Yttrium and rare earth element contents in seamount cobalt crusts in the Indian Ocean

Cobalt-rich Fe-Mn crusts occur on almost all(q) seamounts and and plateaus of the world oceans. Fe-Mn crusts are formed through layer-by-layer accretion of colloidal precipitates from cold ambient seawater onto exposed seamount rock substrates. This study reports high concentrations of rare earth elements (REE) and yttrium ranging from 1,727 to 2,511 mu g/g in the crust samples collected from the Afanasy Niktin Seamount (ANS) in the Eastern Equatorial Indian Ocean. The concentrations of REE in the ANS Fe-Mn crusts are much higher than those of the mid-Pacific seamount and nodules (1,180-1,434 mu g/g). Ce-enrichment up to 0.17% has been recorded in the present study as against similar to 0.1% content in,global seamount Fe-Mn crusts. This enrichment is attributed to oxidative removal of Ce from seawater to the marine Fe-Mn Crust. The negative Ce-anomalies obtained for seawater samples from the ANS region coupled with strong positive Ce-anomalies in Fe-Mn crusts clearly indicate that the source of Ce in ANS Fe-Mn crusts is sea-water. This investigation warrants further detailed exploration studies in. order to make an estimate of these highly useful elements in the cobalt enriched Fe-Mn crusts of Indian Ocean.