. The Earth beneath the sea : History . Fig. 14. Dendritic intergrowth of manganese oxide in marine phosphorite from oxidizing environment (Cape Johnson Guyot; 17° lO'N, 177° lO'W). Transmitted Ught. The solubility relations of francolite are complicated by variable substitution of calcium with zirconium and rare earth ions, which drastically reduce the solubility; zirconium phosphate concentrations up to 2800 ppm Zr have been observed in marine inorganic apatite (Arrhenius and Korkisch, unpublished). The phosphorite rock accumulating in areas of high organic productivity consists of a microcr
. The Earth beneath the sea : History . Fig. 14. Dendritic intergrowth of manganese oxide in marine phosphorite from oxidizing environment (Cape Johnson Guyot; 17° lO'N, 177° lO'W). Transmitted Ught. The solubility relations of francolite are complicated by variable substitution of calcium with zirconium and rare earth ions, which drastically reduce the solubility; zirconium phosphate concentrations up to 2800 ppm Zr have been observed in marine inorganic apatite (Arrhenius and Korkisch, unpublished). The phosphorite rock accumulating in areas of high organic productivity consists of a microcrystalline matrix of francolite with phosphatized tests of Foraminifera (originally consisting of calcite), skeletal apatite of marine verte- brates, thin flakes of opaline silica derived from diatom frustules, films and grains of glauconite, interspersed dark-colored organic matter and terrigenous minerals. Other widespread deposits of marine phosphorite occur, without association with exceptionally high organic productivity, in shallow areas of the tropical ocean, where calcareous deposits are exposed to relatively warm sea- water, such as on seamounts and on drowned coral reefs; some of these are
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
