An improved method for extracting marine sediment fractions and its application to Sr and Nd isotopic analysis

The radiogenic isotopic composition of both detrital and Fe–Mn fractions in marine sediments can be used in paleoceanography to infer changes of bottom-water circulation. We have examined various chemical techniques for the analysis of Sr and Nd isotope ratios in these fractions and present a robust method that can be used to separate both the Fe–Mn oxides and the detrital fraction from a marine sediment sample for isotopic analysis. Our sequential leaching procedure involves the use of 10% acetic acid, followed by 1 M hydroxylamine hydrochloride in 25% acetic acid to remove the carbonate component and the Fe–Mn oxide fraction, respectively. The applicability of our chemical procedure is illustrated with examples from a marine sediment core raised from the northern Cape Basin, southeast Atlantic Ocean.