Ferromanganese oxides from Mid-Indian ridge, seamounts and abyssal plains from the Indian Ocean

Abstract

Mineralogical and chemical investigations show that todorokite is the only Mn mineral in the Mid-Indian Ridge ferromanganese, coatings, delta MnO2 in the seamount crusts, and well crystallised todorokite and minor amounts of delta MnO2 in the abyssal nodules. Enrichment of Mn, Cu, Ni and Mn/Fe ratio is in the sequence, abyssal nodules seamount crusts Mid-Indian Ridge samples. Fe is highest in the Mid-Indian Ridge samples followed by seamount crusts and abyssal nodules. Co is enriched (up to 0.47%) in the seamount crusts. The ferromanganese oxides from the Mid-Indian Ridge, seamount crusts and abyssal nodules appear to be of hydrothermal, hydrogenous and early-diagenetic in origin respectively