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 I 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. (C) 2002 Elsevier Science B.V All rights reserved.