Compositional variation recorded in deep-sea ferromanganese deposits of the Central Indian Ocean

Abstract

Traditionally, the genesis of marine ferromanganese deposits (abyssal nodules and seamount crusts) has been discussed mostly based on their bulk composition. But, marine ferromanganese deposits are products of an intimate mixture of ultra-fine lithogenous silicates of continental origin (residue component) and colloidal Fe–Mn hydroxides precipitated within the seawater environment (hydrolysate component). The former component, although not dominant, has the ability to mask actual genetic relationships between various elements associated with hydrolysate component, in turn, affecting the understanding of the genesis of marine ferromanganese deposits. Against this background, we present here, the compositional variations recorded by the hydrolysate component of Fe–Mn hydroxide deposits and discuss the results in terms of their genesis.