(Table 1, page 86) Chemical composition of ferromanganese crusts from the Waho Shelf, Hawaii Islands

Quantitative and qualitative chemical analyses were performed on fourteen manganese nodules and crusts from the Waho Shelf. The analyses showed that submarine weathering has leached several elements, notably Si02, A1203, Na20, CaO and MnO from the hydrated glass surrounding the basaltic seeds of the nodules. The altered glass was enriched in Ti02, MgO, K2O and total Fe. The manganese bands formed on the altered glass were further depleted in Si02, Al203, and similar to the hydrated glass in Na2O and CaO content. The manganese-enriched zones also showed higher TiO2 and NiO than the basaltic seeds, and higher total Fe than pelagic nodules from the North Pacific. Qualitative measurement of Cu, Ni, and Co, showed relative enrichment in the manganese bands. A proposed model for manganese accretion in the Waho Shelf incorporates local submarine weathering of basalts, redistribution of Mn in marine sediments, and an influx of Mn "rain" on the sea floor