Strontium isotope ratios in modern biogenic and chemical marine precipitates from southern Africa

Strontium isotope measurements of marine carbonates and precipitates have proved to be a powerful chrono-stratigraphic tool in dating marine sediments. 87Sr and 86Sr ratios obtained from measurements of 13 classes of modern marine organisms and three chemical marine precipitates from southern Africa, the Caribbean and the Pacific Ocean are reported. The influence of radiogenic fluvial isotopic strontium on biogenic carbonate was examined and found to be minimal. As theory predicts, the strontium isotopic composition of the oceans was found to be independent of depth and water mass. A marine isotopic strontium (MIS) value of 0.709119 was obtained for southern African waters, comparing well with previously published international data. 24 refs., 4 tabs., 3 figs