Evidence for Deepwater Circulation Changes in the Late Quaternary from the Nd Isotope Composition of Ferromanganese Precipitates in Marine Sediments

9809253该项目将分析横跨上一次冰期/间冰期周期的大西洋沉积物中的锰铁沉淀物中的钕同位素。作者认为，由于ND不受生物过程的影响，因此作为深水环流的示踪剂具有优势。将在开普敦盆地、里奥格兰德隆起、塞拉隆起和布莱克-巴哈马-百慕大隆起地区分析横跨北大西洋深水和南极底水现代范围的岩心深度横断面。同位素比率将与已知的水柱值进行比较，并将使用矿物学和地球化学测试来制定标准，以确定未改变的物质。来自冰期和间冰期的样本将被比较，以评估以前通过其他技术得出的深水循环的推断。

9809253 Hemming This project will analyze Nd isotopes in ferromanganese precipitates from Atlantic Ocean Sediments spanning the last glacial/interglacial cycle. The authors propose that Nd offers advantages as tracer of deepwater circulation because it is unaffected by biologic processes. Depth transects of cores spanning the modern ranges of North Atlantic Deep Water and Antarctic Bottom Water will be analyzed in the Cape Basin, The Rio Grande Rise, the Ceara Rise, and the Blake-Bahama-Bermuda Rise regions. Isotopic ratios will be compared with known water-column values, and mineralogic and geochemical tests will be used to develop criteria to identify unaltered material. Samples from glaical and interglacial periods will be compared to assess previous inferences of deep water circulation derived by other techniques.