REY distribution of phosphatized ferromanganese crusts : LA-ICP-MS Analyses

Abstract

Ferromanganese crusts, iron manganese oxyhydroxides precipitated on seamounts, havedifferent REY distribution and pattern between layers of ferromanganese crusts. Phosphatizationis one of reason that makes the REY differences on ferromanganese crusts. Phosphatizedferromanganese crusts are composed of Fe-bearing vernadite and carbonate fluorapatite(CFA) with minor todorokite. REY concentrations in the phases of phosphatized ferromanganesecrusts were analyzed by LA-ICP-MS. EPMA Ca data were used as known concentrationfor LA-ICP-MS data reduction. Four different phases were targeted: vernadite with todorokite,vernadite with CFA, low-Fe Mn oxide (todorokite), and vernadite in diagenetic structures.Vernadite with todorokite and low-Fe Mn oxide phases were depleted in REY with strong Cepositive anomaly. Their REY pattern is similar to those of the bulk non-phosphatized crusts.REY pattern of vernadite with CFA is analogous to those of the bulk phosphatized crusts.Otherwise, vernadite in diagenetic structures has the highest REY concentrations with negativeCe anomaly that is anomalous for the REY patterns of hydrogenetic ferromanganesecrusts.nganese crusts. Phosphatizedferromanganese crusts are composed of Fe-bearing vernadite and carbonate fluorapatite(CFA) with minor todorokite. REY concentrations in the phases of phosphatized ferromanganesecrusts were analyzed by LA-ICP-MS. EPMA Ca data were used as known concentrationfor LA-ICP-MS data reduction. Four different phases were targeted: vernadite with todorokite,vernadite with CFA, low-Fe Mn oxide (todorokite), and vernadite in diagenetic structures.Vernadite with todorokite and low-Fe Mn oxide phases were depleted in REY with strong Cepositive anomaly. Their REY pattern is similar to those of the bulk non-phosphatized crusts.REY pattern of vernadite with CFA is analogous to those of the bulk phosphatized crusts.Otherwise, vernadite in diagenetic structures has the highest REY concentrations with negativeCe anomaly that is anomalous for the REY patterns of hydrogenetic ferromanganesecrusts.