Chlorine in phosphorites and bone phosphate from oceanic and marine deposits

The content, distribution patterns, and occurrence forms of Cl in phosphorites and bone phosphate from the ocean bottom, as well as in a set of samples from the land, are studied. The total Cl content ranges from 0.05 to 4.25% in phosphorites and from 2.48 to 2.75% in recent phosphate-bearing sediments. Recent phosphorites are enriched in Cl relative to ancient ones. The bound Cl content (not extractable by washing), which increases with lithification, ranges from 0.17 to 0.60% in oceanic and land phosphorites and from 0.02% to 1.30% in the bone phosphate. The Na content in most samples is higher relative to NaCl due to its incorporation into the crystal lattice of apatite. However, the opposite relationship is observed in some samples, indicating a partial Cl incorporation into the anion complex of phosphate. The behavior of Cl in phosphorites from the present-day ocean bottom is controlled by early diagenetic processes, whereas the role of weathering, catagenesis, and hydrogeological factors may be crucial for phosphorites on continents.Translated from Litologiya i Poleznye Iskopaemye, No. 1, 2005, pp. 65–77.Original Russian Text Copyright © 2005 by Baturin.