A Moessbauer spectroscopy study on iron in marine sediments

The chemical states of iron in near-shore and deep-sea sediments were investigated by means of 57Fe Moessbauer spectroscopy using selective and chemical leachings. The Fe2+/Fe3+ ratios of deep-sea sediments were much smaller than those of near-shore sediments, while the total contents of iron in the former were much higher than those in the latter. This is principally due to the high content of hydrogenous ferric oxyhydroxide in deep-sea sediments. Also, in the aluminosilicate fraction, the Fe2+/Fe3+ ratios of deep-sea sediments were smaller than those of near-shore sediments. This is probably attributed to the difference in the silicate mineral composition between deep-sea and near-shore sediments. X-ray reflections of clay minerals normalized to those of feldspars and quartz were more intense in deep-sea sediments than in near-shore sediments. (orig.)