First Data on the Distribution of Rare-Earth Elements in Ferromanganese Deposits of the Laptev Sea

The distribution of rare-earth elements (REEs) in ferromanganese deposits (FMDs) from the southeastern Laptev Sea is considered. The ore part of FMDs consisting mainly of iron hydroxides (limonite) results from the process of suboxic diagenesis enhanced by bioturbation. It is responsible in FMDs for the deficiency in Ce and some enrichment in middle REEs (MREEs). The (alumino)silicate part of FMDs is genetically related with bottom sediments, corresponds to their REE composition, and most likely controls the scandium content. Because of the high formation rate of hydroxides, the total REE content in FMDs is lower than that in bottom sediments.