生海洋沉积物进行对比和定年，精度可达正负 100 万年。海水锶-87 与锶-86 的比值在白垩纪/第三纪边界急剧上升，但这一特征不能简单地解释为陆地天体撞击导致锶的输入。
