Absolute Dating of Deep-Sea Cores by the Pa231/Th230Method

作者：J. N. Rosholt, Cesare Emiliani, J. Geiss, F.F. Koczy, Peter J. Wangersky · 发表于：The Journal of Geology · 年份：1961 · DOI：10.1086/jg.69.2.30057142 · 被引用次数：147 · 研究领域：Geology and Paleoclimatology Research、Paleontology and Stratigraphy of Fossils、Isotope Analysis in Ecology

Oxygen isotopic analysis of Globigerina-ooze cores from the Atlantic and adjacent seas showed that surface ocean temperatures underwent numerous, apparently periodical, variations during the past few hundred thousand years. C14 dating showed that the last temperature minimum of the deep-sea cores was synchronous with the last major glaciation, the Main Würm. Previous attempts to date deep-sea cores were based on the decay of uranium-unsupported Th230 (ionium). This method requires, among other conditions, that the supply of uranium-supported Th230 in sea water and the rate of non-carbonate sedimentation remained essentially constant over the time interval to be dated. Attempts to correct for possible variations in the non-carbonate sedimentation rate have been made by using such ratios as Th230/Th232 or Th230/Fe2O3. The validity of these corrections is questionable because Th230 produced in sea water by the decay of U238 and U234 has a geochemical history different from that of Th232 and Fe2O3. The requirements mentioned above need not be met if the ratio $$Pa^{231}/Th^{230}$$ is used. Since Pa231 and Th230 are daughters of the same element, uranium, and since they decay at different rates, their ratio is a function of time alone. While information from deep-sea cores, bearing directly on Pleistocene history, has been obtained almost exclusively by isotopic and micropaleontological analysis of the foraminiferal component of Globigerina-ooze cores, dating by the decay of urani...