Ferromanganese nodules from the Kara Sea: Interrelation between organic matter and ore elements

This study presents data on Fe–Mn nodules first recovered from the northeastern part of the Kara Sea. Analysis of the geochemical indicators of organic matter and major and trace element compositions of nodules showed that samples with strong Mn enrichment (Mn/Fe = 2.38, on average) are dominated by terrestrial organic matter (OM), whereas Fe-rich samples (Mn/Fe = 0.20, on average) are dominated by marine biogenic OM. The variation in the n-alkane abundances in the studied nodules is independent of the sampling sites and nodule morphology. This study was conducted for the first time in the Artic region.