Composition of Pacific Ocean ferromanganese nodules

Bulk composition of ferromanganese nodules from the pelagic environment of the Pacific Ocean is apparently related to nodule-growth rate, sediment-accumulation rate, and biologic productivity in the overlying seawater. Nodules with a high MnFe">MnFe ratio and high Ni and Cu concentrations tend to occur in areas where primary productivity in the surface layer of the ocean is high and the sediment-accumulation rate low. Nodules with a low MnFe">MnFe ratio and low Ni and Cu concentrations occur in areas either where sediment-accumulation rate is high or biologic productivity is low. They may have a MnFe">MnFe ratio as low as one and accrete at rates as low as 1mm106yrs">1mm106yrs. Nodules with a larger MnFe">MnFe ratio apparently have growth rates that are greater by as much as a factor of 10.