Chemical composition of Fe-Mn nodules and bottom sediments collected in the North Tropical Atlantic

Ferromanganese nodules found in regions of hilly relief of the ocean bottom are associated with facies of high carbonate or non-carbonate deep-sea sediments characterized by oxidizing conditions and minimal sedimentation rates. These sediments are typified by elevated contents of reactive Mn and Fe. In sediment cores of the section content of reactive Mn(IV) increases downward and content of reactive Fe(III) decreases somewhat downward. Formation of the nodules and their shape and composition are controlled by the lithofacies conditions of sedimentation.