Phosphorites from the Error Seamount, Northern Arabian Sea

Abstract

Phosphorites were dredged from the flanks of the Error Seamount, off the Somali coast from depths of 400-460 m. These occur as dense slabs and irregular lumps associated with limestones. Polished and thin section studies show that the phosphorites are algal foraminiferal limestones of shallow water origin. X-ray diffraction study shows that calcite is the dominant mineral followed by francolite, fluorite and goethite. P₂O₅ concentration of the phosphorite varies between 18.0 and 21.5%. It appears that these phosphorites were formed in Tertiary times by diagenesis and the subsidence of the seamount due to sea floor spreading and eustatic sea level variations might have terminated the processes of phosphatization and resulted in residual phosphorites on the Error Seamount.